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Evolutionary psychology
seeks to identify and understand human psychological traits that have
evolved in much the same way as biological traits, through adaptation to
environmental cues. Furthermore, it tends toward viewing the vast
majority of psychological traits, certainly the most important ones, as
the result of past adaptions, which has generated significant
controversy and criticism from competing fields. These criticisms
include disputes about the testability of evolutionary hypotheses,
cognitive assumptions such as massive modularity, vagueness stemming
from assumptions about the environment that leads to evolutionary
adaptation, the importance of non-genetic and non-adaptive explanations,
as well as political and ethical issues in the field itself.
Evolutionary psychologists contend that many of the criticisms against it are straw men, based on an incorrect nature versus nurture dichotomy, and/or based on misunderstandings of the discipline. In addition, some defenders of evolutionary psychology assert that critics of the discipline base their criticisms on a priori political assumptions, such as those associated with Marxism.
Examples of critics and defenders
The history of the debate from a critic's perspective is detailed by Gannon (2002). Critics of evolutionary psychology include the philosophers of science David Buller (author of Adapting Minds), Robert C. Richardson (author of Evolutionary Psychology as Maladapted Psychology), and Brendan Wallace (author of Getting Darwin Wrong: Why Evolutionary Psychology Won't Work). Other critics include neurobiologists like Steven Rose (who edited Alas, Poor Darwin: Arguments against Evolutionary Psychology), biological anthropologists like Jonathan Marks, and social anthropologists like Tim Ingold and Marshall Sahlins.
Responses defending evolutionary psychology against critics have been published in books including Segerstråle's Defenders of the Truth: The Battle for Science in the Sociobiology Debate and Beyond (2000), Barkow's Missing the Revolution: Darwinism for Social Scientists (2005), and Alcock's The Triumph of Sociobiology (2001). Other responses to critics include Confer et al. (2010), Tooby and Cosmides (2005), and Hagen (2005). Furthermore, in one frequently quoted rebuttal of most such critics, psychologist Anne Campbell posited that such people merely believe “evolution stops at the neck”.
Criticism of key assumptions
Massive modularity
Evolutionary psychologists have postulated that the mind is composed
of cognitive modules specialized to perform specific tasks. Evolutionary
psychologists have theorized that these specialized modules enabled our
ancestors to react quickly and effectively to environmental challenges.
As a result, domain-specific
modules would have been selected for, whereas broad general-purpose
cognitive mechanisms that worked more slowly would have been eliminated
in the course of evolution.
A number of cognitive scientists have criticized the modularity hypothesis, citing neurological evidence of brain plasticity and changes in neural networks in response to environmental stimuli and personal experiences. Steven Quartz and Terry Sejnowski,
for example, have argued that the view of the brain as a collection of
specialized circuits, each chosen by natural selection and built
according to a "genetic blueprint", is contradicted by evidence that
cortical development is flexible and that areas of the brain can take on
different functions. Neurobiological research does not support the assumption by evolutionary psychologists that higher-level systems in the neocortex responsible for complex functions are massively modular. Peters (2013) cites neurological research showing that higher-order
neocortical areas can become functionally specialized by way of synaptic plasticity and the experience-dependent changes that take place at the synapse
during learning and memory. As a result of experience and learning
processes the developed brain can look modular although it is not
necessarily innately modular. However, Klasios (2014) responds to Peters' critique.
Another criticism is that there is little empirical support in favor of the domain-specific theory. Leading evolutionary psychologists Leda Cosmides and John Tooby have
found that performance on the selection task is content-dependent:
People find it easier to detect violations of "if-then" rules when the
rules can be interpreted as cheating on a social contract.
From this Cosmides and Tooby and other evolutionary psychologists
concluded that the mind consisted of domain-specific, context-sensitive
modules (including a cheater-detection module). Critics have suggested that Cosmides and Tooby use untested
evolutionary assumptions to eliminate rival reasoning theories and that
their conclusions contain inferential errors. Davies et al., for example, have argued that Cosmides and Tooby did not
succeed in eliminating the general-purpose theory because the adapted
Wason selection task they used tested only one specific aspect of deductive reasoning and failed to examine other general-purpose reasoning mechanisms (e.g., reasoning based on syllogistic logic, predicate logic, modal logic, and inductive logic etc.). Furthermore, Cosmides and Tooby use rules that incorrectly represent
genuine social exchange situations. Specifically, they posit that
someone who received a benefit and does not pay the cost is cheating.
However, in real-life social exchange situations people can benefit and
not pay without cheating (as in the case of receiving gifts or
benefiting from charity).
Some critics have suggested that our genes cannot hold the information to encode the brain and all its assumed modules. Humans share a significant portion of their genome with other species
and have corresponding DNA sequences so that the remaining genes must
contain instructions for building specialized circuits that are absent
in other mammals.
One controversy concerns the particular modularity of mind theory
used in evolutionary psychology (massive modularity). Critics argue in
favor of other theories.
Environment of evolutionary adaptedness
One
method employed by evolutionary psychologists is using knowledge of the
environment of evolutionary adaptedness (EEA) to generate hypotheses
regarding possible psychological adaptations. Part of the critique of
the scientific basis of evolutionary psychology is that it often assumes
that human evolution occurred in a uniform environment, whereas critics
suggest that we know so little about the environment (or probably
multiple environments) in which Homo sapiens evolve, that explaining specific traits as an adaption to that environment becomes highly speculative.
