anthro test 3

flores

Flores is one of the Lesser Sunda Islands, a group of islands in the eastern half of Indonesia. n September 2003, at Liang Bua Cave in western Flores, paleoanthropologists discovered small skeletons that they described as a previously unknown hominin species, Homo floresiensis.

Earliest anatomically modern humans

The earliest known remains of Cro-Magnon-like humans are radiocarbon dated to 43-45,000 years before present that have been discovered in Italy[3] and Britain,[4] with the remains found of those that reached the European Russian Arctic 40,000 years ago.[5][ The earliest known fossils of anatomically modern humans such as the Omo remains from 195,000 years ago, Homo sapiens idaltu from 160,000 years ago, and Qafzeh remains from 90,000 years ago are recognizably modern humans.

Turkana Boy

Turkana Boy, now called Nariokotome Boy, is the common name of Homo erectus[1] fossil KNM-WT 15000,[nb 1] a nearly complete skeleton of a hominin youth who lived during the early Pleistocene. This specimen is the most complete early human skeleton ever found. It is believed to be between 1.5 and 1.6 million years old. The skeleton was discovered in 1984 by Kamoya Kimeu, a member of a team led by Richard Leakey, at Nariokotome near Lake Turkana in Kenya

Ardipithecus

About 4.4 million years ago Ardipithecus ramidus was first reported in 1994; in 2009, scientists announced a partial skeleton, nicknamed 'Ardi'. The foot bones in this skeleton indicate a divergent large toe combined with a rigid foot - it's still unclear what this means concerning bipedal behavior. The pelvis, reconstructed from a crushed specimen, is said to show adaptations that combine tree-climbing and bipedal activity. The discoverers argue that the 'Ardi' skeleton reflects a human-African ape common ancestor that was not chimpanzee-like. A good sample of canine teeth of this species indicates very little difference in size between males and females in this species. Over 100 specimens of Ardipithecus ramidus have been recovered in Ethiopia. Even though it has some ape-like features (as do many other early human species), it also has key human features including smaller diamond-shaped canines and some evidence of upright walking.

Sagittal crest

A sagittal crest is a ridge of bone running lengthwise along the midline of the top of the skull (at the sagittal suture) of many mammalian and reptilian skulls, among others. The presence of this ridge of bone indicates that there are exceptionally strong jaw muscles. Some Australopithecus afarensis and the robust australopithecines (Australopithecus robustus, boisei, and aethiopicus) had sagittal crests. Among the living primates, the most prominent sagittal crests are found on adult male gorillas. Humans do not have them.

carbon dating

C (Half-life = 5730 years) dating is the only absolute technique in which actual once living remains are tested by comparing the constant 12C to the remaining 14C an idea of how old the artifact is can be determined only useful up to ~ 40,000 years

First Family

First Family", is a collection of prehistoric hominid teeth and bones. Discovered in 1975 by Donald Johanson's team in Hadar, Ethiopia, the "First Family" is estimated to be about 3.2 million years old, and consists of the remains of at least thirteen individuals of different ages.[1] They are generally thought to be members of the species Australopithecus afarensis. There are multiple theories about the hominids' cause of death and some debate over their species and sexual dimorphism.

Laetoli

Laetoli is a site in Tanzania, dated to the Plio-Pleistocene and famous for its hominin footprints, preserved in volcanic ash. Based on analysis of the footfall impressions "The Laetoli Footprints" provided convincing evidence for the theory of bipedalism in Pliocene hominins Dated to 3.7 million years ago, they were the oldest known evidence of hominin bipedalism at that time. Subsequently, older Ardipithecus ramidus fossils were found with features that suggest bipedalism. With the footprints there were other discoveries excavated at Laetoli including hominin and animal skeletal remains. Analysis of the footprints and skeletal structure showed clear evidence that bipedalism preceded enlarged brains in hominins. At a species level, the identity of the hominins who made the trace is obviously difficult to precisely construe; Australopithecus afarensis is the species most commonly proposed. Mary Leakey went to Laetoli in 1976 and within weeks found 13 hominins - Au. afarensis the Laetoli footprints consisted of over 20,000 footprints of which the footprints of Au. afarensis were discovered dated ~ 3.56 Ma footprints were a result of a volcanic eruption spewing ash and tephra around which was soon followed (luckily) by rain, this in turn formed a kind of natural cement that preserved the footprints

Mousterian

Mousterian is a name given by archaeologists to a style of predominantly flint tools (or industry) associated primarily with Neanderthals (Homo neanderthalensis). They date to the Middle Paleolithic, the middle part of the European Old Stone Age. Dates 600,000 - 40,000 BP Acheulean (1.8-0.1 Ma) Lower Paleolithic (c. 3.3 Ma - 300 ka) Oldowan (2.6-1.7 Ma) Middle Paleolithic (300-45 ka) Mousterian (150-40 ka) pear-shaped "hand-axes" associated with early humans. Acheulean tools were produced during the Lower Palaeolithic era across Africa and much of West Asia, South Asia, and Europe, and are typically found with Homo erectus remains. It is thought that Acheulean technologies first developed in Africa out of the more primitive Oldowan technology as long ago as 1.76 million years ago, by Homo habilis.[citation needed] Acheulean tools were the dominant technology for the vast majority of human history.

