快猫短视频

THESE days you can be sure that whenever a scientist discovers a new wrinkle
in the way the human mind works, some sort of Darwinian explanation will not be
far behind.

Take the research reported last month by psychologists at the University of
Texas in Austin. It showed that while people find it easy to remember the
direction of objects moving towards them or away from them, they have little
recall for the spin direction of rotating objects
(快猫短视频, 5 February, p 15).
And the explanation? Easy. Natural selection never had cause to
equip us with such a memory mechanism.

Our ancestors would obviously have needed to know whether an animal they were
hunting was approaching or retreating, but rotating objects would have been
largely absent from the rough and tumble of their lives. Ergo, we don鈥檛 remember
enough about rotation from past experiences to be able to intuitively, say, pull
a car out of a spin. We have to learn to do such things by rote.

Now don鈥檛 get me wrong. I鈥檓 not ideologically opposed to such pat
evolutionary answers, unlike many social scientists who regard culture as
all-powerful in determining how we think and behave. I just wonder whether these
Darwinian explanations help or hinder further scientific investigation. Indeed,
as a practising psychiatrist, I find myself wondering this more and more as I
watch evolutionary thinking being repeatedly used to explain the existence of
mental illnesses and personality disorders.

If these conditions are so bad for us, goes the well-rehearsed logic of the
Darwinian approach, why didn鈥檛 natural selection weed out the genes that make us
vulnerable? Answer: a tendency to depression or paranoia or whatever must have
conferred some subtle survival benefit on our ancestors that kept the genes in
the pool. Identify those benefits and, hey presto, you have a rationale for the
condition.

Thus, paranoia could be helpful because suspiciousness might be beneficial in
environments that are not as safe as they seem. Some forms of depression might
exist because withdrawing from the social fray might actually be a good thing
when you鈥檙e competing with people who could injure or kill you if you tried to
assert yourself. And even severe postnatal depression could have hidden
Darwinian benefits, according to anthropologist Edward Hagen from the University
of California in Santa Barbara.

Hagen suggests that since the mothers most likely to suffer are those in bad
relationships or tough circumstances, postnatal depression is evolution鈥檚 way of
telling mothers not to waste valuable reproductive effort investing in offspring
who are unlikely to thrive. In other words, it鈥檚 no senseless accident that
severely depressed mothers sometimes neglect or even kill their infants. They
are doing it at the behest of genes whose silent command is 鈥渄on鈥檛 bother with
this one鈥�.

Are such explanations useful or harmful? Paradoxically, I think they are
both, for reasons that can be explained by looking at that other all-embracing
approach to understanding behaviour, Freudianism.

Freud, of course, proposed that sexuality was the driving force of human
behaviour. This finds more than an echo in the evolutionary psychologist鈥檚 view
that we are trapped by sexual strategies to maximise the replication of genes.
Freud had us in thrall to repressed sexual memories and psychic energies
spilling out of the unconscious; evolutionary psychology has us in thrall to
genes and innate neural mechanisms adapted to suit the needs of our
hunter-gatherer ancestors.

There is a second echo: Freud produced ingenious explanations for behaviour,
but backed away from generating testable predictions that could confirm or
falsify his hypotheses. He famously argued that when a patient vociferously
rejected an analyst鈥檚 interpretation, this was good evidence it was right, and
if the patient agreed with the doctor鈥檚 exposition, this also was evidence it
was right. Well, evolutionary psychology suffers from a related, albeit less
extreme, form of the problem. It might seem to generate testable predictions,
but on close inspection you usually find some sort of circularity in the
argument, or that the predictions either offer no more insights than common
sense or are plain wrong. The evolution of the human mind, alas, has left no
fossils.

Darwinian attempts to explain depression bear this out. Evolutionary
psychology predicts, for example, that older mothers giving birth for the first
time should be less prone to postnatal depression than younger first-time
mothers, as their current infant could be their only chance to reproduce. In
fact, older first-time mothers are even more prone to postnatal depression.

And if other forms of depression really are the result of a neural adaptation
designed to make some of us keep our heads down when it would be dangerous to
assert ourselves, you鈥檇 think antidepressants would reverse this. In fact, Lynne
Marrow and her colleagues at the University of Wales, Swansea, found no evidence
of this when they gave antidepressants to socially withdrawn rats. If anything,
the rats tried even less hard to pick fights with the dominant members of their
group.

This suggests that you don鈥檛 have to be depressed to realise that asserting
yourself isn鈥檛 worth it: although their depression was apparently lifted, the
treated rats still didn鈥檛 bother, presumably because they thought they would
fail. Depressed people give up trying even when victory is clearly
possible鈥攖hat is precisely why depression is so puzzling.

Despite these shortcomings, evolutionary psychology, like psychoanalysis, is
undeniably attractive because of the apparent coherence and simplicity of the
explanations it offers. And it鈥檚 this appeal that I think is both potentially
useful and potentially harmful.

Harmful, because, like theorising about the unconscious, evolutionary
psychology might discourage scientists from looking for more productive
explanations for mental illnesses. Useful, because we already know that many
psychiatric patients can benefit greatly from being given a comprehensible
account of their otherwise frightening and confusing symptoms. For this purpose,
why shouldn鈥檛 Darwin be at least as effective as Freud?

Think about it. Since largely abandoning Freud, all therapists have had to
offer patients seeking explanations is a hodgepodge of one-off theories and
speculations, some based on brain chemistry, some on behaviour, and each
specific to just a single condition or even symptom. At a stroke, evolutionary
psychology can provide patient and therapist with a unifying framework for
thinking about all symptoms and all mental illnesses. A woman suffering from
postnatal depression might feel hugely relieved to be told that her condition
has an evolutionary explanation. Why should we deny her that relief?

The benefit of evolutionary psychology for patients is that it could help
them to stop endlessly asking why. For scientists, that is precisely its
danger.