Human molecular evolution since the human-chimpanzee divergence

Published on March 18, 2015   24 min

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My name is Katherine Pollard. I'm a Senior Investigator at the Gladstone Institute and a professor of human genetics and biostatistics at the University of California, San Francisco. Today, we're going to be talking about human molecular evolution since the human-chimpanzee divergence.
My lab studies the genetic basis for what makes us human. From an evolutionary perspective, this is the same as asking what makes us different from chimpanzees and other apes. Chimps are our closest living relatives on the tree of life, and we had a common ancestor about 6 million years ago.
Despite the fact that humans have often thought of ourselves as particularly unique, from many points of view, we are just typical apes. Even some traits, such as tool making or counting, that were previously thought to be specific to humans, have been observed in non-human primates and other animals. However, for every similarity to chimpanzees, there are also interesting differences. These include our unique spoken language and also our susceptibility to a number of deadly diseases. For example, primates can all become infected with immunodeficiency viruses very similar to HIV, yet the resulting AIDS disease is much more severe in humans.
Humans and chimps also differ in their leading causes of death. Because of antibiotics and other medical advances, infectious disease is not a top killer of humans or our domestic animals, such as dogs. Instead, we have very high rates of cardiovascular disease and cancer. This is partially due to our living longer into old age than other primates as well as diet, smoking, and other effects of our environment or lifestyles. However, chimpanzees and gorillas in captivity now receive excellent medical care and live to be quite elderly, but they still do not have the prevalence or severity of cardiovascular disease and cancer seen in humans, and this is true even when the non-human primates are sedentary and eat a high fat diet. This suggests the genetics also plays an important role in explaining why humans have such a different disease profile from chimpanzees. In the genomic era, comparative medicine now seeks to identify the genetic risks that are unique to humans.

Human molecular evolution since the human-chimpanzee divergence

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