Brain evolution gene found, according to ScienceNOW 20 April 2005. Geneticists at the Kumming Institute of Zoology in China have been comparing genes involved in brain function in humans and many different animals, to see if they can identify the gene changes that enabled human brains to evolve. They have found a gene named PCAP precursor, which encodes several different proteins for brain development and function. It seems this gene stayed much the same over eons of evolution “but then, sometime after humans and chimps diverged it evolved at warp speed in the human lineage”. One sequence in this gene called the “unidentified domain” or UD appears to have changed “about seven times faster than it did in other mammals, and shows signs being positively selected for in evolution”. UD has been previously considered to be “junk DNA” because it didn’t seem to be translated into a protein. The Kumming Institute team suggest it codes for a regulator of other parts of the gene.
Editorial Comment: The difference between human and chimpanzee versions of this gene may help to explain differences between human and chimp brains, but it does not prove that one evolved from the other. The conclusion that this gene underwent rapid evolution is not a fact, it is an assumption based on an already existing belief in evolution in order to explain how different the PCAP is in chimp and humans. The facts are: chimp and human PCAP genes are more different from each other than chimp and other animal PCAP genes. This is because chimps are animals, and have brains that are more like animal brains than human brains.
“Rapid evolution” is often used as an excuse to explain large differences between creatures considered to be close on the evolutionary timetable, but this is a story that doesn’t explain anything. Furthermore, we now have yet another instance where “junk DNA” has been found to have a function and is not evolutionary detritus. It is far more logical to believe that big differences between different life forms exist because they were separately created to function differently and all the contents of their genome are there for a purpose. (Ref. genetics, neurology, human)