The evolutionary psychologists John Tooby and Leda Cosmides state
that research is confined to certainties about the past, such as
pregnancies only occurring in women, and that humans lived in groups.
They argue that there are many environmental features that are known
regarding our species' evolutionary history. They argue that our hunter-gatherer ancestors dealt with predators and prey, food acquisition
and sharing, mate choice, child rearing, interpersonal aggression,
interpersonal assistance, diseases and a host of other fairly
predictable challenges that constituted significant selection pressures.
Knowledge also include things such as nomadic, kin-based lifestyle in
small groups, long life for mammals, low fertility for mammals, long
female pregnancy and lactation, cooperative hunting and aggression, tool
use, and sexual division of labor. Tooby and Cosmides thus argue that enough can be known about the EEA to make hypotheses and predictions.
David Buss also argued that the EEA could be sufficiently known
to make predictions in evolutionary psychology. Buss argued that aspects
of the environment are known - the Earth's gravity was the same, as was
its atmosphere. Dinosaurs and giant Carboniferous insects were extinct
and humans still lived in groups, while there were two sexes. Groups
consisted of old and young members, healthy and sick, varying degrees of
relatedness and so on. Buss notes that while some critics agree that
the general environment is known, the specific selection pressures might
never be understood due to being highly context sensitive. David Buller
used an analogy including birds, observing that while all male birds
must attract all female birds, they do so in different ways; Buller
alleges that the evidence is simply not available to be able to
determine which the specific mate-attraction problems for humans.
However, Buss argues that this can be solved by proposing different
evolutionary psychology hypotheses and uses data, confirmation
strategies and discovery heuristics to determine which ones can be
advanced. Furthermore, Buss argues this criticism is selectively
sceptical - Buss notes that Buller had no problem writing confidently
about the evolved mate functions of bird species, of whom there is even
less knowledge about selective pressures, so it is not clear why Buller
is willing to infer the mating strategies of ancestral birds by
analysing living ones yet is unwilling to infer the mating strategies of
ancient humans by analysing living humans.
John Alcock argues that the fact that many traits in humans are
presently adaptive is suggestive that they originally developed as
adaptions. This is because if an organism diverges too much from its
original environment, it is unlikely that its traits will be adaptive to
the new, changed environment and it is at risk of going extinct. Thus
evolutionary psychologists doubt that the modern world is largely novel
compared to that of the EEA.
Steven Pinker argues that there is enough evidence available
about the historical environments humans evolved in for evolutionary
psychologists to make inferences and predictions from. Pinker argues
that the evidence indicates that the ancestral environment lacked
"agriculture, contraception, high-tech medicine, mass media,
mass-produced goods, money, police, armies, communities of strangers,
and other modern features", which Pinker argues all have profound
implications for minds that evolved in such an environment.
Testability of hypotheses
A frequent criticism of evolutionary psychology is that its
hypotheses are difficult or impossible to test, challenging its status
as an empirical science. As an example, critics point out that many
current traits likely evolved to serve different functions from those
they do now, confounding attempts to make backward inferences into
history. Evolutionary psychologists acknowledge the difficulty of testing their hypotheses but assert it is nevertheless possible.
Critics argue that many hypotheses put forward to explain the adaptive nature of human behavioural traits are "just-so stories";
neat adaptive explanations for the evolution of given traits that do
not rest on any evidence beyond their own internal logic. They allege that evolutionary psychology can predict many, or even all,
behaviours for a given situation, including contradictory ones.
Therefore, many human behaviours will always fit some hypotheses. Noam Chomsky argued:
- "You find that people cooperate, you say, 'Yeah, that
contributes to their genes' perpetuating.' You find that they fight, you
say, ‘Sure, that's obvious, because it means that their genes
perpetuate and not somebody else's. In fact, just about anything you
find, you can make up some story for it."
Leda Cosmides argued in an interview:
- "Those who have a professional knowledge of evolutionary biology
know that it is not possible to cook up after the fact explanations of
just any trait. There are important constraints on evolutionary
explanation. More to the point, every decent evolutionary explanation
has testable predictions about the design of the trait. For example, the
hypothesis that pregnancy sickness is a byproduct of prenatal hormones
predicts different patterns of food aversions than the hypothesis that
it is an adaptation that evolved to protect the fetus
from pathogens and plant toxins in food at the point in embryogenesis
when the fetus is most vulnerable – during the first trimester.
Evolutionary hypotheses – whether generated to discover a new trait or
to explain one that is already known – carry predictions about the
nature of that trait. The alternative – having no hypothesis about
adaptive function – carries no predictions whatsoever. So which is the
more constrained and sober scientific approach?"
A 2010 review article by evolutionary psychologists describes how an
evolutionary theory may be empirically tested. A hypothesis is made
about the evolutionary cause of a psychological phenomenon or phenomena.
