Tuesday, March 6, 2012

Euvoluntary Exchange, Sympathy, and Evolution

Two interesting examples.

1.  Is generosity adaptive?  It used to be verboten to suggest that group selection worked across species (though it might work within a species, for hives or nests of eusocial insects).  But now we can ask, is generostiy adaptive?  Notice that this is NOT altruism, exactly.  Interesting.

Evidence from economic games played in the laboratory for real money suggests humans are both trusting of those they have no reason to expect they will ever see again, and surprisingly unwilling to cheat them—and that these phenomena are deeply ingrained in the species’s psychology. Existing theories of the evolution of trust depend either on the participants being relatives (and thus sharing genes) or on their relationship being long-term, with each keeping count to make sure the overall benefits of collaboration exceed the costs. Neither applies in the case of passing strangers, and that has led to speculation that something extraordinary, such as a need for extreme collaboration prompted by the emergence of warfare that uses weapons, has happened in recent human evolution to promote the emergence of an instinct for unconditional generosity.

I'm not so sure.  Smacks of a "just so" story.

2.  On the other hand:  the incredible shrinking wholly mackeral ball.  Do watch:

Bait ball, bait ball, watcha gonna do?  Whatcha gonna do when tuna come for you?

My colleague Emerson Niou insists that this behavior is a straightforward one-shot PD.
That is, this behavior is NOT adaptive, at the group level, but it is adaptive at the individual level.

a.  If somehow the mackeral could signal, "1, 2, 3....GO!" they could all skedaddle at once, in random directions, before predators gather in large numbers.  The bluefin would have had to concentrate on single skedaddlers, instead of taking a bite of the ball, and then another, and then another.

b.  However, if I expect you to skedaddle, I should stay in the (for now) relative safety of the bait ball, while you lead predators away (and, of course, you die, because one loan mackeral can't escape the speedy tuna).

c.   If instead  I expect you to stay in the bait ball, I should...stay in the baitball.  In other words, "stay in the bait ball" is an individually dominant strategy, even though the Pareto optimum is "everybody skedaddle now!"

The question is how a species that acts like this survives.  The answer has to be (as commenters pointed out when I discussed this over at KPC) that it just doesn't happen very often.

My question for Prof. Niou is:  why not?  Why would it be rare?  Why aren't mackeral extinct?

(UPDATE: I accidently said "loan mackeral" above. But I left it. Because it's true that a loan mackeral could never escape a loan shark. Man, I kill me...)

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Do you have suggestions on where we could find more examples of this phenomenon?