Monday, July 11, 2011

Men: The "Expendable" Sex

One gender difference that has not received much attention, perhaps due to the political landscape of the last half century, is that it is harder to be a man than it is to be a woman, at least in terms of existence and survival, the very basics of the game of life. Male foetuses are more likely to spontaneously abort, die at birth, die in childhood, die as young adults, die at – well males are more likely to die than females at virtually any age – at least in rich, Western democracies.

Sadly, more insidious cultural, political, and social factors influence the gender ratio in other parts of the world, often to the detriment of women. But in the absence of any deliberate attempt to alter nature, males have a higher mortality than females at all ages. Then how does nature ensure that there are enough males? Well, in actual fact, males are more likely to be conceived than females, and more males are born than females. So, nature corrects for the vulnerability of men by making more of them.

Men are far more likely to suffer from 290 X-linked recessive maladies, because they only have one chance of receiving the dominant (non-disease causing) gene. The Y chromosome doesn’t give them the second chance that women have. Some of the potentially fatal conditions are Duchenne’s muscular dystrophy, agammaglobulinemia, adrenoleukodystrophy, and severe combined immunodeficiency, but there are many, many others in the list of 290 that are exceedingly unpleasant if not lethal. And if genetically-based diseases don’t kill a male, microbe-based diseases are more likely to be lethal. The female immune system fights more pathogens more effectively than the male immune system. This is true in humans and in rats.

Indeed, being male is a deadly gamble in a variety of species. In the animal kingdom females generally outlive males. This is true of arachnids (where she often eats him for supper!), many species of birds, crustaceans, various invertebrates, seals, sheep, and cattle. Only in certain species of fish and bird does research provide an example of males outliving females; but the rule is that she will outlive him.

Over the course of the 20th century, as overall life expectancy has dramatically increased in rich Western democracies, the gender gap in longevity has also increased. Women have benefited more than men, because the gains in longevity have largely been due to the eradication of diseases (i.e., internal factors) and birthing of children. This suggests that it is the external factors which remain and have a strong influence on the gender difference in terms of health and mortality.

Women outlive men in rich countries because men do things that have lethal consequences. Men disproportionately die from accidents (automobile, military, occupational, etc.) and destructive behaviours (smoking, alcohol, drugs, etc.). The very act of survival seems to be more of a challenge for men. Indeed, men take more risks than women in general, something we’ll discuss in greater detail when we examine which sex is indeed lousier at driving. Men also perceive less danger and risk in a given circumstance, suggesting that not only are men willing to take greater risks than women, but they are also less aware of the risks they do take. Even the use of drugs reflects the male tendency to take risks. She takes legal drugs prescribed by doctors; he takes illegal drugs prescribed by pushers.

From an evolutionary perspective, it’s reasonably easy to see why nature would create such fragile, risk-prone men. Let’s start with a population of 1000 males and 1000 females in some hypothetical culture. If 999 males died for some reason, 1000 new babies could be added to the population in the next year, greatly increasing the species’ survival prospects (and what a lucky boy he would be!) But if 999 women died for some reason, only 1 new person could be added to the population in the next year (and how many men would die or be seriously maimed fighting for the opportunity to be the father!) One little accident or deadly microbe and the whole species would be wiped out, regardless of how many men were left. Nature seems to have made men the “expendable sex”, providing them with an mortality-prone biology and a deadly behavioural repertoire. So what’s the benefit of having all these fragile but dangerous men around? You’ll have to check back next month for the answer! How’s that for a cheap teaser?


