- News Home
17 April 2014 12:48 pm ,
Vol. 344 ,
Officials last week revealed that the U.S. contribution to ITER could cost $3.9 billion by 2034—roughly four times the...
An experimental hepatitis B drug that looked safe in animal trials tragically killed five of 15 patients in 1993. Now,...
Using the two high-quality genomes that exist for Neandertals and Denisovans, researchers find clues to gene activity...
A new report from the Intergovernmental Panel on Climate Change (IPCC) concludes that humanity has done little to slow...
Astronomers have discovered an Earth-sized planet in the habitable zone of a red dwarf—a star cooler than the sun—500...
Three years ago, Jennifer Francis of Rutgers University proposed that a warming Arctic was altering the behavior of the...
- 17 April 2014 12:48 pm , Vol. 344 , #6181
- About Us
Humans, Chimps Wear Different Genes
11 December 2003 (All day)
Despite decades of study, geneticists don't know what makes humans human. Humans and our kissing cousins, chimpanzees, share practically all of our DNA. But new research reveals key differences between chimp and human genomes.
Michele Cargill, a geneticist at Celera Diagnostics in Alameda, California, and her colleagues examined 7600 genes shared by chimps, humans, and mice, identifying those that had more than the expected number of base changes, given the normal mutation rates in each species. They concluded that 1547 human genes and 1534 chimp genes had experienced relatively rapid changes that likely endowed a survival advantage. The mouse data helped the team determine how the genes had changed over evolutionary time.
In both chimps and humans, many genes involved in cell signaling and amino acid metabolism have undergone major changes since the time of the species' last common ancestor 5 million years ago. But the genes didn't follow the same track in the two species, suggesting that they faced different pressures from natural selection. In humans, 27 of 48 olfactory proteins and three of 21 hearing proteins showed significant accelerated change, whereas that was not true in the chimp. In contrast, the chimp's genes for mesoderm development and skeletal structure had changed more.
The rapid evolution of olfactory genes in humans is puzzling. Because humans no longer rely strongly on their sense of smell to survive, any changes were assumed to have had no effect or a negative effect. But the new study suggests that some olfaction genes have been evolving in a positive way: Their changes appear to have been selected for during human evolution. The genes may have promoted certain dietary changes or informed sexual selection, says co-author Andrew Clark, a population geneticist at Cornell University in Ithaca, New York.
The work, reported in the 12 December issue of Science, “is a valuable start to the genomic approach to identify ‘humanness,' ” says Ajit Varki, a glycobiologist at the University of California, San Diego, who adds that comparing human and chimp genes to the genome of a closer relative than mice, such as another great ape, would reveal even more genes that defined the branches of the primate family tree.