Occlusal Relief

Occlusal Relief - is the relative 'up and down' surface of teeth, such as those present for shearing crests. Those with really flat molars eat fruit and nuts, while those with lots of occlusal relief eat tough food, as it helps to slice through (leaves, meat, insects). In general, hominins tend to have very flat molars, especially Paranthropus (who also had small incisors) Flora: Leaf eaters have scratches in one direction, while fruit and nuts will leave pitting. Fauna leaves micro-scratches that are lined E. Africa and S. Africa diets have shown to be different due to this research Australopithecus africanus had some pitting, Paranthropus robustus had lots of pitting, so it seemed that Paranthropus boisei should have even more pitting but actually had none; there was no evidence for hard food eating (perhaps some fruit and leaves, but that's about it).

Dates of the earliest potential and probably hominins

Paranthropus robustus ~ 1.0 - 2.0 Ma large zygomatics (cheek bones) has a sagittal crest large post-canine dentition the mandibular muscles connect through, and along, the temporal fossa (increased jaw strength) large masticatory complex very small forehead face is described as a "dish face" type shape EQ: 3.0 Australopithecus africanus ~ 2.1 - 2.6 Ma more organathic face larger brains / cranium size small canines that wear at the tip - they function as part of the grinding complex bicuspid premolars larger post-canine dentition (megadont) smaller anterior dentition EQ: 2.7 Sexual dimorphism in Au. africanus no canine dimorphism (even in males)

K/Ar dating

Potassium-argon dating: aging based on the content of potassium-argon. This is commonly used in rocks. The half life of potassium is 1.3 billion years 40K/40Ar: (Half-life = ~ 1.25 to 1.36 billion years) stable potassium (39K) is measured to the relative amount of radioactive potassium (40K) and then compared to the amount of argon remaining in the sample can be used for the most ancient objects (3.6 ~ 3.8 billion years)

Earliest cave paintings

The Chauvet-Pont-d'Arc Cave in the Ardèche department of southern France is a cave that contains the earliest known and best preserved figurative cave paintings in the world,[ dates fall into two groups, one centered around 27,000-26,000 BP and the other around 32,000-30,000 BP.

Dmanisi

The Dmanisi skull, also known as Skull 5 or D4500, is one of five Homo erectus skulls discovered in Dmanisi, Georgia Described in a publication in October 2013, it is believed to be about 1.8 million years old and is the most complete skull of a Pleistocene Homo species,[1][2] and the first complete adult hominin skull of that degree of antiquity.

The Taung Child

The Taung Child (or Taung Baby) is the fossilised skull of a young Australopithecus africanus. It was discovered in 1924 by quarrymen working for the Northern Lime Company in Taung, South Africa. Raymond Dart described it as a new species in the journal Nature in 1925. The Taung skull is in repository at the University of Witwatersrand.[1] Dean Falk, a specialist in brain evolution, has called it "the most important anthropological fossil of the twentieth century." estimated to be from 2.5 Ma Raymond Dart, then the head of the department of anatomy at the University of the Witwatersrand in Johannesburg, South Africa, became interested in fossils found at a limestone quarry at Taung near Kimberley, South Africa in 1924.[3][4] The most promising of these was a skull of an odd ape-like creature presenting human traits at the eye orbits, teeth, and, most importantly, the hole at the base of the skull over the spinal column (the foramen magnum); its placement indicated a human-like upright posture and implied a high probability that this hominid-to-hominin primate had achieved bipedal, as opposed to quadrupedal locomotion.

Australopithecus anamensis

When Lived: About 4.2 to 3.9 million years ago Australopithecus anamensis has a combination of traits found in both apes and humans. The upper end of the tibia (shin bone) shows an expanded area of bone and a human-like orientation of the ankle joint, indicative of regular bipedal walking (support of body weight on one leg at the time). Long forearms and features of the wrist bones suggest these individuals probably climbed trees as well. Jaw remains suggest that this species was the direct ancestor of Australopithecus afarensis

Molars and occlusal relief

investigated the dietary adaptations of A. afarensis and early Homo by looking at the three-dimensional topography of their teeth. the shapes of the teeth are expected to reflect diet because the teeth themselves are adaptations for processing food. looking specifically at primates, high-crowned teeth that interlock between the upper and lower jaws are adapted to shearing foods, in a manner analogous to the pinking shears of a seamstress. actions necessary to process leaves and insects primates that specialize on other foods, notably fruits or harder objects like seeds, tends to have flatter teeth without high crests. These teeth useful for crushing or grinding foods.

Plesiadapiformes

s an extinct (and possibly paraphyletic or polyphyletic[1] [2] [3] ) order of mammals. The group is either closely related to the primates or a precursor to them. Many are too derived to be ancestral to primates, but the earliest Plesiadapiformes had teeth that are strongly indicative of a common ancestor. Plesiadapiformes first appear in the fossil record between 65 and 55 million years ago,[4] although many were extinct by the beginning of the Eocene. They may have been the first mammals to have finger nails in place of claws.[

