Undeniable (28 page)

If you want to really get inside those instincts, try examining your own responses to a few game theory–type thought experiments that have more of a real-world twist. The following scenario is rather different—it involves danger and rescue—but like the Prisoner's Dilemma it shows how strongly we make choices that are driven by our inherited evolutionary tendency to be altruistic.

Suppose your house or apartment is burning. You are in the house with your kid and your mother. In this admittedly creepy scenario, you only get to save one. You are only allowed to carry out either your kid or your mother. (The cat and dog are on their own.) Everyone picks his or her own child. Now, suppose it's your mother and your brother's child. Everyone picks the kid. Now suppose it's your mother and a
stranger's
child. People still tend to save the kid. Apparently we are inclined to favor a child who could grow up and have children of his or her own in the future. The impulse to keep the species going often overrules the impulse to look after your own kin.

This exercise probes the nature and the limits of the drive within us to save members of our family. In evolutionary biology, this drive is called “kin selection.” We work hard to preserve or, in this case, save members of our kind to whom we are related, with the nature of the relationship influencing the intensity of the drive. Scientists express it this way—bear with me for a simple mathematical expression:

b
>
c/r
(benefit is GREATER THAN the cost divided by your kinship relationship)

The trick here is the relationship is a fraction, based on the amount of genetic similarity between you and the other person; that fraction is called the r-value. Your own son or daughter comes in with an r-value of ½, because half of his or her genes came from you. Your grandkid comes in at ¼ and so on. So, the closer the relationship, the more benefit you feel you've received for any given effort, i.e. any given cost. This has been observed and documented in nature. But there is a little bit more to it.

Who doesn't love and respect groups of vervet monkeys, in which sisters and aunts and other females help care for each other's infants? (Zoologists really do refer to a “barrel” of monkeys.) Who doesn't love even more the red squirrels who adopt a stranger's buck or doe (baby squirrel) if the mother and father have disappeared? Kin selection, at least for us humans, is easy enough and reasonable to understand in evolutionary terms. When it comes to the burning building, though, this equation doesn't tell the whole story. The fraction on the right-hand side never goes to zero: You, as a human, will tend to save the kid even if he or she is completely unrelated.

You can imagine that families and extended families who nurtured the offspring of their family, i.e. their tribe, barrel, pod (whales), or dray (squirrels) do better, i.e. have more healthier offspring who go on to produce more offspring—children and grandchildren—than those who don't nurture so well. Even schools of certain shrimp protect their young as a group effort.

It is fascinating to note that bees do it. So do ants and termites. In these enormous swarms of individuals an overwhelming majority of them do not reproduce. They were born as offspring of a queen and her few male drones. Biologists reason that, because they share so many genes with the queen, they are driven by motivations deep within their DNA to behave in a way that ensures, to the extent possible, the continuation of their swarm. You may have read accounts or seen videos of the ants that stop at nothing to advance through a forest. You may have encountered a potentially deadly swarm of bees, each of whom will kill herself to sting you and drive you away. It's suicide for the greater good. What else could it be that drives these behaviors other than the creatures' relationships to one another? It's natural selection driven by kinship. Evolutionary biologists call it kin selection.

Biologists have often written about how all this game theory and kin selection plays out among our fellow humans. I know that, as an uncle, I would do just about anything to preserve the lives and well-being of my nieces and nephews, and especially of their offspring, my grandnephews and grandnieces. It's a crazy feeling. But, I know that feeling is there, and I cannot work my way around it. That's not a bad thing, I suppose. It's deep within me and all of us. This same sort of avuncular and tauntular (my own coinage for having the characteristics of or pertaining to an aunt—it's a word strangely missing from the English language) behavior is observed in a pride of lions, for example. Uncle lions often become beta-males and are subservient but helpful all at once. Even though they are not the parent, they are deeply genetically invested. Such is life.

