Human Evolution Washu Midterm 1
Mosaic Definition
dif types of habitats are close to each other
Hadar Formation
- Hadar formation - Erosion exposes members from underneath
Homology Definition
- Homology: characters shared by taxa that are inherited from a common ancestor - Inherited similarities
Homoplasy Definition
- Homoplasy - shared character that was not inherited from a common ancestor - Trait that evolved in parallel of through convergence between two groups - Gives misleading information - Ex. Fish and whales have converged on the same morphology independently : the cigar shaped body bc of environment - Ex. Bats and birds evolved wings in parallel: having wings in a homoplasy - Bats are more closely related to monkeys than birds
K/Ar and Ar/Ar used on volcanic rock/ash
- K found inside magma - When hot and flowing around --> decays into argon - When lava cools (ex basalt layer) --> crystalline structure traps isotopes - Potassium glass??? - Goes back hundreds of millions of yrs (goes back to beginning of evolution)
Law of Superposition and exceptions
- Law of Superposition: higher stratographic members are usually younger than members below - Not true in some caves w/ complex stratigraphy: younger deposits are found on top - Ex. Sinkhole: fill up w/ sediments --> erosion removes sediments but leave some hanging from wall in cave --> new sediments on floor/under older sediments - Helps calculate ages of fossils within a region
Relationship between insulation and glaciation
- Less insulation --> more glaciation (and vice versa) - More solar radiation --> less glaciation
Metamorphic rocks
- Metamorphic rocks: crystalline structure or nature has changed bc of intense pressure and/or heat - Through intense pressure - Ex. Sediments that fold through tectonic activity -- creates intense pressure and can transform the nature of crystals that make up the rock - Through intense heat
Monophyletic vs Paraphyletic Groups
- Monophyletic: all of the descendants of an ancestral taxon (LCA) - Groups are nested in each other - ex. primates are nested within mammals - Paraphyletic groups: don't include all of the descendents of a LCA - "unnatural" group bc it doesn't reflect evolutionary history - shouldn't give these groups names in a taxonomy - ex. fish, reptile
Four causes of evolution
- Mutation - appearance of new alleles (generally through an error in gametes --> producing a novel allele) --> changes allele frequencies - Migration = gene flow (individual disperses into a dif population and breeds) - Genetic Drift: random removal of alleles from the gene pool (nothing to do with the genes of the individual) -- ex environmental disasters - Selection: heritable variants are subjected to a selective pressure where the favorable traits are passed down more frequently
Notochord definition
- Notochord: semi rigid gelatinous rod that runs down the back - Important for survival of our ancestors - Muscles would attach there and contract of muscles --> swim very fast and evade predators
Olduvai Gorge
- Olduvai Gorge: famous human fossil site - Sediments originally deposited by water - Tectonic activity - Creates rift and low areas where water can accumulate --> lakes --> sediments are deposited and buried - Tectonic activity pulls two continental plates apart --> sediments get fractured and exposed
Ontology and Histology definition
- Ontology: study of the thing that is true (a reality that is true) - Histology: study of how we know something is true or false (theoretically)
Orbital sources of climate variability (4)
- Orbital sources of climate variability - Eccentricity- Earth's orbit changes from circular --> elliptical --> circular --> etc - At 100 kyr intervals - Elliptical: on avg the Earth receives less solar radiation for the yr --> Earth tends to be colder - Present day: more circular (slightly elliptical) --> Earth is pretty warm - Tilt/obliquity - For northern hemisphere: summer --> northern part is tilted towards sun and southern hemisphere is tilted away from sun - Northern and Southern hemisphere have inverted seasons - Tilt varies w/ 41 kyr intervals - High tilt cycles--> polar regions get more direct sunlight --> less accumulation of ice --> Earth is on avg warmer - Present day: tilt has neutral effect on climate - Precession: "wobble" in axial tilt - Affects timing of when seasons occur relative to point in orbit of when Earth is close to or farther away from Sun - Varies w/ 23 kyrs intervals
Sedimentary rocks definition
- Sediments: Little particles that get deposited as sheets - Ex. Wind and water pick up and move particles - Wind can blow and water erodes and moves particles across landscapes to be deposited in different places - Can be loose, don't have to be hard - Can consolidate and form rocks through pressure - ***ONLY type of rock that contains fossils - gradual accumulation of sedimentary deposits
What influences climate? (4)