Then the researcher makes predictions that can be tested. This involves
predicting that the evolutionary cause will have caused other effects
than the ones already discovered and known. Then these predictions are
tested. The authors argue numerous evolutionary theories have been
tested in this way and confirmed or falsified. Buller (2005) makes the point that the entire field of evolutionary
psychology is never confirmed or falsified; only specific hypotheses,
motivated by the general assumptions of evolutionary psychology, are
testable. Accordingly, he views evolutionary psychology as a paradigm
rather than a theory, and attributes this view to prominent
evolutionary psychologists including Cosmides, Tooby, Buss, and Pinker.
In his review article "Discovery and Confirmation in Evolutionary
Psychology" (in The Oxford Handbook of Philosophy of Psychology)
Edouard Machery concludes:
- "Evolutionary psychology remains a very controversial approach
in psychology, maybe because skeptics sometimes have little first-hand
knowledge of this field, maybe because the research done by evolutionary
psychologists is of uneven quality. However, there is little reason to
endorse a principled skepticism toward evolutionary psychology: Although
clearly fallible, the discovery heuristics and the strategies of
confirmation used by evolutionary psychologists are on a firm
grounding."
Steve Stewart-Williams argues, in response to claims that
evolutionary psychology hypotheses are unfalsifiable, that such claims
are logically incoherent. Stewart-Williams argues that if evolutionary
psychology hypotheses can't be falsified, then neither could competing
explanations, because if alternative explanations (e.g. sociocultural
hypotheses) were proven true, this would automatically falsify the
competing evolutionary psychology hypothesis, so for competing
explanations to be true, then evolutionary psychology hypothesis must be
false and thus falsifiable.
Edward Hagen observes that critics of evolutionary psychology
often argue that because a trait could have evolved as an adaptation or a
by-product, it is impossible to determine which it is since it evolved
in a past environment and thus evolutionary psychology hypotheses about a
traits origin are untestable. According to Hagen, critics using this
argument have a flawed understanding of science; Hagen argues that
science is fundamentally an abductivist methodology e.g. inference to
the best explanation. Hagen argues that hypotheses compete to provide
the best explanation of a phenomenon, where "best" is measured via
criteria like predicting new and surprising observations, parsimony,
coherence and so on. Abduction does not require scientist to provide
direct evidence for every single prediction. Evolutionary psychology
hypotheses make predictions and thus compete with other hypotheses to
explain traits. Hagen further argues that while some critics conclude
that evolutionary psychology explanations for mental traits cannot be
true because they can't be tested for the above reasons, this is a false
conclusion to draw; even if evolutionary psychology hypotheses could
not be tested, this does not mean they are false, it just means the
evidence for them could not be acquired, not that traits don't exist
because of evolutionary reasons.
Dominic Murphy explains that one of the most common objections to
evolutionary psychology is the "time machine" argument. This is the
argument that while evolutionary psychology can make predictions about
things we should see in the modern world if the evolutionary psychology
hypothesis is true, there are too many alternative explanations for the
origin of a trait which would also predict this phenomenon e.g. a trait
evolving as a by-product could predict the same evidence as the same
trait evolving as an adaptation. Therefore, a potentially infinite
number of alternative historical explanations are possible. Thus without
a time machine, it is impossible to determine which possible
explanation for the evidence seen in the modern day is correct. Murphy
argues this argument is flawed on multiple grounds. Firstly, if an
explanation for a trait is forwarded and a prediction for what we would
see in the modern day is made based on that explanation, then one cannot
just propose alternative explanations. Instead, these alternative
explanations require testable predictions of their own to be forwarded,
preferably multiple different predictions. In addition, not all
explanations may predict the same evidence, thus Murphy argues that if
one explanation predicts a great deal of evidence for modern day
observations and alternative explanations struggle to explain this, then
it is reasonable to have confidence in the former explanation. In
addition, Murphy argues that if the "time machine" argument was applied
to other sciences, it would lead to absurd results - Murphy observes
that cosmologists have confirmed predictions about the Big Bang by
studying available astronomical evidence and current understanding of
particle physics, with no need for a time machine to travel back to the
beginning of the universe. Similarly, geologists and physicists
investigating the hypothesis that it was an asteroid impact that caused
the extinction of the dinosaurs did so by looking for modern day
evidence. Murphy thus concludes that the onus is on the sceptics to
prove why evolutionary psychology is allegedly untestable on "time
machine" grounds if other historical sciences are not, as "methods
should be judged across the board, not singled out for ridicule in one
context."
A similar argument was made by Andrew Goldfinch, who argued that
this entire criticism is due to the issue of underdetermination - many
rival explanations can potentially accommodate a phenomenon, making it
difficult to discern which explanation is the correct one. Furthermore,
one can also challenge the interpretation of an experiment's results,
revise an explanation to accommodate a novel fact or even question the
reliability of the experiments conducted. However, Goldfinch argues that
this is a ubiquitous problem in all of science and not unique to
evolutionary psychology, so it is not clear why this is seen as a
criticism of the field if it would be dismissed elsewhere. Lastly,
Goldfinch argues that one way to distinguish between competing
explanations is to make a distinction between programmes that makes new
predictions and discovers novel facts and those programmes that simply
accommodate the fresh discoveries of other programmes. Those programmes
which are actually making and testing predictions should be favoured
over those simply accommodating the discoveries of others.
