Monday, February 20, 2012

Darwinian Family Values: From Selfish Genes to Altruism

It's a Saturday night in south Louisiana; the weekend before Mardi Gras.  There's going to be parading and debauchery from now through Fat Tuesday, and I intend to see some of it.  But tonight, the rain is pounding against my windows, and I just can't get that excited about going out in it.  So, I'll risk the wrath of Bacchus by staying in and continuing my recent ramblings about ethics.

In my last two posts, I've been considering whether ethical laws are an intrinsic part of nature.  I've concluded there are good reasons to be skeptical about the idea of natural law--the idea that there are clear ethical rules implicit in nature, and that we can use our reason to discover them.  If the natural world evolved through a combination of  basic physical processes and natural selection, then there's good reason to question the natural law idea that everything in nature has a purpose, and that learning our purpose can tell us what is good.  If humans are chance products of natural selection, then we may have no purpose at all.  It seems quite likely to me that we weren't put on earth for any reason.  We are here because we happened to evolve.  I don't mean to wring my hands and say life is meaningless.  I think human life can be incredibly meaningful.  We are smart, curious, social, and talkative creatures living in a world full of wonders.  There are plenty of ways to find rewards and meaning in life.  I just don't think we can assume that we are here to serve some cosmic purpose.

Another reason to be skeptical about natural law is the problem of the appeal to nature fallacy (or naturalistic fallacy), which reminds us that we can't automatically jump from descriptions about how things are to how things should be.  Evolution, for example, has made human males stronger and more aggressive (on average) than human females. In the past, and in some places and subcultures even today, being big and bad enough to outfight or intimidate other males was a successful strategy for having more offspring.  Does that mean men should fight more, since we are, in the mindless evolutionary sense, designed for it?  Certainly not.  The fact that belligerence was a successful strategy in the past doesn't mean it's the right way to act.  Is does not equal ought.

Nature only seems care about what works, not what's right.  However, this doesn't mean nature is irrelevant to morality.  We can't simply ignore the laws of nature, or the realities of human nature, when we decide how we should act.  We can't for example, decide that it's wrong to ever eat any part of another living thing.  We would starve to death. 

On a less drastic level, it's important to know as much as we can about human nature, to gain insight into why we have ethical preferences all.  Is our sense of morality a universal part of human nature, with deep roots in our evolutionary history?  Or are humans born a blank slate, learning the socially constructed rules of our particular culture?  In some circles, it's heresy to claim that human behavior has any intrinsic basis.  It smacks too much of old theories justifying racism, sexism, and the supposed superiority of western ways.  In the last few decades, though, it's been increasingly hard to deny that human nature has been influenced by evolution.  But it's a universal human nature, common to all people, regardless of race.  While our moral sense is obviously modified by the culture we grow up in, it was not created by that culture, at least not entirely.

If evolution is amoral and blind, how did it give us a sense of morality, a sense that some things are good or bad, right or wrong?  Let's focus one aspect of morality for now: altruism.  Altruism occurs when one animal (human or otherwise) does something to help another, at a cost to itself.  Most people feel an urge to help others, at least to some extent, especially if those others are their friends or family.  But we aren't the only animals capable of altruism. Vervet monkeys, for example, will give a loud call if they see a predator.  This warns the other members of the group to be careful, but it also increases the chance that the predator will zero in on it, and have that selfless monkey for dinner.  Wolves that have had a successful hunt will eat their fill, return to the pack, and regurgitate food for others who weren't part of the hunt.  This may be gross, but it's undeniably altruistic.

Now, we don't know if vervet monkeys and wolves feel some sense of obligation or empathy which spurs them to such selfless acts.  Both are fairly-large brained creatures, so it seems likely to me that they do.  In humans, a sense of obligation or empathy is considered a moral sense.  While I don't know if I would say wolves and vervet monkeys are moral creatures, I would say their urges toward selfless behavior could be a precursor of our more sophisticated moral sense.

