Is Pluto a planet or a dwarf planet? Are these two categories even meaningful? The reality is that objects orbiting our sun occur on a continuum from asteroids to planetoids, dwarf planets, and full planets.

Humans like to categorize, however. It helps us wrap our minds around complexity, gives us convenient labels to help sort our knowledge, and hopefully the categories reflect some underlying reality.

Categories often begin as purely observational. We label diseases by what they look like (their signs and symptoms), and then later may have to recategorize them once we know what causes the diseases.

Prior to Darwin, taxonomists categorized all of life according to superficial characteristics. These categories sometimes, but not always, matched the underlying reality of evolutionary relationships. We now have a different system of taxonomy called cladistics, which is purely evolutionary. That’s why birds are now dinosaurs. 

Issues of Race

There is rarely any political implications to categorizing the subpopulations of deer that inhabit North America. When we start categorizing humans, then suddenly the political and social implications are huge, and the very process of categorization comes under scrutiny.

There are many who claim, for example, that human race is a social construct without any underlying scientific validity. For example, Michael Hadjiargyrou, Chair of the Department of Life Sciences, New York Institute of Technology, wrote a commentary in 2014 (which is making the rounds again on social media) in which he claims:

It is history, not science,that reveals how the concept of different human “races” arose, how the term has become widely misused, and how it continues to pervade our planet. In fact, the word race has come to symbolize the division of humanity into segments, divisions that often lead to conflicts.

While I understand where this position is coming from, it has never sat right with me. Perhaps it is partly due to my background as a physician. Within medicine we routinely consider a person’s ethnic and racial background to help determine their risk of various diseases. Medical studies are often stratified by race, and no one thinks twice about it. In fact I have often heard criticism that the failure to do so is a disservice to minorities who are then underrepresented in clinical studies, which means the results might not be broadly applicable to them.

I completely agree with Hadjiargyrou when he writes:

We all evolved from the same ancestors and are, indeed, all virtually genetically identical to each other, making us a single race.

Although I would substitute the word “species” for “race.” Humans are all one species. While we are an outbred species with a great deal of genetic variation, resulting from the fact that we range widely around the world and have been for thousands, perhaps even hundreds of thousands of years, there are no subspecies of humans. We share 99.9% of our DNA. In short there is much more that unites than divides us.

And of course I fully agree with the political point here – every human is equally deserving of dignity and respect and should be treated as an individual, not as a member of some arbitrary group. It is also true that group identity tends to be divisive. We are tribal and tend to think in terms of in-groups and out-groups.  As we become more global it is important to emphasize how similar, rather than how different, all humans are.

What makes me uncomfortable is subjugating the science to a political goal, no matter how noble that goal is. There are two big problems with this. First, it’s important to get the science right. Distorting scientific thinking is pernicious. Second, if we make a valid political position dependent upon a scientific position, then the political position is vulnerable to new evidence, and it almost forces you to distort the science.

Regardless of what we discover about the genetic variation of humans, it is clear that all humans should be treated as equal as an ethical principle. This principle is not dependent upon the scientific fact that race does not exist.

So does race exist?

The scientific question of whether or not race exists is, in my opinion, not completely objectively answerable. It depends. Is Pluto a planet or dwarf planet? Astronomers can reasonably disagree about where to draw the line.

What we can say is that genetic variation within the over 7 billion humans on the planet is not homogeneously distributed. There are populations where certain genetic traits tend to cluster. There is no question about this. This clustering of genetic variation is determined by ancestry, which largely reflects geographical origin. The biggest differences tend to reflect the continent of origin.

We tend to refer to continent of origin as race, and further subdivisions as ethnicity. These are arbitrary dividing lines, just as the line between tall and short is arbitrary. That does not mean they have no basis in reality – that is the false continuum logical fallacy.

Hadjiargyrou makes a couple of specific scientific arguments. Perhaps his most compelling argument is this:

Genetically speaking, studies have shown that there is much greater genetic variation within a given human population (e.g., Africans, Caucasians, or Asians) than between populations (Africans vs. Caucasions), indicating that human variation cannot be subdivided into discrete races.

I agree with the premise but not the conclusion. Genetically speaking, all vertebrates are fish. There is much greater genetic variation within the fish clade than there is between fish and other vertebrates. Land dwelling vertebrates represent a tiny twig on the vast fish genetic tree.

In the exact same way, there is much more genetic variation within Africans, then between Africans an all other human populations. This simply reflects the fact that humans lived in Africa for a long time, evolving extensive genetic diversity, and the population that migrated out of African represents a tiny twig on the African genetic tree. We are all Africans in the exact same way that we are all fish.

The point is that looking at genetic variation within and between groups can be deceiving. It also means, however, that the concept of race can be superficial and likewise deceiving. Lumping all Africans into one race greatly underrepresents the genetic diversity within Africans, while counting Europeans as one race greatly overplays the genetic diversity between African and Europeans.

So Hadjiargyrou has a point – race is scientifically a bit arbitrary and gives us a distorted view of genetic variation. That does not mean, however, that there are not discrete subpopulations of genetic variation within the human population, roughly reflecting continent of origin. This is further complicated, of course, by exchange of genetic material among all human groups. But this has not occurred to the point that the groups themselves have vanished.

Hadjiargyrou’s second point is much weaker.

Biologically speaking, one clear example is that most diseases afflict all of us — diseases like cancers and cardiovascular and neurological disorders, as well as viral, microbial and parasitic infections.

As I stated above, any physician would recognize this statement to be highly misleading. There are genetic disease that exist exclusively in some races or ethnicities and not in others. Africans develop sickle cell anemia; Europeans and Asians don’t.

It would not be prudent to erase all consideration of genetic background from medicine. In fact, if anything such considerations are increasing with our increasing knowledge of genetics and ability to sequence DNA.

Conclusion

While I agree with the political and social point, I disagree with the strong statement that race does not exist or that it is purely a social construct. This is clearly an overstatement of the reality.

To be clear, I am not taking the strong position that race does exist. Rather I am saying that the question is inherently arbitrary, as are all questions of categorization. You have to make choices about which characteristics are meaningful, and where to draw lines. Nature tends to exist on a continuum, and so any dividing lines will have to be arbitrary to some extent.

The social construct of race is distorted from the scientific reality, with that I agree also. The underlying scientific reality is more complex, and the tree of human genetic variation is probably very different from what most people would imagine based upon social and historical categories.

I simply would not go so far as to conclude that scientifically race does not exist. Humans do exist in discrete genetic subpopulations that roughly reflect geographical origin. These genetic subpopulations are useful when it comes to medicine and predicting risk of various diseases. I predict that the medical profession will go on completely ignoring the social debate about race, and treating it as if it exists, because it is a useful medical construct.

Rather than making strained scientific arguments that are not completely valid, it is far better to simply divorce the scientific details from the ethical principles. Even the fact that humans are all one species is not necessarily important to the ethical principles. What if a subspecies of humans existed? Wouldn’t they deserve respect and dignity as sentient beings?

The lesson is clear, and I think Steven Pinker was the first to articulate this (as far as I know) – don’t tie a valid ethical principle to the details of science. It forces you to distort the science, and makes the ethical principle vulnerable to false refutation.