Paranthropus robustus

1938 at the Kromdraai Site in Swartkrans, SK-48 a Paranthropus robustus was discovered fossil exhibited no forehead like Au. africanus but instead had a sagittal crest (bone on the top of the cranium that looks like a 'bone-mohawk') the jaw was heavy and robust comparatively Paranthropus robustus is an example of a robust australopithecine; they had very large megadont cheek teeth with thick enamel and focused their chewing in the back of the jaw. Large zygomatic arches (cheek bones) allowed the passage of large chewing muscles to the jaw and gave P. robustus individuals their characteristically wide, dish-shaped face. A large sagittal crest provided a large area to anchor these chewing muscles to the skull. These adaptations provided P. robustus with the ability of grinding down tough, fibrous foods. It is now known that 'robust' refers solely to tooth and face size, not to the body size of P. robustus. About 1.8 to 1.2 million years ago History of Discovery: When scientist Robert Broom bought a fossil jaw fragment and molar in 1938 that didn't look anything like some of the Au. africanus fossils he'd found during his career, he knew he was on to something different. After exploring Kromdraai, South Africa, the site where the curious fossils came from, Broom collected many more bones and teeth that together convinced him he had a new species which he named Paranthropus robustus (Paranthropus meaning "beside man"). Africa. The average brain size of P. robustus measured to only 410 and 530 cc, about as large as a chimpanzee's

Biostratigraphy

A method of determining the relative date of a layer by identifying fossils biodiversity in the layer and matching them to fossils biodiversity in a different location where the layer has already been dated using alternate methods. However, this is not always exact, because something might go locally extinct in the United States area and remain in Africa for another 10 million years.

Chronometric dating

Absolute dating is the process of determining an age on a specified chronology in archaeology and geology. Some scientists prefer the terms chronometric or calendar dating, as use of the word "absolute" implies an unwarranted certainty of accuracy. usually based upon measuring the rate radioactive decay.

Acheulean

Acheulean (/əˈʃuːliən/; also Acheulian), from the French acheuléen, is an archaeological industry of stone tool manufacture characterized by distinctive oval and pear-shaped "hand-axes" associated with early humans. 1.76 million years BP - 100 thousand years BP came right affter oldwon

Australopithecus afarensis

Australopithecus afarensis is one of the longest-lived and best-known early human species—paleoanthropologists have uncovered remains from more than 300 individuals! Found between 3.85 and 2.95 million years ago in Eastern Africa (Ethiopia, Kenya, Tanzania), this species survived for more than 900,000 years, which is over four times as long as our own species has been around. It is best known from the sites of Hadar, Ethiopia ('Lucy', AL 288-1 and the 'First Family', AL 333); Dikika, Ethiopia (Dikika 'child' skeleton); and Laetoli (fossils of this species plus the oldest documented bipedal footprint trails). Au. afarensis had both ape and human characteristics: members of this species had apelike face proportions (a flat nose, a strongly projecting lower jaw) and braincase (with a small brain, usually less than 500 cubic centimeters -- about 1/3 the size of a modern human brain), and long, strong arms with curved fingers adapted for climbing trees. They also had small canine teeth like all other early humans, and a body that stood on two legs and regularly walked upright. Their adaptations for living both in the trees and on the ground helped them survive for almost a million years as climate and environments changed.

Australopithecus africanus

Australopithecus africanus is an extinct (fossil) species of the australopithecines, the first of an early ape-form species to be classified as hominin (in 1924). Recently it was dated as living between 3.3 and 2.1 million years ago, or in the late Pliocene and early Pleistocene times; it is debated as being a direct ancestor of modern humans.[2] A. africanus was of slender, or gracile, build and has been found only in southern Africa at four sites: Taung (1924), Sterkfontein (1935), Makapansgat (1948) and Gladysvale (1992).[1] classified as a hominin has small canines - similar to hominids parabolic dental arcade the brain endocast inferred a lunate sulcus - part of the occipital lobe that marks the front boundary of the visual area had a relatively large brain centrally located forament magnum indicating bipedalism Au. africanus was anatomically similar to Au. afarensis, with a combination of human-like and ape-like features. Compared to Au. afarensis, Au. africanus had a rounder cranium housing a larger brain and smaller teeth, but it also had some ape-like features including relatively long arms and a strongly sloping face that juts out from underneath the braincase with a pronounced jaw. Like Au. afarensis, the pelvis, femur (upper leg), and foot bones of Au. africanus indicate that it walked bipedally, but its shoulder and hand bones indicate they were also adapted for climbing, A. africanus and Australopithecus afarensis have similar post-cranial morphologies and both exhibit a high degree of sexual dimorphism. However, A. africanus' derived cranial morphology includes a higher forehead, slightly larger cranial capacity of approximately 461 cc, less pronounced brow ridge, smaller canines and large molars. The inferiorly placed foramen magnum, and the morphology of the pelvis demonstrates that A. afarensis was bipedal.

Ideas about why hominins become bipedal

Carrying Hypothesis Darwin was the first to note that individuals carrying and using tools would have a difficult time simultaneously using their hands for locomotion Owen Lovejoy argued that bipedalism may have evolved to enhance reproductive strategies. the males go out to collect food that they must carry back to the females Limitations of this hypotheses: tool use dates back to 2.6 Ma while evidence of bipedal locomotion dates back further to about 4 Ma, before stone tool fossils existed however, tools that were made of materials that do not fossilize were probably used also Energy Efficiency Hypothesis When the home-range grows, individuals need to walk farther and walking on two feet instead of four is much more energy efficient Rodman McHenry studied the oxygen consumption of bipeds and quadrupeds at walking speeds and found that bipeds use 33% less oxygen at walking speeds when bipeds run, they are incredibly inefficient with energy Feeding Hypothesis Suggests that eating bipedally was more convenient and then became an adaptation instead of just a habit Thermoregulatory Hypothesis Proposes that bipedalism raises the amount of body surface area higher above the ground which results in a reduction in heat gain and helps heat dissipation. When a hominid is higher above the ground, they can access more favorable wind speeds and temperatures. During heat seasons, greater wind flow results in a higher heat loss, which makes the organism more comfortable