But the question remains--how did this kind of behavior evolve?  Lots of people figure that animals are altruistic because it helps the group or species survive. After all, evolution is about the survival of the fittest species, right?  Well, not really.  Evolution doesn't seem to happen at the group level, except possibly in very special cases.  Here's why:  let's say you have a group of extremely altruistic monkeys, whose members always share food and help care for each others' offspring.  They always help each other, and because of that, they are a very successful group.  But there is always some variation within any group of organisms.  Occasionally, one will arise within the group that doesn't have "helpful genes".  They never help, and they take advantage of the altruism of the others.  This they will survive better, at the expense of the others.  It also means they have more offspring, who inherit their tendency to take advantage of others.  Very quickly, these non-altruistic monkeys will get more and more common in the population, until the group is no longer composed mostly of altruists.  To the extent that acting for the good of the group is not conducive to survival and reproduction of the individual, it is not--to use the evolutionary biologist's term--an evolutionarily stable strategy.

Actually, what matters most in evolution is not the even success of the individual, but of particular genes.  Individual living things are ephemeral--most only live a few years at best. An individual's particular combination of genes are also ephemeral.  In sexually reproducing organisms, each one has a unique genome, a mix of the genomes of their parents.  If they reproduce, they will pass 50 % of their genes on to each of their offspring, and each of them will have their own unique combination of genes.  What lasts across generations are individual genes.  For the last few billion years, genes that happen to be good at getting themselves replicated have increased at the expense of genes that weren't as good at replicating.  Over time, the world has come to be populated by organisms whose genes are good at replicating themselves.  As Richard Dawkins explains in The Selfish Gene, whole organisms are vehicles designed by genes for the purpose of replicating those genes.  Of course, neither the organism or the gene is conscious of this.  A gene has no consciousness at all, and an organism that acts in a way that spreads its genes isn't conscious of why it's doing so.  A mother alligator cares for her babies because her brain and hormones tell her to, not because she's thinking about how best to spread her genes.  This is true for people, too.  We care for our children because we feel an intense love for them, rarely considering that this love has anything to do with our genes.

Caring for children is so automatic for most people that it doesn't even seem like altruism.  It's just what you do.  But it is altruism in the sense that the parent is making sacrifices for the child.  Often big sacrifices.  Once I had a dog that had puppies.  She was a wonderful mother, and nursed them all the time.  Before long, her hair started falling out, because her puppies were getting nutrients she needed for herself.  She was sacrificing her health (albeit unconsciously) for the sake of other creatures--her puppies.  The immediate reason she did this is because she felt (and I'm convinced she had feelings) an overwhelming urge to do so.  But the ultimate, evolutionary reason she felt that way is that each one of those eight puppies held copies of her genes.  I say copies because genes can't pass themselves on.  They can only pass copies of themselves on.  This means it doesn't matter, in terms of the gene's success, that those copies are in another organism.  In fact, it works out well, because one organism can have many offspring, producing multiple copies of many of its genes (multiple copies of all of them, if it reproduces asexually, but that's a different topic). 

Today, this "gene's eye" view of evolution is often known as the "selfish gene" theory, because it was explained in the brilliant book of the same name by Richard Dawkins.  Other scientists, especially W.D. Hamilton, George Williams, John Maynard Smith, and Robert Trivers, came up with the basic idea of looking at evolution at the level of the genes.  As Richard Dawkins would readily admit, he was just explaining it.  As he would also admit, the title of the book has caused a lot of misunderstanding.  He called the book The Selfish Gene because genes tend to do whatever it takes to get themselves replicated, whether or not this is good for the individual organism.  A male preying mantis has an intense urge to mate with a female preying mantis, even though she is quite likely to bite his head off in the midst of their passion.  It's a risk worth taking, as far as his genes are concerned, because he is getting them reproduced.  As long as more genes are replicated in the long run, the misfortunes of Mr. Mantis are irrelevant to evolution.   This is the sense in which genes are selfish.  The mistake is to conclude that selfish genes always create selfish organisms.  Genes do whatever it takes to get themselves replicated.  Sometimes selfish organisms do this most effectively, but oftentimes, altruism works just as well.

We've already seen one way this is true: with parental care of offspring.  But altruism in nature goes beyond that.  If all genes become widespread by making copies of themselves, those copies don't have to be in direct offspring.  An organism's offspring, as I mentioned, have copies of 50% of its genes.  But so do its parents and siblings.  This means that if it doesn't have offspring, but helps two of its siblings survive and reproduce, the effect is the same in terms of gene replication.  This means natural selection will tend to produce organisms that act altruistically toward their relatives.  The closer the relation, on average, the more altruism.  While siblings share 50% of their genes, cousins only share 25% of them (on average, as always).  If we look at how the world works, that's exactly what tends to happen.  Some animals do take care of their siblings' offspring, but they don't spend as much time with them as their own offspring.  My aunts and uncles were all very kind and generous to me, but they didn't raise me.  They raised their own children.  That's how evolution made us.

