Human Variation

For a 2018 Intro-to-Anthropology class on “Human Variation,” we read a chapter on “What about Human Variation?” in the textbook Anthropology: What Does it Mean to be Human? Also read “How race becomes biology: embodiment of social inequality” by Clarence Gravlee (2009).

For a 2021 update using the 5th edition of Anthropology: What does it mean to be human? see Human variation is more complicated than biological race and the YouTube lecture:

These readings were for Intro to Anthropology 2018. The previous class had been on Homo sapiens and the next class began the section on archaeology.

Evolution & Race

As we discussed in our very first class, Anthropology was born during European colonialism. At the time, Europeans were asking some fundamental questions like: How do we explain difference? Are other people equally human?

Ideas of racial determinism were used to justify conquest and subordination. The racial classification schemes, mostly developed in the 1500s-1800s, continue with us today.

From the 1860s, ideas of evolution were harnessed to justify existing inequalities. These incorrect ideas about evolution and race are what we call scientific racism.

Anthropology on Evolution & Race

Academic anthropology was part of the nineteenth century, and many anthropologists endorsed these views. However, anthropology began to argue that race does not determine behavior. Race is not determining of language or culture. Race simply does not work to describe cultural difference.

For the most part, the separation of race and culture has become accepted. What many people still cannot understand is how racial classifications are also inadequate to describe biological difference.

Evolution & Human Variation

The Modern Evolutionary Synthesis or “neo-Darwinism” combined Darwinian mechanisms with Mendelian heredity. “In anthropology, perhaps the most significant contribution of neo-Darwinism was the way it undermined the nineteenth-century anthropological concept of ‘biological race,’ refocusing attention on a new understanding of biological species” (Lavenda & Schultz 2018, 144).

The crucial question then became whether traditional race categories were a useful way to biologically describe human difference.

Species & Subspecies

Species fact: humans can all interbreed, and produce viable interbreeding offspring. We do it whenever we come in contact. “In neighboring populations there is much overlapping of genes and their phenotypic (physical) expressions. Throughout history whenever different groups have come into contact, they have interbred. The continued sharing of genetic materials has maintained all of humankind as a single species” (American Anthropological Association Statement on Race).

If we can biologically sort humanities into races, it would be a designation at the subspecies level. There is no evidence whatsoever of species designation at the level of human beings. The last possible species designations are for Neandertals and Denisovans. But given the genetically documented interbreeding, some anthropologists feel Neandertals and Denisovans could be considered sub-species or races.

Subspecies Sorting

Is there enough biological difference within the human species to classify human beings into groups?
YES, Human variation is real and important.
Do these classifications represent consistencies, patterns and concordances equivalent to traditional race ideas?
NO, biological variation is much more complex than traditional race categories (see Gravlee, 49).

Concordance or co-variation VERSUS Clinal or independent variation

Clinal: most features, like skin color change gradually (Lavenda & Schultz, 148). Other features vary independently of each other, as we know from classic Mendelian genetics and re-combinations. Although there is definitely a lot of human biological variation, classifications by different criteria produce different groupings.

How can we explain biological difference?

Some biological differences in humans can be explained by natural selection. Natural selection explains sickle cell patterns as present in areas where malaria is prevalent (Lavenda & Schultz, 157-158). Contrary to US stereotypes that sickle cell is an “African” trait, it is also found in Greece, Saudi Arabia, and India. Sickle cell is also an example of how traits can be adaptive in one environment but very maladaptive in others.

Sexual Selection might help to explain certain traits considered “beautiful.” And there is also a lot of randomness to human variation, brought about by mutation, gene flow, genetic drift (Lavenda & Schultz, 156-57)

What about skin color?

Skin color demonstrates clinal variation. The best explanation for this variation seems to be natural selection & Vitamin D absorbency (Lavenda & Schultz, 160-161). Although sexual selection is an important evolutionary mechanism–and surely implicated in skin color–recent research confirms natural selection (see the Smithsonian page on Modern Human Diversity – Skin Color).

