The descent and domestication of man is guaranteed, in fact it has been recognized since Darwin's time. Just as the genetic traits of domesticated animals are selected generation upon generation, and may only be partially reversible through cross-breeding, the same is obviously true of humans.

In addition, the descent of man from pre-hominid ancestors has hugely increased the number of genes in our DNA, and has not merely mixed them. What genes can be added to our DNA is unknown! But if nature is any indication, there are likely millions of people already possessing additional genes. Only time will tell if they are successful.

Darwin said it is the tendancy of all species to reproduce in larger numbers than can survive, and that this will guarantee that there will always be competition -- competition that tends towards the improvement of a species generation upon generation. But he also said that the difference between 'species' and 'race' is non-existent, based on the observation of almost infinite graduations of character between the varieties of animals. For example, a bulldog and a terrier can reproduce and we know that they are probably descended from a single wild variety. This is demonstrated by cross-breeding and yielding the (nearly) wild variety. However if a naturalist were told that the bulldog and terrier were discovered in the wild, then he would assume they *were* the original species! The same with people. We are a domesticated species, individuals are more popular because of their traits, and they have better chances to succeed in life. In the lower primates, these 'chiefs' are often the progenitors of an entire troop, and the lower casts are not allowed to breed with the females until they can overpower the leader.

The more vigorous a group is the numerous they will be and the more various their descendants will be, the more niches they will fill, and some will become dominant (more numerous). Over millions of years such diversification and natural selection has favored larger brains. Unfortunately this has also led to more dangerous childbirth, since the larger skulls of newborns have more difficulty getting through the birth canal, which is confined by narrow hips needed to facilitate walking upright. In the last few decades this dangerous childbirth has routinely been dealt with by cesarean section. Fortunately, because the volume of a brain increases with the cube of the radius, so the skull need not increase in size much to cause a huge increase in the number of brain cells. The advantage of this adaptation would seem to be fortuitous and obvious, but it may never happen if both the mother and child die during the birthing process, i.e. the child cannot pass on it's genes if it is dead.

Due to the evidence that larger brains lead to more successful people, it would seem to be an obvious use of genetic manipulation to make childbirth easier for babies with larger skulls. And I have no idea how that could be achieved! I don't even care to speculate.