This is sort of a strange book. One the one hand, it highlights some recent research about sex differences in morbidity and mortality that might be linked to the possession of XX vs XY chromosomes, which is its main goal, but on the other hand it projects a sensationalist and at times perverse narrative style that necessarily distorts many of the findings. I’m going to focus on this aspect of the book because the science is pretty straightforward. This narrative style is basically to define a meaningless term, in this case it’s “genetic superiority,” in such a way as to lead you to the inevitability of the author’s conclusion as indicated in the title. Moalem actually defines “genetic superiority” to mean advantages in longevity and immunity, and then proceeds to show how males are more vulnerable than females, on average, in this context. He argues strongly that this difference arises mainly in possessing two X chromosomes versus one.
It has been known for a long time that recessive X-linked disorders, for instance, are more common in males. These include conditions like color blindness, hemophilia, and some developmental disorders. Additionally, mosaicism of the X chromosome in female cells might provide them some advantages in immune functioning, and this research is a little more recent. These findings are very interesting and especially topical in the current climate. But they are not really that controversial, in my view. I have heard about them for years in classes, literature, and textbooks when doing my PhD work in biomedical science. It has been long proposed to explain, along with many other factors, the differences in longevity between men and women. On that front, the book has merit and brings some interesting facts to light. The only controversial point is that Moalem almost completely neglects that social factors, such as lifestyle or work differences, could be partly responsible. He mentions it a few times, but doesn’t give it the consideration it deserves in my view. Nevertheless, no overall problems with the information presented.
His language and narrative style is really the issue here. “Genetic superiority” is a silly term and not a real concept in biology. Define the criteria however you like and force whatever conclusion you want. The question is should we even have a criteria for such a concept at all? I understand he has a precise definition he is using, but it sows confusion in my view. From a biological and evolutionary perspective, organisms face different challenges and adapt differently to their environments, and so males and females adapted to different challenges to perpetuate their genes and represent two evolved strategies for that purpose. Organisms will compromise their longevity for benefits in other areas, and those compromises come out differently for males and females of many organisms. Do we argue for the “genetic superiority” of males because they are faster, stronger, have higher lung capacity, more red blood cells, greater psychomotor capacity, less likely to have depression, better spatial abilities, have higher pain tolerance, etc? Or how about the “genetic superiority” of whites over blacks because they are less likely to get diabetes, obesity, high blood pressure, and live longer? Already you can see the issue with this invidious language, as it encourages a kind of divisive thinking and differential valuation of groups. And if you think a book with the opposite title (which could be written with evidence of the differences favoring males mentioned above) would not generate enormous outrage for exactly this reason, I have a bridge to sell you.
Don’t get me wrong, the book is an interesting read and I don’t doubt at all that Moalem has good intentions at heart, despite the problematic way he chose to frame the issue. But ultimately I didn’t necessarily learn anything that new or surprising. There’s interesting science here, but the presentation often leaves much to be desired.