by Randy Crum

Created on: May 30, 2008   Last Updated: March 10, 2009

Evolution is unavoidable. Therefore human evolution is unavoidable.

There is evidence that humans are still evolving. For example some 700 relatively new genes have been discovered in the human genome just within the last 5000 to 15,000 years. (See http://www.nytimes.com/2006/03/07/science/07evolve.h tml.) Other studies show what would seem to be a predictable trend: increases in brain size in humans over the last few thousand years (Evans, Patrick D. et. al. 2005. Microcephalin, a gene regulating brain size, continues to evolve adaptively in humans. Science 309: 1717-1720.) There are numerous other examples of human evolution taking place that are available in the scientific literature.

It is not really a question of whether or not humans will continue to evolve.

They will.

Even the direction of evolution is difficult to predict. Evolution is based on random inputs - mutations. So not only must some genetic characteristic be favored by natural selection, it must also occur as one of the possible random inputs in the first place.

However there is one thing that we can comfortably predict about human evolution - it will take place at a much slower rate in the future than it has in the past.

There are three factors affecting this slow rate of evolution.

First, evolution takes place most rapidly in small, genetically isolated populations. In such populations a specific genetic characteristic can become a part of the entire population's genome in a relatively few generations. Humans evolved into different races in populations which were genetically isolated from each other.

The human population, however, is currently very large - and continuously growing larger - as well as far from genetically isolated. With few exceptions it is possible to get from any place on Earth to any other place on the planet in 24 hours or less. Therefore the number of human generations required to have a new genetic characteristic become common throughout the human genome is very large.

The second factor is modern medicine. Natural selection works to eliminate genetic characteristics that cause early death or an inability to reproduce efficiently. Humans have developed modern medical practices, medications and techniques that allow people to live longer and have children where they might not have been able to do so in the past. Those are undoubtedly good things. But those techniques and procedures decrease the ability of natural selection to control evolution.

The third factor slowing down the

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