MALES' DNA PROPELS EVOLUTION, STUDY SAYS

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MALES' DNA PROPELS EVOLUTION, STUDY SAYS
11 April 2003 - University of Chicago

In the battle between the sexes, there's one area where males dominate females, they have a higher rate of genetic mutation, driving the evolution of the species, according to research published Thursday.

The finding could help settle a debate among scientists that challenges the prevailing theory of what pushes evolutionary change in humans.

"Mutation is the ultimate source of variation," said Wen-Hsiung Li, a University of Chicago evolutionary geneticist. "Your ancestors and my ancestors accumulated different mutations, which is part of the reason why you and I look different."

It is also the reason why humans and chimpanzees diverged from a common ancestor between 5 million and 6 million years ago, he said. Mutations occur at a random rate and can be either beneficial or harmful to an organism.

Li and co-investigator Kateryna Makova report in the British science journal Nature that the mutation rate of human, chimp, gorilla and gibbon males is five to six times greater than their female counterparts.

Evolutionists believed for more than half a century that the high male mutation rate was the driving force of evolutionary change because sperm stem cells are constantly dividing to produce sperm.

When cells divide, there is a greater chance that an error could be made in copying DNA, which produces a genetic mutation. A female is born with all of the eggs she will have in life, and they do not divide, reducing the chance of genetic alteration.

This mechanism of evolution was recently challenged by studies at the Whitehead Institute and the International Human Genome Sequence Consortium, which reported that the male mutation rate was less than twice that of females.

The findings left evolutionists in a quandary because the rate of genetic mutation was too small to make a difference in evolutionary change.

Makova said the U. of C. study "is independent proof of the dominant male in producing mutations for molecular evolution."

The Chicago researchers determined the mutation rate by measuring genetic changes in the Y chromosome, which only males have, and a nonfunctional segment on chromosome 3, half of which comes from the mother and half from the father.

Since the Y chromosome is constantly being made in sperm during cell division, it has a greater chance of undergoing genetic errors, Li said. Half of the chromosome 3 segment comes from the nondividing eggs of the female and is less vulnerable to having genetic errors incorporated in its DNA.

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About: University of Chicago
The University of Chicago was founded in 1890 by the American Baptist Education Society and oil magnate John D. Rockefeller. The land for the new university, in the recently annexed suburb of Hyde Park, was donated by Marshall Field, owner of the Chicago department store that bears his name.

In 1929, Robert Hutchins became the University's fifth president. During his tenure, Hutchins established many of the undergraduate curricular innovations that the University is known for today. These included a curriculum dedicated specifically to interdisciplinary education, comprehensive examinations instead of course grades, courses focused on the study of original documents and classic works, and an emphasis on discussion, rather than lectures.

During the late 1950s and early 1960s, the University began to add modern buildings to the formerly all-Gothic campus.

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