It goes even beyond that. As the thought experiment extends to include our human family, our kin-selection choices expand to include the whole of humanity, as happens to those who imagine saving a stranger's child over their own mother, even though the child's r-value to you is very small indeed. At some point, all of humankind seems like kin. This unfortunate mom isn't going to have any more kids, but that child might. We owe ultimate allegiance to the survival of the species.

This is not just a hypothetical situation. As I write, there was a recent, highly celebrated incident in which a firefighter in Houston, Texas, risked his life by directing his fire truck ladder to set right up against an enormous apartment-house fire. The building was unfinished, and the wind carried the flames through the open-frame lumber like a hot knife through soft butter. The firefighter got right up next to the building, which allowed a construction crewman to jump from the flaming unfinished building to the ladder. A moment later the building collapsed in a flaming hot mess, missing the two men by millimeters. The incident was caught on video.

All of North America watched as one of these two unrelated guys risked his life to save a stranger. We celebrated their bravery and especially the selflessness of the firefighter. Newscasters speculated as to whether or not they'd ever have reason to sit down together for a beer or just go their separate ways. There was no question in any viewer's mind whether the firefighter and his team on the truck below did the right thing. Of course they did. Saving another life is what we do, whether we're related or not. Thinking a little further along this line, one can imagine that those among us who would not save another's life are generally unwelcome. They are, we might assume, less likely to meet a husband or wife and produce kids to carry those miserable genes into the future.

Altruism is not a moral or religious ideal, no matter what some people might tell you. It is an essential, biological part of who or what we are as a species.

 

29

COSTLY SIGNALS

There's an old saying around the gym, among the guys who work out and lift weights: “More curls; more girls.” For those of you unfamiliar with this time-honored advice, it refers to doing bicep curls with weights to build up a man's arms for no other purpose than to be attractive to women. Jesse Rafalski, a professional trainer, directs his clients on how many repetitions one should do with each weight and in what configuration. He may be the best trainer in Hollywood, and he offers this wisdom: “No matter what they say or tell you, women like muscles.” My sister Susan is a student of these things and assures me that it's absolutely true. It seems that Darwin's concept of sexual selection is alive and well and living in gyms across North America.

Really, that should come as no surprise. Our species is prone to it as much as any other that reproduces sexually. Human males seek out females who appear to be highly fertile, which is a likely reason why human females have permanently enlarged breasts—unlike almost all other mammals. Human females seek human males that, according to what they can assess, are well suited to raising children. He has to be a good provider and protector, one worthy of a female's trust. That said, bump into him, then give a quick squeeze. To wit, check out his arms first.

Perhaps this interest in bodybuilding is left over from our ancestors' early days on the savannah. The modern man living in a city (as more than half the world's population now does) will seldom have to lift anything especially heavy. He will not have to defend his home or cave, or his mate, from dangers akin to lions, and tigers, and bears. Instead, he will have to be smart enough and diligent enough to compete with other men for females. Biceps curls are generally no longer an essential part of being a good protector, and certainly not of being a good provider. But there is a way in which biceps are still relevant. The reason that men work out today may not be to send signals to females; it may be to send signals to other men. These signals come at a cost in time, effort, energy, and resources. If you've ever watched the guys at the gym, you know that some of them spend a
lot
of resources.

By appearing strong, an animal sends a signal to enemies and to members of his or her own species, “I am dominant. I am worthy of respect. Do not mess with me!” I am paraphrasing a bit. The important idea is that it costs something to send signals. It takes time to do biceps curls. It takes resources and practice to wear high heels. Perhaps more objectively from a human scientist's point of view, it takes energy and athleticism to pronk, if you're a springbok.
Pronk
is a South African verb that means “to jump vertically.” It's a behavior common among the diminutive African antelope, and is a good example of a signaling strategy used by an animal other than us.