Selection for altruism toward relatives is known as kin selection, and it accounts for most of the altruism in nature.  But it only goes so far.  It doesn't lead to absolute altruism, even toward ones children or siblings.  If there are two siblings, and only enough food for one of them to survive, kin selection theory predicts each will try take the food for itself.  Yes, if one of them lets it's sibling have the food, and then dies, 50% of its genes would have survived.  But if it takes the food itself, 100% of its genes have survived.  So, even close relatives don't share the exact same interests, genetically speaking, unless they are identical twins.  This means there's a lot of conflict in nature, even among members of immediate families.  In some cases, when an individual can spread its genes more effectively by surviving at the expense of its family members, kin altruism is selected against.  This is apparently the case in the Sand Tiger shark.  This shark gives birth to live young, but only two of them.  The shark has a double uterus, and in each branch, the shark embryos eat each other, until only one remains.  Evolution doesn't always encourage niceness, even among brothers and sisters.
This unsettling image brings up an extremely important point.  I want be perfectly clear that, while I do think evolution created most of our moral impulses, such as our urge to treat relatives well, I don't think these impulses are the best we can do morally.  As I discussed in the last post, nature is amoral.  Evolution encourages altruism when altruism is useful for spreading the most genes.  When it isn't useful, it isn't encouraged.  Our genes, in their mindless quest to replicate themselves, gave us large brains, capable of reflecting on our impulses, and (with a good bit of willpower) choosing which ones to follow, and which ones to resist.  And some of our natural impulses should definitely be resisted.

In any case, it seems likely to me that altruism between related individuals gave rise to some of our basic, morally-laden emotions, including love, the urge to nurture and protect, and our sense of loyalty to family.  In human societies, we are constantly using family metaphors to encourage bonding, cooperation, and loyalty among unrelated people.  Students in fraternities and sororities call each other brothers and sisters.  Catholic priests are called "Father".  Americans talk about our Founding Fathers, while Russian's talk about Mother Russia.  Confucius saw society as a large family, and believed that the kind of loyalty and hierarchy that made a good family (as he saw it) would also make a good society.  This extension of the family metaphor into larger groups has been a mixed blessing, of course.  On the one hand, it's built cooperative groups capable of accomplishing far more than they would have if they hadn't cooperated.  On the other hand, it can be used by tyrants to justify their power (Big Brother is watching you), and it can lead to a nasty kind of tribalism, where people abuse those that aren't part of their societal "families".

I don't want to get caught up in how the family metaphor is extended to unrelated people, at least not now.  My main point in this post is that the moral impulses humans feel have an evolutionary history that began long before humans did.  But it isn't common to all animals.  Many animals feel no impulse at all to treat other members of their species well.  If parental care isn't adaptive, they don't even feel the need to treat their own babies well. Many frogs simply leave their eggs in a pond, and then go about their business.  It's probably safe to say that this frog doesn't have any particular sense of good will or fair play toward other frogs.  However, animals that practice parental care--even solitary ones such as bears--do seem to feel an obligation to protect and care for other bears--if those bears are their own offspring.  In social animals, individuals may feel an urge to care for the rest of their family, not just their own offspring.  In many small groups of animals, most individuals are related, so they may feel a general altruism toward all their fellows (though they are likely to feel more of it towards immediate kin).

Of course, there's a lot more to human morality than altruism between relatives. We also have a sense of the sacred, of fairness, of loyalty, and of moral outrage when we think these things are being violated.  If I'm going to consider the origins of these impulses, then I have a lot more work to do.  However, I think it makes sense to start by looking at how some animals began to have the sense that they should be benevolent or cooperative to certain other animals (instead of ignoring them, chasing them away, or killing them).  One way this happened is though kin altruism.  But it's not the only way.  Unrelated animals do cooperate in nature, and some may even form friendships, develop a rudimentary sense of fairness and empathy, and trade favors.  This kind of cooperation isn't as strong as kin altruism, though, and it's prone to shifting alliances and exploitation by cheaters.  This is where social life among animals turns into a real soap opera.  But this post is long enough, so I'll talk about that in the next episode.

The Selfish Gene - Richard Dawkins

The Expanding Circle:  Ethics and Sociobiology - Peter Singer

Meerkat image © goldencolt -