Primates

Rhinal sulcus position

A fold in all mammals. Can tell you how much of the brain is new development and how much is ancient. In tree shrews and insectivores, the rhinal sulcus is pretty high up, large paleocortex, not much in way of new brain structure. In primates, the old part of the brain is pretty small, low rhinal sulcus.

ear ossicles

3 - incus, malleus, and stapes. Define origin of mammals and allows us to ID mammals in the fossil record verses reptiles, which only have the stirrup/stapes and jaw bones. Formed from now redundant jaw bones.

Chimpanzees dental formula

3 molars, no bilophodonty. Instead have oblique crest. 4 cusps and crest in the upper, 5 cusps in lower. In Y5 molar pattern (in hominids) , early relatives of hominoids and in early humans. Now has been reduced to 4 in humans.

Mammal snout

3 turbinal bones, transverse lamina, and cribiform plate separates nasal and oral cavities.

Placental mammal ancestral dental formula

3-1-4-3. Generally reduced by evolution, dolphins went back to having more.

Microchoerus brain

45 million years ago Eocene tarsiiformes. Has a sylvian sulcus, ancient part is pretty small, pushed downwards by expansion of the brain.

Primate molars

5 upper cusps and 4 lower cusps, not a triangle.

Tree Shrew tooth comb

6-too incisors comb, but no canines.

Goeldi's Monkey

Abberrant marmoset/tamarin. Intermediate form, weighs 500 g. Typically has one infant and has more maternal care. Small but day active. Has claws but only 1 infant, intermediate between the two types of new world monkeys.

Small intestine vs body size

Absorbs digestive waste, scaled to energy need. The more energy needed, the longer the small intestine will be. Slope of the curve is 0.75, same slope as for basal metabolic rate vs body size graph.

Colugos

Actual sister group to primates. Flying lemurs, actually glide through the air. Also occur in southeast Asia.

Ekgmowechashala

Adapiform fossil originally thought to be part of omomyidae.

Europolemur klatti

Adapiform hindlimb skeleton found in Messel site Germany. From the Eocene, part of a group of long-digited fossils, most likely approximates early euprimate hand proportions. Has a grasping hallux and there's evidence that it had nails instead of claws.

Pronycticebus gaudryi

Adapiform, has bony bar behind the eye.

Notharctus

Adapiform. 55 mya. Resembles modern true lemur very closely, although the brain size is significantly smaller. Hindlimb domination and free ectotympanic annulus within the auditory bulla, like in modern lemursLarge eye suckets as well. Grasping feet and hands, and long limbs.

Pronyctice neglectus

Adapiform. Has what looks to be a grooming claw on the second digit of each foot, like modern strepsirhines, has dental formula 2:1;4:3. Has a petrosal bulla and a postorbital bar. May have been nocturnal or crepuscular, based on a relatively large orbital size.

Smilodectes

Adapiform. Lived in North America during the middle Eocene. Possesses a postorbital bar and grasping thumbs and toes. Superficially very similar to Notharctus but skull resembles sifaka rather than lemurs. Also has hindlimb domination.

Primate fossil geographical distribution

Adapiforms and omomyiformes have a northern continental distribution (Asia, Europe, and North America), while unquestioned strepsirrhines and haplorhines have a distribution predominantly confined to southern landmasses. Northern outliers, south may not have had a good fossil record.

Obstetric Dilemma

Adaptation to bipedalism decreased size of bony birth canal but exigencies of tool use selected for larger brain. Sacrum, at base of vertebrae strengthens pelvis, broad compared to great ape. Head backwards through 2 90 degree rotations may well have made assistance at birth necessary. Fetus also delivered at a much earlier stage of development.

Oligocene Fayum Simians

Aegyptopithecus and Apidium are known from substantial fossil evidence. All fayum primates have many similarities to new world monkeys. Deep lower jaws, fused jaw in front, complete eye socket, eyes directly forward, cutting teeth, and a smaller brain than moden primates but biffer than other species at the same time period.

Old World Monkey and Apes location

Africa, South Asia, and South East Asia

Loris Location

Africa, South Asia, and South-East Asia

A. africanus dentition

After A. afarensis. Shows another increase in postcanine tooth size, which would suggest an increase in the sizes and abrasiveness of foods. However, molar microwear doesn't show degree of pitting one would expect from classic hard-object feeder. Hadn't specialized in hard objects, emphasized dietary bredth. Subsequent robust australopithecines show hard-object microwear and craniodental specializations, suggesting a substantial departure in feeding adaptive strategies early in the Pleistocene.

Types of Indri subgroup primates

Ahavi: Nocturnal, weigh 1 kg. Sifaka - diurnal, weigh 3.4 kg, have a varied social organization. Indri - diurnal, weigh 6.3 kg, monogamous family groups.

New World Monkeys

All diurnal except owl monkey. Also known as platyrrhines due to their flat noses and well separated nostrils. Most species are primarily frugivorous, with the exception of howler and woolly spider monkeys, where the proportion of leaves in the diet matches that of fruit.

Maternal Energy hypothesis

All mammals have the largest brains that are compatible with the metabolic resources available to thei mothers during gestation and lactation. Therefore, should not be expected that relative brain size will be specifically linked to a given behavioral function.Neonate brain mass of primates lie above other mammals, different life history.

Neandrathal differences

Arched brow ridges, larger openings and heads, short legs relative to arms, big chests, large olfactory region that supports neck. Bigger endocranial volume, may be due to larger eyes and visual cortices. If that's adjusted for, brain sizes about the same as Homo sapiens. May be due to cold stress.

Basic mammalian limb structure

Arm: humerus -> radius/ulna -> carpals ->metacarpals -> 3 phalanges. Leg: femur -> tibia/fibula -> tarsals -> metatarsals -> 3 phalanges

Bulla types

As hearing develops, eardrum becomes more versatile and develops different solutions to protecting and exposing ossicles. 6 types.

Hypothesis of snout reduction effect

As snout decreases, olfaction decreases and vision increases. Snout is actually still pretty long and has upper teeth attached, snout is reduced due to reduction of anterior teeth, which doesn't imply decreased olfaction.

Cooked Starch's Importance to Reproduction Success

Can affect menstruation cycle. In womb, fetal growth is directly correlated with maternal glucose concentration, and during lactation, an additional 70g of glucose is needed per day, and when weaned, young can digest cooked starch easier.

Activity patterns in primates

Can either be nocturnal or diurnal. Day-active primates tend to be larger than nocturnal ones. Also true for mammals in general.

Reductions in digestive tract summary

Can either have a large stomach with bacteria or a large caecum with bacteria, not both. All reduced are humans and mammalian carnivores, large stomach is insectivores, large caecum is folivores.

Mamallian skeleton change possibilities

Can lose elements or fuse them together, but don't gain new ones. Variation on a general ground plan.

Howler Monkey vs Spider Monkey brain

Howler monkey has a smaller brain and body size and eats primarily leaves, and the spider monkey is a fruiteater. Spider monkey cortex has many more fissures than howler monkey cortex.

Types of New World Monkeys

Marmosets and tamarins - small clawed forms True New World Monkeys: Owl Monkey Titi Squirrel Monkeys Capuchin Howler Monkeys Woolly monkeys and woolly spider monkeys

Carnivore snout

Maxilloturbinal for moistening air, ethmoturbinal and nasoturbinal for smell. Cribiform plate allows nerves to go from olfactory bulb to olfactory cavity. Ethmoturbinal is new, so we know smell is important for mammals.

Homunculus

New world monkey fossil. Known from two incomplete lower jaws, cheek teeth, femur, and radius. Has cutting incisors, raised jaw hinge, real eye socket, 3 premolars and molars.

Tremacebus

New world monkey fossil. Might have been nocturnal and have large eyes like the owl monkey.

Howler Monkeys

New world monkey. Considerably heavier than the others. Strong sexual dimorphism, which is unusual in new world monkeys. Eats equal amounts of leaves and fruit. Live in medium sized multi male troops containing between 10-20 individuals. Females carry single infants from birth onwards without any cooperation from males. Quadrupedal and hanging motions. Have loud vocalizations.

Squirrel Monkeys

New world monkey. Eat plants and animals, but are more arthropod focused. Smallest new world monkey, mainly quadrupedal. Unusual in that they have strict mating seasons.

Capuchin

New world monkey. Medium sized and has a well developed prehensile tail. Very large brain to body ratio.

Titi

New world monkey. Thought to be very closely related to the owl monkey, and has a similar diet but is smaller and more active. Uses quadrupedal running and agile leaping.

Prosimian Fossils brain size

Pleasiadapiforms really small, Eocene and miocene almost all below average. Compared to today relatively small. Tarsiers reached levels similar to today. Below EQ = 0, and below line.

Plesiadapis tricuspidens skeleton

Plesiadaptiform fossil. Has almost a complete skeleton. Has a bony sac around eye. Claws and no grasping hands or feet.

Purgatorius

Plesiadaptiform fossil. Only evidence of connection to primates is based on teeth, but much more is required to generate a more convincing case to include them as ancestors of primates. All we have is teeth and ankle bones. 65 mya in North America, so people thought that was the origin but it isn't.

Plesiadapis tricuspidens skulls

Plesiadaptiform fossil. Skulls from France and US are very similar. Encephalization is about a quarter less that expected for a living mammal of it's size, and half or less than that of any known primate or colugo. Primate like teeth and ears. Small lateral eyes.

Starch

Polysaccharide that can be broken down into glucose. Found in foods like wheat, oats, barley, plantains, potatoes, and peas.

Allman-Pettigrew Model

Posits that orbital convergence improves image quality by converging the optic axis.

Plesiadapiforms

Predominant in the Paleocene epoch before the Eocene, 55-65 mya, and were traditionally allocated to the order Primates. However, the phylogenetic link is questionable between them and primates, and could alternatively be related to colugos (arboreal gliding mammals) instead.