The modern concept of race originates in the colonial encounter. In this encounter, people from the furthest ends of the clinal variation where placed together in the Americas and assigned roles based on a racial classification.

The earth goes around the sun

For many years, the science of race–which goes against our perception of the world that we have been socially taught–seemed very secure. In 1964, Livingstone pronounced that “There are no races, there are only clines” (in Lavenda & Schultz, 148; see Gravlee, 50, point #1). As the evolutionary synthesis demonstrated, individually-inherited traits could differently combine (Gravlee, 50, point #2), and Darwin had shown us that there is “no such thing as a fixed species” (Lavenda & Schultz, 39).

In 1972, geneticist Richard Lewontin published “The apportionment of human diversity” (1972) which demonstrated there was more diversity within so-called races than between them (Gravlee, 50, point #3).

Since around 2003: “Is race still a social construction?”

In the early 2000s, some scientists challenged Lewontin’s findings. In an Op-Ed, “A Family Tree in Every Gene” (Leroi 2005) there was a claim that despite within-group variation, clusters could still be discerned (see Gravlee, 47).

There has been more genetic testing for ancestry, but see the box, “Branches but Few Roots” (Lavenda & Schultz, 153-155). Medicines have been sold on the basis of race, and there has been a rise in television shows featuring forensic anthropology. One forensic anthropologist posed the question as “If races don’t exist, why are forensic anthropologists so good at identifying them?” (Sauer 1992). [I’ve posted about this as a “race revival” that attacked the anthropological paradigm.]

Forensic Anthropology

Measurements give us a probable ancestry estimate. These estimates depend on the context of remains.

One interesting example comes from bones found in a creek in Iowa (Konigsberg et al. 2009):

  • In world database, probably Easter Islander
  • In context of Iowa, probably white
  • If had been found in Gary, Indiana, probably black
  • If found in Hawaii, probably Native Pacific Islander

In other words, bones do not tell us skin color or typical ethnic or racial markers–they provide a probable ancestry estimation which must be matched against current population and racial classification schemes. [For a much more detailed argument, see “Race Reconciled Re-Debunks Race.”]

Race & Biology

Humans do vary biologically, with potential health effects, and even for abilities like “intelligence” (Lavenda & Schultz, 161-62). Race can be seen as a “culturally constructed label that crudely and imprecisely describes real variation” (John Relethford, “Race and global patterns of phenotypic variation” [2009, 20])
But these crude labels are socially and historically real, influencing access, opportunities, and outcomes. These labels often have greater health effects than ancestry, and with even greater effects for abilities like “intelligence”

How do we do race in the United States?

Hypodescent = child’s race “lowered”
White + Black = Black
In some states, laws by fraction
1/4, 1/8, 1/16, 1/32
In extreme cases, the “one drop” rule: Some people have changed their race by crossing a state line.

Some people can change race by getting on a plane. Latin American and Caribbean classifications can be different. Some countries use hyperdescent or recognize mixtures as mestizo or mulatto. Or like Brazil, have many color categories for skin.

See this 2016 article 220 years of census data proves race is a social construct.

HOWEVER, Race ≠ Fiction (Gravlee, 53)

The cultural construction of race has real effects. In 2015, the average white household had 16x the wealth of an average black household. See The Racial Wealth Gap. This gap has consequences for housing, education, and healthcare.
The consequences are also biological, like infant mortality rates, life expectancy, and health.

Biocultural Approaches (Lavenda & Schultz, 7)

Our social practices, ideas, and classifications have biological implications. Because of human plasticity, poverty and political marginalization–especially in early childhood–can have profound biological effects. “Race becomes biology through the embodiment of social inequality” (Clarence Gravlee in Lavenda & Schultz, 151). [I’ve tried to provide a longer summary of this great Gravlee article as Race Becomes Biology, Inequality Embodied.]

The previous class was on Homo sapiens and the next class began the section on archaeology.

For a 2021 update, see Human variation is more complicated than biological race and the YouTube lecture based on the 5th edition of Anthropology: What Does it Mean to Be Human?: