Genetic Deletions In Human DNA Lead To Bigger Brains And No Penis Spines

A new study has come out in today's issue of Nature that talks about the missing stretches of DNA that make humans different from chimpanzees. We last shared a common ancestor with chimpanzees 5 million years ago and this study focuses on two of the many missing stretches of DNA. The differences in our genes lead to humans developing larger brains and also losing penile barbs.

Deletions are also known as mutations or missing stretches of DNA. Gill Bejerano of Stanford University is an author of the study and said they found more than 500 deletions in the human DNA that are present in chimpanzee DNA. Only 2 percent of the DNA in our genome makes protein-coding genes, the rest helps regulate and coordinate gene activity.

Two areas where deletions happened occurred around a neural development gene and another around a hormone-signaling gene. The neural development deletion lead to a boost in cerebral cortex growth and "it probably lead us to become the thinkers we are today," said Bejerano. The deletion around the hormone-signaling gene probably lead to the removal of penile barbs, like the ones found in chimps and cats. The barbs, or penis spines, are known to trigger female ovulation and increased sensitivity but reduced male duration during sex. Bejerano suspects that the removal of penis spines helped men last longer and lead to more monogamous relationships.

[via Wired]