It is a somewhat common misconception that modern humans are no longer evolving, or at least are evolving at a far slower rate than their more apelike ancestors. This error may have come about because many of the changes that have taken place in humans over the past 5,000 years have not been visible, but rather occur at the level of the genome. And according to a study by anthropologist John Hawks, data shows that more changes have taken place in the human genome in the past 100 to 200 generations than at any other time in the entire evolutionary history of the species.
International HapMap Project
Data from the International HapMap Project, a multinational public resource devoted to finding genes associated with human diseases, clearly demonstrates that over the past five millennia, the human genome has changed 100 times faster than at any other point in its history. Analysis of the DNA variations in the database showed evidence of recent evolution in seven percent of the human genome, a huge portion amounting to about 1,800 different genes.
Natural Selection and Disease
By the far the biggest catalyst behind the recent selection in the human genome has been disease, as populations struggle against the pathogens that constantly assail them. In the last 10,000 years, epidemics of smallpox, cholera, and other diseases have altered the human genome, by ruthlessly culling humans with no resistance and selecting for those individuals whose genes provided greater immunity.
And as recently as four millennia ago, an HIV-resistant gene called CCR5 arose; it is now present in approximately ten percent of Europeans.
Farming and Lactose Tolerance
A commonly known example of recent human evolution is the selection for lactose tolerance in humans. Normally, the gene that allows milk digestion is "turned off" once humans hit their teens, but the slow spread of dairy farming among European populations favored the individuals whose lactose tolerance gene remained functional into adulthood.
Reasons for Rapid Evolution
According to Hawks and his team, the reasons behind this explosion of human evolution are many. Disease resistance and cultural evolution are perhaps the largest factors, but he also points out that the enormous size of the human population — currently more than 6 billion people globally — contributes to the rapidity of natural selection because there is so much genetic variation for nature to work with.
Source
- Thompson, Andrea. "Human Evolution Speeds Up." LiveScience. 10 Dec. 2007. Web. 21 June 2011.
Jenny Ashford - Jenny Ashford is a writer and graphic artist from central Florida. Her main area of interest in her Suite 101 articles is science, with a ...
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