Researchers in the faculty of medicine in Stanford university recently found out that big brains and a softer penis is the result of a DNA loss in our evolutionary road. By comparing the human DNA and chimpanzee's (our nearest evolutionary relatives), they found out that most of our differences are the result of the loss of a DNA sequence. Having monogamous relationships is apparently based on the loss of the penile spine. Animals like chimps and dogs, have a penile spine, which leads to a more competitive mating system.
Female chimps and other species advertise their interest in mating when they are fertile, that's the only time in their cycle where they are sexually receptive. As oppose to human where female ovulation is hidden (DNA-wise) and they are receptive over a more extended period of time. This is why our penile spine was lost alone the years, so we can form a longer-term bonding rather than some brief encounters. Woman claim that they are not the source of all problem in the world, I'm starting to doubt that.
510 DNA segment is the reason the spine is missing in humans and highly conserved in chimps. At the same time this discover was made about the penile spine, the same researchers notices that those deletions occur near genes involved in neural development. They then discovered that this gene also affect another one called GADD45g that is responsible of suppressing neural cell growth. This is very cool because less DNA can actually mean less bones but it can also mean more since this loss means a growth in the brain. I bet there are women who are going to try to find out more way to remove some sequences in the men DNA and others that will try to bring back the penile spine.
If you don't know what a penile spine is there's a very good example for those who own big dogs, sometimes when your dogs sits he's penis comes out and this is not due to a sexual arousal but it's involuntary. Dogs like chimps have a penile spine so in slang term they have a boner all the time but the skin around it kind of covers it and it's only when they get in certain positions that it comes out.
These findings mean that some day scientist might be able to create a very intelligent man with an extremely small penis or a very stupid one with a very big penis. I think it's scary.