- Solar radiation (=insolation): amount and intensity of sunlight reaching the Earth - Varies over geological time - Plate tectonics - Arrangement of continents over surface of Earth - Interactions w/ ocean circulation - Ocean circulation - Atmospheric circulation
Stratigraphy and stratum
- Stratigraphy: patterning/layer of sedimentary layers - Stratum: a sedimentary layer - Important for understanding age of fossils
Uranium/Thorium Dating in caves
- Uranium in ground water dissolving surrounding rock --> carbonates get dissolved inside water --> at low frequencies the carbons will precipitate out --> redeposit carbonate rocks (speleothems aka stalactites and stalagmites) - Drops and peaks from water dropping onto ground - Rocks trap radioactive uranium inside - Th (daugher isotope) can be detected - Using ratio --> figure out how old sediments are - Can date cave deposits up to a few hundred thousand years
Orbit cycles and climate change
- Variation in insulation causes various squiggles - Variation in orbital cycles: the way the Earth orbits around the sun impacts the amount of Sun reaching surface
Vertebraes vs Tetrapods vs Amniotes
- Vertebraes: boney spine - Tetrapods: four weight bearing limbs is a derived characteristic - First colonized land - Vertebrates no longer restricted to oceans - Amniotes: have a water tight membrane around embryo - Reproduction no longer had to be tied to water - Could lay eggs on land
2 Patterns of evolutionary change
- Anagenesis: evolutionary transformation within a lineage - May result in a new species or a version of the previous species - Cladogensis: splitting of lineage
Fluvial and lacustrine deposits
- Animals die at water hole or die at another place and are carried by water - Rivers move sediments and erode rocks - Lakes can be turbulent but when they calm down the sediments settle
Antarctic glaciation
- Antarctic glaciation: Drop in temperature between pal and eo - Probably due to plate tectonics - South America is still attached to antarctica & Australia is rlly close to antarctica - South America and Australia move away from Antarctica --> changes ocean currents - Cold water is constantly deflected up to equator --> ocean water is warm --> climates are generally warm throughout Earth - But as SA and Aus move away --> formation of Antarctic Circumpolar climate (water circulates around Antarctica and never moves towards equator) --> North and South pole get colder --> on average ocean water becomes colder --> global climates get colder
Paleoecology w/ Baboons and Carbon
- Baboons tell you about relative coverage of trees - Carbon gets passed on to animals that eat them - Have specific type of enamel for each type of carbon - Carbon 13 is preserved in all tissues, and some of it is preserved in the fossil record
Relative vs. Absolute Dating
- Biostratigraphy and Stratigraphy are examples of relative dating - Once you assign years (ex. 2 million yrs ago), no longer relative dating --> absolute dating
how radioactive dating works (ratio)
- Can compare ratio of parent to daughter - As ratio increased --> greater amount of time spent trapped in crystal
How is carbon used for radioactive dating?
- Carbon dating used on bone - Radioactive isotopes of carbon get incorporated into tissues (ex. Bones) which are preserved in geological record - Bc carbon 14 is decaying in bones, daughter and parent isotopes get trapped - Can be used to date bones up to 40 thousand yrs old bc carbon decays quickly - More useful for dating relatively young specimens
Types of paleo anthropologic sites
- Cave desposits - Lacustrine/fluvial sediments: sediments deposited by water
Clade Definition
- Clade: group that includes all of the descendants of a given last common ancestor - Monophyletic group - A natural group that reflects evolutionary history - Therefore names that we assign to groups must be monophyletic - Clades correspond to hierarchy in taxonomy
Biological Species Concept (BSC) isolating mechanism
- Ernst Mayr - Biological Species Concept (BSC) - A species is a population of actually or potentially interbreeding organisms that are reproductively isolated from other such groups (unable to produce offspring with other groups) - Isolating mechanism - prevents production of viable offspring - Helps identify dif species - Mules are Sterile offspring: never be any horse genes that move into the donkey population and vice versa - Lineature is a dead end - Evolutionary perspective: as if mule never existed - Hybrid sterility
Evolution definition
- Evolution is the change in allele frequency over time (change in genetic composition of a population over time) - Even though phenotype percentage may change, if allele frequency doesn't change --> no evolution
Biostratigraphy examples w/ rodents and pigs
