Recently, there was much amusement in the labs whilst we watched the consternation unfurl, when Scientist’s announced that after re-examining semen samples taken from Vietnam war veterans, they’d discovered that men with higher IQs have better quality sperm.

The Smarty-pants set took this as confirmation that spending your time studying difficult sums or reading Shakespeare trumps working out and spending your spare time developing bulging biceps; whilst the Muscle boys were up in arms, claiming: Everyone knows a good complexion and nice hair are better than a large IQ. Pretty girls only like Athletes and Bodybuilders – therefore Intellectuals must be destined to die lonely and dateless.

The humorous point is that both camps appear to have confused ‘inclusive fitness‘ of an individual as part of a species with ‘personal fitness‘ such as one might see in a Gym. The downside, we believe, is that this misunderstanding encourages a dangerous myth that Evolutionary fitness is simply a matter of grading masculinity, rather than an expression of the human race’s ability to survive as a species.

People with an understanding of current Evolutionary science will realise that a number of factors feed into ‘inclusive fitness‘, whilst both ‘personal fitness‘ and ‘intelligence’ are simply theoretical optimum conditions – i.e. once one reaches a threshold level of personal fitness and intelligence, then any further advances are a bonus, rather than a guarantee that your genes are markedly better than anyone else’s.

Certainly, some women prefer Bodybuilders, and those Bodybuilders will have an advantage with those women. Just like some women prefer Intellectuals, and those Intellectuals will have an advantage with those women.

Clearly, the person who has trouble catching their breath after running for a bus is certainly at a disadvantage to the rest of the population, whilst the person that can’t work out how to make sense of the Bus timetable is also at a disadvantage to the rest of the population. However, human beings live in an altruistic society, where we usually co-operate to help each other out.

Thus, if I’m not personally fit enough to lift heavy objects all day, I can pay someone to do it for me. Likewise, if I’m not intelligent enough to fix my broken computer, then I can pay someone to do that for me too.

Inclusive fitness and intraspecific competition

Charles Darwin recognized that the interests of individuals are very often synchronized with the interests of their larger groups. As an example, consider the amazing visual acuity of a Hawk, which, at a distance of about a quarter of a mile, can spot a motionless brown mouse in a pile of dry leaves – Eyesight is of paramount importance to hawks, which find food by cruising at great distances above ground level in search of rodents and other small prey.

The fact that hawks see so well is not an accident. The bird’s complex optical hardware and neural software has evolved over millions of generations, in which those Hawks with the best eyesight caught more prey, and hence left more offspring, than their more nearsighted conspecifics. So, the ability to see clearly at long distances is a trait that is advantageous not only to individual Hawks but also to Hawks as a species. Thus, if all hawks had sharper eyesight, the entire species will fare better.

The same is also true of very many other traits and abilities – if all Cheetahs could run a little faster, Cheetahs as a species would fare better, if all Chimps were more intelligent, Chimps as a species would fare better; if all Sharks had a keener sense of smell, Sharks as a species would fare better, etc. etc.

However, there are many other traits and abilities, for which this pattern does not hold.¹ Consider, for instance, the antlers of the male Elk. Natural selection has favoured individual males with larger antlers because the broader an individual male’s rack of antlers the more likely he was to prevail against his rivals for reproductive access to females. Over millions of generations, this advantage led to a gradual increase in the size of Elk antlers, and today the antlers on some males span almost five feet. But, whereas larger antlers help any given male gain advantage over others, they confer no similar advantage for male Elk as a group. In fact, the contrary is true, they are positively harmful.

The reason is that broader antlers make it more difficult for Elk to escape from predators. Once a pack of wolves chases a male Elk with a five foot rack of antlers into the woods, the Elk is trouble. Twist and turn though he might, he simply cannot transport these appendages through trees quickly enough. This is a serious disadvantage, and it might seem that natural selection could not possibly have favoured Elk who were thus encumbered.

