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ANTC17 midterm notes.docx

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Larry Sawchuk

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multiple choice, short answer, fill in the blank and definitions. 5 most important aspects of human evolution - Variation already exists in a population - Survival of the fittest - Natural selection *** - Sexual selection - Descent with Modification  ask for what this is Who does evolution act upon? Upon population as a whole Species - A group of creatures which breed together and produce viable and fertile offspring - May be similar in appearance (deer) or variable (dogs - poodles and chihwahwa can produce offspring) - May all live in one part of the world (polar bears) or in many parts of the world (right whales) - Share behavioral traits relatingto social groups, food preferences, reproductive strategies, etc. - Species have a shared behavioral and social grouping, meeting, eating, etc. - Distinguish between members of own species and others o i.e. Giraffes – ones from different places wont mate although they are same species, because they have different mating ritual. Darwin 1859 - Natural Selection - Human Origin in Decedents of Men. Pre-enlightenment period - Genesis - 6 days - The technology they had after they got kicked out of Garden – they learned how to deal with metal or iron etc. this will be important in learning tools and humans History of Origin - ArchBishop Ussher 1650AD - Origin of the Earth and therefore humans based on his interpretation of the bible - Analyzed bible for age of earth - The world must be 4004 B.C. on October 23 . rd Enlightenment Period Catastrophists - Georgy Cuvier o If only 6000 years old, then global and violent catastrophes to explain canyons, mountains o He started to notice that there is constant change –rivers are eroding cannons. o A thing like mountain building was thru the idea of catastrophe. o This was one point of view during enlightenment period. - Burnet (1681AD) o He started to focus that there is also slow erosion by water, wind, and ice Uniformitarianism - Buffon 1749 AD o “to learn about the earth, study the earth” – processes are known, natural, and observable o He had to retract the statement for being fear of persecuted. - Hutton (1788AD) o Said the same thing but it has to be hundreds of thousands of years old, not just 6 days. He said the earth was slow working, uniform, and natural processes - Lyell o After 100 years after Hutton, he said earth had to be at least 100 000 years old by saying “present is the key to the past” - Chalmer o Maybe it was Ussher that was wrong, not the bible. Linneus 1758 - Comparative biology - He categorized humans amongst animals by calling us Homo sapiens. - He tried to do it to worship God but he invertly classified humans as animals. - 7 basic layers or taxon levels o kingdom, phylum, class, order, family, genus, species - Binomal system - Homo Sapien (wise man) - Species arms. You can see that they all have primitive pattern in arms. They all have single armbone. The top right bone belongs to a bird. Conclusion of Enlightenment Period - People accepted it and rejected bible. It was the conclusion of Enlightenment period o Fossils o Extinct animals o Strata and stratigraphy 1 evolutionary theory - Lamark came up with the idea. o Inheritance of acquired characteristics  wrong o Progression towards perfection (like giraffe got long neck due to reaching far for trees)  wrong o Adaptation to environments  right - There was this idea of perceived final goal. Natural selection - Variation already exists between individuals of the same species that allows for adaptation to changing environment - Coincidentally better adapted to an environment = higher reproductive success - This increases this trait within the species - Variation is RANDOM with NO DIRECTION - Mechanism of evolution = natural selection *** On the Origin of Species 1859 - If a population of geographically separated and reproductively isolated, the different population will be exposed to different population pressures - As changes are selected over time, they MAY become 2 different species o Humans never separated into different species, just race. This is where things might change in future. Darwin’s finches - Grant and Grant 2002 o Adaptation o Existing variation o With no direction - Darwin didn’t even recognize that all was same species, but he recognized that finches looked very different based on morphology of beak (related to diet) - Draught o Wiped insect. o The finches didn’t have small beaks but to open seeds. o They already had capacity of opening seeds but they could feed themselves better after the draught. - Rain returned o Insects returned o The new generation started having small insect-sized beaks again - Change depends on environment - Change works on the trait variation already present in a population - No direction Mendel - Crossbreed. 