When geneticist Mary Claire King became the first scientist to compare the genes of chimps and humans in 1975, she was in for a surprise. The humans and chimpanzees were not 50 percent similar genetically, or 60 percent, or even 80 percent, they were 98 to 99 percent similar, nearly identical. All of the differences between us and them, must relate to the 2 percent.
What has followed has been a rich and detailed consideration, a consideration that is still very much underway, of the 2 percent. We now know many of the genes that lead human chimpanzee immune systems to be so different, and have some suspicion as to which genes are associated with chimpanzees never get the kind of heart attack we get (for more on that, see the last three chapters of The Man Who Touched His Own Heart). But there was a catch.
While geneticists were comparing humans and chimps, another tribe of biologists, parasitologists, were doing something very different, tallying lists of the species that live in chimps or live in humans (and every other species for that matter). For parasitologists these included both big things (worms and mites, for instance), little things, such as protists, and truly tiny things including viruses. But there was a barrier to progress. The parasitologists studying humans and those studying chimpanzees, they weren’t friends. And so while each group had a tally of the organisms found in their study animals, the tallies were not compared, EVER. But such a comparison is important. A large proportion of the genes (and their products, including proteins, but also our behaviors and much more) of any organism are those of its parasites and pathogens.Someone with more than one worm species, for instance (many people have more than one worm species), may actually be dragging around more worm genes than human genes! We are what eats us.
Read full, original article: Chimps and Humans are Les Similar than We Thought