Here come two points about human evolution – the first is one that I imagine is not surprising to you, but the second may be, and might make you wince.
First, the animal in this photo is not an ancestor of us Homo Sapiens. We did not evolve from apes but share a common progenitor that goes back over six million years. (As a point of reference, Homo Sapiens evolved about two- to three-hundred thousand years ago.) Onto the second point, which is about our distant ancestors’ male anatomy. In fact, they possessed very different components: hard, spiny spikes along the penis. These spines exist today in mammals like cats and chimpanzees, but not among Homo Sapiens — and it isn’t because of our genes.
Our DNA is only about 2% protein-coding, or genes. The other 98% has epigenetic value that scientists are rapidly learning about today. Called “junk DNA” (honestly I wrote this story because of the pun), some of the work that these deoxyribonucleic acids do is *silence* genes from being turned on. This is super important! How else would my eyeball know that it shouldn’t grow fingernails? Or that a penis shouldn’t grow spines?. Scientists suggest that spiked penises might favor male progeny when there is a lot of competition for sexual partners, and when copulation has to be quick. The lack of spines for humans means more pleasurable and longer sex, and perhaps favors more monogamous mating patterns.
Source(s): _Nature_, “How the penis lost its spikes,” by Zoe Cornyn, 9 March 2011, DOI: 10.1038/news.2011.148. “Genetic errors nixed penis spines, enlarged our brains,” _Wired_, Dave Mosher, March 9, 2 011, @ wired.com. Image and some info from _Scientific American_, “Image reveals what last common ancestor of humans and apes looked like,” by Charles Q. Choi, August 10, 2017.