Primate diets

Primate diets consist of either insects, fruit or leaves, or fruit, and sometimes mixes. Mainly frugivores, smaller bodied primates eat smaller fruits. Small primates get protein from arthropods, large primates get protein from leaves. 20% of primates eat at least some gum.

Marsupial locomotion morphology

Primate like foot, has a divergent toe with a flat nail. Marsupials evolved from tree-living common ancestor, so terrestrial marsupials are specialized. Similar trend in placental mammals.

Visual predation hypothesis

Primate-specific adaptations arose to effectively hunt insects in small terminal branches of trees. Hands specialized with grabbing insects and claws interfered with gripping small prey, and padded grip facilitates stealthy approach, but tamarins have claws and can catch insects. Forward facing eyes provide accurate info on location of small insects, forwards-facing eyes occur in many predators, not clear if vision is main sense for detecting insects.

Angiosperm Radiation hypothesis

Primate-specific adaptations arose to effictively access fruit in small terminal branches of trees, concurrent with diversification of angiosperms in Paleocene and Eocene. Grasping with hands instead of claws is more effective, no real evidence explaining hand adaptation. Forward facing vision to see through leaves better and be frugivores.

Fine Branch Theory

Primates exploited niche of narrow branches when became arboreal. Led to different gait in primates, to keep weight on hind limbs, have cross gait, not parallel. Seen in other arboreal species that go on narrow branches too.

Ways to have neonates with larger brains at birth

Primates have. Can either have larger neonates or smaller neonates with larger brains. Second is what occurs.

Active brain growth

Selection on specific parts of the brain, major rearrangements. Restricted to later growth. Interesting studies look at specific regions of the brain and how they've been increasing. Only brain grows.

Hypotheses on Obstetrical dilemma

Thermoregulation: constraint on body width and heat production Extrauterine spring: extrenal stimulus is needed for brain development. High-energy/low nutrient: increased fetal mass or stunted pelvic development.

Brain folds

Thought originally to show intelligence and complexity, actually a reflection of bigger brains. Tarsier brain has hardly any folds, gorillas is highly folded. Found it just means bigger in the cat family, where brains remain the same in organization, but the bigger the brain, the more folded the surface becomes.

Smith Arboreal Theory

Thought that primate ancestor is terrestrial and shrew like that became arboreal. Olfactory receptors weren't enough guidence in the 3D environment of trees, and so repalced olfaction and mouth manipulation with vision and grasping forelimbs.

Optic Nerve Foramen

Where optic nerve passes through, can look at size to see how many inputs there are. Bigger in diurnal species compared to nocturnal. Increased sensitivity in nocturnal by having many sensors that input to one ganglia, need to pool to get more input.

Human sexual dimorphism

Women have greater curvature in bottom spine vertebrae because leaning back more due to future pregnancy. Angle where hip sockets fuse is bigger in females than males, wider sacrum that is pushed out of the way. Pelvis size changes as women age, and gets narrower as gets older.

Gender differences in pelvis

Women's notch is relatively wide and shallow, have a high width to depth ratio, but men's is low since their notch is narrow. Angle more open in front of pelvis, less acute in women. Females have a rounded canal, almost circular. Women have a relatively wide sacrum, somewhat wider hops and hip joints farther apart. If pelvis not preserved, makes it more difficult to determine gender in fossil record. Doesn't affect locomotion efficiency between women and men, but within women, locomotor cost increases with distance between hip joints.

Marsupial Female Tract

Young develop more in pouch than in womb. Not primitive, derived. Twin uteruses, birth canal develops during pregnancy down middle and can't fuse with side vaginas with common connection, which sperm travels through.

Precocial

hatched or born in an advanced state and able to feed itself almost immediately. Have longer pregnancies. Ex: horse, cows, chimpanzees. All primates

Heterodonty

having different types of teeth

12 features of primates

Arboreal adaptations, live in tropical forests, grasping hands and feet, skin ridges, hindlimb domination, large and frontal eyes, good 3D vision, relatively large brain, single or few infant, carry infants, extended life history, social networks.

Sportive lemur dental formula

0-1-3-3 on top, bottom is 2-1-3-3. Incisors are gone in the upper teeth, act as a pad for leaf eating instead. Subfossil Megaladapis has same dental formula.

Cenozoic Era

65-now mya. Paleogene, neogene, Quarternary.

Endocast

A cast of the inside of a skull; helps determine the size and shape of the brain. Much more detail in actual brain, but can get a good idea of size and main features of external shape. Can see blood vessel that runs along the fold between lateral and frontal lobe.

Bony bars non-primate presence

Also seen in tree shrews, which was one of the reasons that they were mistaken for primates. They're also present in several carnivores, fruit-bats, horses and several other even toed ungulates, some hyraxes, sea-cow, and some marsupials.

Flat nail

Always on the big toe but others have on other digits, may be a reduction of claws. Claws are deep and superficial layers, but nails are only superficial layers. New world and olw world monkeys have 2 layers, apes and humans have 1 layer.

Professor Martin's view on primate placenta ancestral state

Ancestral state of placenta in primates was moderately invasive. Lemurs and lorises shifted to less invasive placenta and tarsiers and simians shifted to more invasive.

New World Monkey Fossils

Aotus dindensis: modern aotus Neo-saimiri: like modern squirrel monkey Stirtoni: seems like close relative of howler monkeys

Mammal vs Primate sensory receptors

Mammals have deep sensory receptors with dead skin on top. Primates have sensory skin on top in between ridges, called Meissner's corpuscle. Give resistance to slippage while grasping and moving and touch sensitivity.

Ankle Double joint system

Oblique axis on lower joint between talus and calcaneus. Similar mechanism to lever arm and load arm, and allows tree-living primates to turn 90 degrees. Humans have lost most of this due to bipedalism.

Kleiber's law

Observation that for the vast majority of animals, metabolic rate scales to the 3/4 power of the animals mass.

Altricial

Offspring that are completely dependent on parental care. Have relatively short pregnancies. Ex: hamsters, hedgehogs, mice, tenrec (Madagascar hedgehog like species).

Theropithecus

Old world monkey fossil. Mid to late pliocene. Terrestrial monkey, most likely folivore. Very large 43.8 kg.

Victoriapithecus

Oldest old world monkey skull fossil, from middle miocene, 17 myo. Canines are 2:1:2:3. Most likely quadrupedal.

Vomeronasal organ

Olfactory organ specialized for odors specifically important to one's own species. Common ancestor of old world monkeys + apes had a secondary phase of olfactory reduction. Common ancestor of apes and humans had functional receptors but a complete loss of the organ, and humans have had a strong gene reduction with further loss of vomeronasal genes. No old world monkeys have it, only remnants.

Rooneyia brain

Oligocene tarsier form. Clearly has a sylvian sulcus. Relatively little ancient structure. Still has a substantial olfactory bulb but a bit small.

Aegyptopithecus brain

Oligocene, can hardly see olfactory bulb in dorsal view. Rhinal sulcus just visible from the side. Slightly bigger brain case than in modern lemur.

Owl Monkey

Only nocturnal new world monkey. Like the potto and slow loris, has a much lower basal metabolic rate than expected for a mammal of that body size. Father involved in carrying the young. Eats fruit and arthropods. Has huge eyes

Opsin Evolution

Opsin genes evolve through duplication and mutation. Vertebrates used to have 4, and rods diverged last from green opsin. Red/green was the first. Color evolved before black and white.

Problems with Arboreal Theory

Other arboreal mammals lack these adaptations, may be due to evolutionary constraints preventing them from evolving these traits, like the marsupial pouch. Ancestor assumptions aren't true. Arboreal non-primates can perform just as well in environment and with same movements than primates without these adaptations, possibility of current selection pressure. Higher primates have smaller interorbital space, reducing distance cues, counterintuitive, means higher stereoscopic vision at close range is more important for them.

Primate bulla

Outgrowth from hard petrosal connect it to ectotympanic to bulla. Split into lemurs, lorises, and tarsier types.

Australopithecus morphology changes related to birth

Over past 4 million years, brain size tripled. Ribcage got wider as it went down, inference is that gut was relatively large. Had large brained bigger bodied babies, so birthing difficulties may have begun with them.

Pads vs ridges

Pads are characteristics of lower primates. Ridged is ridged skin like fingerprints over feet, and are in higher primates.

Haplorhines

Dry nose primates. Tarsiers, new world monkeys, old world monkeys, apes.

Types of bushbabies

Demidoff's bushbaby Allen's bushbaby Needle clawed bushbaby G. crassicaudatus.

Clark Arboreal Theory

Depends on tree shrews being primitive lemuroids. Ancestor is tree-climbing with claws, high olfactory senses, and small eyes and brain. Tree shrews are an intermediate with larger visual cortex and reduced olfactory capabilities, but this isn't true.

Primate reduction in smell

Differs based on species. Bushbaby has 4 well developed turbinals, but diurnal lemurs have a huge reduction. Reduction in smell connected to diurnal activity. Tarsius only has 3 turbinals, and no transverse recess or lamina to flow air around and trigger receptors.

Mesozoic Era

250-65 mya. Triassic, Jurassic, and Cretaceous periods.

Natural endocast

Natural matter seeps into skull and takes the shape.

Insectivore bulla

Produce extra bone below extotympanic membrane, connect to petrosal.

Howler Monkey dental formula

2-1-3-3. Spade like incisors, mandible fused at midline.

Variegated Lemur

2-5 kg. Diurnal. Has twins raised in a nest that mother carries in mouth.

Humans

Striding bipedalism, large brain size, use of language.

Aye-aye dental formula

1-0-1-3. Rodent like dentition with 1 incisor on each side, large gaps. Always growing and wearing away to be sharp.

Gentle Lemur

1-1.5 kg. Specializes on bamboo. Is diurnal, possibly crepuscular.

Qesem Cave

200-400k years ago. Evidence of extensive, repeated use of fire. Ashes found with burnt bone. Unlikely that high frequency of burn sites would be caused by natural combustion, possible hearth.