3:1 - He found that traits in offspring are not either passed solely by either parent. Traits are passed in small, independent genes from both parents - Allele o Different variation of genes o It can be eye colors but there will be different alleles for eye color. - Independent assortment o Just because you have dominant genes it doesn’t mean it will be passed on more. o Recessive genes will as much as dominant genes will - Homozygous state: for a given trait, individual receives the same gene form from parents. Green and green - Heterozygous state: individual receives 2 diff genes from parents. Green and yellow - The whole set of diff forms for a given gene is known as alleles. o Sometimes the yellow allele was expressed (appeared in the plant) o Sometimes the green allele wasexpressed - Dominant gene – always expressed in the individual who carries them such as green peas - Recessive gene – expressed only if they are homozygous (if no dominant gene is present) Terms on your midterm *** - Genotype: all genes in an individual. Genotype represents our real genetic structure or DNA - Phenotype: the visible individual o If you paint your nails or dye your hair o The expression of genetic dominance o Physical changes caused by events in the individual’s life - Genome: the entire range of alleles in a species; the gene pool - Most physical traits represent complex associations of several diff genes o Gene complexes often include genes on completely diff chromosomes o Some genes can be co-dominant – blend together rather than dominating or submitting (hair color) o Sometimes the nature of one gene determines the dominance or recessively of another Class experiment - Non-metric traits - Darwin’s tubercle - Hair whorl direction - Thumb dominance - Tongue curling - Earlobes attached - Fingers same length What causes new traits? - Changes in genes - Changes in chromosomes - New complexes or combinations between genes 3 processes of evolution *** - Mutation – the only direct way in creating new alleles - Gene flow - Genetic drift Mutations - Advantageous, deleterious or neutral - Random mechanical errors during DNA synthesis – sickle cell anemia o Can be good, bad, or neutral. o Sick cell anemia = neutral. o Homozygous state: most individual doesn’t make to reproductive age = bad o Heterozygous state: cell doesn’t deter completely and prevents malaria from entering the body = good - Chemical pollution - Cosmic nuclear radiation - Insecticides Genetic drift - Individual demes – fission - Founder effect o In a small population, there may be only a few individuals who possess a particular genes  If these individual don’t have offspring, that gene is lost from the gene poll of that population o In a small population, everyone is closely related, in-bred  Mutations spread quickly though the population  Easy for a mutated form to become “the norm” i.e. Bad mutation can become the norm Genetic flow - Opposite from above - If people split into demes, separate breeding populations they will have undergone some natural selection - If 2 demes start to interbreed, then new genetic material is introduced or flows into both gene pools - Offspring will have new genetic combinations - Gene flow acts to homogenize populations, preventing speciation Theories of speciation (how species develop) - Gradualism o All populations are changing all the time, gradually changing into new forms and forming new species - Punctuated equilibrium o Stable population goes through catastrophic change  rapid change and produce new species  adaptive radiation Neo-Darwinian approach - Many species have status quo - No need to change because they are perfectly adapted. - Morphology and Time Humans are primates - Bipedal - Forward facing eyes - Opposable thumb – grasp - Most live in tree – arboreal. So we will look in trees when looking for fossils - Dentition - Large brain size relative to body size *** - Infant dependency – humans are unique that they have childhood - Manipulate the arboreal environment thru grasping and dexterous hands and feet What are main primate groups? o Lemus, Lorises, Tarsiers NW o Apes, Humans OW - We are not evolved from apes, we ARE apes. Similarity between apes and us - Y5 - 2:1:2:3 dental structure - Large body size - Large brain size Classification schemes for primates - Phonetics o Linnean style o Similarities, and differences o Old way of doing it - Cladistics o New way of doing it o Through shared derived traits – it is shared because we have common ancestor. - Analogies o Similar trait shared by 2+ species but unrelated evolutionarily; convergence o The wings of a bat and butterfly = different ancestor but same way of dealing w environments. - Homologies o Similar trait shared by 2+ species thru inheritance from a common ancestor o Pattern of long arm bone then 2 forearm bones “Eve” Cann et al 1987 - Origin of Human species o Genetic studies on modern populations o mtDNA high mutation rate, follows female lineages o Variation was highest in African women - mutated more often than other groups o Standard rate of mutation at 2 to 4% per million years o Africa is the origin of Homo sapiens and been around 200,000 years ago *** Krings et al 1997 - Same species? - Neanderthal DNA o mtDNA from the type specimen o Compared to modern humans o Outside the range of variation o Mutation rates place divergence from homo sapiens at 300 to 800,000 years ago o Therefore no admixture - They managed to amplify the DNA samples they have and compared to humans. - Problem of the study o There is only one sample to represent all the population. o Using that same clock suggested that this shared ancestors with human beings 300-800,000 years ago. This means no admixture because Homo sapiens was around for only 200 000 yrs. Tuff Break - You have to be aware of individual bias including your own - He guided chronological ideas in terms of identifying the sample age - Homo Hablis o They are not talking about giant swings of time. Why is it so important that it