Men have lost the DNA code that once made human penises spiny!

Because of evolution, species routinely faze out parts that are not necessary and focus on developing more helpful characteristics. One area where this has occurred is the penis! If you were to look at the penis of a chimpanzee for example it is coated in several small barbs of keratin, which is a hard tissue.

This used to be present in humans as well, but it is believed that the DNA code for this specific trait disappeared around 700,000 years ago before modern humans split from Neanderthals. In total, scientists believe there are around 510 DNA deletions that have occurred during human evolution.

By deleting unnecessary traits, other changes occurred such as larger brain sizes and the removal of whiskers on our face! It is believed monogamy could have potentially led to the removal of spiny penises because men no longer compete against several mates at once to impregnate a female! The spines used to help destroy other sperm that were present and ensure the reproduction of the male genes!

(Source)