Weighing against this disadvantage, however, was the fact that Elk with the broadest antlers had access to more females and, despite their briefer lives, therefore left more offspring. As long as this advantage was more than sufficient to compensate for the increased risk of death from predation, natural selection continued to favour bigger antlers. Eventually however, the advantage from further increases in size no longer outweighed this risk, and from that point antlers grew no further.

The important message of this story is that even though all Elk would clearly do better if every animal’s rack of antlers were trimmed by half, it would not be advantageous for any single animal to trim his antlers. Thus, if a mutant male were born with half-sized antlers, he would be at a hopeless disadvantage in the competition for mates. He might survive to a ripe old age, but in evolution what counts is not how long he lives but the number of grandchildren he leaves; and a mutant with stubby little antlers simply will not leave many grandchildren.

Similar forces appear to explain the exuberant plumage of the Peacock. Drab Peahens favour males with the longest and brightest tail feathers¹. And, experimenters have shown that males with artificially augmented tail feathers are almost always much more successful than other males in acquiring mates. The most common hypothesis for this is that a vibrant tail display is a credible signal that the male is in robust health; a view that is supported by findings that plumage deteriorates sharply in animals with heavy parasite loads.² The logic is that females are likely to have more grandchildren if they mate with males having genes promoting parasite resistance.

In any event, once Peahens came to favour Peacocks with longer tail feathers, natural selection relentlessly began culling males with the shortest displays in each generation, leaving us with modern Peacocks whose tails can reach five feet or more. But like larger antlers on male Elk, longer tail feathers entail costs. They make males not only less able to escape predators but also more likely to attract their attention in the first place. Peacocks as a group would fare much better if each bird’s tail display were shorter by half. Yet, any lone mutant with a shorter tail display would be at a hopeless disadvantage.

Sexual dimorphism (significant sex differences in size within a species) provides another vivid illustration of the conflict between individual and group. Many Bull elephant Seals, for example, weigh over a ton, and can be more than twice as big as their female counterparts. This enormous difference in size was driven by the advantage enjoyed by slightly larger males in their battles with one another for access to females. The victorious males typically command large harems, thereby eliminating a majority of their rivals from the reproductive sweepstakes.

But, whereas size is advantageous in the contest for reproductive access to females, it is disastrous in numerous other ways. It increases caloric requirements, with mature Bulls needing to eat hundreds of pounds of fish each day just to stay alive. It is also disadvantageous in that the victorious breeding males are so large that they sometimes crush their females to death during the act of mounting them. The largest animals may also be more prone to a variety of orthopaedic problems.

As with the evolution of antlers and tail feathers, the advantages of becoming slightly larger eventually came into balance with the disadvantages, and the weight of surviving males stabilized. As before, however, there is nothing attractive about this outcome from the perspective of male Elephant Seals as a group. Each animal would fare much better if all were considerably smaller. The most able fighting males would still gain access to the most females, while most of the disadvantages of excessive size would be avoided. Yet, here too, the problem cannot be solved at the individual level. A smaller mutant would gain the advantages of not needing so much food and not crushing any female he mounted – but these advantages would be swamped by the fact that he would be unlikely to gain access to any females in the first place.

All these examples illustrate Darwin’s central insight that natural selection can, and often does, favour traits that increase the reproductive fitness of individuals at the expense of larger groups. If a trait serves the interests of both individuals and the groups to which they belong, so much the better. But when conflicts arise, individual interests often prevail.

Armed with this insight, modern Behavioural Biologists have begun to make sense of a long list of animal behaviours that are obviously counterproductive at the species level. Thus, in many of the more polygynous species, such as Lions, a successor’s first act on defeating a dominant male is to kill all the young offspring left behind. This practice accelerates the fertility cycle of the lactating females, and thus serves the genetic interests of the conquering male. Yet it is utterly wasteful from the perspective of Lions as a group.