Homo erectus dentition

1.8 mya to 100k ya. Dental arcade smaller than that of Australopithecine species, linked to cooked food. Prognathism (jaw protrusion) was reduced within the species. Likely that first meat eaten by early homo came from scavenging and not hunting. Likely used tools to crush the meat to make it more easily consumable, even before fire became widely used to cook food. Larger teeth than Homo sapiens, but smaller than earlier Homo's, and incisors start to show shovel-shape appearance, due to change towards hunter-gatherer diet.

H. rudolfensis dentition

1.9 million years ago. Has large rear teeth, even relative to estimated body size.

H. ergaster

1.9 to 1.4 million years ago. Teeth near modern condition. May be first fire keepers, if claims for control of fire in South Africa 1.5 mya are confirmed.

Australopithecus locomotion adaptations

1st primate with upright bipedal movement. Lacked many of the morphological adaptations necessary for efficient bipedal movement. Pelvis, sacrum, and femur resemble those of a modern human, but has many arboreal characteristics, like long, slender appendices and a funnel shaped rib cage. As time passed, adapted to life on the ground and began to move more and more upright, until rise of genus Homo.

Mongoose lemur

2 kg. Nocturnal nectar feeder.

Homo Erectus evolutionary changes and starch

2 million years ago, although evidence of hearths only 250k ago. Substantially increased height and body weight: cooked starch allowed increased size to be maintained. Gut Reduction: Cooked starch requires less enzymatic action to digest and less volume of consumed food to glean the same energetic output. Teeth reduction and facial shortening: Cooked starchy foods require less manual tearing and chewing to digest. Larger relative brain size: Based on modern humans, brain uses up 25% of body's energy and 60% of body's glucose, could be handled with cooked starch. Body Structure compatible with long distance running: Cooked starch allowed for sustained energy for that type of locomotive activity. Multiplication of salivary amylase genes, increase of starchy foods in the diet, need to be able to digest more things.

Old World Monkeys dental formula

2-1-2-3 top and bottom. Monkeys specialized, not apes. Bilophodonty, transverse cutting ridges.

Indri dental formula

2-1-2-3, with 2 premolars on each side, 4 incisors in tooth comb. Eats fruits and leaves.

Human dental formula

2-1-2-3. Evolution reduces the number of teeth. We fit upper and lower teeth together.

Marmoset and tamarin dental formula

2-1-3-2. Only ones to lose molar and not a premolar. Don't erupt 3rd molar because they reduced their body size.

Tarsier dental formula

2-1-3-3 on the upper teeth and 1-1-3-3 on the lower teeth. Only eat animals so no grinding. Upper molars are triangles, lower molars are heal and triangle. Most primitive dentition, as all other primates have lost lower triangle, no development of 4th cusp.

Fork-crowned lemur dental formula

2-1-3-3, 3 molars and a tooth comb. Eats gum. Canine like premolar.

Mouse lemurs dental formula

2-1-3-3, tooth comb and 1 canine on each side. Eat insects and fruits

Loris and bushbaby dental formula

2-1-3-3. 6 tooth tooth comb in lower jaw, and 2 incisors and 1 canine came from each side.

Goeldi's monkey dental formula

2-1-3-3. Have a stabbing canine. Intermediate species, has a small molar but not lost.

Importance of increased locomotion efficiency

As vegetation in Africa became more widely spread, daily distance traveled by early humans increased, and amount of energy spent traveling increased greatly. 15% increase in efficiency would save average hominid 500 kJ a day, so would be a great advantage. Compared to energy used in primates for locomotion, about half as expensive.

Limitations in finding origin of cooking

Ash, charcoal, burnt bones, and other signs of fire use are not well-preserved in the fossil record over time. Limited fossil record. Difficult to determine intentional use of fire.

EQ trends and problems

Australopithecus Afarensis already had a bigger brain size relative to body size. Australopithecus africanus had EQ 2.7, Homo Habilis had 3.6, we have 5.8. Underestimating effects because we are using modern apes as a point of comparison, but fossil apes have smaller EQ.

Claws in primates

Aye-aye, marmoset, and tamarin have claws on all other toes besides big tow. Tarsiers, bushbabies, leumurs, and lorises all have grooming claws to facilitate communal grooming.

Partial correlations for brain mass

BMR and brain mass partial correlation. Either increase gestation or BMR, two alternative strategies.

Brain Size Variation

Bell curve. Has nothing to do with IQ, Einstein is near the bottom. More to do with nutrition.

Necrolemur

Best known genus among fossil tarsioids. Has several fairly well preserved skulls from same French Eocene deposit. Resembles tarsiers in bell shaped dental arcade, general structure of ear region, and several other morphological details.

Importance of free hands in hominids

Bipedalism allowed Australopithecine to have their hands free, which could then be used to forage on the move, giving them a greater reach. Also allowed for ability to use tools.

Cribiform plate

Bone with lots of holes for nerves.

Auditory bulla/middle ear

Bony structure developed to protect 3 ossicles. Present in lemurs and lorises.

postorbital bar

Bony strut around the outer margin of the orbit. Obvious feature that has been seen for a long time as the defining feature of euprimates. At birth, tarsiers lack a postorbital bar or septum, have a postorbital plate and almost complete bony socket instead. . Development of postorbital bar in ancient euprimates and subsequent development of postorbital septum in haplorhines served to isolate the eye from temporal jaw musculature.

Equation for log brain weight

Both primate and non-primate lines have the same slope, but the intercepts are different. The slope is the same as basal metabolic slope, so BMR has a connection to brain weight.

Mammal dentition

Bottom has the mandible, which is all teeth, and the dentary, which is a single bone in the lower jaw. On top is the maxilla (canines, premolars, molars) and pre-maxilla (incisors)

Developmental Cost Hypothesis

Brain size is trade off between growth and production, we have to live longer for it to work.

Scaling of brain size in primates

Brain size vs body size, lines for non-primate mammals and primates, and primate line is higher than non-primates, showing they have bigger brains than expected. Homo appears to be even above the primate line. Regression lines are parallel. Log-log scale so the allometric equation are straight lines. Mammals nearest humans are porpoises and dolphins, which also have large brains for their body.

Carnivore bulla

Bulla has a bony floor from ectotympanic extension.

Infraorbital foramen scaling

Bundle of whisker nerves pass through the foramen, and the size of the foramen indicates how important whiskers are. Haplorhines have a small foramen but strepsirrhines have larger foramen, but still small when compared to other mammals. Ground-living has good hearing and smell and more whiskers, but tree-living has fewer whiskers and reduction in olfaction.

250k Fire Use

Burned bones and clay found at sites containing human tools in Africa and Asia. Animal scat and other flammable organic accumulation there as well, indicates natural combustion. Not conclusive evidence.

Types of Lorises

Bushbabies Lorises of South and Southeast Asia Potto and angwantibo of Africa All are nocturnal and weigh 2 oz to 2 pounds. Have a huge range.

G. crassicaudatus

Bushbaby. Has suprisingly little leaping but has powerful hindlimbs.

Human occlusion of cheek teeth

How they fit together. Lower teeth can be triangles with 3 cusps or heel with 2 cusps, and upper teeth are all triangles. Triangles fit together to slice, and heel and triangle fit together to grind.

Origin of Cooking and Digestion changes

Can no longer survive/reproduce on raw diet, dietary limitations make it energetically impossible to consume enough calories. Origin of cooking can be determined by date of loss of dietary adaptations. Digestion system shrinks, digestion rate increases, and adaptations for detoxification are reduced, but in soft tissue so impossible to directly measure in fossil record.

Modeling gaps in fossils

Can use a mathematical model of how may gaps there are to see their effect. The only thing you are sure about is number of extant species, random branching of possible evolutions to find the number of extinct ones. Only found 3% of expected past extinct species. Can look at gap between earliest known fossil and likely first common ancestor, and the space in between is underestimation time.

Why bipedalism?

Cause of evolutionary change from quadrupedalism to bipedalism in early humans have been unknown for many years. Early studies showed that bipedalism movement was much less energetically efficient than moving on all fours at identical speeds, so many anthropologists questioned why the change occurred. However, more recent studies have proven that walking on all four limbs is less efficient than using only 2. Have to consider importance of endurance.

History of potential fire use

Chesowanja fire-hardened clay fragments, 1.4 mya. Analysis showed heating must have been 400C, can't rule out forest fire. Koobi Fora, 2 sites show evidence of control of fire by Homo erectus at 1.5 mya, reddening of sediment associated with heating material to 200-400C, can't rule out forest fire. Wonderwerk cave, 1 mya evidence of fire use. Bnot Ya'akov Bridge, Israel, evidence that H. erectus or H. ergaster controlled fire there between 790k and 690k years ago. Claim widely accepted.

Great Apes

Chimpanzees, gorillas, orangutans. Larger body size but great diversity in terms of diet and social organization. Orangutans are largest tree living, chimps are our closest relatives, and Bonobos are derived from them and live across a river.

Marmosets diet

Clawed new world monkey. Eat sap and gum. Makes holes in bark to get sap with short tusk/canine and long incisor as a sharp chisel. Has no enamel on rear surface, dentin wears away and becomes a chisel.

Tamarins diet

Clawed new world monkey. Gouging adaptation with long-tusk, stabbing canine. Eats mostly fruit.

Geological evidence for bipedalism

Climate changes during the miocene period probably thinned out forests in East Africa. Some of the primates in this changing climate stayed in the trees and these became ancestors of gibbons and siamangs. Many hominoid species left arboreal homes for the ground in order to forage. Evolved to be able to forage with both hands while moving, led to upright movement. Explains why bipedalism evolved, but not how.

Cochlea

Coiled, bony, fluid filled tube that coils into skull. Allows for long-range sound detection. Gave mammals increased ear sensitivity compared to other vertebrates.

Common ancestor dental formulas

Common ancestor for all 2-1-4-3, also have grasping teeth that were lost when got grasping hands. Lemurs 2-1-3-3 New World 2-1-3-3 Old World 2-1-2-3, with functions for better cutting edge

Female tract primates

Common channel for urine and reproduction. Having one uterus is rare in mammals. Prosimians is divided, simians have fused. Higher primates also lost membrane to make sure egg gets into oviduct funnel.

