Human History is Written in Genes

Though we consider our species incredibly advanced, 99% of our gene sequence is identical to the gene sequence of chimpanzees. And though we consider our species incredibly diverse, even going as far as to attack fellows of our species on account of their phenotypes, we are genetically even less different from other human beings than from chimpanzees- less than 1% to be precise. In context of the scientific, genetic explanation for human diversity, our previous hypotheses about our origin and the distinction between races seem outdated.

            For one thing, it’s highly likely that all the humans on earth are descended from a single mother, a “mitochondrial eve”(Shreeve, 62)*. We know this because mitochondrial DNA is passed down directly from mother to child with all the previous mutations preserved, and the earliest and most ubiquitous mutation originated in Africa. Scientists deduce that a group of people in Africa decided to migrate out because the genetic markers of those people still appear all around the world. This means that everyone alive today is descended from those people who lived in Africa. Scientists have isolated the most common and thus the earliest genetic markers, and the San bush people of southern Africa, the Biaka Pygmies of central Africa, and tribes in eastern Africa seem to be the source of those genetic markers. Scientist Spencer Wells met with the San people, and they exhibit various phenotypes present in other groups of people. The scientific explanation for the population of the earth- that humans are the ones who did the traveling and the creating, not creator gods- chafes with traditional origin stories. For example, Wells received a flat-out denial of his research from an Aboriginal man who chose to support the origin stories of his own culture. Nevertheless, evidence indicates all humans are distant relatives from Africa.

             Race as defined by skin color is also a social construct that genetics refutes. Skin color varies from light to dark as an adaptation to millennia of sun exposure, and doesn’t exclusively indicate genetic similarity. People from Africa may have the same skin tone as Aboriginal Australians, and still be genetically distinct in almost every other way. It is true that different evolutionary populations have common polymorphisms- Alus and short tandem repeats are two types of gene sequences that are inheritable. Scientists can group people based on the amount of common Alus or short tandem repeats they have, but with varying degrees of accuracy. There is debate over whether it’s even useful to group populations based on gene sequences that don’t inherently code for anything vital to survival. But there is research that indicates some populations have adaptive traits from long ago that are medically relevant to disease treatment and prevention today. If people can be categorized into their genetic groupings, doctors can better search for genetic traits that may influence their diagnoses and treatments. Despite the potential benefits of grouping people genetically, it is still too close to the practice of racial profiling for many scientists’ comforts.  

            Gene sequencing supports the theory of evolution by demonstrating the similarities between humans and other primates. It also shows the process of random mutation and natural selection over time. The human population is one of the best sources of raw data on evolution. We have populations with very little immigration, we have populations who have emigrated to other climates, we have populations who have mixed in one region, and we have populations who have mixed in many locales. Though genetic sequencing hits some controversial nerves on origin and race, disrupting social constructs may be exactly what we need to progress as a species.  

*Shreeve, James. "The Greatest Journey Ever Told." National Geographic. March 2006. pages 62-69.