Adam Hunt has proposed that 'Just-so story' critiques can be
avoided if a systematic approach for assessing a trait is developed,
applicable to every describable trait an organism possesses. This
'DCIDE' Method (Description, Categorisation, Integration, Depiction,
Evaluation) aims to counter cherry-picking, 'reasoning from the
conclusion' and 'just-so' critiques by providing a repeatable formula
for weighing the evidence prior to the selection of a specific organism
trait to explain.
Alleged disregard for alternate explanations
Environmental explanations
Critics
assert that evolutionary psychology has trouble developing research
that can distinguish between environmental and cultural explanations on
the one hand and adaptive evolutionary explanations on the other. Some
studies have been criticized for their tendency to attribute to
evolutionary processes elements of human cognition that may be
attributable to social processes (e.g. preference for particular
physical features in mates), cultural artifacts (e.g. patriarchy and the
roles of women in society), or dialectical considerations (e.g.
behaviours in which biology interacts with society, as when a
biologically determined skin colour determines how one is treated).
Evolutionary psychologists are frequently criticized for ignoring the
vast bodies of literature in psychology, anthropology, sociology,
archaeology, linguistics, philosophy, history, and the natural sciences.
Both sides of the debate stress that statements such as "biology vs.
environment" and "genes vs. culture" amount to false dichotomies, and outspoken critics of sociobiology such as Richard Lewontin, Steven Rose and Leon Kamin
helped to popularise a "dialectical" approach to questions of human
behaviour, where biology and environment interact in complex ways to
produce what we see.
Evolutionary psychologists Confer et al. argue that evolutionary
psychology fully accepts nature-nurture interactionism, and that it is
possible to test the theories in order to distinguish between different
explanations.
Other evolutionary mechanisms
Critics
point out that within evolutionary biology there are many other
non-adaptive pathways along which evolution can move to produce the
behaviors seen in humans today. Natural selection is not the only
evolutionary process that can change gene frequencies and produce novel
traits. Genetic drift
is caused by chance variation in the genes, environment, or
development. Evolutionary by-products are traits that were not specially
designed for an adaptive function, although they may also be
species-typical and may also confer benefits on the organism. A "spandrel" is a term coined by Gould
and Lewontin (1979a) for traits which confer no adaptive advantage to
an organism, but are 'carried along' by an adaptive trait. Gould
advocates the hypothesis that cognition in humans came about as a
spandrel: "Natural selection made the human brain big, but most of our
mental properties and potentials may be spandrels – that is, nonadaptive
side consequences of building a device with such structural
complexity". Once a trait acquired by some other mechanism confers an adaptive advantage, it may be open to further selection as an "exaptation". Gould argues that one cannot mistake the utility of a trait in the current environment for its adaptive origin. On the other hand, evolutionary psychologists suggest that critics
misrepresent their field, and that empirical research in evolutionary
psychology is designed to help identify which psychological traits are
prone to adaptations, but also which are not.
Edward Hagen argued evolutionary psychology's reliance on
adaptive explanations is grounded in the fact that the existence and
survival of life is highly improbable. Hagen argues that most organisms
do not survive to reproduce and that is only through adaptations that
organisms can hope to do so; alternate explanations like genetic drift
are only relevant if an organism can survive and reproduce in the first
place and it is the fact that organisms do manage survive and reproduce,
despite the odds against such a thing occurring, that evolutionary
psychologists are interested in. Similarly, Steven Pinker argues that complex organs like eyes require
many precise parts in exacting arrangements, which indicates they
evolved via selective pressure, as it would be extremely improbable for
such an arrangement to arise fortuitously out of genetic drift or as a
byproduct of another trait. Hagen also argues that a way to distinguish spandrels from adaptations
is that adaptations have evidence of design (that is to say they did not
simply arise by pure chance but were selected for). While Hagen agrees
that one can risk over-attributing adaptation, he observes that one can
also risk under-attributing it as well. Hagen argues that tonsils can
become infected and it needs to be known whether or not it is safe to
remove them. Insisting that tonsils could just be spandrels is not
helpful, whereas hypothesising that they may be adaptations allows one
to make predictions about them to see if they do have a function and
thus whether or not it is safe to remove them. Conversely, Steve Stewart-Williams argues that it is not true that
evolutionary psychologists do not consider non-adaptive explanations,
arguing that evolutionary psychologists have suggested alternate
explanations such as byproducts, observing that the hypothesis that
obesity is caused by a mismatch between ancestral and modern
environments is one of the most famous cases of a byproduct explanation
in evolutionary psychology. Pinker makes a similar argument, arguing that evolutionary psychology
has long held the view that things such as art, music, science, religion
and dreams are probably byproducts or spandrels of other mental traits.
Laith Al-Shawaf argues that evolutionary psychologists use
adaptations as a starting point for research - if the evidence in favour
of the adaptation hypothesis fails to materialise, evolutionary
psychologists will abandon it, so it is untrue to claim that
evolutionary psychologists do not consider alternate hypotheses. Sven Walter observes that while critics of adaptationist hypotheses
argue that alternative evolutionary explanations could exist, what these
alternative explanations are and how they lead to the kind of traits
evolutionary psychologists study is not always elaborated upon (for
example, if a trait is proposed to be a byproduct rather than an
adaptation, it is not always clear what it is supposed to be a byproduct
of). Thus Walter argues that if there is no reasonably plausible alternative
hypothesis, if the adaptationist hypotheses is logically plausible and
if empirical evidence exists to support it, then there is thus
reasonable support for the evolutionary psychologist's adaptationist
hypothesis.
