Genomics Professor Katherine Pollard explored the genetic basis for being human in a video presentation titled “What Makes Us Human. Here a rather dramatic announcement from her talk:
Mouse and rat actually have a common ancestor longer ago than human and chimp, and some people will be surprised by that. They will say, “We are so much more different than a chimp . . . mouse and rat must be pretty similar.” Actually mouse and rat on average are much more different from each other than we are from a chimp, and that’s sort of a humbling fact to keep in mind.
We’re not exactly like chimpanzees, of course, but there are quite a few overlaps (as well as differences), which Pollard explores beginning at the 4-minute mark. Surprisingly, young chimpanzees have a better competency in counting and numbers than young humans. At the 11-minute mark, you can see that the human genome is 95% similar to that of a chimp (or 99%, depending on how you define similarity), and that it is 28% similar (or 89%, depending on definition of similarity) to the genome of a mouse.
At the 31:00 mark, Pollard offers a visual mapping of comparisons between humans and many other species of whom the genome has been mapped (chimp, gorilla, old world monkeys, new world monkeys, mouse, chicken and fish). For instance, we split off from the common ancestor we shared with chickens about 300 million years ago, we split off from the common ancestor we had with fish about 400 mya. We split off from the common ancestor we had with mice about 75 mya. We split off from the common ancestor we share with chimps only 6 million years ago.
Full genome sequencing has resulted in the conclusion that “after 6.5 [million] years of separate evolution, the differences between chimpanzee and human are ten times greater than those between two unrelated people and ten times less than those between rats and mice.”
For more information from Katherine Pollard (and other scientists studying comparative genomics), consider these BBC radio discussions on shows hosted by Richard Dawkins. Pollard appears on Episode 2. This same episode contains a fascinating discussion of the loss of human genes relating to smell (compared to our ancestors) and the gaining of genes relating to color vision (a duplication of a gene that allowed dichromatic vision in mammals other than great apes).