Why do males die younger than females?

I have a hypothesis that explains why in many (most?) species, males have a shorter life expectancy than females. My apologies if this has been thought of before, or if it’s already well-known. It’s quite likely that I’m re-inventing the wheel here, that I’ve come across the current explanation before somewhere, and have simply forgotten. I have a keen interest in evolutionary theory, but I’m not a biologist.

The hypothesis is this: males are subject to more exploitation by parasites than females, because in general parasites “want” their host species to thrive. Over the course of a lifetime, this greater exploitation takes its toll.

In non-monogamous species, males are useful for fertilizing the eggs of the females, but not much else. In effect, after donating sperm most of them are redundant. They use up the food supply that could otherwise swell numbers of individual members of the species, and hence safeguard the species itself. In non-monogamous species, too many males are “bad for the species”. Drone bees consume as much nectar as honey-producing females. Male elephant seals consume far more fish than their smaller female counterparts, and few of them even get to donate sperm.

Farmers — in effect, human parasites of animals used as food — know all this, and so they usually kill males apart from the few needed to fertilize females. In doing so, they strengthen the species they parasitize, in the sense of increasing their numbers and assuring their future. Through domestication, the humble jungle fowl of Asian forests has become the mighty chicken, found in huge numbers all over the world. Much the same applies to cattle and sheep, which now occupy much of the earth’s surface.

Most parasites (such as microbes) are brainless, but through the process of natural selection they adopt “strategies” which can promote their numbers. In most cases, these strategies ensure that their host species do well enough to function reliably as hosts. The parasites aren’t actually thinking as human farmers think, of course, but over many generations they stumble upon similar strategies, which become established as the parasites that benefit from them proliferate.

With sex ratios, the “interests” of species and genes conflict. What’s “good for the species” is a much larger proportion of females than males, at least in non-monogamous species. But what’s “good for the genes” is a roughly equal number of males and females (as explained by Fisher’s Principle). The fact that in most species the ratio of males to females is indeed 1:1 makes a compelling case for a gene-centered understanding of evolution (a la Richard Dawkins’ Selfish Gene), and against group selectionism.

This hypothesis (I hesitate to call it “my” hypothesis) should be easy enough to test, as it entails that there should be a greater difference in male–female life expectancy in non-monogamous species than in monogamous species. It also entails that many of the diseases we associate with early male mortality (such as coronary heart disease, possibly suicide) may in fact be partially caused by infection by microbes.

The tyranny of conditioning

From a very early age, I detested learning by rote. My refusal to engage in this soul-destroying activity led me to my first brush with criminality, when I tried to cheat when reciting the seven times tables.

I’m not the only one who has a deep distaste for learning by rote. What is rather surprising, perhaps, is that some people seem to have a genuine liking for it. Witness the eagerness with which so many take to learning foreign languages, with new vocabularies, irregular verbs, unpredictable genders of words for inanimate objects, and so on — all of which require tedious repetition and absorption.

It seems to me that there is a telling difference here of temperament — between those who assume education is essentially a matter of acquiring good habits of thought, and those who assume education is essentially a matter of getting a better understanding. Both types of people embrace education as a good thing, as a vital aspect of personal growth, but the former expect and even welcome an onerous period of habit-formation to achieve it. The latter embrace a sort of intellectual “principle of least action”: whatever is sufficient to explain is “all we need to know”. That attitude can look downright lazy to fastidious habit-formers.

The difference in temperament extends far beyond education. Here I’ll just touch on how it emerges in attitudes to mental illness, and in politics.

People who assume that education is a matter of acquiring good mental habits tend to think that mental health issues — from mild neuroses to out-and-out illness — are to be overcome by means of conditioning. For example, a phobia of spiders is supposedly overcome by coming into ever-closer contact with them — letting them crawl over one’s hands and so on. At the end of the conditioning process, the patient has “got used to the idea” — in other words, he has changed his habits.

Now I am no Freudian, as I think his understanding of the mind was badly mistaken in many respects. Yet I think he was importantly right, both factually and morally, in thinking that the way to better mental health was not through conditioning, as above, but through self-understanding. Let us put aside the details of such self-understanding, such as whether it really involves uncovering unconscious desires or phantasies. The important thing is that therapy is aimed at enlarging one’s understanding of oneself, rather than at achieving greater “self-control” through the acquisition of new habits. Rather than trying to instil such habits, a Freudian therapist would encourage exploration and experiment, with its attendant risks.

This difference of temperament can also be seen in political thought, where a deep division exists between Rousseau and Hobbes (almost everyone has an affinity for one or the other of them). Rousseau thought that by the time humans reach adulthood, they have been corrupted by the bad conditioning of modern society, and the solution to this problem is counter-conditioning. We must acquire new “habits of the heart” (as Tocqueville called it, re-phrasing Rousseau). Unlike Rousseau, Hobbes thought humans were born selfish, and there’s no way to change that; but by understanding ourselves better we will agree to an imperfect compromise in which the most important freedoms are safeguarded.

I think it’s pretty obvious that the current enthusiasm for minimum alcohol pricing, for special taxes on fat and sugar, and the rest of it, comes from the “conditioning” side of the divide. If people eat or drink too much, the idea goes, they should be re-educated by acquiring new habits. By putting unhealthy foods and alcohol that little bit further from reach, new habits will take root.

Let us pass over the fact that the attempt to instil new habits involves coercion, and that such coercion is discriminatory, because only a select few are poor enough to be affected by modest price increases. Let us pass over the issue of legislators making laws that they themselves are not subject to. The question remains: Is conditioning — enforced learning by rote — the right way to achieve personal growth?

My temperament says No. As alcohol prices have fallen in Ireland, Irish people have cut down on alcohol. I think this is because affordability enables younger people to learn how to drink, to educate themselves through exposure, experiment, and increased self-understanding rather than through the forced acquisition of a habit.