Steven Gangstead argues that demonstrating that a trait is
beneficial is not sufficient to prove it is an adaptation. Rather, to
show something is an adaptation it must be shown that it exhibits
special design. Special design is when a trait performs a function
(function meaning it increases the reproductive fitness of the organism)
effectively and it is difficult to conceive of an alternative scenario
where the trait would have evolved. Gangstead observes that the eye is
an extreme example, as it is highly effective at the function of seeing,
yet it is difficult to conceive of a scenario through which it would
have evolved other than one where it was selected for its optical
properties and thereby its function of sight. Evolutionary psychologists
have also argued that a lack of special design is evidence of a trait
being a byproduct rather than an adaptation; for example, it has been
found that men find women's scent more attractive when they are fertile
phase than their infertile luteal phase. While men finding this scent
more attractive may be an adaptation, there is no evidence that women
possess the adaptation to smell better when fertile, instead it is
likely a byproduct of changing hormone levels, which men have been
selected to detect and differently evaluate. Evolutionary psychologists consider evidence that a trait is an
adaptation if it has many features that are improbably well suited to
solving an ancestral adaptive problem, that the phenotypic properties
are unlikely to have arisen by chance alone and that the trait is not
better explained as a byproduct or the consequence of some other
adaptive problem. To show a trait is a byproduct, it must be shown that
something else is an adaptation and then that the trait in question is a
side effect of that adaptation. Co-opted exaptationist and spandrel hypotheses have an additional
evidentiary burden compared to adaptationist hypotheses, as they must
identify both the later co-opted functionality and the original
adaptational functionality, as well as what caused the trait to be
co-opted to their new function; it is not sufficient simply to propose
an alternative exaptationist or spandrel hypotheses to the adaptationist
one, rather these evidentiary burdens must be met. Leda Cosmides argues that raising the objection that a trait could be a
spandrel is meaningless because an organism contains a potentially
infinite number of spandrels. Instead, one must demonstrate what the
trait is a spandrel of, rather than simply just suggesting it could be a
spandrel.
Berry et al. argue that critics of adaptationist hypotheses are
often guilty of uncritically accepting any alternative explanation
provided it is not the adaptationist one. Furthermore, the authors argue
that while critics insist that "adapative function" refer only to
original adaptive function the trait evolved for, they argue that this
is a nonsensical requirement. This is because if an adaptation was then
used for a new, different, adaptive function, then this makes the trait
an adaptation because it remains in the population because it helps
organisms with this new function. Thus the trait's original purpose is
irrelevant because it has been co-opted for a new purpose and maintains
itself within the species because it increases reproductive success of
members of the species who have it (versus those who may have lost it
for some reason); nature is blind to the original "intended" function of
the trait.
Durrant et al. agree that alternative explanations to adaptation
have to be considered. The authors argue that an issue with
adaptationist explanations is underdetermination.
A theory is underdetermined when the evidence used to support it could
be equally used to support one or more other competing theories.
Underdetermination is an issue in science due to the problem of induction; in the great majority of cases, the truth of the data does not deductively entail the truth of the hypothesis. While this is an issue in general in science, sciences which deal with
unobserved entities and processes, which evolutionary psychology does,
are particularly vulnerable. Even if the theory can make predictions,
these predictions do not necessarily confirm the hypothesis, as
competing theory could also predict it; the authors argue that the
prediction of novel facts does not necessarily mean acceptance of the
theory, historically speaking, observing that while Einstein's theory of
general relativity is famously held as being accepted because it
predicted light would bend around black holes (which was unknown at the
time), neither Einstein nor many of his contemporaries regarded it as a
strong confirmation of his theory. Durrant et al. thus propose that the
problem of underdetermination can be solved by judging competing
theories on a range of criteria to determine which one best explains
phenomena by having the best explanatory coherence; criteria suggested
include explanatory breadth (which theory explains the great range of
facts), simplicity (which theory requires the fewest special
assumptions) and analogy (the theory is supported by analogy to theories
scientists already find credible). Thus any criticism of adaptationist
theories must demonstrate that an alternative theory offers greater
explanatory coherence than the adaptationist one.
Other overall areas of criticism
Alleged ethnocentrism
One
aspect of evolutionary psychology is finding traits that have been
shown to be universal in humans. Many critics have pointed out that many
traits considered universal at some stage by evolutionary psychologists
often turn out to be dependent on cultural and particular historical
circumstances. Critics allege that evolutionary psychologists tend to assume that
their own current cultural context represents a universal human nature.
For example, anthropologist Susan McKinnon argues that evolutionary theories of kinship rest on ethnocentric
presuppositions. Evolutionary psychologists assert that the degree of
genetic relatedness determines the extent of kinship (e.g., solidarity,
nurturance, and altruism) because in order to maximize their own
reproductive success, people "invest" only in their own genetic children
or closely related kin. Steven Pinker,
for instance, stated "You're either someone's mother or you aren't".
McKinnon argues that such biologically centered constructions of
relatedness result from a specific cultural context: the kinship
category "mother" is relatively self-evident in Anglo-American cultures
where biology is privileged but not in other societies where rank and
marital status, not biology, determine who counts as a mother or where
mother's sisters are also considered mothers and one's mother's brother
is understood as the "male mother".
