Home Video U.S. World Politics Justice Entertainm ent Tech Health Living Tr avel Opinion iRepo rt Scientists are seeking to understand the underlying reasons why humans and chimpanzees have key differences. (CNN) -- You've read the headline, and it probably made you giggle. Go ahead. Get it out of your system. Then take a deep breath and consider how evolution affected a few specific body parts, and why. Humans and chimpanzees share more than 97% of DNA, but there are some fairly o bvious differences in appearance, behavior and intellect. Now, scientists are learning more than ever about what makes us uniquely hum an. We know that humans have larger brains and, within the brain, a larger angu lar gyrus, a region associated with abstract concepts. Also, male chimpanzees have smaller penises than humans, and theirpenises have spines. Not like porcupine needles or anything, but small pointy projections on the surface that basically make the organ bumpy. Gill Bejerano, a biologist at Stanford University School of Medicine, and colleagues wanted to further investigate why humans and chimpanzees have such differences. They analyzed the genomes ofhumans and closely related primates and discovered more than 500 regulatory regions -- sequences in the genome responsible forcontrolling genes -- that chimpanzees and other mammals have, but humans do not. In other words, they are making a list of DNA that has been lost from the human genome during millions of years ofevolution. Results from their study are published in the journal Nature. Think of it like light bulbs and their switches, where the light bulbs are How the human pe nis lost its spines Website for those born this way Tornado apparentl y touches down in Alabama TV exec convicted ofbeheading to learn fate Columnist David Broder dies NewsPulse Most popular stories right now Explore the news with NewsPulse » How the human penis lost its spines By Elizabeth Landau, CNN March 9, 2011 1:00 p.m. EST EDITION: U.S. INTERNA TIONA L MÉXICO Set edition preference Si gn up Log in NewsPulse Money Sports STORY HIGHLI GHTS Humans lack a switch in the genome that would "turn on" penile spines, sensory whiskers Some scientists theorize that the absence of spines encourages pair bonding Chimpanzees and mice both have penile spines and sensorywhiskers RELATED TOPICS Biological Anthropology Genomics Life Sciences Primates Y ou'v e selecte d the U .S. Edition. Would you like to make this your defa ult edition? Y es | No Close How the human pe nis lost its sp ines - CNN.com htt p: //www. cn n.com /2011/HEAL TH/03/ 09/ pe nis.s pi nes .g enes/index .h tml 1 of 5 3/9/2011 1:47 PM
