Altruism has been a subject of intense social science speculation since Darwin.

The first real discovery was by the evolutionary biologist William Hamilton in 1964. He noticed a very interesting explanation for altruism. If you are faced with a choice of either your death or the death of three siblings, you can increase the expected number of your genes in the next generation by choosing you own death. This is because, on the average, you and a sibling have half your genes in common. Assuming you and your siblings are destined to have the same number of offspring, they will send one and a half times your potential contribution of your genes into the next generation. This argument may not convince you, but innumerable biological studies support it. Google “altruism” along with “naked mole rats,” “meercats,” or “howler monkeys.”

Here is an over-simplified example of gene-serving altruism. Suppose Alice and her three sisters are threatened by a man with a gun. If they scatter and run, each has a 50 percent chance of surviving. But if Alice rushes the gunman, the others will escape while he shoots her. Why should Alice rush the gunman? Alice has brown eyes so carries the gene for brown eyes. While some of her sisters might have blue eyes, it is likely that at least two of them carry genes for brown eyes. If all the genes had a meeting to vote on what Alice should do, the brown genes would say, “If Alice rushes the gunman her brown gene will die along with her, but all the rest of the brown genes will have a chance to replicate. If Alice doesn’t sacrifice herself two of the sisters will die probably taking more than one brown gene. So, Alice should rush the gunman.”

You might have followed this reasoning, but at a certain point you must have thought “Hey, genes don’t talk to each other, and they couldn’t know how many of their copies were inside the sisters—and there was no time to figure this out anyway!”

Describing it as if the genes and the sisters are figuring this all out as the gunman approaches is obviously ridiculous, but it’s a good way to explain it to humans whose brains are geared for interpersonal politics.

So, Hamilton proved that it was natural to sacrifice for your children, siblings, and other relatives. Unfortunately, it also provided a justification for tribalism since unrelated people probably share fewer of our genes.

Why might people cooperate with or sacrifice for strangers? Steven Pinker’s The Better Angels of Our Nature: Why Violence Has Declined presents extensive evidence that we’re getting nicer, but exactly why is not clear.

Darwin introduced the topic of group selection, saying, “If one man in a tribe . . .invented a new snare or weapon, the tribe would increase in number, spread, and supplant other tribes. In a tribe thus rendered more numerous there would always be a rather better chance of the birth of other superior and inventive members.”

In other words, “It’s better to grow the size of the pie rather than the size of one’s slice, because the growth of the pie will outpace the shrinkage of one’s slice.” For the sake of discussion, assume a group has two distinct types of people, altruists who obey an altruism gene or meme and deadbeats who lack either. In an isolated group the altruists will lose ground because they give the deadbeats a reproductive advantage. For example, altruists might care for orphaned deadbeats lacking altruism. Something else must go on for altruism memes to survive.

Altruists could punish deadbeats, in effect reducing their numbers, but deadbeats can retaliate. Also, punishing is not altruistic.

Religions propagating a meme saying, “Do unto others as you would have them do unto you,” can help grow altruism.

The most recent attempt to argue the case that altruism, or at least cooperation, grows is the book Ultrasociety: How 10,000 Years

of War Made Humans the Greatest Cooperators on Earth. In a nutshell: Suppose two groups, A and D, go to war, and the one with more altruists has an edge because they sacrifice more for each other, e.g. by falling on hand grenades. Assume As kill more Ds than they lose. Then, other things being equal, the altruist/deadbeat ratio grows larger since D had a higher proportion of deadbeats.

The implications of this theory are unpleasant: To grow altruistic traits, one has to have tribalism. Aside from killing them, the winners could enhance their traits’ growth by raping and enslaving them, teaching their children (at least) the value of cooperation. Think Genghis Khan.

How would we escape from this dismal situation? It won’t do any good for the entire human race to become one big tribe, because then the fallacy of the growing pie kicks in. Going to war with an extraterrestrial tribe might help. A more likely enemy is the COVID-19 virus. Robots are another.