Evo-Ed: Integrative Cases in Evolution Education

Cases for Evolution Education

Are Races Biological or Societal

As applied to human populations, race is a societal construct, not a biological concept.  Human brains are good at putting things into categories. Two are Us and Them, which leads to separation along cultural dichotomies such as sports teams, clothing, customs and “race”.  Racial concepts are not innate, but emerge from cultural biases.

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PowerPoint Slides

Are There Races Among Humans?

Some biologists, primarily entomologists and plant biologists, apply the term “race” to populations that vary significantly from one another. These variations include chromosomal, genetic, geographical and/or physiological differences.  Most vertebrate biologist use the term “subspecies” to denote differences within a species, rather than “races”.

Subspecies have 1) sharp genetic boundaries among them and/or 2) separate evolution lineages, as evidenced by phylogenetic and genetic analysis. 

global UV patterns

This table summarizes an analysis of the genetic differences among humans and chimps.

The genetic differences within individual humans in a population (93.2%) are much greater than the genetic differences among populations (2.5%) and greater than the genetic differences among geographically defined “races” (4.3%). Comparatively, chimpanzees have less genetic variation among individuals in a population (64.2%) and more genetic differences among geographically delineated “races” (30.1%).  These data show that there are no sharp genetic boundaries (=genetic differences) among human populations and that chimpanzees are much more genetically diverse across geographical boundaries.

Analysis of population genetic data shows that the second attribute of subspecies, having separate evolutionary lineages, does not apply to humans.  If this were true, graphing data related to differences in DNA would produce a graph with discontinuities or “breaks” in geographical distributions of humans (see graph below).  Comparing genetic differences among and between human populations (known as the FST statistic) shows the opposite:  continuous, smooth and relatively small differences.  These data reflect the tendency of humans to migrate and interbreed, resulting in the mixing of genetic information.

evolutionary lineages

But humans nonetheless categorize one another (and ourselves) by "race", which itself is often correlated to skin color. Since genetic data do not support the idea of human races (or "subspecies"), race is a social construct, persistent in societies, both ancient and modern. If "race" is indeed a construct that is unsupported by a genetic analyses among humans, why are we prone to making these kinds of categorizations?

The human brain instantaneously categorizes things, including surface features of humans.  This response leads to categorizing others as Us and Them. Categorizing occurs within milliseconds and begins with the neural input to the amygdala. The amygdala mediates unconscious emotions such as aggression, fear and anxiety. These are responses to something “different” in the environment and are not always accurate and brainoften inappropriate. Information from the amygdala is forwarded to the prefrontal cortex, which mediates responses to social situations. The prefrontal cortex sorts things out – follows rules and puts things in categories- when presented with information from the amygdala, other neural inputs, and hormones. It integrates emotional and cognitive aspects of social life. In terms of race, this processing is highly variable and has a very strong cultural bias.

"Us" and "Them" categories are fluid and changeable; this particularly applies to racial concepts. Racial concepts are not innate, but emerge from cultural biases. These biases overlay brain processing that generically identifies "Us" and "Them". Thus, human “race” is an idea, a concept, steeped in societal and historical norms. It is variable, fluid and ultimately context dependent.

twins Lulcy and Maria

Figure (left):These two young women, Lucy and Maria, were born at the same time to the same mother and father. They have other siblings, each with distinctive skin color and hair texture.

Lucy identifies herself as white and Maria identifies herself as black. They are using cultural definitions that are not based on a quantitative genetic anaysis to define their identities.

Read the full story here.


The concept of human races is a powerful idea. It is the basis for racial profiling, racial identity, racial prejudice, racial pride, racial politics etc. The race concept can be a basis for both cohesion (Us) and divisiveness (Them). Humans identify others and themselves based on perceived ideas of race.  Historical circumstances contribute to the definition of “race”.  Since these circumstances change over time, so has the notion of “race”, as reflected in various attempts to collect census data. The egregious use of racial concepts, racism, is responsible for some of the worst behavior exhibited by humans: slavery and genocide.

References:                                                                                              

  • Kubota, et al. 2012. The Neuroscience of Race. Nature Neuroscience 15(7): 940 – 946.
  • Alan R. Templeton. 2013. Biological races in humans. Studies in History and Philosophy of Biological and Biomedical Sciences 44: 262-271.
  • Robert M. Sopolsky. (2017). Behave: the biology of humans at our best and worst. Penguin Press.