Lemur Location

Confined to Madagascar. Separated 85 mya

New World Monkey location

Confined to South and Central America

Problem with social brain hypothesis

Conflict between different social and mating groups. Monogamy has large brain due to coordination abilities for bond maintenance and deception for extra-pair matings. Polygamy has large brain due to cognitive demand to maintain large number of relationships with large number of individuals.

Aye-aye convergent evolution

Counterpart in Australia, Dactylopsila, resembles the Aye-aye in being nocturnal, having an attenuated digit on each hand, and conspicuously well developed incisor teeth.

Hominid Dentition History

Dietary capabilities of the early hominids changed dramatically in the time period between 4.4-2.3 mya. Evidence suggests a dietary shift in early australopithecines, to increase dietary flexibility in the face of climatic variability. Over time, the rear teeth progressively increased in size through Australopithecus and Homo, from A. anamensis and H. habilis.

Fertilized cell process

Doesn't begin to increase in size till implants in womb, just divides. Egg is one of the largest cells in the body. Outer membrane is chorion. Yolk digested, nutrients go through blood vessels, deposit waste into allantois. Converted to blood vessels carrying things from mom.

Visual predation and angiosperm radiation compatibility

Don't disprove the other. Most primates eat both fruit and insects, and both agree that primates evolved to specialize in thin terminal branch habitat, and when no priamte, marsupials fill niche with similar traits, fruits and insects found in close association with each other. Visual predation explains eyes well, and angiosperm radiation explains hands better.

Encephilization Quotient

EQ. Relative brain size. Ratio of actual to predicted brain mass based on the body weight of the species. Insectivores, hoofed mammals,, bats, and rodents at 0, which is on the line of brain size vs body size, primates above.

Apes and Humans groups

Lesser apes Great apes Humans

Brain anatomy

Each side is a cerebral hemisphere that is connected by the corpus callosum, which is a well developed band of connecting fiber between the left and right side. Marsupials don't have this, only have the anterior commissure, which is the ancestral reptile brain connection between the left and right, which is much smaller in mammals. Paleocortex on the bottom is the old brain from reptile days, separated from neocortex by the rhinal sulcus, which runs along side of the brain. Lateral sylvian sulcus is a strong feature, can use to oritent self. Rear is occipital lobe, olfactory bulb controls smell, and cerebellum stores learned program of movement.

Eosimias

Earliest complete dentition from anthropoid primates from late middle eocene.

Why Rotational birth

Early hominids may have had a rotational form of birth, due to the selective pressure of shoulder width. Large size reached by Homo 1-1.5 mya was only possible when a rotational mechanism was developed.

Euprimate fossils

Early tertiary fossils. Can generally be placed to infraorder Adapiforms or Omomyiformes. Later forms (late Oligocene, early Miocene) have been linked more closely to natural groups of modern primates, and are direct relatives. Adapiforms have been linked to the strepsirrhine side of primate tree, and Omomyiformes to the haplorhine side, specifically tarsiers. However may not be directly linked, and may constitute a separate adaptive radiation of early primates.

Primitive condition of primate placenta

Early theory was that primitive condition was a noninvasive placenta, but later highly invasive placenta was more efficient, and that humans have most derived invasive placenta. However, does not stand when we consider pregnancy length and state of offspring at birth.

Gummivores

Eat gum for polymerized sugars. Need bacteria to break down sugars. Eat with feet up, head down to keep feet from getting sticky. Bushbabies, fork-crowned lemur has gum as 90% of diet.

Bushbaby tooth comb

Eats gum, used to feed on the gum and harvest it from the Acacia tree. First few incisors are fused into a big comb, canines are retained.

Tarsiers and old world monkeys bulla

Ectotympanic ring becomes a tube, further prevents independent vibration. Independent evolution for the two groups, as it is seen as the ancestral condition for old world monkeys. Tube grows after birth, so use it to age human and old world monkey skulls. We never see the bony canal/tube in other fossils, so not ancestral condition for common ancestor. Necrolemur has a tube, but ring still freestanding inside bulla.

Loris and new world monkey bulla

Ectotympanic ring fuses to petrosal bulla outside. Seen as primitive, and was likely condition for common ancestor, since it prevents independent eardrum vibration that occurs with freestanding ring. New world monkeys like this.

Moderately invasive placenta

Endotheliochorial. Some penetration of the inner wall of the womb occurs and maternal blood vessels come to lie directly against the chorion. Carnivores, elephants, sea cows, and tree shrews.

Energetics of Gestation and Growth Hypothesis

Energetic constraints of both mother and fetus determine gestational length and fetal growth. Average maximum sustained metabolic rate is twice the basal metabolic rate, and this limit is reached after the 2nd trimester, then plateaus in 3rd trimester, even though fetus energy demand increases exponentially. Not exclusive with obstetrical dilemma. However, lactation is still energy provided by mother, and exceeds max sustainable metabolic rate.

Weaning costs to mothers

Energy costs of gestation are not very high but increase linearly over time, lactation is much higher. Suckling stimulus can produce a delay in sexual cycling. Speed of transferring maternal mass to child varies among species. Weight of child determines weaning, threshold weights, about 4 times more than neonatal weight.

Paleogene epochs

Eocene, oligocene, miocene, pliocene, pleistocene, holocene.

Adapiforms

Eocene. Lemur like, some fossils more than others.

Noninvasive placenta

Epitheliochorial. No significant breakdown of maternal tissues. Chorion and uterine episthelium right next to each other. Hoofed mammals, dolphins, whales, and pangolins. Always in precocial systems, so has to be advanced and not primitive.

Tarsiers diet

Exclusively insectivores, also eat snakes.

Ancestral molars

Extra cusp on upper (4) and lost one on lower (2), allows for more grinding.

Cost of brain

Extremely high. 20% of BMR but only 2% of mass, clear that a lot of energy is invested in the brain. Humans unique from chimps in that we continue having rapid brain development after birth. At birth, 50% of energy foes to brain.

Eye Shape in Primates

Eye is relatively short compared to height and relatively flat.

Euprimate eyes

Eyes are relatively large and rotated forward to some extent. This enlarges the binocular field in which an object can be seen simultaneously with both eyes, an essential precondition for 3D vision. Not present in plesiadapiforms. Dioptic benefits of orbital convergence as well, relating to reflection of light, but these are primarily obtained in nocturnal animals

Human digestive system

Falls below line on all of the digestive tract vs body size graphs. All aspects reduced, we have a small digestive tract.

Allen's Bushbaby

Feeds on fallen fruits and supplements with animal prey. Relies more on vertical clinging and leaping.

Needle clawed bushbaby

Feeds on gum exudates. Similar adaptation found in gum feeding fork crowned lemur.

Jones Arboreal Theory

First adaptation was forelimbs and hindlimbs diferentiating. Hindlimbs used for support and propulsion, forelimbs for grasping supports on trees. Preadaptation for food gathering.

Primate evolutionary history

First radiation of primates in the Cretaceous period, and after the K/T extinction, a seconf one occurred in the tertiary.

ischial tuberosity

Flattened area at bottom of pelvis, recieves weight of sitting, hardened skin over it. Sitting pads depend on tuberosity width. Small width and tuberosity in apes and humans. Old world monkeys have larger ones if sitting on tops of branches or tree dwelling.

Diet types to know

Folivore = leaves Insectivore = insects Frugivore = fruits

Diet trend with body mass

Folivores are the biggest, omnivores are in the middle, insectivores are the smallest. Metabolic rate increases with body size, but rate of increase slows, because energy/unit of body weight decreases as size increases. Smaller monkeys use energy more quickly than bigger ones, which can eat and store calories as far with enzymes.

Stomach size vs body size

Folivores have the largest stomach proportional to body size.

Intermembral index

Forelimb length/hindlimb length. Helps us understand differences in locomotion for the 4 categories.

Woolly spider monkeys and woolly monkeys

Form a fairly close-knit set of species that are characterized by quire heavy body weights, like howler monkeys, and possession of fully prehensile tails. Run quadrupedally above branches, but spend much of their time suspended beneath branches, especially during terminal branch feeding, assisted by the prehensile tail. Multi-male troops containing 10-20 individuals, which may vary according to availability of suitable fruit. Biggest type of new world monkey.

Endocast of Eocene Adapis

Formed olfactory bulb using mirror images. 40 million old brain. Optic nerve comes through channels, blood vessel tells us where rhinal sulcus is. Frontal lobe overlaps olfactory bulb. Expanding brain, primitive to be able to see bulb, as we see in plesiadapiforms. Rhinal sulcus already pretty far down.

Lemur subfossil

Forms of giant lemurs found. Humans probably hunted to extinction.

Adapis parisiensis

Fossil lemeroid adapiform genus. Convincing evidence of sexual dimorphism, which is interesting because no modern prosimians experience pronounced sexual dimorphism. Continuous decline in size in proto-adapis.

Navarette experiment

Found weak correlation between digestive tract and brain, reverse from expensive tissue hypothesis.

Lemur bulla

Freestanding ectotympanic ring enclosed inside bulla.

Subdossil lemur brain

From Madagascar. More folds in cortext than any living lemur. Today we don't have such big lemurs.

Early old world monkey brain

From miocene. Olfactory bulb really small in relation to the rest of the brain. Clear sylvian sulcus.

Mammal limbs

Front to back motion of limbs, limbs underneath the body, no lever arm.Reinforced heel bone and elbow for movement.

Bat brain patterns

Frugivorous bats have larger brains than insectivorous ones, some suggest this is due to selective pressures from a more complex feeding strategy in frugivores. However, piscivores have highly complex feeding strategy and have smaller brains than the fruit eaters. Shows that we have to be very cautious in making causal statements when looking at correlations in the data.

Odorant receptors evolution and process

Gained around 1000 odorant detectors through gene duplication, making a random array. Smells come into cavity, will randomly trigger some of the receptors. Uses G protein-coupled 7-transmembrane protein detection system, same as vision. Each receptor type goes to the same glomeral.