Mrs. Ples

Dart's theory—that the skull known as the Taung child was a human ancestor—was supported by Robert Broom, a paleontologist with the Transvaal Museum of natural history in Pretoria.[9] In 1936, the Sterkfontein caves yielded the first adult australopithecine, substantially strengthening Dart's claim for Broom. Later, Broom classified an adult endocranial cast having a brain capacity of 485 cc (found by G. W. Barlow) as Plesianthropus transvaalensis (near-man from Transvaal). In April 1947, while blasting at Sterkfontein, he and John T. Robinson discovered a skull belonging to a middle-aged female[10] (catalogue number STS 5) which he also classified as Mrs. Ples, whose cranial capacity is only about 485 cubic centimetres, was one of the first fossils to reveal that upright walking (bipedal locomotion) had evolved well before any significant growth in brain size.[11] And, in comparison to modern apes, Dart noted as with the Taung child the lack of facial (prognathous) projection, a character in common with advanced hominines. Mandibular prognathism is a protrusion of the mandible, affecting the lower third of the face. Alveolar prognathism is a protrusion of that portion of the maxilla where the teeth are located, in the dental lining of the upper jaw

Carbon isotopes

In tropical and subtropical environments, the tissues of plants that follow a C4 photosynthetic pathway, mainly grasses and some sedges, tend to be enriched in 13C relative to 12C. In contrast, the tissues of plants that follow a C3 pathway, mainly trees, shrubs, bushes, and forbs, tend to be much poorer in 13C. The tissues of plants that follow the Crassulacean acid metabolism (CAM) photosynthetic pathway, mainly succulents, resemble C4 plants in 13C enrichment, but they were probably rarely important ... Plants incorporating a C3 pathway are selective in their use of carbon isotopes. Most plants native to temperate regions have C3 pathways... if it is a tree, shrub, legume, or tuber; there is good change that it is a C3 plant. A few examples of C3 foods are: rice, wheat, coffee and teas, grapes, peanuts, potatoes, lemons, apples, and carrots. This category encompasses the majority of leafy plants. Deer, rabbits, gophers, and other animals that consume C3 plants also have a C3 isotopic signal. Plants that have C4 pathways discriminate against carbon isotopes, creating a different isotopic signature from those of C3 plants. C4 plants tend to grow in hot and arid, or tropical climates. A few examples of C4 foods are: corn, seaweed, pineapple, amaranth, sorghum, millet, and sugarcane. Additionally, crassulacean acid metabolism plants (just remember them as CAM plants), such as cactus, also have a C4 signal and marine animals produce C4 isotopic signals. Differences in carbon isotope signals of people, specifically those of C3 and C4 can tell us a lot about dietary preference. For example, a diet predicated on deer and acorns will have a heavy C3 signature and look different then a diet incorporating corn, or marine resources.

Olduvai Gorge

Olduvai Gorge, or Oldupai Gorge, in Tanzania is one of the most important paleoanthropological sites in the world; it has proven invaluable in furthering understanding of early human evolution The British/Tanzanian paleoanthropologist-archeologist team Mary and Louis Leakey established and developed the excavation and research programs at Olduvai Gorge which achieved great advances of human knowledge and world-renowned status. Homo habilis, probably the first early human species, occupied Olduvai Gorge approximately 1.9 million years ago (mya); then came a contemporary australopithecine, Paranthropus boisei, 1.8 mya, and then Homo erectus, 1.2 mya. Homo sapiens is dated to have occupied the site 17,000 years ago. The site is significant in showing the increasing developmental and social complexities in the earliest humans, or hominins, largely as revealed in the production and use of stone tools. And prior to tools, the evidence of scavenging and hunting—highlighted by the presence of gnaw marks that predate cut marks—and of the ratio of meat versus plant material in the early hominin diet. The collecting of tools and animal remains in a central area is evidence of developing social interaction and communal activity. All these factors indicate increase in cognitive capacities at the beginning of the period of hominids transitioning to hominin—that is, to human—form and behavior.

Orrorin

Orrorin tugenensis is a postulated early species of Homininae, estimated at 6.1 to 5.7 million years It is not confirmed how Orrorin is related to modern humans. Its discovery was an argument against the hypothesis that australopithecines are human ancestors, as much as it still remains the most prevalent hypothesis of human evolution as of 2012.[1] If Orrorin proves to be a direct human ancestor, then australopithecines such as Australopithecus afarensis ("Lucy") may be considered a side branch of the hominid family tree: Orrorin is both earlier, by almost 3 million years, and more similar to modern humans than is A. afarensis. The main similarity is that the Orrorin femur is morphologically closer to that of H. sapiens than is Lucy's; there is, however, some debate over this point.[6] Living around 6 million years ago, Orrorin tugenensis is the one of the oldest early humans on our family tree. Individuals of this species were approximately the size of a chimpanzee and had small teeth with thick enamel, similar to modern humans. The most important fossil of this species is an upper femur, showing evidence of bone buildup typical of a biped - so Orrorin tugenensis individuals climbed trees but also probably walked upright with two legs on the ground. Tugen Hills region of central Ken

