Natural selection is a powerful mechanism that has generated all of life’s diversity, including the human species. Yet natural selection is not the only selective force at work in the evolution of life, especially in human populations. Human culture has had a selective force in crafting the genotype and phenotype of Homo sapiens. In consideration of this point, the following illustrates the many ways that human culture has acted as a selected force on human evolution.
There are a variety of physiological changes in Homo sapiens that have occurred with cultural changes. Many of these changes can be directly observed in the fossil record. A pinnacle example is the increase in brain size along with cultural development. Accompanying the swelling of the brain, Homo sapiens began designing tools for hunting and kindling fires for cooking during the Paleolithic era. The ability to construct tools spread like wild fire throughout human cultures and was passed down from one generation to the next. However, the brain size of the Hominids in these cultures was comparable to the size of a chimpanzee brain. Mental capacity only began to expand with the advent of language, giving rise to the technological innovations and artistic expressions that are manifest in contemporary culture.
The diet of various cultures had a selective force in shaping the jaw size of Homo sapiens. Modern Homo sapiens have a smaller jaw size than more archaic Homo sapiens. Food captured in the wild tends to be harder and more difficult to chew. Larger jaws were necessary to digest this type of food. With the use of fire, however, cooked food became softer and easier to chew. Cooking food may have relaxed environmental pressures for large jaws (Lewens, 2013). As a corollary, the overall jaw size of Homo sapiens decreased.
A particularly strong selective force cultural evolution has had on human evolution was the advent of agriculture. Sustaining crops and raising cattle was originally quite bad for human populations. Because of dense populations of cattle, virulent maladies such as smallpox, malaria and tuberculosis began to circulate (Lieberman, 2013). Our teeth, brains and bodies began to diminish. However, humans soon developed new alleles that helped them better digest these foods.
Cultural evolution has chiseled the human genotype as much as the human phenotype. In regards to the former, one way that cultural evolution has had a selective force on genes is how lactose intolerance has waxed and waned in European populations. Children originally evolved to consume breast milk from their mothers only during infancy. Most people had a gene that deactivated the ability to digest milk after infancy (Wade, 2001). With the domestication of cattle, people began to consume milk on a regular basis.
The human body was not originally tuned to digest large quantities of milk. As a corollary, some populations were lactose intolerant. People who could digest milk could consume more nutrients. The evolutionary advantage to this proved so great that it began to spread throughout the European population. As a result, very few people today are lactose intolerant.
Human evolution has influenced cultural evolution and cultural evolution has influenced human evolution. With the creation of tools and fire, human cultures were able to cook food. Tender food alleviated the selective pressures for large jaws, leading to a dental reduction in human populations. Yet human culture was relatively primitive prior to the advent of language. Accompany the development of language, technological innovations and artistic expressions burgeoned in human cultures. Human cultures began to consume large quantities of milk with the rise of agriculture. As a result, people who could consume milk had an evolutionary advantage over people who could not consume milk. Thus illustrates the many ways that biological changes and cultural changes have co-evolved.
- Lewens, T. (2013). Cultural Evolution. Retrieved from Stanford Encyclopedia of Philosophy: http://plato.stanford.edu/cgi-bin/encyclopedia/archinfo.cgi?entry=evolution-cultural
- Lieberman, D. (2013). How Our Stone Age Bodies Struggle To Stay Healthy In Modern Times. Retrieved from NPR: http://www.npr.org/2013/09/30/227777434/how-our-stone-age-bodies-struggle-to-stay-healthy-in-modern-times
- Wade, N. (2001). Human Culture, An Evolutionary Force . Retrieved from New York Times : http://www.nytimes.com/2010/03/02/science/02evo.html?pagewanted=all&_r=0