was older than 2 million years ago? o In their minds, it was one of the early specimens. If it were younger than Homo Erectus then of course you would want your sample to be younger. - What are 2 competing main methods to date methods in Tuff Break? o Argon-Argon/Potassium-Argon dating o Pig teeth method - In the past we had to reply on these methods but there has been 2 things that have been discoveries that transformed the way we think of ages. o Nuclear physics – the fact that some elements have different radio reactivity o Construction of mass spectrometers – they isolate beam of particular atom and bend. If this is a beam of carbon, it will bend on different degrees because they have different atomic rates. It will measure the actual number. South and East Africa - We have evidence that bipedalism started not in savanna necessarily but more in the tropical forests. - East Africa o the giant geology o 4-5 million years old sediments. - South Africa o Mine sites o Only through the active tunneling deep into the earth will get us one. - Archeological visibility *** 2 different archeological sites - Open site: o best thing is that it represents single event or occupation. o It is easy to radio activate. o Palimpsest 다층적 - Cave site/rock shelter: o Cluster formation of cave. o Rock shelter is it looks like cave but not. How do we find sites? - Morphological features o Sources of water, firewood, etc.  lead to shelter - Field survey o Surface walking o Subsurface investigations  Electrical resistivity survey  Proton magnetometry  Ground penetrating radar o Random testing  Test pitting Chronology - Relative dating methods o Stratigraphy o Cross-dating - Absolute dating o Radiocarbon (C14) o Potassium-argon (K-Ar) o OSL (Optically Stimulated Luminescence) Stratigraphy at Sehonghong Carbon dating - Site A o Layer 1 – small blades o Layer 2 – scrapers o Layer 3 – adzes (C14 1000+- 50 BP) o Layer 4 – large blades o Layer 5 – Handaxes o Layer 6 – No tools - Site B o Layer 1 – small blades o Layer 2 – Adzes o Layer 3 – no tools - Therefore Layer 2 in Site B probably dates to around 1000 +- 50 BP - You find a sample in one site and same thing in the other site, they should be the same age. Cross dating - What are 2 major things that can cause sediments to move around? o Burrowing animals o Water – water table can rise. When yellow and black sediments are mixed, they turn grey Radiocarbon dating C14 - All forms of life contain carbon o So does food that organisms eat everyday o Living organisms constantly replenish C14 atoms through the food chain - Carbon exists in 3 forms or isotopes: o Carbon 12 is common and stable (99%) o Carbon 13 is rare and stable (<1%) o Carbon 14 is very rare and radioactive - decaying - The proportion of 12C to 13C isconstant through the living world. 14C begin to decay (slowly) into N14 - C14 atoms have a half-life of 5,730 years - C3 tree - C4 tropical (has more C13) Calibration curves - Northern hemisphere: INTCAL09 - Southern hemisphere: SHCAL04 - Marine: MARINE09 +DeltaR - Mixed feeder: need to know %marine protein - Calibration programs: OXCAL 4.1 or CALIB 5.0 - Every year there is variability in solar flares. So there is no constant ratio, it fluctuates. You have to take that into account. - Computer will do it for you. - We have plants in the mixed layer of the ocean but sometimes, esp in cold region, there is thermo-healing circulation. o Cold water in Polar Regions sink to deep ocean, taking that carbon with it. o Rather than coming back up, it gets trapped in Reservoir *** in the deep ocean so there is old carbon problem. o It continues to decay in the deep ocean then eventually it comes back up to the surface. Old water comes to surface and mix with surface water. o This means if you were to go to the ocean today, it wouldn’t say its today old but it is 400-500 years old (old carbon). o That is what Marine Curve does. - Apply a marine curve – it is very important Potassium-Argon dating (K-Ar Dating) - Potassium 40 (radioactive solid) decays into Argon 40 (inert gas) - Works only in volcanic or monomorphic scenarios - When a volcano erupts, the hot lava releases all gases, including Argon. - Thus, all Argon 40 found in a lump of cooled lava is the product of radioactice decay of Potassium 40 in the original lava - 100,000 to 2 billion years ago - P40, which is radioactive solid, will decay. - When volcano erupts it will only have P40 - If you know how old the bottom and top layers are, you know how much the middle one is. OSL – Optically Stimulated Luminescence - As opposed to organic materials or lava, OSL is used to date Quartz Crystals - When buried, qtz crystals absorb radiation from surrounding rocks (crystal lattice) - Optically stimulate the crystal and measure the amount of radiation emitted - Know how long the quartz wasburied, or at least the last time it was exposed to sunlight - Must also know the local DOSE rate - A few hundred years ago 100,000 years ago - Cristal has imperfection in itself. When you bury corpse, it trap electrocals. If you are careful and collect samples of these quartz crystal (sample) in a dark room before you get to the lab, they will release all electrites they captured. You can easily work out the ratio. - Thermo luminescence – what are they doing? They are relying on heating of the quartz. This is why TL works on burnt things - In both cases you need sample of dose rate of that rock. Environment - Oxygen– temperature - Carbon and nitrogen – vegetation - Palynology – vegetation - Faunal (animal) remains – local ecology Oxygen isotopes (C16/O18) - Indicator of temperature o O16 bonds with ice (rare) o O18 bonds with water (common) - Left chart: constant deposition. This introduces error because some winter can be colder than other. - Middle chart: o X axis  shows whether O16 is redundant or lacking o Y axis  time o Find today. It crosses X on -2.25. Earth has been warming for the past 1000 years. o Odd numbers = warm o Even number = cold Stable Isotopes of C and N - Carbon differentiates between o C3 and C4 plants OR  C3 plants = trees and bushes.  