Proconsul

Proconsul is an extinct genus of primates that existed from 23 to 25 million years ago during the Miocene epoch. Fossil remains are present in Eastern Africa including Kenya and Uganda. The gibbons, great apes and humans are held in evolutionary biology to share a common ancestral lineage, which may have included Proconsul hey had a mixture of Old World monkey and ape characteristics, so their placement in the ape superfamily Hominoidea is tentative, with some scientists placing Proconsul outside it, before the split of the apes and Old World monkeys. Proconsul's monkey-like features include pronograde postures, indicated by a long flexible back, curved metacarpals, and an above-branch arboreal quadrupedal positional repertoire. The primary feature linking Proconsul with extant apes is its lack of a tail; other "ape-like" features include its enhanced grasping capabilities, stabilized elbow joint and facial structure. Proconsul was definitely not suspensory like modern apes. Early ape-like creatures Similarities to apes: Y-5 dental pattern with bilophodant molars Large brain size No tail No iscial colosity Differences from apes: More lumbar vertebra More monkey-like back Limb proportions--arms are shorter than legs No evidence of knuckle walking

Shanidar cave

Shanidar Cave (Kurdish: Şaneder or Zewî Çemî Şaneder; Arabic: كَهَف شانِدَر‎‎) is an archaeological site located on Bradost Mountain in Iraq.[1] The remains of ten Neanderthals, dating from 35,000 to 65,000 years ago, have been found within the cave.[1] The cave also contains two later "proto-Neolithic" cemeteries, one of which dates back about 10,600 years and contains 35 individuals.[2] The best known of the Neanderthals is Shanidar 1, who survived several injuries during his life, possibly due to care from other members of his band, and Shanidar 4, whose body lay beside a flower that can either be explained as evidence of burial rituals or animal contamination.

Sterkfontein

Sterkfontein (Afrikaans for Strong Spring) is a set of limestone caves. Numerous early hominin remains have been found at the site over the last few decades. These have been attributed to Australopithecus, early Homo and Paranthropus. n 1936, the Sterkfontein caves yielded the first adult Australopithecine, substantially strengthening Raymond Dart's claim that the skull known as the Taung child (an Australopithecus africanus) was a human ancestor. In 1947 he found the almost complete skull of an adult female (STS 5) A. africanus (or possibly that of an adolescent male). Robert Broom initially named the skull Plesianthropus transvaalensis (near-man from Transvaal), but it became better known by its nickname, Mrs. Ples. Mrs Ples is now defined as a member of A. africanus. In 1997, a near complete skeleton of a second species of Australopithecus (StW 573) was found in the caves by Ronald J. Clarke; extraction of the remains from the surrounding breccia is ongoing. The skeleton was named Little Foot, since the first parts found (in 1995, in storage) were the bones of a foot. Excavations continue to this day and finds now total some 500 hominids, making Sterkfontein one of the richest site in the world for early hominids. Sk-48 - one of the best preserved Paranthropus robustus skulls found that some fossils showed signs of lumbar lordosis

Expensive tissue hypothesis

The brain is a very expensive organ in metabolic terms. Each unit of brain tissue requires over 22 times the amount of metabolic energy as an equivalent unit of muscle tissue. There is no correlation across mammals, however, between the relative size of the brain and the relative basal metabolic rate. The Expensive Tissue Hypothesis explains this apparent paradox by looking at the metabolic cost of the brain in the context of the costs of other metabolically expensive organs in the body. The results show that the increase in brain size in humans is balanced by an equivalent reduction in the size of the gastro-intestinal tract. In other words, the increased energetic demands of a relatively large brain are balanced by the reduced energy demands of a relatively small gastro-intestinal tract. The size of the gastro-intestinal tract is dependent on both body size and the quality of the diet. It is argued that humans (and other primates) could not have developed a relatively large brain without also adopting a high quality diet that would have permitted a reduction in the relative size of the gastro-intestinal tract. Dietary change is therefore viewed as a prime releaser in brain evolution. It is argued that a high quality diet is necessary for the evolution of a relatively large brain. However, the change to such a high quality diet, which involved an increased proportion of animal based products, need not have been one of the prime movers in brain evolution.

Savanna hypothesis

There are many ideas about the role of the environment in human evolution. Some views assume that certain adaptations, such as upright walking or tool-making, were associated with drier habitat and the spread of grasslands, an idea often known as the savanna hypothesis.

Regional continuity

Under the Multiregional evolution hypothesis, the first humans to leave Africa 1.8 million years ago never divided into different species. Instead, these populations always exchanged genes with each other through recurrent gene flow. Today, we are part of this same species, which has evolved greatly over time to a very different morphology and behavior from the first humans. The low genetic differences among human populations are a result of a history of gene flow between ancient populations. Our present morphology and behavior have greatly changed from archaic humans because of natural selection in a global human population. Resemblances between archaic and modern humans in some parts of the world are the result of ancestry. breeding