However, evolutionary psychologists point out that their research actually focuses on commonalities between
people of different cultures to help to identify "human psychological
nature" and cultural universals.
It is not a focus on local behavioral variation (which may sometimes be
considered ethnocentric) that interests evolutionary psychologists;
rather their focus is to find underlying psychological commonalities
between people from various cultures.
Alleged reductionism and determinism
Some critics view evolutionary psychology as influenced by genetic determinism and reductionism.
Evolutionary psychology is based on the theory that human physiology and psychology are influenced by genes.
Evolutionary psychologists assume that genes contain instructions for
building and operating an organism and that these instructions are
passed from one generation to the next via genes.
Lickliter and Honeycutt (2003) have argued that evolutionary psychology is a predeterministic and preformationistic
approach that assumes that physical and psychological traits are
predetermined and programmed while virtually ignoring non-genetic
factors involved in human development. Even when evolutionary
psychologists acknowledge the influence of the environment, they reduce
its role to that of an activator or trigger of the predetermined
developmental instructions presumed to be encoded in a person's genes.
Lickliter and Honeycutt have stated that the assumption of genetic
determinism is most evident in the theory that learning and reasoning
are governed by innate, domain-specific modules. Evolutionary
psychologists assume that modules preexist individual development and
lie dormant in the structure of the organism, awaiting activation by
some (usually unspecified) experiential events. Lickliter and Honeycutt
have opposed this view and suggested that it is the entire developmental
system, including the specific features of the environment a person
actually encounters and interacts with (and not the environments of
distant ancestors) that brings about any modularity of cognitive
function.
Critics argue that a reductionist analysis of the relationship
between genes and behavior results in a flawed research program and a
restricted interpretation of the evidence, creating problems for the
creation of models attempting to explain behavior. Lewontin, Rose, and
Kamin instead advocate a dialectical
interpretation of behavior in which "it is not just that wholes are
more than the sum of their parts, it is that parts become qualitatively
new by being parts of the whole". They argue that reductionist
explanations such as the hierarchical reductionism proposed by Richard Dawkins will cause the researcher to miss dialectical ones. Similarly, Hilary Rose criticizes evolutionary psychologists' explanations of child abuse as excessively reductionist. As an example she cites Martin Daly
and Margot Wilson's theory that stepfathers are more abusive because
they lack the nurturing instinct of natural parents and can increase
their reproductive success in this way. According to Rose this does not
explain why most stepfathers do not abuse their children and why some
biological fathers do. She also argues that cultural pressures can
override the genetic predisposition to nurture as in the case of
sex-selective infanticide prevalent in some cultures where male offspring are favored over female offspring.
Evolutionary psychologists Workman and Reader reply that while
reductionism may be a "dirty word" to some it is actually an important
scientific principle. They argue it is at the root of discoveries such
as the world being made up of atoms and complex life being the result of
evolution. At the same time they emphasize that it is important to look
at all "levels" of explanations, e.g. both psychologists looking at
environmental causes of depression and neuroscientists looking the brain
contribute to different aspects of our knowledge of depression. Workman
and Reader also deny the accusation of genetic determinism, asserting
that genes usually do not cause behaviors absolutely but predispose to
certain behaviors that are affected by factors such as culture and an
individual's life history.
Steven Pinker argues that the charge of reductionism is a straw
man and that evolutionary psychologists are aware that organisms develop
due to complex interactions between genes and the environment. Pinker
argues that Lewontin, Rose and Kamin misrepresented Dawkins in this
regard. Pinker argues that when evolutionary psychologists talk about
genes "causing" behaviour, they mean that said gene increases the
probability of a behaviour occurring compared to other genes, which is
averaged out of the organism's evolutionary timescale and the
environments it has lived in. Pinker argues that this is a
nonreductionist and nondeterminist view of genes, which is common in
evolutionary biology.
Disjunction and grain problems
Some
have argued that even if the theoretical assumptions of evolutionary
psychology turned out to be true, it would nonetheless lead to
methodological problems that would compromise its practice. The disjunction and grain problems are argued to create methodological
challenges related to the indeterminacy of evolutionary psychology's
adaptive functions. That is, the inability to correctly choose, from a
number of possible answers to the question: "what is the function of a
given mechanism?"
The disjunction problem occurs when a mechanism appears to respond to one thing (F), but is also correlated with another (G). Whenever F is present, G is also present, and the mechanism seems to respond to both F and G. The difficulty thus involves deciding whether to characterize the mechanism's adaptive function as being related to F, G, or both.
"For example, a frogs pre-catching mechanism responds to flies, bees,
food pellets, etc.; so is its adaptation attuned to flies, bees,
fleebees, pellets, all of these, or just some?"
The grain problem refers to the challenge in knowing what kind of environmental 'problem'
an adaptive mental mechanism might have solved. As summarized by
Sterenly & Griffiths (1999): "What are the problems 'out there' in
the environment? Is the problem of mate choice a single problem or a
mosaic of many distinct problems? These problems might include: When
should I be unfaithful to my usual partner? When should I desert my old
partner? When should I help my sibs find a partner? When and how should I
punish infidelity?" The grain problem therefore refers to the possibility that an adaptive
problem may actually involve a set of nested 'sub-problems' "which may
themselves relate to different input domains or situations. Franks
states that "if both adaptive problems and adaptive solutions are
indeterminate, what chance is there for evolutionary psychology?"
