Here is the article I mentioned.
Disclaimer: the article represents the opinions of the author only, and not necessarily that of this poster nor the Straits Times.
The Straits Times Wednesday, February 21 2007 (Page 19)
Review
The Issue of Race
What’s genes got to do with it?By Andy Ho
Senior WriterI do not celebrate Chinese New Year, which my family and friends think is a crass denial of my Chinese genes. But is there really a genetic undercarriage to my racial identity?
It was upon the completion of the Human Genome Project in February 2001 that we were told any two unrelated human beings were 99.9 per cent alike in their genomes. (Your genome is that complete ordering of all the DNA building blocks called nucleotides that you carry.)
More recently, statistical modelling suggests that all of us who are alive today, regardless of race, share a common ancestor who lived just 3,500 years ago, circa 1415BC. The bottomline: There are no races to speak of, genetically.
But six years on, “the molecular reinscription of race” in medicine and policing has already begun, says Professor Troy Duster, a New York University sociologist who spoke on the issue at the School of Humanities and Social Sciences, Nanyang Technological University, recently.
But just a few years after it was proclaimed that there is no genomic basis for race, some scientists are making exactly the oppposite claim.
If there is no genomic basis to race, why would US studies show that Chinese Americans need less of the blood thinner called warfarin than white Americans, say?
Or, consider a study reporting how 5 to 10 per cent of Europeans, but only 1 per cent of Japanese, carry a non-functioning version of the CYP2D6 gene which involved in breaking down some 40 different drugs. There must be racial genes!
Of course, that the study also reports how Europeans themselves show an equally wide range in the frequency with which they carry the gene — from 10 per cent in northern Spain to 1 per cent in Sweden — is largely ignored in media reports.
That is, the differences within a “racial group” — white Europeans, say — can be just as great as those between “races” — Europeans versus Asians, for instance.
Anyway, whatever the millenarian pronouncements of 2001, most scientists, doctors, lawyers, bureaucrats, journalists — and probably everyone else in between — did not summarily drop race as a scientific term or stopped believing it was a biological given.
After all, scientists are brought up the same way as non-scientists, so their own experience of race as something real is difficult for them to dispute. Our social and racialised conditioning reinforces racial stereotypes as being real.
Thus when people talk about race, they think they know what they mean because they think they can see it with their own eyes.
Yet, did you know that the curvaceous diva Mariah “Flesh Flash” Carey is supposed to be a black woman? I did not, until last year, because she looks Caucasian. So what you see may not be what you think you are getting. And despite all your confidence about knowing what race someone may be, you are likely to be quite incoherent if I asked you to define what race itself means.
Yet some forensic scientists have taken to arguing that race is inscribed in our genomes. In 2005, for example, a Stanford University statement said: “A recent study conducted at the Stanford Medical School challenges the widely held belief that race is only a social construct and provides evidence that race has genetic implications.”
If we are 99.9 per cent alike genomically, then we are 0.1 per cent different. Since the genome is made up of three billion base pairs (or nucleotides), that difference works out to be a whopping three million positions.
Prof Duster, who chaired the Joint Advisory Committee on Ethnical, Legal and Social Issues for the Human Genome Project, notes that 90 per cent of all that is “junk DNA” whose function remains unknown. But that still leaves potential differences in 300,000 positions. If those differences were arranged systematically, according to geographical groups, then we may well have the beginnings of a genomic basis for race after all.
But they are not. There are no genetic differences that are only to be found in all people of one race but not people of other races. In fact, the differences tend to be distributed in a continuous, overlapping fashion across geographically separated populations.
Non-human species — say, tigers and lions — exhibit far more between-group genetic differences than do humans, so many animal species have genetically recognisable subspecies. Using the same genetic criteria that are applied to non-human species, humans simply do not possess subspecies — or races.
Think of it this way: A trait like black hair may be encoded by Gene A but more than one gene may code for that same trait. If I know you have that Gene A, I can predict — assuming I have not seen you before — that you have (naturally) black hair. Conversely, just because I have seen you and know that your hair is naturally black does not also mean I can infer that you carry Gene A. You might carry another gene that does the same thing. Thus even if a gene strongly determines a trait, two people with the same trait — black hair — may not carry the same gene for that trait.
Now for the $64 question: If there are no discrete, genomically defined races, on what basis do some forensic scientists — and a complicit media — claim that DNA tests that crime scene investigators carry out can actually disclose a suspect’s race?
Such claims are grounded in assumptions about a suspect’s recent genetic ancestry which, in turn, are based on tests for different markers on the genome. (Markers are positions at which scientists can detect a genetic difference among individuals.) Computers then sort through your particular marker combination to guess what proportion of your recent ancestry originated in East Asia, for example.
There are two shortcomings with this approach, though. First, scientists must decide which markers and how many of them to use. They also decide what reference populations to compare the markers against to infer the frequencies with which these markers occurred in ancient times.
Then there are assumptions about how fast, how far, and where these ancient people migrated to as well as their birth and death rates, etc. Sometimes, assumptions are necessary to make statistical massaging of the data possible but sometimes they are made because scientists simply do not have any relevant data about ancient migration patterns, for instance.
Second, scientists must decide how many clusters of genetic markers (“races”) they want the computer to crank out. One data set can produce any number of clusters, depending on what the computer is instructed to do. Anywhere from two to 16 clusters have been produced.
Scientists must also tell the computer how to scale the clusters: Using different but equally valid statistical methods, the same data can make individuals from different continents cluster together, or segregate people from one continent into different clusters.
Thus a single data set may produce continental, intercontinental, inter-continental, or sub-continental clusters. Yet continental clusters are not intrinsically more important than sub-continental or inter-continental clusters: After all, just 4 to 5 per cent of genetic variation occur primarily between groups from different continents.
But folk belief holds races to be groups of people who developed quite separately on different continents in times past, so continental clusters are taken to mean that race is inscribed in the genome. In truth, it is just that the technique assigns ancestry by continent of origin. The tests, however, could have been designed non-racially.
So it remains true that race is socially constructed — by forensic scientsts with some high-tech smoke-and-mirrors.
Still, while race is not genetic destiny, it is quite real. As Prof Duster notes, race is not a measure of an individual but an interactive measure of how an individual perceives another.
So while there are no Chinese genes impelling me to celebrate Chinese New Year, family and friends who do not respect my reasoned decision try to. But I just ignore them.
andyho@sph.com.sg