  1. You are correct to note that increased male mortality is the result of both biological and behavior factors. Indeed, I agree that the advanced technologies in relation to childbirth and internal diseases are significant contributors as well. Our culture really needs to focus more on the health of men and I would not be surprised if a good chunk of women's longevity advantage is the result of the amounts of greater attention placed on women's health.
    However, there seems to be a common tendency to result to these cliché (and downright wrong) "evolutionary" explanations for the greater mortality of men or why they take more risks, almost all of which invoke some form of group selection. First, evolutionary adaptations arise because it is good for the individual and the genes that implement them. Individuals are competing against individuals, not populations versus populations, or species versus species. This is exactly why the sex ratio is about 50:50. Nature values both sexes equally and invests equally in them because they are both equally good genetic survival strategies. It's called Fischer's Principle. Evolution is about individuals passing on as many copies of their genes as possible, not species survival or individual longevity. There are countless examples of species that have gone extinct because adaptations appeared that were good for individuals were not good for the species in the end.
    Thus, to argue that males die sooner because of some "expendability" to a population is not a good explanation. Who are males expendable to? Surely not to themselves and certainly not to their parents, as they carry their parent's precious genes. Perhaps they are expendable to a small population (as you pointed out with your hypothetical example), but nature does not care about the growth of a population. Keep in mind that when a population is too large, females actually become more expendable than the males because competition among various males ensures robust genetic diversity. Also, females sometimes live longer than males in populations where males are the rarer sex (in which females are more expendable).
    A better explanation would incorporate the male reproductive strategy. That is that male competition (and thus risky behavior) is important to male reproductive success when they are younger. Keep in mind that longevity is not the goal, but individual reproductive success is. Longevity is a means to end, not the end itself. Organisms that are good at reproducing themselves in a short amount of time live less than those who do not. So any trait that favored reproductive success over longevity would be selected. Peacocks are an excellent example as the bright, flashy colors make them more vulnerable to predators, but more importantly, attractive to peahens. Risky, competitive behavior among men increases their reproductive success but not their longevity, so it was selected for because they left more descendants. For women, longevity was more important to their success (as they have to invest more time into each offspring), so traits that increased it were selected for. Men simply did not need longevity enhancing genes - it has little to do with any expendability.

  2. Hi Stacy. Thanks for the comment.

    Keep in mind that the word "expendable" is in quotes, suggesting that it is being used in a figurative rather than literal sense. I do not literally think that men are expendable.

    The real principle underlying my argument is one of the fecundity distribution of men versus women, or how offspring are distributed over the population of each gender. You suggest that the evolutionary strategies of males and females are equally effective, but the male strategy is riskier, as evidenced by a less even distribution. Some men are evolutionarry winners and others are losers. This is less pronounced among women, at least until we get to fairly modern societies where things have evened out.

    But you seem to miss the implications of some of your own arguments. Many Alpha males die young because, as you correctly point out, evolutionary success depends upon sexual selection (gaining access to more females than your male competitors) not survival. Women reproduce more slowly and so have to live longer to reproduce many offspring. That is exactly the figurative sense in which I was using the word "expendable". Males quickly spread their seeds then die. Females live on.

  3. Census counts are not accurate. They are done by governments which are political organizations. Politics is about fitting the status quo because if you do not then you are marginalized and in international politcs it is no different.If a country does not folow the status quo countries wil cut off trade, wage war, even stage assasinations, etc. Feminism is the status quo in international politics as the UN places a high priority on women's rights. So what measures the status of women in a society? Life expectancy. So for a country to show that women's rights are protected and to fir the status quo, they are not going to say men live longer as that would isolate the country and cause scorn from the international community. They won't say the sexes live equally long because that would be paying lip service. So they are going to say that women live longer. They order it to be top secret on grounds of national security. The job gets done.

    Now governments have killed millions of people during World War 2, have lied about WMD's, plotted assassinations, etc. Fudging a few census numbers is not a big deal to them.

    Most census counts are based on guesses and estimates. There is no falisfiability. If there are results are found to be wrong they are never corrected as science is not the goal of governments. Medical pot will never be approved by the FDA because it will always be illegal by the federal government. The FDA is thus not a scientific organization. The Census is no different.

    Newspaper Obituaries are considered valid counts by the scientific community. The results...Men 78 Women 75.

    The journal Science has publsihed articles on the Amish community and found that males lived onger than women. This does not prove that men outlive women but it shows conflict with the notion that women outlive men as by the government censuses.

  4. Statistics are also an abstraction. They are not something that can be observed. You can see a computer or phone in front of you but the number of phones cannot be seen until every phone is counted. The other thing is what do you count? You can go with sample sizes but that and randomness is subjective.