Primate fossils of modern aspect

Gap of 9 million years in fossil record, primates certainly appeared 55 mya. Low sampling levels lead to skewed image of where branching occurred.

Lesser Apes

Gibbons, siamangs. Smallest of the apes. Arboreal, and have specialized forelimbs for tree swinging. Plant diet. In southeast Asia. Siamungs have a sac for very loud calls, and no sexual size dimorphism, but coloration differences.

Tarsier Births

Give birth to very large babies and have long gestation at 6 months. Have problems at birth as well. Clearly primates can get away with a small pelvis in relation to brain size.

Reproductive Tract development

Gonads develop by the kidneys. Mullerian (male) and Wolffian (female) ducts develop and are bilaterally symmetrical, breaks fown in opposite gender. Develops into womb and male reproductive tract.

When were early primates active?

Good evidence to believe that they were nocturnal.

Great apes and chimp births

Great apes similar in body size, can give birth in an hour or two, babies head is forward. Chimps are born with 40% of their adult brain size.

Benefits of Cooking

Greater nutrient extraction, increased digestibility of plants, easier consumption of meat, increased efficiency. Leads to caloric intake increase and increased reproductive success.

Gelada baboon

Guenon old world monkey that is exclusively terrestrial. Feeds and move exclusively on the ground, commonly shuffling along on its hindquarters. Sleeps on cliff faces during the night. Extreme example of terrestrial living primate.

Types of Old World Monkeys

Guenon subgroup macaques/cheek pouch monkeys: manageys, baboons, drills, geladas, guenons, and patas monkeys. Leaf-monkey subgroup: langurs, probiscis monkeys, colobus monkeys.

Types of ear shapes

Halp - rounded ear Strep - pointed ear

Human raw starch digestion

Have 2 alpha-amylases, one in salivary glands and one in pancreas/small intesting, that does a slow and incomplete digestive process. Chewing breaks up starchy foods and mixes with enzymes. Resistant starch can't be digested, but can be fermented by intestinal microbes into fatty acid short-chains, delivers 50% of energy to human consumer.

Cooking's effect on starch

Heat collapses starch's structure, making it less tough to split into glucose monomers, and degrades amylose, letting alpha-amylases have a greater effect, softens starchy food to reduce energetic chewing costs and feeding times. Greatly increases digestibility.

Non-thermal processing

Heating food but not enough for full thermal benefits. Employed by chimps and earlier hominins than Homo erectus.

Highly invasive placenta

Hemochorial. Further penetration of womb's inner wall breaks down the walls of maternal vessels and pools of blood directly bathe the chorion. Easier diffusion.

Primates increased brain size

Higher primates 35 mya already had advanced brain size. Long held assumption that all primates reduced olfactory bulb doesn't hold up. No way we can say primates have the biggest brains, even though they are somewhat distinctive. On plot of brain size vs body size, some primates lie below the regression line, other things are larger, can only say on average they have larger relative brain sizes. What differed was rate. Humans above line at highest point.

Higher primate snout

Higher primates lose the transverse lamina, so the air goes to lungs without moistening. 2 ehmoturbinals instead of 4. Loss in olfaction. Can determine loss by looking at cribiform plats and ethmoid.

Simian Make-up

Higher primates. New World Monkeys, Old World monkeys, apes and humans.

Effects of Raw Food Diet

Higher proportions of raw food in diet correlates with a lower BMI, leads to loss of menstruation in half of people. Not due to vegetarianism, because true even if eat raw meat, and untrue for vegetarians eating cooked food. Not due to calorie restriction, food intake isn't limited, because always hungry.

Relaxin

Homone that increases felexibility during birth and facilitates the birth process.

Human fetal brain and body development

Human birth takes place at last viable moment. Humans have a prolongation of fetal brain growth. Takes 12 months to reach maturity reached in other primates in terms of rate of brain growth slowing to postnatal patterns. Humans exposed to world with very immature brains, 1/4 developed at birth. Human development is 9 months in womb, 12 months outside for 21 months total. However, humans are not immature compared to other primates with respect to body size.

Human vs Chimp brains

Human brain is rounder and larger, and we can reconstruct the shift from fossil evidence. Australopithecus had brain around the same weight as chimps, but the ratio of brain to body size is much larger in Australopithecus than chimps. Body was growing too, so can't just use cranial capacity, need to use ratio. Both ratio and cranial capacity grow through Homo species.

Human skeleton adaptations

Human rib cage is cylinder shaped, not an inverted funnel. Presence of waist, apes have little space between top of pelvis and rib cage, may be linked to endurance running. Humans have low slung pelvis that is just as wide as great ape pelvis but distance between hip sockets is larger; broader based for balance, more stability. Human toe brought in with other digits, no longer grasping organ, possibly for shock absorption.

Humans precocial or altricial?

Humans are an exception to newborn primates are precocial, because the head size is altricial. There's also a lack of hair, which is a secondary development in humans. Fetus loses lanugo soft hairs before birth. Humans called secondarily altricial.

Odorant clusters loss

Humans have lost 50% of clusters of odorant detectors. New world primates have lost 15% of their original clusters. Old world primates lost 30% of original clusters. Howler monkey also lost 30%, has tri-color vision, shows evidence of a trade-off of olfaction for vision. Considered direct evidence that simians have reduced olfactory system, and is more concrete evidence than smaller snout.

Test of Obstetrical Dilemma Hypothesis

If you birth a baby at the same stage of development as a chimp neonate, where brain is 40% of adult brain, need only a 3 cm increase in mother's pelvic inlet. This is within range of pelvic dimensions seen in modern human female populations, without any mechanical disadvantage or locomotor cost.

Precocial or altricial primitive?

In birds, precocial condition is primitive. In mammals, altricial condition is primitive, and precocial condition independently occurred in at least 10 different lineages. Newborn primates are altricial, born with eyes closed off by a membrane, then re-opens. Fossil evidence confirms that newborn type was established early in the evolution of every major group of animals.

Tooth combs

In lemurs, lorises, and tree shrews. Independently evolved, all different. Feeding adaptation for gum, secondarily used for grooming. See damaged ones in adults, and marks on trees.

Squirrel Monkey sexual dimorphism

In pelvis. Pubis length is higher compared to length of blade in females, no need to limit in males cause nothing to get in the way of. Balancing locomotion with birth capabilities.

Who has Meissner's Corpuscle

In primates, but also elephants, mice, and opossums as a pressure detector. Unclear whether primitive mammalian feature, or specialization in primates. Not present in tree shrews, instead have unspecialized nerve ending, but may be independent loss. Lower primates have parallel ridges and tactile pads and new world monkey's don't have pads but ridges extend down.

Tree shrew vs primate suckling

In tree shrews, the mom keeps the neonates in a separate nest and feeds them once every 48 hours, suckling in schedules like many other mammals. Primates however, have suckling on demand.

Passive brain growth

Increase in brain and body size, minor rearrangements. Passive growth may either affect early periods of ontogenetic brain development or produce a generalized increase in cell proliferation in later periods.

Arguments against Homo erectus using cooked starch

Increased energy budget may just be due to eating more meat, not necessarily cooking, but doesn't explain morphological changes. If cooking evolved in Homo heidelbergensis, there's little anatomy changes between Homo erectus and them, and lots to make erectus. May be due to non-thermal processing, but raw food diet shows how important thermal processing still is to bodily functioning and increased energy budgets.

Pregnancy length

Increases in size. For example, African elephants take 22 months. Precocial mammals also have longer than altricial. Women vs cheetahs of similar weight, women's pregnancy was 3 times longer.

Rotational birth

Infant cranium is longer than the anterior-posterior dimension of pelvic inlet, requiring the head to enter the inlet facing sideways. Longest axis of neonatal head is sagittal dimension and longest axis of maternal pelvic inlet is transverse dimension, so fetal head enters birth canal with sigittal axis aligned with mother's transverse axis/facing the side. Since birth canal is not straight tube of unchanging shape, human fetus must rotate as it passes through. At the end, facing downwards, would need assistance, could cause umbilical cord to wrap around neck, shoulders can also get stuck.

Balance organs

Inner ear, can measure sizes of 3 inner canals. Looking at canal ratio vs body mass, agile leapers have bigger canals than slower climbers. Trend only holds for primates, not all vertebrates. Plesiadapiforms below trend, and have small semicircular canals, but aren't agile.

A. afarensis dentition

Intermediate in Australopithecus. Similar to A. anamensis in relative tooth sizes and probably enamel thickness, but it showed a large increase in mandivular robusticity. This increase may be due to changes in peak force magnitude or degree of repetive loading in mastication. Hard and abrasive foods may have become even more important components of their diet.

Lieverman book Dentition

Irrefutable evidence of tool use 2.6 mya. Meat and tougher plants were broken down, overcoming obstacle of flat teeth that are poorly adapted to eating meat.

Dryopithecus

Large ape fossil. Genus of extinct apes known from Eurasia during late Miocene period. The structure of its limbs and wrists show that it walked in a way similar to modern chimpanzees but it used the flat of it's hands, like a monkey, rather than knucle-walking like modern apes. Diet likely dominated by soft fruit according to microwear.

Proconsul

Large ape fossil. Lacked extreme specializations for brachiation found in modern lesser apes and is distinct from all modern apes. Despite dental similarities to Dryopithecus, it is actually quite distinct in phylogenetic terms and may not be directly linked to the adaptive radiation of the great apes and humans. No longer any justification for regarding it as a subgenus of Dryopithecus. Likely a fruit eater based on dental microwear.

Oreopithecus

Large ape fossil. Unusual because postcranial skeleton has typical ape-like features, such as relatively elongated arms and complete loss of the tail. Pelvis shows certain striking resemblances, at least superficially, to that of humans. Likely a leaf eater based on dental microwear.

Energy rich strategy

Larger ranges and group size. Fruit eaters.