Franks also states that "The arguments in no sense count against a
general evolutionary explanation of psychology" and that by relaxing
assumptions the problems may be avoided, although this may reduce the
ability to make detailed models.
Neglect of individual genetic differences
A
common critique is that evolutionary psychology does not address the
complexity of individual development and experience and fails to explain
the influence of genes on behavior in individual cases. Evolutionary psychologists respond that their discipline is not
primarily concerned with explaining the behavior of specific
individuals, but rather broad categories of human behaviors across
societies and cultures. It is the search for species-wide psychological
adaptations (or "human nature") that distinguishes evolutionary
psychology from purely cultural or social explanations. These
psychological adaptations include cognitive decision rules that respond
to different environmental, cultural, and social circumstances in ways
that are (on average) adaptive.
Replication crisis
Evolutionary psychology has been subject to scrutiny as part of the broader replication crisis
in psychological science. A growing number of studies have failed to
replicate key findings related to mating preferences, risk-taking, and
hormonal influences, raising questions about the robustness of several
foundational claims.
A 2015 large-scale replication effort by the Open Science Collaboration
attempted to replicate 100 psychological studies from high-impact
journals. While 97% of the original studies reported statistically
significant results, only 36% of the replications did so, and
replication effect sizes were on average about half those of the
originals (r = .197 vs. r = .403). These results suggested
that many psychological effects, including those in evolutionary
psychology, may be less robust than previously assumed.
Several well-known evolutionary psychology effects have come
under direct challenge. For example, the hypothesis that women’s
preferences for facial masculinity fluctuate across the ovulatory cycle
has failed to replicate in high-powered studies using salivary hormone
assays and within-subject designs. One such study (N = 584) found
no compelling evidence linking hormonal changes to masculinity
preferences, contradicting prior research based on less rigorous
methods. Similarly, replication attempts have found no reliable effect of mating-related priming on risk-taking or consumer behavior, and no consistent evidence for the "watching eyes" effect that
predicted prosocial behavior in the presence of subtle cues of
observation.
Critics argue that findings in evolutionary psychology are especially vulnerable to researcher degrees of freedom and p-hacking.
Harris, Pashler, and Mickes (2014) noted that flexible analytical
decisions, such as the selection of fertility windows, can dramatically
alter results and may have contributed to false-positive findings in
studies on ovulatory effects.
Specific areas of controversy
Rape and attraction to aggression
Smith et al. (2001) criticized Thornhill and Palmer's hypothesis
that a predisposition to rape in certain circumstances might be an
evolved sexually dimorphic psychological adaptation. They developed a
fitness cost/benefit mathematical model and populated it with estimates
of certain parameters (some parameter estimates were based on studies of
the Aché
in Paraguay). Their model suggested that, on average, the costs of rape
for a typical 25-year-old male outweigh benefits by a factor of ten to
one. On the basis of their model and parameter estimates, they suggested
that this would make it unlikely that rape generally would have net
fitness benefits for most men. They also find that rape from raiding
other tribes has lower costs but does not offer net fitness benefits,
making it also unlikely that was an adaptation.
Beckerman et al. (2009) disputed explanations of male aggression as a reproductive strategy. In a study of the Waorani tribes, the most aggressive warriors had the fewest descendants.
Waist-to-hip ratios
Others have criticized the assertion that men universally preferred women with a waist-to-hip ratio (WHR) of 0.7 or the "hourglass" figure. Studies of peoples in Peru and Tanzania found that men preferred ratios of 0.9. Cashdan (2008), investigating why the average WHR among women was
higher than 0.7, wrote that a higher WHR was associated with higher
levels of cortisol and androgens, and argued that these hormones caused
better stress response, and higher assertiveness and competitiveness,
respectively. She argued that these effects were also adaptive and
counteracted the mate-attracting and fecundity effects of lower WHR, and
that women's WHR was higher where they are more dependent on their own
hard work or where the environment is difficult, and lower in societies
where they gain resources by attracting a mate, with male preferences
shifting accordingly. A 2019 review of numerous hypotheses concluded that researchers should
focus on differentiating the conclusions of different analyses of these
hypotheses, considering a lot of the contradictions within the data and
the vague definitions of "mate-value". Recent studies utilizing stimuli that match what is found in the local
culture show that men display a cross-cultural consensus in preferring a
low waist-to-hip ratio (i.e., hourglass-like figure), with some
fluctuation depending on whether the local ecology is nutritionally
stressed. Congenitally-blind men also display a preference for hourglass figures in women.
Behaviors that reduce reproductive success
"Maladaptive" behaviors such as homosexuality and suicide seem to reduce reproductive success
and pose a challenge for evolutionary psychology. Evolutionary
psychologists have proposed explanations, such that there may be higher
fertility rates for the female relatives of homosexual men, thus
progressing a potential homosexual gene, or that they may be byproducts of adaptive behaviors that usually
increase reproductive success. However, a review by Confer et al. states
that they "remain at least somewhat inexplicable on the basis of
current evolutionary psychological accounts".