- Ex. Rodents - Evolve very quickly to environment and can find evolution in types of mice that are preserved in each strata - Ex. Changes in molar teeth of pigs - Older: pigs w/ smaller molar teeth than younger sediments - Can infer the time the organism was alive using features - Fossils at other site are same age as pigs from this site bc of same molar size (but don't know exact age) - Help calibrate relative ages of sediments and fossils
Reconstructing past environments w/ foraminifera
- Foraminifera: single-celled organisms that live in the ocean and build a shell around themselves - After an organism dies, a rain of foraminifera fall down to the ocean floor w/ it - Shells provide clues about environment bc composed of calcium carbonate (which have oxygen): O2 is from ocean - Two stable isotopes of oxygen, 18 (heavy) and 16 (light) - Incorporated into water molecules: water w/ oxygen 18 are heavier than oxygen 16 - Oxygen 16 evaporates more easily (bc lighter) than oxygen 18 which precipitates - Oxygen 16 evaporates more easily --> disproporately removed from ocean --> forms clouds w/ higher ratio of 16:18 --> oxygen 16 deposited on land (ex. Glaciers) - Water in ocean has disproportionately higher concentration of oxygen 18 - In cold periods: foraminifera shells formed w/ more oxygen 18 (oxygen 18 enriched) In warm periods --> smaller ice sheets --> larger portion of precipitated water will stay as liquid and flow back to ocean --> most of oxygen 16 that's take out is returned to ocean --> shells have higher concentration of oxygen 16 (aka oxygen 18 depleted)
Brown bear + polar bear hybrid? (relevance to BSC)
- Gene flow between both populations - No total barriers between both species - Are brown bears and polar bears dif species? --> exception to BSC
Geological formation and Members
- Geological formation: many sediments distributed in layers over a wide area - Members: major stratigraphic units in geological formation
Evolutionary Species Concept (ESC
- George Gaylord Simpson - Evolutionary Species Concept (ESC) - helps when examining fossil record bc BSC isn't helpful - A species is an unbroken lineage of populations linked by ancestry and descent - Morphology of a population evolves over time - Reproductive continuity - No reproductive isolation just bc newer generation can't breed with older generation (bc they're dead) - Unbroken lineage --> one species
2 rates of change of transformation in species
- Gradual transformation in species - Accumulation of small changes over a long period of time - Phyletic gradualism: evolution by small intermediate steps - Describes rate of change - Punctuated equilibrium - Stagnant over time - A lot of anatomical changes over a short period of time and settles around new equilibrium - Ex. Ancestral population buds off (founder's effect) and then later stabilizes as a dif species
Identifying Grazers vs Browsers w/ Carbon
- Grazers vs browsers depending on how much carbon 13 is in the enamel of their teeth - Elevated carbon 13 values in grazers than browsers - Tells you what they ate and type of plants in that habitat
Volcanic ash between sediments (radiometric dating)
- Grey lines represent volcanic ash atop of each layer of sediment - Ash contains elements that are used to determine precisely how old it is - Principles of radioactivity - certain types of crystals have radioactive isotopes - Radiometric dating - rate of decay is determined by half life (Absolute dating method) - How long crystal has been decaying - Can decay into an isotope or different element - Decays inside isotope -- both daughter and parents isotopes are stuck inside crystal
When climate changes -->
- When climate changes --> broad scale environment change --> individual habitats change - Resulting in migration- disperse across landscape - Mixing populations that were once separated - Separating populations that were once together - More intensified/new selection pressures
2 Types of Homology
1. Synapomorphy: shared, derived character that is inherited from a recent LCA (aka traits that define groups) 1. Ex. Bony skull for vertebrates; 4 weight bearing limbs for tetrapods; amnion for amniotes; a. Bony skull evolved from ancestor that did not have one and therefore is a derived characteristic of vertebrates i. Having a bony skull is a synapomorphy of verterbrates b. Tetrapods: four weight bearing limbs is a derived characteristic; primitive characteristic is to not have weight bearing limbs bc ancestors didn't have i. Four weight bearing limbs in a homology and specifically a synapomorphy c. Amniotes: descended from ancestors that don't have amniotes --> derived characteristic --> synapomorphy d. Synapomorphies of mammals: hair, mammary glands, warm blooded Symplesiomorphy - shared primitive characteristic inherited from a distant LCA - provides no info about phylogeny - Presence of a bony skull will not tell u how closely related humans are to monkeys vs horses - Synapomorphies give you direct info about phylogeny - Symplesiomorphy gives you info about groups much larger than the ones you're interested in
