Re: Trivers' Reciprocal Altruism

From: Liz Lee (
Date: Tue Nov 04 1997 - 19:58:13 GMT

Here is my summary/critique of Trivers.

Reciprocal Altruism

Trivers is offering an explanation for altruism, arguing that the
earlier model of kin selection (suggested by Hamilton) is insufficient.
Altruism is defined as behaviour which benefits the recipient, who is
not closely related, to the detriment of the benefactor, and it is of
greater benefit to the recipient than cost to the performer. He
proposes that altruism can be accounted for by natural selection, which
favours reciprocal altruism and the identification of "cheaters" who
fail to reciprocate. Trivers suggests that concepts, qualities and
emotions such as friendship, dislike, moral aggression, gratitude,
sympathy, trust, suspicion, trustworthiness, guilt, dishonesty and
hypocrisy are adaptations designed to regulate the altruistic system.
The system weighs the relative costs and benefits of any action, with
an internal tally of what one owes, and what is owed to one being

Examples from other species are cited to show that kin selection cannot
be the sole reason for altruistic acts, specifically, cleaning
symbioses and warning calls. Cleaning behaviours between different
species of fish have been observed and proposed as acts of altruism
because they fulfil the above definition. Small fish (Wrasses) enter
the mouth and gills of a larger fish (Groupers) and clean off the
ectoparasites which would otherwise cause disease, the groupers could
simply allow the cleaning process to finish and then eat the wrasses,
but they don't. In fact, even fish raised in solitude, with no contact
with any fish other than those it eats, will not only not eat a wrasse
when it is dropped into the tank, but will open its mouth ready for
cleaning. The fact that fish 1) do not eat their cleaners, 2) behave
in a certain way when ready to be cleaned (change colour or perform
definite movements), 3) warn the cleaner when about to move off at a
risk to own safety, 4) will fight off a second predatory fish if it is
not in "cleaning" guise, is seen as evidence of acts of acts of
altruism towards a second species.

o why don't the groupers eat the wrasses? Observations of the large fish
show that they return to the same areas to be cleaned time after time, and
use the same cleaners, to eat their cleaners would mean either going without
a cleaner (and risking disease and death) or having to find a replacement
cleaner who may not be as efficient as the original. It is not in the
groupers best interest to eat its cleaner, but that doesn't detract from the
fact that it puts itself at some risk in protecting it.

In studying the warning cries of birds the relevant points are - 1)
that the bird giving the cry is at risk of predation in giving away its
own position and 2) that dispersal rates are high and so it is unlikely
that the warning is being given to a close relative. Trivers does point
out that warning other birds of a predator's presence is
self-protective in that it subdues the noise coming from the group and
reduces the risk of discovery. So warning other birds at a risk to
yourself is an altruistic act.

The two above examples of cross-species altruism and non-kin altruism
lead onto Trivers' explanation of human reciprocal altruism. It works a
little like this; I am programmed to choose to help you , and to expect
that act to be repaid at some stage in the future, if the act is not
repaid for some time, it will earn "interest" and you will have to
repay in a more elaborate way. If you do not repay me, I will feel some
antipathy towards you, this may make you feel guilty and lead you to
act kindly towards me or a third person. I will not be too upset as
long as I am the recipient of a similar act within a reasonable period
of time, by anyone. I am also programmed to detect whether you are
trying to cheat the system by acting as recipient but never benefactor,
this may make me suspicious of you and label you as a dishonest person
to be treated accordingly.

Altruistic acts may be performed to aid integration into a group, or
increase the size of a group of friends, but it is the psychological
system outlined above which Trivers considers most important. What is
missing is a detailed breakdown of the influence and effect of
environment and context on altruism, we behave one way in one situation
and another in the next, there is a lack of consistency which the model
cannot account for. Despite what Trivers says, we do act altruistically
to those who repeatedly fail to reciprocate. For diverse reasons, we
may have come to accept that they as individuals do not pay back, but
still like them for other reasons. Altruism towards those who cannot
reciprocate is not unusual - helping down and outs or those sleeping
rough, foster care and adoption for example. But these are conscious
acts and the point of reciprocal altruism, and its relative costs and
benefits, is that it is largely a subconscious system at work. Even
when one fails to reciprocate, we may not register this fact at first.

There is a point of view which suggests that there is never a truly
disinterested act of kindness towards a second person. Even if an act
is performed anonymously, without anyone else being aware, the
benefactor will know and feel good to have done it, therefore the act
is done to make the performer feel good. This is a view I find
particular hard to sympathise with, I do believe there are some truly
"good" people. Am I naive?

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