One thing we discussed at the ScienceBlogging09 meeting in London in August was the relationship between blogging and more formal scientific communications. Henry Gee suggested that blogs are for half-baked ideas, that can then be criticized in the blogospheric oven before being let out into the formal literature in the knowledge that the idea has been heated through, with a nice glazing applied. It’s odd, then, to read something in the formal literature that is less well baked than most blog posts.
The piece in question is a News and Commentary article in the latest Heredity titled “Sequencing one sex or the other has to be justified: Gender genomics and equality”. The authors want to argue that we should pay attention to the sex of the individuals we sequence. Why? Well…
because, for instance, recent reports on the molecular basis of social complexity in honeybees (Apis mellifera) highlight a critical relevance of sex-specific genomics by exploring the biochemical mechanisms of the differences between the contribution of females (Vergoz et al., 2007) or males (Mattila and Seeley, 2007) to cooperative behaviour within the hive.
So the genetic structure of a colony can affect the colony. Genotype affects phenotype, so this is no surprise. But how does that affect the DNA sequence? We aren’t told. The nearest we get it this, later in the article:
Genomics has only begun to scratch the surface in determining how interactions among genes and gene products influence the genotype, and it seems plausible that such interactions could differ between males and females.
Influence the genotype? That would be news. What references do they give? Um, none. Now, we know that retrotransposons can flit around and create all sorts of mayhem, but that’s hardly systematic. I think it’s a stretch to say that they are a major problem, even more so that there would be a sex biased difference.
Let’s sit down and talk this through carefully so we can see what the authors are suggesting. Sequencing genomes means finding the sequence of the DNA of a representative individual (or a consensus of several individuals) of a species. If there is no difference between sexes, it doesn’t matter which sex you take – the genome will be the same. Are there differences? Well, in humans we know that there are differences between the sex chromosomes, but this is why the human genome project sequenced both the X and Y chromosomes. So it looks like the sequencers did give some thought to this. What about the other chromosomes? Well, as these are inherited randomly from both parents, there shouldn’t be any sex-biased difference in sequence.
But despite all this, there may be some bias in the choice of sex. After all:
the honeybee DNA was taken from several drones derived from a single queen, which resulted in the sequence of the haploid male genome.
They sequenced a male, the naughty chauvinists!
Oh, wait a moment. Let’s think like (asexual) biologists. Like many hymenoptera, honeybees are haplo-doploid, so males are haploid and females are diploid1. Sequencing a haploid individual makes sense, because you only have one copy of each sequence to worry about: you don’t need to worry about which copy of a sequence you are dealing with. And, because the genes are passed on randomly from the mother, we know that taking several males will give us the mother’s genotype. In other words, in this case it makes sense to sequence males.
Overall, the cry to be careful about which sex is sequenced is silly on biological grounds – we know enough about sex determination to take care, and the authors don’t present any evidence that there is a problem (go and check – it’s really wooly). But I’ve left the best ’til last. The authors ask “Why does such gender genomics matter?” and answer (the emphases are mine)…
Because our generalizations are only as good as the model systems on which they are based. For many years, the model for virtually all processes in humans and non-humans alike was the male, with females representing a special case; an exception to be studied after the representative subjects had been described. In medical research, this paradigm led to the disproportionate use of male subjects, whether rodents, monkeys or humans, in basic research on anatomy and physiology as well as studies of disease, an imbalance that has only been addressed in the last few decades (Zuk, 2002). In our human society, it has meant that women in atypical roles are often undervalued compared with their male counterparts, leading to relatively slower advancement for women with equal qualifications.
Seriously? The reason sexism exists is because science treated males as the norm? We have that much power? Or is this utter tosh?
If this article had been a post on a blog with a reasonable number of readers, I’m sure they would have pointed out the problems with the arguments. The half-baked nature is better accepted, and the authors would have been able to refine their arguments, so that they made more sense. But for a published article, I would expect the authors to have done this themselves. There are three authors, so surely one of them would have said “hang on a moment…”.
I worry about the effect this sort of article has on gender equality. Radical feminism already has a reputation for taking things too far, and even if it may be partly deserved, overall I think we do have to treat problems of discrimination seriously. But that doesn’t mean every aspect of science is tainted with sexism: we have evidence which suggests it doesn’t affect refereeing (at least on average!), for example. And worrying about every possible problem is counter-productive: we end up wasting time balancing non-existent inequalities, when we could be concentrating on the problems that do matter. That’s not so say that e shouldn’t look at whether the choice of individuals to sequence is sexist, but rather that we should still do it critically. If the best argument you can come up with is so poorly done that bits of the cake are still frozen, then perhaps there isn’t anything there. Just quietly announce it as a success, and move on to look at the next potential problem. the pessimist in me says that you’ll find a real problem eventually. And then I’ll be happy to leap in and support doing something about it – whether it is symbolic (e.g. making sure that we don’t just celebrity sequence middle-class males), or more down to earth.
Hauber M.E., Sewell, M.A. and Zuk, M. (2008). Sequencing one sex or the other has to be justified: Gender genomics and equality. Heredity 101: 395; doi:10.1038/hdy.2008.83
1 Actually, it’s a bit more complicated than this. Honeybees have a system called complementary sex determination. They have a sex determining locus. If an individual is heterozygous, i.e. they have two different alleles at the locus, they become female. If they they only have one allele, they become male. this can happen if they are halpoid (“hemizygous”), with only half a genome, or if they are diploid but both copies of the sex determining gene are the same.