The Next Step in Human Evolution
Some scientists claim human evolution has come to an end. Modern agriculture, sanitation, and medicine have resulted in large, stable human populations insulated from natural selection. Despite the reduction in natural selection pressures, one modern human subpopulation meets the criteria for rapid evolution.
For a population to evolve, novel mutations must be beneficial for the individual possessing them resulting in the production of more offspring. Over time this will result in a shift in the frequency of individuals with the novel mutation in the population. These shifts can happen rapidly if population size is small and individuals lacking the novel mutation are eliminated from the breeding pool.
With the increase in college and post-graduate educational opportunities for women, educational homogamy, the pairing of equally educated individuals, has risen. In 2010 for the first time, more women than men in the United States received doctoral degrees allowing for educational homogamy in the PhD population.
Level of education is highly correlated with intelligence and intelligence is highly heritable. Since intelligence is polygenic (the result of many genes), the combination of different genes for intelligence in the offspring of PhDs can result in the production of offspring with even higher intelligence. Highly intelligent offspring are also likely to obtain PhDs and marry other PhDs. Offspring with lower intelligence will most likely not obtain PhDs and so will remove themselves from the PhD breeding pool.PhD non-PhD breeding events are rare among monogamous PhDs as highly intelligent individuals have low rates of infidelity and intelligent women more effectively use birth control.
Previously, increases in human intelligence were limited by association with deleterious traits like myopia, autism and allergies. With the advent of modern medicine, these individuals can now survive to adulthood and enter the PhD breeding pool.
Chemists and biologists are also exposed to higher than normal levels of mutagenic chemicals increasing the likelihood of novel germline mutations. Although the majority of these mutations may have null or negative effects, high mutation rate is a key factor in rapidly evolving species.
Over time greater intelligence in PhD offspring will result in greater competition for PhD programs increasing selection pressure for intelligence in the PhD population. In as few as 30 generations, PhDs as a population could become physically and mentally distinct from the rest of the human species.