Paeoecology w/ Bovids
Can tell time with pigs and weather with bovids Bovids evolved to be habitat specific Open and dry environments vs dry forested environments vs wet Closed = forested habitats - Type of bones left over reflects habitat - Relative abundance of each type of bones/fossils - May give idea about predominant habitat type
Solar radiation with northern/southern hemisphere
Earth closest to Sun --> more solar radiation during northern hemisphere winters --> moderated winters --> not much glacier formation Less solar radiation during Northern hemisphere summers --> moderated summers Roles between Northern and Southern hemisphere will be reversed in 10 kyrs from now
Periods and Epochs in Cenozoic
Harry Plays Pool More Often Eating Pie Halocene --> Pleistocene --> Pliocene --> Miocene --> Oligocene --> Eocene --> Paleocene H: 0.012 Mya; Origin of agriculture, cities, etc Ple: 2.6 Mya; Ice Ages, Origin of Homo Pli: 5.5 Mya; Origin of australopiths Mio: 23 Mya; Earliest hominins (human evolution begins) Olio: 34 Mya, Radiation (divergence) of anthropod primate Eo: 55 Mya; Radiation of primate Paleo: 65 Mya; Origin of Primates
Igneous rocks definition
Igneous rocks: rocks formed principally through heat - Molten rock and then cools and hardens
Classification of humans
King Philip Said, "Come Over on a Sunny Sunday For Tea, Good Travels" Kingdom --> Phylum --> Subphylum --> class --> order --> suborder --> superfamily --> family --> tribe --> genus --> trivial Another Cheetah Vanished Monday at 5 Pm Hugging Hairy Hippos Holding Huge Sombreros Animalia/Metazoa --> Chordata --> Vertebrata --> Mammalia --> Primates --> Haplorhini --> Hominoidea --> Homminidae --> Homini --> Homo --> sapiens
How are fossils formed?
Living organism dies --> rests on sediments --> soft parts disappear (decay or eaten) and only hard parts remain--> sediments continue to cover it --> minerals in sediments will leach into fossil and fossil takes on characteristics of sediments around it resulting in an imprint --> ex erosion takes place and sedimentary layers on top are eroded --> part of fossil is exposed to surface --> fossil is at risk of being eroded and destroyed
Events during Mesozoic, Paleozoic, and Precambrian
Mes: Age of Dinosaurs, Origin of mammals Paleozoic: Origin of modern phylum; Earliest vertebrates; earliest chordates Precambrian: origin of life
Paleoecology definition and method
Paleoecology: reconstructing past habitats Look at fauna and flora to reconstruct Most is fauna (bones)
Phyletic Tree vs Cladogram
Phyletic Tree -gives specific information about time - explicit info about ancestry and descent Cladogram - no specific info about time - no direct info about ancestry and descent - branches show recency of common ancestors - Nodes are hypothetical taxa
Types of cave deposits
Sinkholes: formed when there's a water soluble bedrock (ex. Limestone or other material made out of (calcium) carbonate) - Water soluble --> water can create cavities - Underground cavern created by water - Chimney that opens up to outside world (vertical cave) --> things fall into vertical hole --> dirt, animal bones - In Africa: fig? trees grow by caves and their roots absorb water by shaft opening and exploit water pooling at bottom of cavity - Unoccupied - Fossils accumulated by carnivores or death trap - Sediments are often consolidated as breccias - Creates a cone as sediments fall into hole --> creating layers - Mix water, carbonates, and dirt = natural cement - Bones that fall into hole are encased in cement and are preserved well --> minerals leach into bones --> forming fossils --> top sediment layers are eroded --> fossils are discovered - Caves and rockshelters: within carbonate rocks as long horizontal tubes - Remains of ancient underground rivers - Part of tube is truncated and opens up - Caves provide shelter - Occupied - Fossils are typically things used by humans bc habitation caves - Controlled fire, tools, etc - Fossils accumulated by hominins - Discarded bones or burials - Sediments often unconsolidated
2 Systematics
Systematics- science of diversity - Taxonomy: system of classifying organisms into groups - Linnean hierarchy (like a set of russian dolls) - Phylogeny: pattern of evolutionary relationships between "taxa" - Taxonomy and phylogeny are intimately related to each other - Categories: represents levels or ranks in each taxonomial hierarchy - Taxa: individual units, groups w/ their own name representing certain types of organisms
Boundaries between each era, period, and epoch are defined by
major changes - ex. mass extinctions - major ecological differences in fossils
Fossilization definition
transformation of the hard tissues (sometimes soft parts are preserved) that are preserved and minerals from surrounding sediments are leached into hard parts and