Homo habilis

When Lived: 2.4 million to 1.4 million years ago This species, one of the earliest members of the genus Homo, has a slightly larger braincase and smaller face and teeth than in Australopithecus or older hominin species. But it still retains some ape-like features, including long arms and a moderately-prognathic face. Its name, which means 'handy man', was given in 1964 because this species was thought to represent the first maker of stone tools. Currently, the oldest stone tools are dated slightly older than the oldest evidence of the genus Homo. A team led by scientists Louis and Mary Leakey uncovered the fossilized remains of a unique early human between 1960 and 1963 at Olduvai Gorge in Tanzania. The type speciman, OH 7, was found by Jonathan Leakey, so was nicknamed "Jonny's child". Because this early human had a combination of features different from those seen in Australopithecus, Louis Leakey, South African scientist Philip Tobias, and British scientist John Napier declared these fossils a new species, and called them Homo habilis (meaning 'handy man'), because they suspected that it was this slightly larger-brained early human that made the thousands of stone tools also found at Olduvai Gorge. This species, along with H. rudolfensis, is one of the earliest members of the genus Homo. Many scientists think it is an ancestor of later species of Homo, possibly on our own branch of the family tree. Naming this species required a redefining of the genus Homo (e.g., reducing the lower limit of brain size), sparking an enormous debate about the validity of this species. H. habilis' brain capacity of around 640 cm³ was on average 50% larger than australopithecines, but considerably smaller than the 1350 to 1450 cm³ range of modern Homo sapiens.

Homo rudolfensis

When Lived: About 1.9 million to 1.8 million years ago There is only one really good fossil of this Homo rudolfensis: KNM-ER 1470, from Koobi Fora in the Lake Turkana basin, Kenya. It has one really critical feature: a braincase size of 775 cubic centimeters, which is considerably above the upper end of H. habilis braincase size. At least one other braincase from the same region also shows such a large cranial capacity. Originally considered to be H. habilis, the ways in which H. rudolfensis differs is in its larger braincase, longer face, and larger molar and premolar teeth. Due to the last two features, though, some scientists still wonder whether this species might better be considered an Australopithecus, although one with a large brain!

Homo floresiensis

When Lived: About 100,000 - 50,000 years ago Remains of one of the most recently discovered early human species, Homo floresiensis (nicknamed 'Hobbit'), have so far only been found on the Island of Flores, Indonesia. The fossils of H. floresiensis date to between about 100,000 and 60,000 years ago, and stone tools made by this species date to between about 190,000 and 50,000 years old. H. floresiensis individuals stood approximately 3 feet 6 inches tall, had tiny brains, large teeth for their small size, shrugged-forward shoulders, no chins, receding foreheads, and relatively large feet due to their short legs. Despite their small body and brain size, H. floresiensis made and used stone tools, hunted small elephants and large rodents, coped with predators such as giant Komodo dragons, and may have used fire. The diminutive stature and small brain of H. floresiensis may have resulted from island dwarfism—an evolutionary process that results from long-term isolation on a small island with limited food resources and a lack of predators. Pygmy elephants on Flores, now extinct, showed the same adaptation. The smallest known species of Homo and Stegodon elephant are both found on the island of Flores, Indonesia. However, some scientists are now considering the possibility that the ancestors of H. floresiensis may have been small when they first reached Flores.

Paranthropus boisei

When Lived: About 2.3 to 1.2 million years ago Like other members of the Paranthropus genus, P. boisei is characterized by a specialized skull with adaptations for heavy chewing. A strong sagittal crest on the midline of the top of the skull anchored the temporalis muscles (large chewing muscles) from the top and side of the braincase to the lower jaw, and thus moved the massive jaw up and down. The force was focused on the large cheek teeth (molars and premolars). Flaring cheekbones gave P. boisei a very wide and dish-shaped face, creating a larger opening for bigger jaw muscles to pass through and support massive cheek teeth four times the size of a modern human's. This species had even larger cheek teeth than P. robustus, a flatter, bigger-brained skull than P. aethiopicus, and the thickest dental enamel of any known early human. Cranial capacity in this species suggests a slight rise in brain size (about 100 cc in 1 million years) independent of brain enlargement in the genus Homo. Paleoanthropologists actually found the first fossils belonging to P. boisei in 1955, but it wasn't until Mary Leakey's 1959 discovery of the 'Zinj' skull (OH 5) that scientists knew what they had found was a new species. 'Zinj' became the type specimen for P. boisei and, soon after, arguably the most famous early human fossil from Olduvai Gorge in northern Tanzania. This species was nicknamed Nutcracker Man for its big teeth and strong chewing muscles, which attached to the large crest on the skull. Those features show that Paranthropus boisei likely ate tough foods like roots and nuts. But dental microwear patterns seen on P. boisei teeth are more similar to living fruit-eaters with fine striations, rather than large, deep pits seen in the teeth of living species that eat grass, tough leaves and stems, or other hard, brittle foods. While the morphology of P. boisei skull and teeth indicate it could have chewed hard or tough foods, dental microwear analysis does not demonstrate that they regularly did so, suggesting a wider, more diverse diet for P. boisei. It's possible that this species only ate hard or tough foods during times when its preferred resources were scarce, relying on them as fallback foods.

Sahelanthropus

When Lived: Sometime between 7 and 6 million years ago Sahelanthropus tchadensis is one of the oldest known species in the human family tree. This species lived sometime between 7 and 6 million years ago in West-Central Africa (Chad). Walking upright may have helped this species survive in diverse habitats, including forests and grasslands. Although we have only cranial material from Sahelanthropus, studies so far show this species had a combination of ape-like and human-like features. Ape-like features included a small brain (even slightly smaller than a chimpanzee's), sloping face, very prominent browridges, and elongated skull. Human-like features included small canine teeth, a short middle part of the face, and a spinal cord opening underneath the skull instead of towards the back as seen in non-bipedal apes. Some of the oldest evidence of a humanlike species moving about in an upright position comes from Sahelanthropus. The foramen magnum (the large opening where the spinal cord exits out of the cranium from the brain) is located further forward (on the underside of the cranium) than in apes or any other primate except humans. This feature indicates that the head of Sahelanthropus was held on an upright body, probably associated with walking on two legs. Some of the oldest evidence of a humanlike species moving about in an upright position comes from Sahelanthropus. The foramen magnum (the large opening where the spinal cord exits out of the cranium from the brain) is located further forward (on the underside of the cranium) than in apes or any other primate except humans. This feature indicates that the head of Sahelanthropus was held on an upright body, probably associated with walking on two legs.

