Genetic Errors Nixed Penis Spines, Enlarged Our Brains

[image error]

Geneticists have linked the physical appearance of humans to patches of DNA lost in the 5 million years since we shared a common ancestor with chimpanzees. One loss prevented men from growing penile barbs, which chimps possess. Another enlarged some regions of our brain.

"We can know what makes us human, what makes us physically different from other animals and why," said developmental geneticist Gill Bejerano of Stanford University, an author of the March 10 study inNature. Only 2 percent of the DNA in our genome forms protein-coding genes. The rest, once called "junk DNA," helps control and coordinate gene activity. Out of this regulatory coordination, physiological complexity emerges.

Bejerano's team started by comparing the genomes of chimpanzees and macaque monkeys, which share a 20-million-year-old common ancestor. They identified regions that hadn't changed in chimps, then compared these to corresponding stretches of the human genome. They found more than 500 mutations known as deletions, or stretches of DNA present in chimps but lost in humans.

Full Story at Wired