C4 plants are tropical plants.  Grass are recent. o Terrestrials and Marine protein - So we can use this C and N to find out when grass appeared. - We can use same scale, but only when there are no C4 plants. - They have same signature so it is hard to differentiate the 2. - We are lucky that the plants, trees, and bushes use 3 molecules to photosynthesize carbon. - In Nitrogen, we find trophic level. o Delta (difference between) depending on environment it is selected for or against. o Unite: “per mil”. - We get the value (range between -33 and -21) - But C4 pathways range from -7 and -15 so we say the average is -12. - These 2 do not overlap so this is method available to us - It is always negative because it was standardized against what is not negative. - As carbon moved thru the food chain, we see Fractionation. o If a rabbit eats plants, carbon will lay in its bones but the ratio is shifted (fractionation). o 5 mil per stage. o This is why it will show -21 or so. o Rabbit that eats nothing but tropical plants will only have -5. o But if the rabbit eats both, it will be somewhere in between. This gets complicated. - Fractionation works differently in different parts of the body. - The group on the top (in the graph after this) o individuals that don’t eat corns but salmons, they will have both high nitrogen and carbon. o Then you can find out their diet. Human Origins - Must look at the earliest members of our Order – Primates. - Primate? (how we distinguish whether the fossil is primate or not) o Opposable thumb o Infant dependency o Stereoscopic vision and vision is the dominant sense (dogs –smell) o Clavicle o Large brain relative to body size Models of associated behavior - Uniformitarianism o The idea that things behave the way we do today cuz of the they did in the past - Parsimony or Occam’s razor o If there are many explanations, usually the simplest one is the right one. o Doesn’t necessarily mean it is right though General definition of Primates - Arboreal mammals (adaptation to live in trees) - Vision-dominated senses (no focus on smell) - Large complex brain to body size - Complex social organization - Long gestation and infant dependency - Typically one young per pregnancy - Manipulate an arboreal environment through grasping and dexterous hands and feet Fossils – bones and teeth How are we going to use these fossils to distinguish them to be primate vs. dogs or cat? *** - Dentition - Crania o Post orbital bar  Primates need bone things to protect their eyeballs because it is the dominant sense, whereas dogs nose is dominant o Eyes forward  Dental formula o Sagittal crest - Post-crania o Nails instead of claws o Opposable thumbs/toes o Clavicles - Another category o Large skull to body Primate anatomy - Grasping foot with divergent Hallux (thumb) - Presence of nail on Hallux and most other digits - Elongation of the heel - Dominance of hindlimb duringlocomotion - 5 digits on the fore and hind limbs with opposable thumbs and big toes (Hallux) - Tactile pads on end of digits - A complex visual system with stereoscopic vision, high visual acuity, and colour vision - Orbits encircles with bone – bar or fully enclosed sockets - Reduced number of teeth compared to primitive mammals - Trend number of teeth compared to primitive mammals - Trend toward holding the torso upright - Retention of the collar bones - 2 mammary glands We are from Lagomorpha - They share almost identical morphology - They are directly related to functional behavior and loco-motion (how they move around on land) - Be comfortable with different dentition and what they represent - 2:1:2:3 Functional morphology - Humans have thicker enamel - Directly related to enamel – we need to know how thick it was - Shape of the teeth o Left dental shape  Unlikely to be on human lineage  Cusps are tall and sharp because they tend to eat things like grass and insects they need to sheer thru them o Right dental shape  Low rounded cusps  Apes, human lineage Dental microwear o How what they eat affects their teeth o A – monkey – deep pits in enamel o B – homo erectus o C – homo hatelus (sp?) o D – they have scratch marks on enamel o We can study their diet depending on their enamel Inferring body size from diet - We can usually associate body size depending on diet. - At the top there is ratio of browsers and grasser *** o C4 eaters: Browsers eat trees and bushes o C3 eaters: Grassers eat grass - Insectivore tends to be very small. - We use modern primates to interpret the past PALEOCENE/EOCENE Adaptive radiation – when newhabitat comes up it spreads Strepsirrhini – wet nosed primates Haplorrhini – dry nose primates - Rhinarium (dominated by sense of smell) - No rhinarium - The most primitive - Post-orbital plate  Orbit is now bony support being - Post-orbital bar invested in those eyes - Elon
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