“Light will be thrown on the origin of man and his history.” This last statement by Darwin in Origin has been taken by Jones and expanded to include updated evidence that we now know legitimizes evolution for humans as well, that man also “follows the rules that govern the whale and the AIDS virus (310).” We have also had to adapt to our environments given the genes we inherited. Over time this is apparent in the switch from hunter/gather subsistence to the introduction of agriculture. Once thought to be a sign of progress, many anthropologists now claim farming to be the worst mistake in human history. Marxist theory aside, it has taken a toll on our bodies, our social order, and the environment we create for ourselves. Humans have had to evolve to eat different foods, live within larger societies, and yet still maintain enough genetic diversity to move on and survive. How do large community groups affect human populations and their genes (greater mating pool, exposure to disease, etc)?
The study of disease among human populations is evidence enough for what and where our history lies. Jones uses the example of sickle-cell anemia as an earlier adaptive defense for malaria which still haunts millions of people today. Diseases afflicted within humans must be fought off, and the body has developed genes for this still persistent today. However, other poisons exist (tobacco, pollution, radio waves) that have recently emerged. Contemporary populations will see if we can adapt to the cancers that plague us now as a result. What is cancer, and how does it relate to the body, and how will evolution play a role in the future?
There are about a hundred thousand genes to make a human. Sixty percent of us in industrialized countries will die as a result of the genes we inherited. There are 4000 diseases caused by single gene defects alone, such as cystic fibrosis, muscular dystrophy, and hemophilia. Two copies of the gene must be mutated for a person to be affected by one of these disorders known as autosomal recessive (or dominant) disorder. A person with the disease usually has unaffected parents who each carry one copy of the mutated gene. Two unaffected people, who each have one copy of the mutated gene, have a 25% chance with each pregnancy of having a child affected by the disorder. Genes can also affect X and Y chromosomes. Many disorders are difficult to study when genes aren’t the only factors. How might environment influence disease in conjunction with genetic inheritance?
Though not a fan of using Wikipedia in reference, here is a long list of genetic disorders with causal type of mutation and the chromosome involved:
http://en.wikipedia.org/wiki/List_of_genetic_disorders
Genetic epidemiology source complete with Power Point slides:
http://www.dorak.info/epi/genetepi.html
Human evolution can be looked at using concepts throughout Jones’s book: geography, migration patterns, geology, morphology, etc. What is most unique, however, is the evolution of our brain. Why it is that we started walking upright and began making conscious decisions is yet to be determined, but it is the brain that sets us apart from the other organisms, and why it is that we can sit here and think ourselves somehow special from other animals. With more and more hominid finds we are forced to reevaluate how our family tree divides. Researchers now know that human evolution did not follow a linear line of progression but instead took many paths. As the only surviving species of the genus Homo, what does that say about our ability to survive and will that change for the future? How do our concepts of history change with each new find? How have studies changed in relation to finds like “Lucy?” Without these “missing links” how can we explain human evolution in relation to the rest of the animal kingdom? And how much of us are governed by our genes, and how much by culture?
BBC articles:
http://www.bbc.co.uk/sn/prehistoric_life/human/human_evolution/index.shtml
Illustrations of evolution:
http://www.evolution-textbook.org/content/free/figures/ch25.html
Smithsonian National Museum of Natural History:
http://anthropology.si.edu/humanorigins/faq/encarta/encarta.htm
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Jones states that eight tenths of all human variation resides within individuals in a population. In other words there is more variation within a population than there is between two populations. He also states that humans have not had time to build up the genetic diversity seen in other species due to our recent divergence from our relatives. Given that we have plenty of genetic room for diversity and adaptation, why are humans still uniform by Jones’s observation? The size of the human brain has doubled in size in just over two million years. Jones claims that the brain makes us human. What type of adaptive situation results in an intelligence strategy as opposed to a more common brute strength strategy?
ReplyDeleteHumans have invested a large amount of evolutionary equity into increasing brain size. Jones attributes social behavior as a cause of increased brain size. I am not sure if we will ever be able to directly trace the ascent of the human species, but I think that part of human behavior is inquisitiveness and the ability to solve complex and abstract problems. Yet we still retain behaviors observed in our close relatives such as alliance-formation, and feces tossing. Does the human brain truly account for the complex behaviors that are attributed to human society?
I remember an argument brought up in Integrating Anthropology last fall that goes along with Zach's post. In Peterson and Wrangham's 'Demonic Males', it shows that ape social behavior is analogous to human social behavior in alliance formation, war, violence, male dominance, and the like. In cultural anthropology, we prefer to look at these behaviors within their own social and historical context, not reducing them to biological factors. Jones does bring up interesting points, though, on what makes us human and what sets us apart from our biological ancestors: namely larger brain size on a smaller frame. However, since we share so much genetic information with our ancestors (namely chimpanzees) does it give possibility to social behavior being evolved from our ancestors? Are Chimpanzees primitive analogues to Human behavior?
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