Debate over implications
Ethical
Many critics have argued that evolutionary psychology and sociobiology justify existing social hierarchies and reactionary policies. Evolutionary psychologists have been accused of conflating "is" and "ought",
and evolutionary psychology has been used to argue against social
change (because the way things are now has been evolved and adapted) and
against social justice (e.g. the argument that the rich are only rich
because they've inherited greater abilities, so programs to raise the
standards of the poor are doomed to fail).
It has also been suggested by critics that evolutionary
psychologists' theories and interpretations of empirical data rely
heavily on ideological assumptions about race and gender. Halford Fairchild, for example, argues that J. Philippe Rushton's work on race and intelligence
was influenced by preconceived notions about race and was "cloaked in
the nomenclature, language and 'objectivity'" of evolutionary
psychology, sociobiology and population genetics.
Moreover, evolutionary psychology has been criticized for its
ethical implications. Richardon (2007) and Wilson et al. (2003) have
cited the theories in A Natural History of Rape where rape is described as a form of mate choice that enhances male fitness as examples. Critics have expressed concern over the moral consequences of such
evolutionary theories and some critics have understood them to justify
rape. However, a 2011 study found that after reading an article on
evolutionary psychology theories, men did not judge male criminal sexual
behaviour significantly differently to a control group, while those
exposed to an article on sociocultural theory judged criminal sexual
behaviour much more harshly than both the control and evolutionary
psychology groups; the authors speculate that the study participants had
a native bias towards the evolutionary psychology theory that was
temporarily trumped by exposure to the alternative theory, while
acknowledging that this short-term study does not reflect larger-scale
and longer-term impacts of theory on behaviour.
Evolutionary psychologists caution against committing the naturalistic fallacy – the idea that "ought can be derived from is" and that "what is natural" is necessarily a moral good. In the book The Blank Slate, Steven Pinker contends that critics have committed two logical fallacies:
The naturalistic fallacy
is the idea that what is found in nature is good. It was the basis for
Social Darwinism, the belief that helping the poor and sick would get in
the way of evolution, which depends on the survival of the fittest.
Today, biologists denounce the Naturalistic Fallacy because they want to
describe the natural world honestly, without people deriving morals
about how we ought to behave -- as in: If birds and beasts engage in
adultery, infanticide, cannibalism, it must be OK. The moralistic fallacy
is that what is good is found in nature. It lies behind the bad science
in nature-documentary voiceovers: lions are mercy-killers of the weak
and sick, mice feel no pain when cats eat them, dung beetles recycle
dung to benefit the ecosystem and so on. It also lies behind the
romantic belief that humans cannot harbor desires to kill, rape, lie, or
steal because that would be too depressing or reactionary.
Similarly, the authors of A Natural History of Rape, Thornhill
and Palmer, as well as McKibbin et al. respond to allegations that
evolutionary psychologists legitimizes rape by arguing that their
critics' reasoning is a naturalistic fallacy in the same way it would be
a fallacy to accuse the scientists doing research on the causes of cancer of justifying cancer. Instead, they argue that understanding the causes of rape may help create preventive measures.
Political
Part
of the controversy has consisted in each side accusing the other of
holding or supporting extreme political viewpoints: evolutionary
psychology has often been accused of supporting right-wing politics,
whereas critics have been accused of being motivated by Marxist view points.
Linguist and activist Noam Chomsky has said that evolutionary psychologists often ignore evidence that might harm the political status quo:
The founder of what is now called "sociobiology" or "evolutionary psychology"-the natural historian and anarchist Peter Kropotkin-concluded
from his investigations of animals and human life and society that
"mutual aid" was a primary factor in evolution, which tended naturally
toward communist anarchism...Of
course, Kropotkin is not considered the founding figure of the field
and is usually dismissed if mentioned at all, because his
quasi-Darwinian speculations led to unwanted conclusions.
Chomsky has also said that not enough is known about human nature to point to any political conclusions.
In a review of Steven Pinker's book The Blank Slate, which draws partially on evolutionary psychology, Louis Menand wrote:
In general, the views that Pinker
derives from 'the new sciences of human nature' are mainstream
Clinton-era views: incarceration is regrettable but necessary; sexism is
unacceptable, but men and women will always have different attitudes
toward sex; dialogue is preferable to threats of force in defusing
ethnic and nationalist conflicts; most group stereotypes are roughly
correct, but we should never judge an individual by group stereotypes;
rectitude is all very well, but 'noble guys tend to finish last'; and so
on.
Evolutionary psychologist Glenn Wilson
argues that "promoting recognition of the true power and role of
instincts is not the same as advocating the total abandonment of social
restraint". Left-wing philosopher Peter Singer in his book A Darwinian Left
has argued that the view of human nature provided by evolution is
compatible with and should be incorporated into the ideological
framework of the Left.
Researchers conducted a 2007 study investigating the views of a sample of 168 United States PhD psychology students. The authors concluded that those who self-identified as adaptationists
were much less conservative than the general population average. They
also found no differences compared to non-adaptationist students and
found non-adaptationists to express a preference for less strict and
quantitative scientific methodology than adaptationists. A 2012 study found that evolutionary anthropology
students were largely of a left-liberal political stance and differed
little in political opinions from those of other psychology students.
