I remember, as a child, seeing in a museum the skeletons of birds, bats and apes, and someone pointing out to me that they all had the same bones in their arms. It was the first time I grasped that we all had a common evolutionary ancestor, though at the time I hardly thought about it in those terms and probably just wanted to gawp at the dinosaurs.
But then someone showed me the redundant little hip bone in the skeleton of a dolphin. Why have they got hips when they don’t even have hind fins? Because at one time in their evolutionary past, they did. They’ve just gradually lost them. At one time in their past, dolphins didn’t live in the sea; they lived on the land and walked on four legs.
I remember just accepting this fact. It was only much later that I realized how powerful an idea it is. Anatomy can be used to communicate that we all — all living things — share an evolutionary past. We can use anatomy to look at when things evolved. So, for example, we can look at fossils of hands to find out when the thumb evolved (Answer: sometime in the monkey lineage).
Compare and contrast
And it is one of the markers of the progression of evolutionary biology that we can now look at other characteristics that we share and see how we differ — where they came from. Even things less physical than hands and legs; things such as emotions, morals and our sense of fairness.
With clever experiments, the evolution of these traits can now be studied. For example, there is a game that economics researchers like to get volunteers to play called the ultimatum game.
It’s a simple game. There are two players, a proposer and a responder, who have to divide up a reward. It doesn’t matter what the reward is, just as long as it can be divided up — say, a crate of beers that have been provided for a party or a bundle of notes found in an envelope. One player, the proposer, decides how much of the reward he will offer to the other player, the responder. There’s no arguing allowed over how it is divided up — this is the ultimatum game, after all.
Little or nothing
But the responder does have power. He can accept his share of the reward, or he can reject it, in which case neither player will get a share. Think about what you would do, say, if your friend got ¥1 million on condition that he shared it, and he offered you ¥100,000.
Working purely rationally, you should accept the ¥100,000. But we’re not like that. When playing this game for real, most people will reject derisory offers and walk away with nothing. They get nothing, but they get the satisfaction of punishing the proposer for being greedy. This experiment demonstrates that we have a sense of fairness. It’s unfair for someone else to get ¥900,000 and me to get ¥100,000.
Now, just like paleontologists look at fossil hands to pinpoint the timing of the evolution of the thumb, we can compare ourselves with other animals to see if they also have a sense of fairness. All that would need to be done is to get those animals to play the ultimatum game and see what happens.
That’s what Keith Jensen at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, has done.
Jensen set up a game where two chimps had to share 10 raisins that were visible but unreachable, behind plexiglass. The experimental area was designed so that one chimp, the proposer, could divide up the raisins by moving ropes, and the second chimp, the responder, could accept the deal by pulling a rod that brought the raisins to a hatch where both chimps could access their share. If the second chimp didn’t like the offer, he could reject it by doing nothing. Neither chimp would get the raisins.
And the winner is . . .
So what happened? Chimps showed themselves to be suckers. When the proposer chimp offered just two of the 10 raisins, the responder still accepted 95 percent of the time. Chimps, it could be said, are chumps; they don’t have a sense of fairness.
A sense of fairness is essential to allow the formation and smooth day-to-day running of large societies, say the authors, who published the work in the journal Science last week. This aspect of our interaction with each other could even be one of the things that set us apart from chimps and allowed us our explosive and unfettered success.
As I write this, two of the biggest stories in Japan, or at least two that have caught my eye, are the sacking of sumo stable boss Tokitsukaze over the death of 17-year-old wrestler Tokitaizan and the refusal of officials from the food safety department of the Ministry of Health, Labor and Welfare to accept a petition of 50,000 signatures protesting the annual dolphin slaughter in Wakayama Prefecture.
Why are these big stories? I think it is because they jar against our sense of fairness. I don’t mean to come over like a Victorian gentleman or a bleeding-heart liberal, but it’s just not fair play to haze a teenager to death, as allegedly happened to Tokitaizan, or to round up thousands of dolphins in nets, hack them with spears and then sell their mercury- tainted flesh to shoppers.
The second volume of Natural Selections columns translated into Japanese is published by Shinchosha at ¥1,500. The title is “Hito wa Ima Mo Shinka Shiteru ( The Evolving Human: How New Biology Explains Your Journey Through Life).”