Neanderthals

Where Lived: Europe and southwestern to central Asia When Lived: About 400,000 - 40,000 years ago are our closest extinct human relative. Some defining features of their skulls include the large middle part of the face, angled cheek bones, and a huge nose for humidifying and warming cold, dry air. Their bodies were shorter and stockier than ours, another adaptation to living in cold environments. But their brains were just as large as ours and often larger - proportional to their brawnier bodies. Neanderthals made and used a diverse set of sophisticated tools, controlled fire, lived in shelters, made and wore clothing, were skilled hunters of large animals and also ate plant foods, and occasionally made symbolic or ornamental objects. There is evidence that Neanderthals deliberately buried their dead and occasionally even marked their graves with offerings, such as flowers. No other primates, and no earlier human species, had ever practiced this sophisticated and symbolic behavior.

Relative dating

based on the law of Superposition (the oldest fossil remains will be lower in the ground and the newest will be higher). Relative dating does not give exact dates, it simply indicates whether something is younger or older than it's surrounding. This can be supplemented by Biostratigraphy (see below) which widens the area which can be compared.

Paleomagnetism

based on the polarity of the Earth's magnetic field. Over time, the north and south of the Earth have switched, therefore such switch can be used to measure age. looks at polarity intensity shifts on earth over the course of time can be used to interpret the age of Earth but not very useful for sediment aging

Dental microwear

research done based on the levels of strontium measured in the skeleton plants have high levels of strontium when a herbivore eats plants they gain a certain level of strontium when a carnivore eats the herbivore that contains strontium they gain a much lower level of strontium from the herbivore Andy Sillen did research at Swartkrans on the levels in early hominins problem observed with this method was the level of diagenesis done during fossilization ​diagenesis: postmortem alteration of chemicals in the bones Ar. ramidus is very chimp like - generally eating fruits and leaves ​Au. africanus was shown to have more C3 and a diet similar to a giraffe Pa. robustus is similar to Au. africanus in both diet and concentration of C3 ​Pa. boisei had high levels of C4 which leads to the conclusion that its diet consisted of more grass Once again drawing the conclusion that East African and South African hominids had totally different diets gives the "last supper" effect that leaves microscopic scratches or pits on teeth from the last few meals eaten fruits leave micro-scratches and pits on teeth fauna leaves micro-scratches that are lined E. Africa and S. Africa diets have shown to be different due to this research

Homo erectus

1.89 million and 143,000 years Early African Homo erectus fossils (sometimes called Homo ergaster) are the oldest known early humans to have possessed modern human-like body proportions with relatively elongated legs and shorter arms compared to the size of the torso. These features are considered adaptations to a life lived on the ground, indicating the loss of earlier tree-climbing adaptations, with the ability to walk and possibly run long distances. Compared with earlier fossil humans, note the expanded braincase relative to the size of the face. The most complete fossil individual of this species is known as the 'Turkana Boy' - a well-preserved skeleton (though minus almost all the hand and foot bones), dated around 1.6 million years old. Microscopic study of the teeth indicates that he grew up at a growth rate similar to that of a great ape. There is fossil evidence that this species cared for old and weak individuals. The appearance of Homo erectus in the fossil record is often associated with the earliest handaxes, the first major innovation in stone tool technology. Early fossil discoveries from Java (beginning in the 1890s) and China ('Peking Man', beginning in the 1920s) comprise the classic examples of this species. Generally considered to have been the first species to have expanded beyond Africa, Homo erectus is considered a highly variable species, spread over two continents (it's not certain whether it reached Europe), and possibly the longest lived early human species - about nine times as long as our own species, Homo sapiens, has been around! Eugène Dubois, a Dutch surgeon, found the first Homo erectus individual (Trinil 2) in Indonesia in 1891. In 1894, Dubois named the species Pithecanthropus erectus, or 'erect ape-man.' At that time, Pithecanthropus (later changed to Homo) erectus was the most primitive and smallest-brained of all known early human species; no early human fossils had even been discovered in Africa yet. roughly 900 cubic centimeters (cc.), which is larger than Homo habilis, but smaller than that of Homo heidelbergensis and other later forms

Megadontia

Australopithecus, dated to have lived 2 to 3 million years ago, is the earliest hominid genus to demonstrate post-canine enlargement, with average post-canine tooth area ranging from approximately 460mm2 and going all the way up to the largest tooth area, 756mm2, which is seen in Paranthropus boisei .[2][3] After Australopithecus, a trend of steady decline in post-canine size is observed, starting in the Homo genus and culminating with Homo sapiens which has an average post-canine tooth area of only 334mm2.

