...that human penises used to have a spine?
http://news.nationalgeographic.com/...ome-science/?source=link_tw20110309news-penis
http://news.nationalgeographic.com/...ome-science/?source=link_tw20110309news-penis
Christine Dell'Amore
National Geographic News
Published March 9, 2011
Men have lost the DNA code that once made human penises spiny, according to a new analysis of the human genome.
Penile spines, which are still present in several modern animals, are usually small barbs of keratin—a type of hard tissue—that line the outside of the organ.
The prehistoric male enhancement existed in the common ancestor of chimpanzees and humans, which lived about six million years ago, according to the gene analysis.
But the "penile spine enhancer" code disappeared from human genes before our common ancestor split into modern humans and Neanderthals about 700,000 years ago, said study co-author Gill Bejerano, a developmental biologist at Stanford University in California.