3
els of populations of co-evolving genes, from the well-
developed area of population genetics, Smith posited
genes that can code for strategies, good or bad, used
in simple strategic problems (the "games" of game the-
ory). Smith proved that these genes, competing to be
propagated into future generations, will evolve strategies
that are Nash equilbria to the strategic problems pre-
sented by the competition. These games include the pris-
oner’s dilemma, a prototypical problem of cooperation,
and hawk/dove, a prototypical problem of aggression and
its mitigation.
Critical to Smith’s theory is that these strategic games,
while played out between phenotypes proximately, are in
fact games between genes the ultimate level - the level
of competition to be propagated. The genes - not nec-
essarily the individuals - influence behavior as if they
were boundedly rational (coding for strategies as opti-
mal as possible, within the limits of what phenotypes
can express given the biological raw materials and pre-
vious evolutionary history) and "selfish" (to use Richard
Dawkins’ metaphor). Genetic influences on behavior are
adaptations to the social problems presented by genes
competing through their phenotypes. Smith called these
evolved Nash equilibria evolutionary stable strategies.
The "epicycles" built on top of the earlier individual
selection theory, such as sexual selection and kin selec-
tion, disappear into this more general model which, in a
Copernican manner, puts the genes rather than individu-
als at the center of the theory. Thus Dawkins’ metaphor-
ical and often misunderstood phrase, "selfish gene", to
describe Smith’s theory.
Few other species cooperate on the order of even Pale-
olithic humans. In some cases - brood care, the colonies
of ants, termites, and bees, and so forth, animals co-
operate because they are kin - because they can help
copies of their "selfish genes" found in their kin. In some
highly constrained cases, there is also ongoing coopera-
tion between non-kin, which evolutionary psychologists
call reciprocal altruism. As Dawkins describes it[D89],
unless an exchange of favors is simultaneous (and some-
times even then), one party or the other can cheat. And
they usually do. This is the typical result of a game
theorists call the Prisoner’s Dilemna - if both parties co-
operated, both would be better off, but if one cheats, he
gains at the expense of the sucker. In a population of
cheaters and suckers, the cheaters always win. However,
sometimes animals come to cooperate through repeated
interactions and a strategy called Tit-for-Tat: start coop-
erating and keep cooperating until the other party cheats
- then defect yourself. This threat of retalation motivates
continued cooperation.
The situations where such cooperation in fact occurs
in the animal world are highly constrained. The main
constraint is that such cooperation is restricted to rela-
tionships where at least one of the participants is more or
less forced to be in the proximity of the other. The most
common case is when parasites, and hosts whose bodies
they share, evolve into symbiotes. If the interests of the
parasite and the host coincide, so that both working to-
gether would be more fit than either on their own, (i.e.
the parasite is also providing some benefit to the host),
then, if they can play a successful game of Tit-for-Tat,
they will evolve into symbiosis - a state where their in-
terests, and especially the exit mechanism of genes from
one generation to the next, coincides. They become as a
single organism. However, there is much more than coop-
eration going on here - there is also exploitation. They
occur simultaneously. The situation is ananalogous to
an institution humans would develop - tribute - which
we will analyze below.
Some very special instances occur that do not involve
parasite and host sharing the same body and evolving
into symbiotes. Rather, they involve non-kin animals
and highly constrained territory. A prominent example
Dawkins describes are cleaner fish. These fish swim in
and out of the mouths of their hosts, eating the bacteria
there, benefiting the host fish. The host fish could cheat
- it could wait for the cleaner to finish its job, then eat
it. But they don’t. Since they are both mobile, they are
both potentially free to leave the relationship. However,
the cleaner fish have evolved a very strong sense of in-
dividual territoriality, and have stripes and dances that
are difficult to spoof - much like a difficult to forge brand
logo. So the host fish know where to go to get cleaned -
and they know that if they cheat, they will have to start
over again with a new distrustful cleaner fish. The en-
trance costs, and thus the exit costs, of the relationship
are high, so that it works out without cheating. Besides,
the cleaner fish are tiny, so the benefit of eating them is
not large compared to the benefit of a small number of,
or even one, cleaning.
One of the most pertinent examples.is the vampire bat.
As their name suggests, they suck the blood of prey mam-
mals. The interesting thing is that, on a good night, they
bring back a surplus; on a bad night, nothing. Their dark
business is highly unpredictable. As a result, the lucky
(or skilled) bats often share blood with the less lucky (or
skilled) bats in their cave. They vomit up the blood and
the grateful recipient eats it.
The vast majority of these recipients are kin. Out
of 110 such regurgitations witnessed by the strong-
stomached biologist G.S. Wilkinson, 77 were cases of
mothers feeding their children, and most of the other
cases also involved genetic kin. There were, however,
a small number that could not be explained by kin al-
truism. To demonstrate these were cases of reciprocal al-