Simians fossil brain size

Larger residual values for brain size than the prosimians. Many fossils below modern mammal average, but a few lie above, and one, Proconsul, had pretty large brain. Hominids progressively closer to modern human brain size, and Proconsul from miocene overlaps with these fossils.

Tarsier eyes

Larger than eye socket, can't rotate eyes. As an adaptation, neck can rotate 180 degrees.

Dolphin births

Largest brain mammals after humans, pretty close to us. Some have same brain size as us with pretty similar body size, and have a similar gestation time. At birth, brain is half the size of the adult brain. No pelvic constraint.

Recent Brain Size trends

Last 30,000 years has been a decline in human brain size. In hominids both brain and body mass shot up, but at a certain point the brain kept growing rapidly while the body did not. Neanderthals then show trend towards bigger brains and bodies, but anatomically modern human predecessors showed decline in brain size and body size.

P. aethiopicus and P. boisei dentition

Later australopithicus species. Scratch patterns on cheek surfaces suggested their dietary habits didn't involve chewing significant amounts of abrasive foods. May have eaten less abrasive brittle C4 plants, which would be consistent with isotopic and dental evidence.

Cooking and life history pattern

Led to shorter weaning time, because infant can eat softer food sooner. Shorter weaning time allows for less time between infants, and shorter interbirth interval, and increased energy for reproduction. However, we have lower reproductive rate than other great apes. Can't see in fossil record.

Primate placenta types

Lemurs and lorises have a noninvasive placenta. Tarsiers and higher primates have a highly invasive placenta.

Pliopithecus

Lesser ape fossil. Small gibbon-sized form from European middle Miocene deposits (9-14 mya), with a body weight estimated at 5.94 from molar dimensions. Arms aren't longer than legs, no tail.

Is one placenta type more efficient than others?

Leutenegger in 1973 found that tarsiers and higher primates consistently have relatively larger newborns than lemurs and lorises by a factor of 3. Tempting to say that invasive placenta is more efficient. However, largest newborns relative to mothers size are in hoofed mammals, dolphins, whales, elephants, and sea cows, but none of these have a highly invasive placenta. Comparison across mammals reveals that newborn size is not connected with invasiveness of placenta.

Theory life span and evolutionary time

Life span has been increasing through evolutionary time, implies the longer ago a group diverged from direct ancestry of hominids, the more reduced its longevity will be. Longevity quotient found to be similar amongst all primate groups other than hominids.

Retina Structure

Light has to go through many structures, not a good design. Has rods and cones. Only diurnal species can really see color, and has more cones. Each type covers different wavelengths.

Trade off factors and other effects on weaning

Litter size affects, a small litter means faster growth and earlier wean. Birthweight establishes initial investment requirements. Other factors are social status, age/rearing experience, mother's body condition, sex of baby (males cost more), and reproductive status. Lots of variability among primates, not a simple species specific life history characteristic. T

Eye diameter vs head and body length

Log plot increases linearly. Many night active species have smaller eyes but still above predictive line, so are owl monkeys and tarsiers. After certain body mass, hard to fit to line.

Significance of Weaning

Longevity associated with late age of weaning. Time after weaning is very vulnerable with high susceptibility to disease, smaller body size makes vulnerable to predators, limitations to nutritional intake and acquiring digestive bacteria, leaving maternal protection, and individual foraging may be inefficient. Life history also based on environment.

How do we know if something is bipedal?

Look at attachment of neck musculature, faramen magnum. Straight down if bipedal, otherwise angled. If thigh bone stands straight up, isn't bipedal. Has to have kneww under pelvis and thigh bone angle for better balance.

Vibrating tympanic membrane ratio

Look at ratio between size of tympanic membrane and stapedial footplate, which will tell us where sound is detected and magnified from. Primates have a large eardrum but not footplate, so they magnify sounds from the eardrum.

Guatamalean kids study

Looked at relationship of IQ with body weight, socioeconomic status, head circumfrence. Highest correlation is between circumference and body weight. Major confounder of socioeconomic status. When removed, no correlations.

Cooking Hypothesis

Looking at time spent feeding vs body size, positive trend. But Humans have large body mass but low time feeding. Predigesting by cooking, spend less time chewing. Need evidence for regular use of fire, but would explain decrease in teeth size, which dated back to beginning of homo. Gut size also decreased.

Opsin Gene duplications and losses

Lorises, galagos, dwarf lemurs, and owl monkeys have only one cone. Durnal howlers, old world monkeys, and apes have trichromatic vision. The rest have dichromatic vision.

Human dental adaptations

Lost bilophodonty. Teeth are smaller and closer together and canines are significantly reduced. Mouth is also smaller. The chewing surface in lower teeth is reduced over time. Reduction may be explained by cooking, as we don't need to spend as long of a time chewing, so don't need huge teeth.

Problems with finding Brain Evolution Reason

Lots of factors, can't just compare 2 values. May be a correlation but secondary reason.

Prosimians Make-Up

Lower Primates. Lemurs, Loris, and Tarsiers.

Bilophodonty

Lower molar has 4 cusps, upper molar has 4-5 cusps. Transverse cutting ridge, good for slicing and grinding.

Teeth length vs skull length

Lower primates on higher line than higher primates. Shorter jaws in higher primates, and we have smaller mouths than apes.

Brain imaging procedure

Make endocast by poring latex in brain case and swirling around, carefully take out through foramen magnum ( hole at bottom where spinal cord connects), fill with plaster. Can form parts using x-ray images if too if too fragile, reconstruction based on mirror image.

Lemur Diversity

Makes up 30% of primate genera and 18% of the primate species, despite being restricted to small geographic area. Example of adaptive radiation.

Why do primates grow so slow?

May have to support unusually large brains, could be negative association between mortality rates and growth rates, so increase changes of reaching reproductive age if benefits of low growth rate outweigh costs of delayed maturity. Faster growth rates could be dangerous since they have to stay at the center of the group to avoid predation, and have to compete with larger animals for food. Diet costs should be low.

Partial correlation

Measure of the strength and direction of a linear relationship between 2 continuous variables while controlling for the effect of one or more continous variables, called covariates. Removes confounding variable.

Theory metabolic efficiency and max life span

Metabolic efficiency and life-time energy expenditure are determinants of max life span. Primates aren't longest lived mammals for body size, surpassed by bats and monotremes, even when metabolic rate is accounted for. Humans and primates aren't only animals with highly developed defenses against normal metabolic damage.

Sacrum Effect on Birth

Middle part of pelvis/vertebrae fused together and to the hip. Wider in humans. Size of opening in humans reduced because squished. Bottom end of sacrum comes forward instead of back as in great apes, could impede and make birth canal smaller. Humans also have pelvic notch in opening, direct result of broadening the blade, high width and is shallow, important for skeleton sex determination.

Nycticeboides

Miocene Lorisoid fossil. Relatively small-bodied, maximum 500 g, and had relatively large eyes.

Cheek teeth

Molars and premolars. Baby milk teeth don't include molars, permanent set does.

Old World Monkeys

Monkeys of Africa and southern and southeastern Asia. Cohesive group in basic morphological terms. Have relatively close-set, downward-pointing nostrils, giving rise to term catarrhine monkeys. All have ischial callosities, which are hardened cutaneous sitting pads.

Homo naledi brain

More human than chimp. Used to be dated 2 million years ago, but based on dating fossil teeth, age range is much more recent at 335,000 to 236,000 years ago.

Gender difference in brain size

Most of the distribution for brain size overlaps, yet Murray argued that men have larger brains than women. Men may have more variation than women, but Murray is also a racist. Probably due to body size

Tree-shrews

Most primitive living primates, now not considered primates. Active by day but very small. Restricted distribution in southeast Asia. 2 caregories, terrestrial tree-shrews and pen-tailed tree-shrews. Phylogenetically closer to rabbits, and it's the sister group to the clade with primates and colugos, which was found using molecular phylogeny.

Strepsirrhines tapetum

Mostly nocturnal and have a tapetum. Even some of the diurnal lemurs have a tapetum, but in others it is missing and we don't know why.

Types of Lemurs

Mouse and dwarf lemurs Sportive Lemur True and Gentle Lemurs Indri subgroup Aye-aye

Evolution of flat nails

Nails likely primitive, as it only requires 2 evolutionary changes instead of 6. Common ancestor of primates had grasping hands and feet with nails on all digits, and common ancestor of mammals had claws with 2 well-defined nails like in tree shrews.

Rhinarium

Naked moist area of skin that surrounds nostrils. Strepsirrhines retain this feature, and curved gap between teeth most distinct in lemurs and lorises. Lost in haplorhines, and upper lip has hairy skin.

Prehensile/grasping tail

Naked skin with Meissner's corpuscles. Like a 5th limb. Biggest in new world monkeys like howler, spider, and capuchin. Tail size depends on terminal branch feeding, which is easier with suspensionary motion. . You will have a bigger tail if you need to go out on thin, long branches to get food, which explains why old world monkeys of equivalent size don't have prehensile tail.

Marmosets and tamarins

New World Monkeys. Weigh 70-550 g. Have claws on most digits, allowing them to move quadrupedally along broad trunk surfaces. Omnivorous, and have a reduced number of teeth. Basic pair living. Has twins with shared placenta that the father carries after birth. They do not build nests, but do use tree hollows Marmosets feed extensively on gum, tamarins don't

Branisella

New World monkey fossil. Found in Bolivia, from late oligocene approximately 26 mya. Small eyes, diurnal. Lower jaw was deep and fused.

South and Southeast Asia Lorises and Potto and angwantibo of Africa

No nests, carry infant on fur from birth. Have slow quadrupedal motion, with a tail that has been reduced to a stump. Omnivores. Solitary, little home range overlap. Since they're slow moving, don't leap. Fore and hind limbs are the same length.

Africa pre-Miocene fossil sites

No none fossil sited in Africa for the Paleocene and Eocene epochs (36-66 mya) that have yielded definite primate remains. Only Gayum site exists in Egypt for the Oligocene epoch. Rash to assume no prosimians in Africa simply due to lack of evidence and bias in fossil record.

