Original Post (with comments)
The concept of status hierarchies gets a lot of play here, but there’s another evolutionary biology concept that is worth a mention. That is the notion of reciprocal altruism. It’s no secret that the attribute that most accounts for the success of Homo sapiens over other hominid species is the ability to cooperate. While some other upright, hairless apes were definitely stronger and more fierce, in the end, it did not matter. What kept humans from extinction was their tendency to band together and do as a group what individuals simply could not. But this begs a question: what does it take to cooperate?

The first thing it takes is trust. When the stakes are life and death, you need to know that your buddy will do his part when the time comes. Maybe you’re springing a trap on a lion, and you get to be the diversion. If your pal doesn’t come through at the right time, there’s a good chance you’ll end up getting your skull crushed by the lion’s massive jaws. So, cooperation requires trust, and the best way to build trust is to build a credit history, so to speak.

In caveman days, humans did favors for one another, and they kept track of who reciprocated. (Thus, we see the emergence of the first accountants. It wasn’t double-entry, to be sure, but hey, they were cavemen.) One who consistently repaid favors built up a good reputation, or credit history, which could be leveraged when needed. It is fascinating to consider that somehow Mother Nature stumbled on the genetics that prompted humans to band together like this, but she did, and it worked…like gangbusters. Things, however, get interesting when you consider that not all favors are equal.

If I have been starving for days and a guy tosses me a scrap of meat, I am profoundly indebted to him. In fact, I’ll gladly give him five times what he give me as soon as I can procure it. (Thus we see the emergence of the character, Whimpy, from Popeye – “I’ll gladly pay you Tuesday for a hamburger today.” Isn’t evolution enlightening?) This is the non-zero sum concept – one man’s famine is another man’s feast. The question is this – why would a guy, a caveman living a high stakes game of evolutionary musical chairs, give me a scrap of meat? I mean, I’m already down on my luck. Though I may intend to give him five times what he gave me, who’s to say I can come up with it? Maybe it’s sympathy.
Was the guy who gave me food being benevolent or selfish? Hard to say. It would seem that giving me a small scrap of meat, the equivalent of giving a handful of change to a homeless person, is a losing proposition. There’s little likelihood that there will be any return on the investment. But remember, the scrap of meat means very little to one who has plenty, so giving it away costs next to nothing. If I repay him, however, he’s gained 500% on his pittance of an investment. That’s pretty solid. What if Mother Nature programmed humans to do this kind of calculation automatically? There are many evolutionary psychologists who believe she did. Sympathy, so says one of the originators of the field, Robert Trivers, is nothing more than bargain hunting at the emotional level.

Consider the idea that every favor you do amounts to an investment in your resources. In a cooperative arrangement, you expect to get a fair return on your investment. Usually, you get back what you put in, though it may be in a different form. But sometimes, sometimes you have the chance to get back a lot more than you put in. You get to make a major profit. This is what happens in non-zero sum situations like the one mentioned earlier. So, suppose natural selection stumbled upon some combination of genes that produces a heart-wrenching response to sad situations where the individual feeling those emotions can make a small investment and potentially expect a generous return? Would that individual not enjoy a bit of an advantage in the limited resources world of cavemen? So long as he came out positive in the long-run (that is, he won more than he lost), he certainly would. There are a couple of points to make here.

The first is that we need to understand that our emotions evolved to get us to do things that are in our best interest from a survival perspective. We fall in love so we can reproduce. We get angry to avoid getting screwed over. We get jealous (at least males do) to avoid raising someone else’s child. And we feel sympathy to alert us to opportunities to get back more than we put in. Of course, I know that many folks recoil in horror at the thought of such a despicable heritage for our gentlest touches. But their resistance changes nothing, and it’s more important to know who we are and why we think and feel the way we do than it is to continue to indulge every fantasy we have about our special place in the universe.

That brings me to my second point. Though our emotions may be somewhat hard-wired, understanding them is the first step in mastering them, and that, my friends, is the grail. I’m not about to say that we can (or should) become Spock from Star Trek. However, one thing is for sure, some emotions do more harm than good. Knowing where they come from and when we can expect them to arise and take over is the key to keeping ourselves on an even keel. I can’t go into all the details of this here (It took me two years to write a book about it), but I can say this – a great deal of the unhappiness that is experienced in this world is the result of our caveman emotions grappling with our immensely prosperous world.
So, the next time you feel sorry for the homeless guy in the street, remember that it’s your genes looking to get a dollar for the quarter in your pocket. Ask yourself, by giving this guy a quarter, am I really helping him or am I making myself feel good? Then decide, rationally, whether or not to give it to him. I care less about what you decide than about how you decide. Get it?