Human and chimpanzee independently evolved bitterness
Although both humans and chimpanzees have individuals who cannot taste the bitter substance phenylthiourea (PTH), different mutations are responsible. This disposition therefore did not arise in a common ancestor, as previously assumed, but only long after the split into the species, explain Stephen Wooding from the University of Utah and his colleagues.
As early as 1939, researchers led by the British geneticist Sir Ronald Aylmer Fisher had determined that a similar proportion of individuals – around thirty percent – in humans and chimpanzees cannot taste PTH and concluded that it originated in the common ancestor. But when the researchers, led by Wooding, compared DNA samples from chimpanzees with those from people who are insensitive to PTH, they found different causes. In the chimpanzee, the change is not in the middle of the gene, as in the human pattern, but at the beginning, they observe.
However, both changes caused the bitter taste receptor to not work. According to this, Fisher's observations are correct, but the conclusions are wrong: It is not about an old common property, but about convergent evolution.
