Why Evolutionary Psychology is Wrong
by J Calverley
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One of the most pervasive and useful theories in the life sciences is the theory of evolution.
According to this theory a species does not come into being out of nothing, rather it comes into being from
another, similar species via a series of changes i.e. one species evolves from another. While the mechanism
for change is contentious, an important aspect of the theory is the mechanism by which any one change
succeeds over any other. This is dealt with by the principle of natural selection. According to natural
selection (or survival of the fittest), changes persist where those changes yield an advantage to the survival
of the species. And, according to evolution the mechanism for persistence is inheritance.
If we apply evolutionary principles to human behaviour we are invited to answer the questions (i) Did that
person do what she did as a result of an underlying innate disposition? And (ii) Is there a survival advantage
to be had from such behaviour?
It is tempting to think that if the answer to both questions is "yes", then we have made progress in explaining
some aspect of human behaviour and we may even be able to predict future behaviour. Being able to explain
and predict behaviour is useful to the psychologist.
While it would be useful if evolutionary principles could play a role in understanding
human behaviour, in this essay I will show that in fact they cannot be so applied - for a variety of reasons.
Suppose we have an evolutionary hypothesis about some episode of behaviour, say crying. Our hypothesis
may be (say) that crying entered the human repertoire because there was a survival advantage in a mothers
being able to locate her child. There is no way to prove that this is the case. We can equally well come up with
alternative hypothesis (crying keeps the mother awake and able to feed the child) or even counter hypothesis
(crying advertises the presence of the child and could attract a predator). Certainly we can say it is true that crying
allows a mother to locate her child, but that does not mean that crying entered the behavioural repertoire on the
back of that benefit.
Since any such conjecture can have an equal claim on being an evolutionary truth, there is no advantage (no
explanatory or predictive value) to be had from trying to frame the conjecture in evolutionary terms.
SURVIVAL OF THE FITTEST ONLY WEAKLY TRUE
A key principle for evolutionary theory is that change in a species is selected for by the survival of those
individuals in whom the change is manifest. But, clearly change may occur which has no net effect on survival
and such a change would neither overwhelm nor disappear in a population. It would simply be present as
part of natural variation. It may or may not be inherited by any evolving descendants of the population. So it is
quite possible for a feature to be introduced into a species without having any impact on its survival chances.
Since we can only conjecture when investigating evolutionary advantage, we cannot even say whether a feature
originally gave evolutionary advantage.
THE PASSAGE OF TIME
A feature may have been introduced for an evolutionary reason which no longer holds sway, even one which
we could have no inkling of. Similarly, a feature introduced without a selective advantage, may at some time
later in the evolution of the species be seen to have an advantage - but it has never been selected for, and
so evolution has nothing true to say about that feature.
THE NATURE OF THE MIND
An individuals conscious behaviour is a result of her beliefs and desires. A rational individual will tend to
follow a logical pattern of behaviour based on those beliefs and desires. It is not obvious what kind of
evolutionary hypothesis can break this kind of rational behaviour. Evolutionary conjecture might have
something to say about, for example, the depth of short term memory involved in decision making - but
then evolution would have it that the brain has evolved to be efficient to the point where rational thinking
is efficient and free from evolutionary influence. So, although the depth of short term memory may be
arrived at by evolutionary pressure, the rational behaviour of the individual using that memory in no way
reflects any evolutionary selection.
ASSUMPTION OF EVOLUTIONARY PEAK
In making evolutionary conjecture there is an assumption that any behaviour has been selected for, or
at least that it has not been selected against. But this assumes that we are at a pinnacle of evolution.
We have no reason to suppose this. We could equally well be on the verge of extinction, and who is to
say which characteristic human behaviour will be the end of us?
In summary then, it would be useful to psychologists to be able to explain and predict human behaviour.
On the face of it, the principle of natural selection provides an attractive way to explaining why humans
behave the way they do. But on closer examination natural selection cannot in fact add anything to our
conjecture about behaviour because we cannot prove "why", or even "that", a particular behaviour was
selected for. Applying evolutionary principle is a red herring and only likely to give false comfort to
hypotheses which lack substance and support.
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Copyright (c) 2000-2001 Jack Calverley. All rights reserved.