A tale of three chimps – Diamond (PDF 1) Diamond explains and questions human being last common ancestor with apes. He then explains how gorillas and chimps haven’t changed a whole lot since we last shared a common ancestor but humans have. Humans have changed greatly in the categories such as increased brain size, and upright posture. Diamond talks about a method where molecules are compared to date back to how many million years ago, the two-species separated. He uses a hypothetical example of tigers and lions. He said if lions and tigers split five million years ago, then the scientists would find out the percentage difference between the two and if the molecules are 100% identical then for every 1% it’s been 5 million years since the species have split. The method used to find the percentage difference is called DNA hybridization. It works by mixing the two species DNA together and melting it. for every 1 degree, Celsius that the melting point is lowered indicates a 1% difference between the two species. This discovery allowed for humans to conclude that we are actually more closely related to chimpanzees (1.6% difference) rather than gorillas (2.3% difference). Another method called DNA clock which uses fossil records dated humans and chimpanzees to diverge about 6-8 million years ago, this discovery changed what people previously knew about where humans come from. Taxonomists had people in a separate family, but this should not be the case. Humans and chimpanzees fall within the same family under homo genius. Diamond says we have yet to discover what from the 1.6% difference allows humans to have different abilities and characteristics. He talks about an experiment where a baby chimp and baby human were raised together in which the baby chimp continued to still look like a chimp and was unable to walk erect. He uses another example to show how a small percentage difference in DNA code can change an animal. There is a lake in Africa known as Lake Victoria. Cichlids are confined to this one lake. There are over 200 variations and they have all evolved from one common ancestor. Their DNA differs from one another by an average of .04% yet some eat other fish, some eat fish eggs, some crush snails and others eat plankton and algae. Little differences in DNA can make a huge difference. Diamond talks about how chimps get tested on and how we lock chimps up in zoos. He talks about how ethically wrong it is to lock up chimps and how the public would feel if they changed the name on the chimp cage at the zoo to homo troglodytes (what they would be called if taxonomists would put humans and chimps in the same genus). He also talks about how humans do not care if medical research is tested on animals, even though it would be most beneficial if It would be done to humans. Also, talks about how Nazi’s experiments on humans were viewed such a terrible thing but performing them on chips is not such a big problem. He ends up saying, if we don’t change our attitude towards apes if we want them to survive; otherwise the only apes that will be around are the ones in the zoo.