If "race" is social, what about sickle-cell and forensic anthropology?

I noticed your reply to one of the questions asking about race and intelligence, you explained that race is a social construct and not a biological reality. I've heard this stated before but, it's never quite made sense to me. If this was the case, why do we see diseases like sickle cell affecting only specific racial groups and how could forensic anthropologists determine race from skeletal remains? I would agree with your answer, there isn't any relation between race and intelligence but, perhaps you could elaborate on your explanation. You seem to have some expertise in the field and I feel like I'm missing something here :P

-Alex


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Hey Alex!

Wow, I am so impressed that you would ask such a thoughtful and well-formed question. I'll try to break my answer down to address the two (related) parts: what do I mean by saying "race is a social construct" and how does this idea correspond to what we know are genetically inheritable traits like sickle-cell anemia. It's a complex and counter-intuitive topic that I take over a week to cover in my class, so I hope my response is not overwhelming.

1) Race as a social construct:

Humans as a species ARE genetically diverse; no one is denying that. However, the idea that what "race" someone is tells you something definite about their DNA is misleading. Our ideas about "race", even though we often think they are based on biological lines and categories, are actually decisions we make -- depending on WHICH parts of our diversity we decide are important.

First of all, how many races ("biological categories") are there supposed to be? In the 1950s, my dad was taught that there were four (and please forgive the antiquated language): "caucasoid," "negro", "mongoloid", and "Australian bushman". Yet our ideas about how many races there are change over time -- you could just as easily find reasons to say there are six categories instead of four, or thirty racial categories instead of six.

The point is that there are no clear biological boundaries that categorize people into a certain number of groups; there is a broad and complex continuum of gene flows across the world, and where we decide to draw racial lines is a cultural, legal, and political decision, which may have little to do even with the "obvious", genetic differences it claims to.

Take skin colour, for example. There are no CLEAR categories that can be made based on skin colour. Two people with identically dark skin may be from two different "races" / ancestral backgrounds: (say one person is "black-West African" and the other "caucasian-Southern Indian"). Two people with objectively different skin tones - one with a pale tan colour and one with dark brown -- may both be identified as "black" -- (or both as "caucasian").

Also, the criteria for who belongs to which race also change over time, and across space -- based on people's ideas. In much of history, arguments were made about Jewish people being of a "different race" than Aryans, or Irish as racially different from the English -- yet today most people regard them as all simply "white". Someone who is considered "black" in the U.S. may travel to South Africa or Brazil and find that they are actually "white" - or another category - there. In each case, people are assigning racial labels which they think says something signficant about biology, but which are really based on different cultural ideas about what "race" means in that place, and about who belongs to which one.

The relatively new ability to map human DNA also tells us interesting things. First, that there is far more genetic diversity among members of any one "race" than there is between two people from different races. Anyone who is perceived as descending from African ancestors is classified with one racial term: "black". But two people from different parts of Africa might share nothing in common genetically (besides the 99.9% of our genes that ALL humans share). Meanwhile, Alex, although you and I are both "white", you could be far more genetically similar to Don Cheadle than to me. It's easy to be mislead when we look to visible human differences, thinking they correspond to deeper genetic similarities. Yet most of our genetic diversity is non-visible, and is shared by people of all "races".

The point is, what we mean by "black" and "white" is more than an observation about actual genetic categories (which don't exist); it is a subjective decision we are making, based on many factors, and the criteria change through space and time (social construct).



2) why do we see diseases like sickle cell affecting only specific racial groups and how could forensic anthropologists determine race from skeletal remains?

Sickle cell is a great example in this context. We know it is a genetic trait, and that it occurs much more frequently in some human populations than others. Yet a closer examination of the distribution of the sickle-cell trait reveals that it is not actually mapped onto racial lines at all, but rather onto something else: the presence of malaria.

Most individuals with sickle-cell trait are at an evolutionary disadvantage: they are much more likely to die than their neighbours, so the trait is selected against and is uncommon in most areas. However, for some reason, carrying the sickle-cell genes provides natural protection against malaria. In areas of the world where malaria is widespread, then, individuals with sickle-cell are more likely to survive than their neighbours, and the trait is selected FOR.

By comparing distribution maps, (see http://images.sciencedaily.com/2010/11/101102130133-large.jpg) we can see that sickle-cell trait (center map) is prevalent in parts of Africa as well as the Mediterranean, the Middle East, and India -- all parts of the world where malaria (bottom map) is common. Although it is genetic, the trait crosses several perceived "racial" lines. At the same time, the perception of sickle-cell as an "African" or "black" trait is also misleading, as the trait is NOT prevalent in, for instance, southern or eastern African populations, even though the peoples there are certainly normally considered "black".

(This, incidentally, puts us right back to your first question. What do we mean by calling all people from Africa "black", as if to imply that they all had something genetically in common that other races don't have? Why aren't there more perceived racial groups within Africa? And indeed there certainly have been, depending on whom and when in history you ask).

Similarly, forensic scientists can tell certain things about a person's probable ancestry, and how they looked, by the structure of their skull bones. Yet these things still require culturally-based interpretation to deduce their "race". Skull A appears to be from a person of Turkish descent. Does that make them the same race as you, or a different one? That's a cultural decision. Skull B appears to be very similar to those of people from northern Europe. Does that mean that that person shares ANYTHING genetically in common with you? Not necessarily.

Alex, this was a very long answer, about a very complex topic, and I hope it has been at least a little helpful. Even though I teach this concept for a living (!), I am still learning about it myself, and I would be really interested if you had any thoughts or comments on ... well, anything that just got said!

Daye