When a dog and his rival each want the same bone, each animal must make a strategic decision in which contextual cues prove crucial. Should he fight for the bone, or defer to his rival and go off in search of another? The typical dog follows a simple decision rule: If his rival is considerably bigger than he is, he defers – if they are roughly the same size, he might fight, depending upon how hungry he is – although if his rival is smaller, he will almost certainly fight, or a least make it known that he intends to.

Thus, it is important that dogs devote scarce neurological capacity to the support of an elaborate mechanism that raises the hackles on their backs whenever they face off against rivals, and as well as this, they must also be able to reach a quick and accurate judgment about how large their rival is.

Hackle-raising makes the animal appear larger, and is therefore more likely to dissuade his rival from fighting. Even though all dogs raise their hackles, only one dog in any pair can be larger than his rival. Dogs as a group would fare better if the neurological capacity that supports hackle-raising were used instead to support better hearing or a keener sense of smell.

Baby birds in their nest must squawk themselves hoarse because their parents make the (not unreasonable) assumption that the bird who squawks loudest must be most in need of food. In the end, of course, there are only so many worms to go around, and nestlings as a group would fare better if all squawked more softly. Yet any individual chick that showed restraint would be much more likely than his siblings to starve.

Intraspecific competition in Human social dynamics

This Darwinian theme of conflict between the interests of individuals and groups also plays out amongst human affairs in countless ways, both trivial and profound. Here is a selection of examples:

Shouting at parties: Whenever large numbers of people gather for conversation in a closed space, the ambient noise level rises rapidly. After attending such events, people often complain of sore throats and hoarse voices from having had to speak so loudly in order to be heard. If all the guests spoke at normal voice levels, they would avoid these problems. And, because the overall noise level would be lower, they would all hear just as well as when they all shout at one another.

So why shout? The problem again stems from the difference between the incentives seen by individuals and those seen by the larger group. Everyone starts by speaking at normal levels, but because of the crowded conditions, it’s difficult for conversation partners to hear one another. The natural solution from the point of view of you and your conversation partner is to simply raise your voices a bit – but that is also the natural solution for all other conversation pairs – and when all raise their voices, the ambient noise level rises, so that no one hears any better than before.

This is certainly wasteful, but here again there is precious little that individuals acting alone can do about it, since if any single conversation pair were to lower their voices while others didn’t, they wouldn’t be able to hear anything. Nobody wants to go home with raw vocal cords, but we humans apparently prefer that cost to the alternative of not being able to engage in conversation.

Anabolic steroid use: The offensive linemen of the Dallas Cowboys, when they won the Super Bowl in 1996, averaged 333 pounds per man, and 300-pounders on the front lines of other teams have become the rule rather than the exception. In the 1970s, by contrast, offensive linemen in the National Football League averaged barely 280 pounds, and the all-decade linemen of the 1940s averaged only 229 pounds.³ One reason that American football players of modern times are so much heavier is that player’s salaries have increased sharply over the past few decades, which has led to much more intense competition for the positions. Size and strength are the two cardinal virtues of an offensive lineman and, other things being equal, the job will always go to the larger and stronger of two rivals. Then, because size and strength, in turn, can be enhanced by the consumption of anabolic steroids, individual players have compelling incentives to consume these drugs.

Yet, if all American football players take steroids, the rank ordering of players by size and strength – and therefore the question of who lands the plum jobs – will be largely unaffected. However, since the consumption of anabolic steroids entails risk of serious long-term health consequences (heightened aggressiveness, severe psychosis, circulatory disorders, testicular atrophy, abnormal sperm morphology, and possibly a variety of Cancers⁴) American football players as a group are clearly worse off if they consume these drugs.

Military arms races: The frantic efforts of nations to acquire more weapons than their rivals is one of the most costly instances of the conflict between individual and collective interests. From each individual nation’s point of view, the worst possible outcome is not to buy armaments while its rivals do. Yet when all nations spend more on weapons, no one is any more secure than they were before.

Most nations recognize the importance of maintaining military parity, and the result is all too often a wasteful escalation of expenditure on arms. All nations would spend much less on weapons if they could make their military spending decisions collectively. And then with the money thus saved, each side could spend more on things that promote, rather than threaten, human well-being.

