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ANTA01 Lecture 2

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Genevieve Dewar

ANTA01 Introduction to Anthropology Lecture 2 Evolution & Genetics Evolution  There are 5 primary aspects of modern evolutionary mechanism.  Adapt to environment  Natural selection  Sexual selection o Male peacock with a larger more colorful tail is more attractive to female peacocks thus the female peacocks are sexual selecting for this trait and in time there will be more male peacocks with bright large tail  Variation already exists in a population  Survival of the fittest What are species?  Species are organisms that are able to breed and produce fertile and viable offspring.  Ligers are a lion-tiger cross which can be created in a petri dish and are sterile.  Mules are a cross between horses and donkeys, and are also sterile.  Thus ligers and mules are not considered species.  The Giraffe’s in East Africa do not like the giraffes of South Africa, because although genetically the same, they do not procreate because they have developed different mating dances, thus these giraffes refuse to procreate so does this mean they are not a species? Pre-Enlightenment/History of Origins  Before Enlightenment, all we knew was that all the animals and technology were created in God’s image. This meant that men were born able to use iron making.  James Usher used the book of Genesis and counted the generations to determine how old the world was.  Catastrophists tried to explain how the earth was formed in only 6,000 years.  However a Reverend had already noticed that things like erosion were occurring which was a slow process. Uniformitarianism  Uniformitarianism is the concept we rely heavily on when we interpret geology, and animals in the past, the ideas that processes that happen today also happened in the past.  Hutton believed processes were slow working, uniform & natural processes, he believed the earth was hundreds of thousands of years old.  Today, the earth is 4 and a 1/2 billion years old.  A theologian Reverend Chalmer said that Ussher did not count the generations properly. Carolus Linneus  Carolus Linneus came up with the binomial system and the use of a genus and species.  Linneus had named humans as one of the animal species, before then humans were thought of as a different entity, not a part of the animal kingdom.  With colonization, people visited other parts of the world and discovered new people not mentioned in the Bible thus thought of them as heathens for not being mentioned in the Bible.  Archaeology, if men were born with iron making abilities, why were their stone tools? So this went against the belief of the Bible.  It was said these ‘thunderstones’ were struck by lightning and make into these perfect tear drop stones. Not true! st Lamarck – 1 mechanism  Lamarck’s second postulation, progression towards perfection, proposes that worms would evolve into humans and humans would evolve into angels.  Lamarck’s third postulation stated that inheritance of acquired characteristics would pass from parent to child. However, not every acquired characteristic would pass from parent to child, such as tattoos.  Thus only the first postulation, adaptation to the environment, was true of Lamarck’s 3 postulations. good exam question Darwin & Wallace  Evolution occurs in populations NOT individuals!  Each one of these islands had finches that looked identical but were not breeding with one another.  Case study by Grant & Grant  After drought, the finches no longer had insect eating beaks, but seed eating beaks. Because there were no insects during the drought. Therefore, through time and sexual selection, the majority that survived has big seed eating beaks. As soon as the drought ended and the insects came back, the majority of the birds had small eating beaks again because the females were selecting for small eating beaks.  how one can see there is no direction as majority of beak size became small again  Survival of the fittest was not one of the characteristics that Darwin came up with himself, Neo- Darwinism, came after the fact.  There are three aspects important in how survival of the fittest works.  Favorable variations promote survival of the individuals in whom their appear o Those traits will be inherited by offspring and the traits will increase in frequency in the population.  Unfavorable variations don’t promote survival o May cause individuals to die at an early age o May make individuals infertile o May make individuals unattractive to other sex  Natural forces are acting to favor the expansion of some traits and the removal of others.  If evolution is the mechanism, what are the processes? What is the source of variation? Three Processes of Evolution  Mutation o Act on the individual  Genetic Flow o Act on the population  Genetic Drift o Act on the population  Darwinism states things occur slowly and change occurs slowly as the environment changes.  Neo-Darwinism states things are stasis until something drastic happens and there is a drastic change, and the finch study supports this theory. Gregor Mendel  The one aspect of evolution and natural selection that Wallace couldn’t explain was how traits get passed on to offspring.  Gregor Mendel figured out how this works, he was a famous monk from Austria and really interested in pea experiments.  A punet square is a basic way to look at potential of how offspring gene combinations will be.  Heterozygous means the composition of two alleles.  If you cross two heterozygous alleles, you obtain 3 heterozygous alleles and one recessive homozygous allele.  If you crossed a Green YY and a Green Yy, you would obtain two dominant homozygous alleles and two heterozygous alleles.  GG- homozygous dominant, gg- homozygous recessive, Gg- heterozygous  Alleles are the whole set of different forms for a given gene.  In terms of the peas green was the dominant gene, and yellow the recessive gene is expressed only when recessive genes are homozygous (there is no dominant gene present).  Just because a gene happens to be dominant doesn’t mean it has a greater chance of being passed on than the recessive gene, this is a statement of independent assortment.  You cannot tell
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