Oligocene/Miocene new world monkeys

No substantial fossil evidence of marmoset and tamarin early relatives. Several other fossils found.

Lorisoid fossil history

No substantial fossil remains for prosimian primates living in Africa before mid-Miocene times 18-20 mya. A single upper molar tooth tentatively identified as a lorisioid has been reported from the Fayum site. Prosimians are generally quire small relative to simians, so sampling bias works against them.

Nocturnal orbital convergence benefits

Nocturnal animals improve image quality in the area of visual field overlap by increasing optic convergence. Also benefit from increased visual feild overlap because their eyes receive twice as many photons from any point in the binocular visual field.

Lens Mass vs Body Mass

Nocturnal species lie above line and diurnal lay on or below line. Nocturnal primates have bigger lenses.

Pen-tailed tree shrew

Nocturnal, more forward eyes and shorter snout.

Tarsiers

Nocturnal, weigh 60-200 g. Confined to island areas in southeast Asia, only 20 species. Specialized vertical clingers and leapers, and balance with distal tail when climbing. Powerful hind legs for vertical leaping. Form rudimentary family structures with monogamous pairs but normally forage alone at night. Largest eyes of any primate, each of which is bigger than the brain.

Sportive lemur

Nocturnal, weighs 600-800 grams. Folivores, so have an enlarged caecum. Use tree hollows as nests and move by vertical clingling and leaping. Named that because they box instead of biting when aggressive.

Thumbs

Non-primates like squirrels use the whole hand to grasp things, primates only use the thumb. Tree shrew uses the whole hand for grasping and claws. No primate lacks this specialized first digit for grasping, but some specialized swingers have lost or reduced thumb on hands, not used to manipulate. Only we have lost grasping power of foot.

True New World Monkeys

None build nests except for the Owl Monkey. Larger in size than marmosets and tamarins. Males carry young extensively.

Nonhuman primate birth mechanism

Nonhuman primate fetal head is normally facing forward or backward instead of sideways as it enters the birth canal. Also differences in fetal head orientation change through birth canal. Nonhuman primates rotated to a variable degree but emerge facing forward with head flexed, humans rotate to exit facing backward with head extended.

Degree of musculature in primates

Normally forelimbs about 35-45%, but reduced to 20% in humans. Hindlimbs in humans is 60%, other primates have 35-45%. Shift takes place between Authstralapithicus and us.

Dental formula

Numerical description of teeth, number of each kind of tooth. Incisors, canine, premolar, molar.

Agriculture theory brain size

Other attributes decrease to advent of agriculture, which may have had initial effect of worsening nutrition if first farmers weren't good at farming. Grain heavy diet is deficient in protein and vitamins, and due to chronic malnutrition, bodies and brains shrunk. However, agricultural revolution didn't arrive in Australia or southern Africa till almost contemporary times, yet brain still shrunk.

Galago tooth comb

Part of lorises. Each incisor is a tiny comb, but unclear what they're used for.

Possible Reason for secondary altriciality

Pelvic size placed a limit on prenatal brain growth around 1.5 mya. Homo habilis is last known hominid that had infants where half the brain growth was completed at birth. In response to pelvic constraint, infant's couldn've become secondarily altricial or shape of pelvis and mechanism of births would have to be changed. Experiment by Ruff estimated pelvic capacity of Homo erectus female could hold modern fetus until 33 weeks, concluded secondary altriciality was necessary in Homo erectus to achieve adult cranial capacity, but thought birth is non-rotational.

Baculum

Penis and clitorus bone, not attached to anything. Most variable bone in mammal bodies. Not in hoofed mammals. When you plot log Baculum length vs body mass, New world monkeys and apes below line, have a reduction.

Streshirines

Wet nose primates. Lemurs and lorises

Primate general skeleton

Primitive skeleton, and common ancestor was likely small and tree living, especially in an environment with skinny trees. All primates except humans have a grasping foot. Have claws if live in broad trees, but most are un-clawed and adapted to fine branch niche. Key to primate motion is central nervous system. Little fusion events. Bipedalism is recent development.

Benefit of placenta invasiveness

Probably involves a trade off in immunity. An invasive placenta must have immunological advantages as well as disadvantages.

What did Australopithecus eat?

Probably put less emphasis on foods that require substantial incisor use, such as those with thick husks and those with flesh adherent to large, hard seeds. Teeth well suited for breaking down hard, brittle foods (fruits and nuts) and soft, weak food (flowers, buds). Not well suited for tough pliant foods (stems, soft seed pods, and meat). Meat may have been eaten in rare occasions, indicated by evidence of tools.

Tree shrews bulla

Produce bony ectotympanic. Thought to have a similar petrosal connection to primates, but in reality the ectotympanic actually fuses in adulthood. Have to look at developmental processes.

Sylvian sulcus

Proper sylvian sulcus is obliquely backward groove between temporal and frontal lobe, very nice feature of the primate brain. Develops in the human brain as the temporal and frontal lobe develops, it's what left after two things have closed up. Is in every primate, unique to primates, but not present in tree shrews.

Expensive tissue hyposthesis

Proposes a trade-off between the size of the brain and digestive tract, which is smaller than expected for our body size. Reduction of mass and oxygen consumption in intestines. Was widely accepted, but tested it in sample of 100 mammals including 23 primates, and found that controlling for body mass, brain size is not negatively correlated with mass of the digestive tract or any other expensive organ. Wouldn't reduce liver because makes glucose, muscles already have low BMR, and heart and kidney are vital.

Hominid arms

Radius and ulna cross in prone position, allow for forearm rotation. Have a primitive, carnivore like elbow joint. Humans retain all primitive hand bones. Joint has material all around it, can move 180 degrees.

Why are primates so isolated?

Reasons unknown. Continental drift may have had some part in group isolation, but much more ancient than primates.

Tapetum

Reflective surface in the eye. 3 types, choroidal fibrous or cellular where the tapetum is behind the retina, or it can be on the retina itself. Reflects light back, doubles chances of seeing light in eyes. Gives eye shine. Normally blue-green, golden yellow in primates due to flat cells of riboflavin in tapetum, which also shifts wavelength.

Theory brain size and lifespan

Relative brain size is determinant of maximum life span. Relationship only found in primates so can't be used to predict max longevity.

Primate vs Mammals life history

Relative to mammals of the same body weight, primates have slower individual growth rates, longer lifespans, fewer babies. Life history variables are often correlated with body size, and allometric scaling of different life history variables are often linked to one another.

Primate growth rate

Relatively slow, because their birth weight is smaller than adult weight. Have to look at proportions of adult weight to see who actually grows faster. Weaned when 1/3 of adult weight. Brains grow at same rate

Primitive mammal eye condition

Relatively small, laterally oriented eyes that show very little convergence, and therefore have only a small area of binocular overlap.

Miocene Lorisoids

Represented by partial jaws and by inference some postcranial material. Progalago, Mioeuoticus, and Komba. Considered as a whole as representative of East African Miocene lorisoids, which were all relatively small-bodied forms. Can compare skulls of Mioeuoticus and bushbabies, looks similar.

3 Hypotheses for postorbital bar in primates

Resisting masticatory stresses Protecting the eye from injury Augmenting rigidity of the orbital margin to enhance visual acuity All but third hypothesis has been discounted.

Tarsiers Location

Restricted to certain islands in Southeast Asia.

Owen vs Huxley

Richard Owen, director of natural history museum, didn't believe in evolution, and Huxley was known as Darwin's bulldog. 1863, argued over man's place in nature. Owen claimed the human brain is unique because of the hippocampus minor, which is shaped like a seahorse, and the hoppocampus bulge. Inside is calcarine sulcus, which Huxley showed evidence it was a feature of all primates.

Types of True and Gentle Lemurs

Ringtail lemur, gentle lemur, mongoose lemur, variegated lemur.

Sakis and Uakaris

Sakis are predominantly frugivorous, while uakaris eat some leaves in addition to a basic diet of fruit. All live in relatively small groups. Red-faced.

Primate groups convergence and frontation

Simians have higher convergence and frontation, prosimians have lower convergence and frontation. Tree shrews are relatively small compared to primates and convergence and frontation is way out of range for primates, have a very large interorbital distance in tree shrews and plesiadapiforms.

Cheek tooth length scaling

Simians have reduced length and wider teeth. Humans have smallest teeth to body size in higher primates. Only other outlier is the aye-aye.

Plesiadapiform primate similarities

Similarity in teeth. Recent discovery of a fairly complete skeleton of Carpolestes appears to show a primate-like grasping foot, and has reopened debate of whether or not plesiadapiforms are ancient primates or not, but most prudent course is to treat them as a separate group.

Human noses

Small ethmoid, simplified nasal cavity, loss in olfaction. Only 2 turbinals, tiny olfactory bulb, no transverse lamina, not a lot of holes in cribiform plate.

Australopithecines dentition

Small incisors, like gibbons and gorillas. Dental microwear data patterns most similar to those of modern-day seed predators and soft fruit eaters. Relatively flat, blunt molar teeth and lacked the long shearing crests seen in some extant hominoids.

Madagascar

Small island but has 6 groups of lemurs, all lemurs only live there.

Mouse and Dwarf Lemurs

Small, omnivorous, nest-living, solitary. Very small, only weigh 60-440 g. Unusual because they can give birth to as many as 3 infants at a time, which they carry in their mouth. Typically seen alone, but females have an elaborate nest sharing system. When food is limited, has a special adaptation where it can store fat in tail.

Energy limited strategy

Smaller home range and group size, leaf eaters.

social brain hypothesis

Social complexity is primary driver of cognitive complexity. Positive relationship between relative brain/neocortex size and group sizes. 2 part system for visio-social cognition. Visual cortex is input device and non-visual cortex processes and encoded social cues, second is more important. Largest relative neocortex sizes in monogamous primates. Used small sample sizes, only looked at neocortex, study that fixed these found it was actually associated with diet, either have more energy or need to remember locations of fruits. We don't know how much brainpower these things actually need.