Overharvesting: Disparities between individual and group incentives have also led to over-fishing of coastal waters, overgrazing of common pasturelands, and over-cutting of forests. The problem is not that individual fishermen don’t know that their activities threaten the viability of coastal fisheries; or that individual hunters don’t recognize that Rhinos are in danger of extinction; or that individual loggers don’t realise that valuable ecosystems are often destroyed by clear-cutting. In each case, individuals know all too well what the collective consequences of their actions will be. Yet when property rights in the use of valuable resources are not clearly defined and enforced, no individual is in a position to take effective action. If a Rhino isn’t killed by one hunter, he will simply be killed by another; fish not taken by one boat will be taken by another; and logs left standing by one company will be quickly claimed by another. In its various forms, the over-harvesting problem has been called “The tragedy of the commons”⁵.

High-heels and Cosmetic surgery: In species in which males invest little in the care of offspring (probably the majority of mammals) males typically battle one another for access to females. But in a small number of species – including Human beings and a handful of other species in which males invest more heavily in the care of offspring – the pattern is somewhat different. In these species, competition amongst males is still common, but we also see competition among females for males. And here again, the Darwinian logic is simple: Whereas females in most species can expect males to contribute no more than their genes and can therefore afford to sit back and let males slug it out, Human females stand to gain a great deal if they can monopolize the services of a relatively able caregiver – and thus, women have an incentive to compete.

Competition amongst Human females plays out in various different ways in different cultures, but invariably at least some aspects of it are wasteful. So, for example, in cultures in which height is viewed as attractive, it’s common for women to wear high-heeled shoes. In cultures in which large eyes are valued, most women wear makeup that makes their eyes look larger. In cultures in which youth is considered attractive, most women use makeup to conceal signs of ageing. In cultures in which body hair is considered unattractive, women may submit to electrolysis treatments. And in cultures that place a premium on large breasts, many women undergo surgical breast augmentation.

All these steps involve costs – sometimes very high costs. Even apparently innocuous actions like wearing high heels can cause foot, ankle and back injuries, tendon shrinkage, and misalignment of internal organs. In a small but not-negligible proportion of cases, cosmetic surgery leads to serious infection, disfigurement, and even death. And yet in each case the advantages that people seek are, to a considerable extent, mutually offsetting. Thus, the height advantage that someone gains from wearing high-heeled shoes is neutralized once high heels become the norm. Yet, as with Military arms races, these costs often cannot be avoided without incurring even greater ones.

To summarise, nobody gets any genetic advantage from spending hours lifting weights, filling out Crosswords or Suduko puzzles. Therefore, it’s only worth continuing those activities if you enjoyed them as pastimes, in the first instance. You may, however, be interested to learn instead that according to the Mayo Clinic, men wanting to make sure their sperm are healthy, are recommended to take a daily multivitamin that contains Selenium, Zinc and Folic acid, since these nutrients are important for sperm function.

References:

1. Cronin, H., The Ant and the Peacock: Altruism and Sexual Selection from Darwin to Today (Cambridge University Press, 1991)
2. Hamilton, W. D., M. Zuk, ’Heritable true fitness and bright birds: a role for parasites?’, Science (1982), 218:384-87
3. Noonan, D., ‘Really Big Football Players‘, New York Times Magazine (December 14, 1997), 64ff
4. Windsor, R.E., D. Dumitru, ‘Anabolic steroid use by athletes: How serious are the health hazards?’, Postgraduate Medicine (1988), 84:37-49
5. Hardin, G., ‘The Tradegy of the Commons‘, Science (1968), 162:1243-48

Be Sociable, Share!

• 

You might also enjoy reading:-

• Peacocks may have lost their sexual attraction
• Robin Baker and the early history of Sperm Wars
• Pheromones
• Chimps trade meat for mating
• Secret sex strategies

Posted by Jonathan in Sociobiology, Sociology

No Comments »