A team of Japanese and South Korean scientists has found a larger difference between male-defining Y chromosomes of a human and a chimpanzee, which indicates faster evolution of human Y chromosomes than other chromosomes.

They found the difference in genetic information between human and chimpanzee Y chromosomes is 1.78 percent, instead of 1.23 percent that had previously been reported by US journal Science.

The team, including scientists from Japan's Institute of Physical and Chemical Research, had the findings published in the online edition of the latest issue of the academic journal Nature Genetics.

According to the researchers, the difference between the Y chromosomes of a human and a chimpanzee is larger than the overall difference in the overall genome sequence, which indicates the accelerated rate of evolution.

They also found no gene "CD24L4" in chimpanzee Y chromosomes. "CD24L4" is related to the composition of the protein on the surface of human immune cells.

The researchers held that it was after the common ancestors of human beings and chimpanzees branched and started their independent evolution about five million years ago did human Y chromosomes acquired gene ��CD24L4��. It might be able to explain the difference between human beings and chimpanzees in immunity against infectious diseases.

By People's Daily Online