I have a thought. Over the past several thousand years, homo sapiens have remained genetically indifferent from their ancestors. With a few variations that determine sex and the other various genetic traits that individualize everyone. My thought is that the reason we have remained stagnant in our genetic development is that we are tolerant of our mate's behavioral disorders and most people only have 1 mate for their entire lives. As seen in various primates, 1 male mates with several females, and most groups have new females joining and leaving. This causes the males genes to be spread to more children and the genes of the different females contribute to more mutations thus possibly increasing the rate of evolutionary development.
Now my theory is that nature has a mechanism for this...even in humans. Human females in particular. I think that the female menstrual cycle is nature's way of telling males to move on. The hormonal imbalance spurred on by the onset of the cycle causes the female to be temporarily abrasive. This may tell the male several things. 1 being that if the male has mated recently, and the cycle occurs, it means the act was unsuccessful. Since nature didnt anticipate us having significant medical technology, so it had to give humans a way to know about miscarriages. The second purpose is that after an an egg gets fertilized, a woman skips her menstral cycle and thats how we know that the mating was successful. In my theory, after the baby is born, the continuation of the menstral cycle may signal to the male that it is time to move on to a different mate thus spreading genetic differences. This, as seen in several different species leads to evolutionary growth. But, the only reason we are identical to our ancestors in africa less than 50,000 years ago, is for 1 reason and 1 reason only: Tolerance of our mates. Humans have made medications to bring the effects of the hormonal imbalances of this monthly event down. In a sense, we are making a dead end for our species through another venue.
Now, this is strictly a theory of mine, and its open for any suggestions and/or
constructive critsisms. I am an amaetur so please excuse any mistakes i have made in this post and help me to correct them