On the savannah in Africa, we can observe a dramatic conflict of predator and prey. The big cats like lions and cheetahs hunt foragers like zebra and springbok (which is also the name of a South African rugby football team). From time to time, when a springbok senses the presence of a big deadly cat, a springbok will jump straight up in the air, quite high. This takes energy. It could wear a springbok feller out.

Why would an animal that might require every last bit of energy and concentration to escape death by lion spend any energy or time bouncing up and down? Apparently, to send a signal to any nearby predators that this particular springbok is fit and ready to flee. If you're a big cat, you have to add that into your attack plans and tactics. Keep in mind that the overwhelming majority of big-cat attacks fail. Most of the time the cats get outrun or outmaneuvered as they stalk and pursue prey. It's a matter of life and death for both animals involved. The cats cannot afford to waste energy any more than the springbok can. Jumping around for no reason in an imminent combat situation seems ill advised, unless it has a costly signaling purpose.

Consider the peacock, the epitome of costly signaling. These guys walk around—and more surprising to me as an engineer, these guys
fly
around—carrying enormous tails. From a sexual selection standpoint, the big brightly colored tail is understandable. The males display the tail to attract attention from peahens. They display the tails in billboard fashion to show a peahen of interest that they are healthy and free from parasites. But, the display seems to serve other, related purposes as well. It shows the peahens that the peacock is strong. And it shows other males that this peacock can outstrut, outfly, outcourt, and generally outcompete them. It shows predators that this peacock can show the tail, hit on the peahens, and still fly away if you come looking for trouble. “You got a problem with that, predator? 'Cuz, I'll give you a problem…” Once again, I paraphrase.

A crucial element of costly signaling is that the cost has to be obviously real. Waste is an essential feature of signaling to a predator or a potential mate. The springbok can't be faking it. Let's say our springbok is in great shape. He or she can jump well right now. A lioness spies the springbok and considers quietly stalking her way in for the kill. Our springbok sees the lioness and pronks expertly; he executes a good high jump and sticks the landing (as we say in gymnastics). The lioness sees that the springbok is fit and probably can't be run down and eaten; she stalks off, leaving the springbok alone.

Now let's suppose that the lioness comes upon another springbok and wonders if perhaps she can grab this one. But in this case, the springbok pronks only half as high as it can—or more important, only half as high as the lioness expects a springbok to jump. She might conclude that the springbok is injured, that it's not up to a full jump and therefore might be a suitable target for an attack. There could be strategy behind this feeble pronk, however. The springbok might be perfectly healthy, but pronk halfheartedly in an effort to entice the lioness to stalk it, which would give his or her vulnerable calf time to slip away. If this is the case, the hero of the story is taking a big chance. The lioness might move more quickly than the feinting springbok thought, and he or she could easily end up getting caught, killed, and eaten.

The thing to notice in these scenarios (which are uncomplicated by variations in the terrain, the wind direction, and other environmental factors) is that our hero the springbok can pronk all he wants. If the lion thinks she can catch the antelope and she's right, the end result is death. In other words, the springbok has to be able to make good on its ability to escape. He or she has to prove that it can outrun or outdodge the lioness and get away. In similar fashion, the lioness has to be able to catch the occasional springbok, or else springboks would not concern themselves with lions.

Perhaps most important, the halfhearted pronk has to be ambiguous enough to introduce doubt in the lioness's mind so that she pauses. The in-between scenario has to really be in between guaranteed success for either predator or escapee.

This in-between version leads me to consider and embrace what's called the handicap principle in evolutionary biology. It means that the feint or the threat must have a clear cost to the organism making the statement about his or her fitness. If springboks could jump effortlessly all day, lions would recognize that their antics had little or no bearing on their fitness as escape artists. The hunter would not be fooled. But near as we can tell, the pronking is tiring. It takes a little bit out of the springbok, and the lioness knows this. She senses that it's hard for the springbok. As a result, she recognizes that if a springbok can jump that high and show off at that level, that springbok is essentially uncatchable. After millennia of these interactions, the deadly interplay is held in a perfect balance.