Piltdown

The Piltdown Man was a paleoanthropological hoax in which bone fragments were presented as the fossilised remains of a previously unknown early human. In 1912 amateur archaeologist Charles Dawson claimed he had discovered the "missing link" between ape and man. After finding a section of a human-like skull in Pleistocene gravel beds near Piltdown, East Sussex, The Piltdown Man fraud significantly affected early research on human evolution.[28] Notably, it led scientists down a blind alley in the belief that the human brain expanded in size before the jaw adapted to new types of food. Discoveries of Australopithecine fossils such as the Taung child found by Raymond Dart during the 1920s in South Africa were ignored due to the support for Piltdown Man as "the missing link", and the reconstruction of human evolution was confused for decades. The skull fragments showed a species with a larger brain than the tuang child, and it was believed to be an earlier species. The idea of a human ancestor that was English and had a bigger brain than the one in Africa was an attractive idea to many, so it was accepted more readily, and was used to show that the Tuang child wasn't as exciting of a find as Dart believed it was.

Early hominin habitats

Thure Cerling's photosynthesis graph C3 (containing 12C) is associated with trees, bushes and forbs C4 (containing 13C) is associated with grass and sedges, generally tropically associated used pedogenic carbonates to measure the amount of C3 or C4 in the fossils calcium carbonate modules that form in soil which are transferred to fauna, then eaten by folivores - the more pedogenic carbonates an organism has the more folivorious it was 5-3 Ma fauna was indicating a rise in C4 and ~1 Ma it was a great majority of C4 leading to the hypothesis that the environment was mostly open and grassy Ar. ramidus is thought to have lived next to a river where there was more forest present, the surrounding areas are thought to be mostly open

Out of Africa hypothesis

is the dominant model of the geographic origin and early migration of anatomically modern humans (Homo sapiens). According to this model, modern humans originated in Africa and started to disperse through the world roughly 50,000 to 100,000 years ago. argues that every living human being is descended from a small group in Africa, who then dispersed into the wider world displacing earlier forms such as Neanderthal and Denisovans no breeding

earliest tools

is the earliest stone tool archaeological industry in prehistory. Oldowan tools were used during the Lower Paleolithic period, 2.6 million years ago up until 1.7 million years ago, by ancient hominins across much of Africa, South Asia, the Middle East and Europe. This technological industry was followed by the more sophisticated Acheulean industry. t is not known for sure which hominin species actually created and used Oldowan tools. Its emergence is often associated with the species

Incisor size and diet

folivores (feed on leaves) tend to have smaller incisors due to the fact that they are useless when eating frugivores tend to have larger incisors to take the initial bite out of a piece of fruit Australopithes generally have flatter teeth and mid-sized incisors Paranthropines generally have flat teeth with small incisors Paranthropines were associated with a grinding masticatory process which generally is from a folivorious diet Australopiths were associated with a sharper and more crushing masticatory process that comes from being omnivorious these different diets caused a variation in the individual digestive systems shearing crests are similar to scissors when chewing and used to slice apart food - generally folivores have these (among larger primates) flatter teeth are used more for grinding motions that require force - generally frugivores have this adaption

little foot

his specimen was found in Member 2, Australopithecus africanus clear evidence of arboreal characteristics as well as bipedal traits long arms, cranially oriented scapulae, thought to spend a good amount of time in trees theorized that it has a slightly opposable hallux, however there is not enough evidence to prove this "Little Foot" (Stw 573) is the nickname given to a nearly complete Australopithecus fossil skeleton found in 1994-1998 in the cave system of Sterkfontein, South Africa.

Homo heidelbergensis

This early human species had a very large browridge, and a larger braincase and flatter face than older early human species. It was the first early human species to live in colder climates; their short, wide bodies were likely an adaptation to conserving heat. It lived at the time of the oldest definite control of fire and use of wooden spears, and it was the first early human species to routinely hunt large animals. This early human also broke new ground; it was the first species to build shelters, creating simple dwellings out of wood and rock. Comparison of Neanderthal and modern human DNA suggests that the two lineages diverged from a common ancestor, most likely Homo heidelbergensis, sometime between 350,000 and 400,000 years ago - with the European branch leading to H. neanderthalensis and the African branch (sometimes called Homo rhodesiensis) to H. sapiens. When Lived: About 700,000 to 200,000 years ago

Evidence for bipedalism in Australopithecus

lumbar lordosis-inward curvature of the lumbar region of the spine that pushes the stomach and butt out. progressive dorsal wedging a.k.a. lumbar lordosis - convexity of the vertebrae right above the pelvis, archedness of the back near the pelvis, our center of gravity is brought backward by this, we stand with virtually no energy use. shows bipedal adaptations of os coxae (pelvis), short and wide orientation as opposed to narrow and long STS-14 showed a reorganization of the glutes to support bipedal locomotion as opposed to quadrupedal locomotion gluteus maximus had slight changes (used more for running than walking) but the notable changes were in the lesser glutes (gluteus minimus and meatus bicondylar angle in sts-14 - the femur is medially angled (distally) like a human instead of straight like a chimp. makes us walk with our feet in nearly a single line centered under the body, instead of directly under the sides of the pelvis - this prevents waddling locomotion foramen magnum- he spinal cord, an extension of the medulla, passes through the foramen magnum as it exits the cranial cavity The foramen magnum is a very important feature in bipedal mammals. One of the attributes of a bipedal animal's foramen magnum is a forward shift of the anterior border; this is caused by the shortening of the cranial base. Studies on the foramen magnum position have shown a connection to the functional influences of both posture and locomotion. The forward shift of the foramen magnum is apparent in bipedal hominins, including modern humans, Australopithecus africanus, and Paranthropus boisei.