Subfossil lemurs

Some found, more modern. Megaladapis and paleopropithecus. Had a curved finger bone, which means suspends on branches. Larger, and some teeth on lemur fossils look like old-world monkeys.

Cooking Dentition changes

Something we can actually track with fossils. Reduction in tooth and jaw size indicates decreased need for chewing. 1.9 mya significant decrease, can't be explained by body size or craniodental reduction, suggests cooking started with H. erectus. Another at 100 kya, maybe a new cooking method.

Tarsiers Phylogeny

Special position among primates in between lemur and loris group on one and hand monkeys and apes on the other. Difficult to get an exact resolution on the phylogeny, because there are so few living species. Researchers who focus on living tarsiers place them with simians, but those who study fossil evidence question this placement.

Sifka locomotion

Specialized vertical clinger and leaper. When comes to ground, jump around and bounce on hind limbs. Bipedal hopping.

Smaller but smarter theory

Speculation that the brain's wiring patterns became more streamlines and/or neurochemistry shifted to boost our cognitive ability. Brains are 2% of volume but take up 20% of energy, if you could rewire and downsize, it would be advantageous to do so.

Reptile limbs

Sprawling gate. Limbs on all sides, front limb bent back and back bent forward with lever arm.

Digestive tract

Stomach then small intestine, then large intestine. At unction between the two intestines is a caecum which could have symbiotic bacteria, which could also be in the stomach. Appendix is attached to caecum. Old world monkeys also have cheek pouches.

Caecum vs body size

Stores bacteria. Chart has a lot of scatter. Gummivores and folivores are above line, as they have a more complex stomach with lots of symbiotic bacteria. Humans and some other primates have lost it completely.

Corneal diameter relative to axial diameter

Study showed that primates differed from other mammals in having large eyes relative body size. Higher primates/antrhopoids have unusually small corneas relative to eye size and body size. Large eyes of basal primates probably evolved to improve visual acuity while maintaining high sensitivity in a nocturnal context. Diurnal strepsirrhines retain larger cornea. Reduced corneal sizes of anthropoids reflect reductions in size of dioptric apparatus as a means of increasing posterior nodal distance to improve visual acuity. Supports conclusion that origin of anthropoids was associated with a change in eye shape to improve visual acuity in context of a diurnal predatory habitus.

Indri Subgroup

Subgroup of Lemurs. Plant eaters. Unique because they lack a tail. Arborial clingers and leapers, sometimes have bipedal hopping when they make infrequent excursions to the ground. Give birth to a single infant that is carried on parent's fur from birth. No nest use.

Leaf-Monkeys

Subgroup of Old World Monkeys. Have a specialized sacculated stomach containing symbiotic bacteria that break down the relatively indigestible cell walls of leaves.

Guenon Subgroup

Subgroup of Old World Monkeys. Show sexual dimorphism, especially among terrestrial species, where males can weigh as much as twice more than females and have larger caning teeth. Larger bodied species tend to eat a greater proportion of leaves or other plant material, but smaller species consume arthropod prey in appreciable quantities in addition to readily digestible plant items like fruit. Quadrupedal, but with great variation in locomotion. Have single infants carried on the mom's back, and known for forming harems. Generally forest living, arboreal species, but for some terrestrial life is relatively common.

Terrestrial Guenon Subgroup

Subgroup of old world monkeys. Species that spend a large amount of time on the ground typically have a hand modification that permits locomotion with the fingers used as a strut. Associated with foraging on the ground, cheek pouch monkeys. Ex: Erythrocebus, Macaca, Mandrill, Papio, theropithecus, and more terrestrial of the managabeys. Vervet monkey and patas monkey are partially terrestrial.

Bushbabies

Subset of lorises. Restricted to mainland Africa. Have an active lifestyle and weigh 65 grams to 1.3 kg. Characterized by a single species that was studied known as Demidoff's bushbaby. Leap, have large forelimbs and tail.

Cartmill Visual Predation Hypothesis.

Suggested that convergent orbits facilitate visual predation on insects on fine branches of the shrub layer of tropical rainforests.

Haplorhines tapetum

Tapetum missing, even in nocturnal species. Came from diurnal ancestor.

Which primate groups are nocturnal?

Tarsiers and owl monkeys are the only nocturnal higher primates. True lemurs are a mixture of diurnal and nocturnal. Indri and Sifaka independently evolved diurnal behavior. Lower primates mostly nocturnal.

Omomyidae

Tarsoids, skulls resemble modern tarsiers. Necrolemur, Nannopithex, and Rooneyia. Have open orbits, meaning that tarsiers formed partially closed orbits independently from higher primates. Tarsiers existed in Eocene.

Nasolacrimal duct

Tear ducts. Fossil evidence that simians have vertical ducts and prosimians have diagonal ducts.

Testes descent

Testes descend from near kidney to a sac, very far back. Tree shrews have testes in pre-penile position like in marsupials, maybe primitive condition. In primates descent has occurred by time of birth, not sexual maturity.

Intermembral index vs body size

The bigger the primate, the more likely it is for them to move underneath branches, so vertical climbing and leaping least likely, then quadrupedalism, then arm swinging. Bigger has balancing problems when traveling on tops of branches, so need arm swinging or quadrupedalism. Humans outlier, our limb length is more like vertical climbers and leapers, weird for body size, longer hindlimbs than forelimbs.

Summary of Hominids dentition

Throughout the hominids there was a shift from C3 to C4 and CAM. Dental microware doesn't demonstrate the food was tougher. However, this may be due to the fact that tools were used to break down the material before eating it.

Primate Adaptations

Thumb Grasping foot Nails instead of claws on big toes, and maybe others. Meissner's corpuscle Prehensile/grasping tail Ischial tuberosity Arm and limb structure Balance organs Ankle double-joint system

Hominid legs

Tibia and fibula remain unfused. Primitive, universal for all primates. Fused would eliminate any sideways movement of ankle. Specializations for terrestrial life means mor efusion, unfused helps move around in complex 3D environment.

Calcarine sulci

Triradiate calcarine sulcus is very characteristic of living primates, tarsiers, lemurs, and humans. Sylvian and calcarine sulci are not in tree shrews. Can't look in fossil records for calcarine sulcus. Not in tree shrews

Aye-aye

Type of lemur. Have claws rather than flat nails on all digits except the big toe, and the middle finger forms a long probe to catch insects. Occupies niche of woodpeckers, probes for wood boring larvae with finger. Female has a single infant which is carried on fur from birth onwards. Has an essentially solitary lifestyle. Rodent like teeth. Completely nocturnal.

First fossil primate

Undoubted relatives of modern primates, or euprimates, first appear in the fossil record at the beginning of the Eocene epoch, about 55 mya. Origin of primates may be in cretaceous, large gaps in fossil record, such as between 30-20 mya.

Grasping foot

Universal for primates. Some primates lose/reduce thumb on hand (Colobus, spider monkey, gibbon).

Plesiadapiform characteristics

Unusual specialization of enlarged anterior teeth. Many primitive features like claws on digits, absence of a postorbital bar, small brain, smooth neocortext, and midbrain exposure. The brain is also much more primitive than that on any true primate.

How we tell how important smell is

Use size of olfactory bone and cribiform plate, a bony area and palate dedicated to smell.

Colon vs Body Size

Used for water reabsorption from food. Most primates above line, since mainly tree-dwelling. They aren't near water, must absorb from food to survive.

Adapids Dentition

Used to push idea that European Eocene adapids were specifically related to discrete groups of lemurs. However, this interpretation conflicts with other evidence that indicates the Adapis species are specialized forms with no direct relationship to modern strepsirrhines. The post cranial bones in Adapis indicate locomotor adaptation was unlike modern lemurs, and any dental similarities are due to convergent evolution.

4 categories of locomotion

Vertical clinging and leaping with hind limbs: tarsiers, lemurs. Not in any higher primates Quadrupedalism: Most common. Lorises, tree lemurs, old world monkeys. Includes leaping between branches but no specialized adaptation. Arm swinging: ape, free-flight gibbons. Brachiation, specialized form with free flying phase. Arms much longer than legs. Bipedalism: humans. Striding and bipedalism are unique to humans, no parallel between other vertebrates.

Warming theory brain size

Warming trend in Earth's climate also began 20k years ago. However, comparable warming periods occurred many times over the previous 2 million years, yet body and brain size regularly increased.

Theories for brain size decline

Warming, nutrition, domestication theory, smaller but smarter.

Domestication theory

We domesticated ourselves to live together in society. In domesticated fox experiment, became smaller, less testosterone, and more docile, likewise we had a similar trend occur. 30 domesticated animals have a 10-15% reduction in brain size. Social size groups negatively correlated with brain size.

Adaptations for speech

We have low larynx and short rounded tongue. Short horizontal and long vertical tube, may have helped us do speech. Chimps have the opposite, so did neandrathal.

Ringtail Lemur

Weigh around 2 kg. Diurnal and spends significant time on all fours, with occasional vertical clinging and leaping among vertical supports. Has one infant at birth, but twins seen more frequently than other diurnal lemur species. Carries infant on mother's fur. Only lemur that spends significant time on the ground. They sit splayed in the sun to warm up in the morning.

Demidoff's bushbaby

Weighs 65 grams. Omnivorous and eats fruits, gums, and animal prey. Has a wide range of locomotion such as clambering, quadrupedal running, vertical clinging and leaping, and bipedal ground hopping. Construct nests and have a similar reproduction to mouse lemurs, in that they use the nest and the infant is carried in the mouth, but only have one infant. Females share nests and have overlapping home ranges.

Caecum

a pouch connected to the junction of the small and large intestines. Important role in digestion, mixes food with mucus.

Maternal Energy Hypothesis

brain size depends on the allocation of maternal resources to fetal and postnatal development. No direct link between behavioral capacities and brain size in mammals.

Snout comprises of...

dentition and olfaction

Cope's Law

during the course of evolution, animals tend to increase in size until they become extinct