Evolutionary Developmental Psychopathology

280 Pages·2001·1.41 MB·English

by  Ian Pitchford

Evolutionary Developmental Psychopathology

by

Ian Pitchford
Email: [email protected]
University of Sheffield
Centre for Psychotherapeutic Studies
School of Health and Related Research
16 Claremont Crescent
SHEFFIELD
S10 2TA, UK

September, 2001
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Evolutionary Developmental Psychopathology

by

Ian Pitchford

Contents

Chapter 1. Introduction: Genealogical Actors in Ecological Roles 3
Chapter 2. The Separation of Contradictory Things 7
Chapter 3. The Problem of Classification in Psychiatry 35
Chapter 4. Evolution and Human Nature 71
Chapter 5. The Society of Mind 107
Chapter 6. Evolutionary Developmental Psychopathology 154
Bibliography 228
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Chapter 1

Introduction

Genealogical Actors in Ecological Roles

Surely the way to encourage people to think about their lives and
to improve them is not to replace one set of coercive determinants
with another, and surely the way to think about responsible action
is not to juggle inner and outer, ultimate and proximate causes,
and hope that reasons and responsibility will miraculously
squeeze through some narrow space where causes collide in per-
sons.
(Oyama, 1985, p. 16)

People, like all other organisms, are not evolved to maximise
health, wealth, happiness or any other trait – but to have descen-
dants, which is the continuation of life.
(Chisholm, 1999, p. 48)

How can psychiatric nosology1 generate an epistemic benefit, and can a scien-
tific taxonomy of mental disorders ever be entirely coextensive with a clinical
taxonomy of such disorders? I shall argue that useful taxonomic concepts for a
science of psychopathology are those representing projectable categories, and
that such categories delineate natural kinds, or non-arbitrary aspects of the
world. I shall also argue that because our attitude towards the treatment of dis-
orders or problems of any kind necessarily involves a complex psycho-social
cost-benefit analysis, clinical taxonomy will always reflect a nonepistemic
agenda that is itself mutable according to the strictures of prevailing norms and
resources. These considerations imply that the search for a single psychiatric
taxonomy based on the natural and human sciences and capable of accommo-
dating the needs of both clinicians and researchers could be futile, and that a
clear acknowledgement of the differing ends of psychiatric treatment and re-
search into psychopathology should be a starting point in the classification of
mental disorders.

1 Nosology is the branch of medicine concerned with the classification and description of dis-
eases.
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Recent attempts to promote the extension of evolutionary theorising to human
psychology and behaviour have awakened renewed interest in a field variously
called Darwinian psychiatry (McGuire & Troisi, 1998), evolutionary psychopa-
thology (Baron-Cohen, 1997), or evolutionary psychiatry (Stevens & Price,
1996). According to some of its most prominent practitioners this discipline ‘in-
troduces a broad and much needed deductive framework; it facilitates the func-
tional analysis of behaviour; it identifies important differences between ultimate
causes and proximate mechanisms, [and] it promotes a reassessment of cur-
rent views about aetiology and pathogenesis’ (McGuire, et al., 1992, p. 89).
However, drawing as it does on the concerns of human sociobiology (Wilson,
1975; 1978), much of the work in evolutionary psychopathology has concen-
trated on the study of adaptive behaviours ‘such as acquiring a mate, sexual
intercourse, having offspring, parent-offspring bonding, stranger anxiety’ and
other ‘general behaviour profiles and patterns of human behaviour… set by the
species’ genome [which], within limits, unfold in predictable ways’ (McGuire, et
al., 1992, p. 90).

Although it is certainly correct that ‘human physiology is importantly influenced
by selective forces’ (Sterelny, 1992, p. 156), which is all that human sociobiol-
ogy requires as a basic justification, there is a serious epistemic asymmetry be-
tween animal sociobiology and human sociobiology owing to the fact that hu-
mans are long-lived and unavailable for scientific manipulation in the form of
controlled breeding experiments. Another problem in considering particular hu-
man behaviours as adaptive is the human capacity to replicate learned behav-
iour through cultural means. Although our culture and social institutions may re-
flect aspects of our evolved psychological mechanisms (Boyer, 1994; Sperber,
1996), our behaviour is certainly

…the result of perceptual inputs, our learning history, and very
complex interactions between distinct psychological mecha-
nisms… very little human behaviour is the result of a specialised
capacity, built by genes that have proliferated in virtue of their abil-
ity to build the device that produces the behaviour. In us, if func-
tionalism is right, there is nothing like a one-one correlation be-
tween behaviours and mechanisms (Sterelny, 1992, p. 168).
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Crawford argues for the distinction between innate adaptation, the genetically
encoded design for the development of proximate mechanisms, and operational
adaptation, the phenotypic psychological processes actually producing the be-
haviour (Crawford, 1993). Inasmuch as the environment in which the phenotype
develops differs significantly from the environment of evolutionary adaptedness
an operational adaptation may be typified by entirely novel features, and may
contribute to behaviours having little bearing on lifetime reproductive success
(LRS). Consequently, as Sterelny suggests ‘we need from sociobiology an evo-
lutionary psychology, not an evolutionary theory of human behaviour’ (1992, p.
170). Two of the field’s early advocates, Leda Cosmides and John Tooby, argue
that to embrace evolutionary psychology

…means shedding certain concepts and prejudices inherited from
parochial parent traditions: the obsessive search for a cognitive
architecture that is general purpose and initially content-free; the
excessive reliance on results derived from artificial “intellectual”
tasks; the idea that the field’s scope is limited to the study of
“higher” mental processes; and a long list of false dichotomies re-
flecting premodern biological thought – evolved/learned,
evolved/developed, innate/learned, genetic environmental, bio-
logical/social, biological/cultural, emotion/cognition, animal/human.
Most importantly, cognitive scientists will have to abandon the
functional agnosticism that is endemic to the field (Cosmides &
Tooby, 1994, p. 42).

Evolutionary psychology eschews what it regards as the behavioural determin-
ism of sociobiology, but it does, however, retain a commitment to a modified
genetic determinism (of mechanisms rather than behaviour) which may itself
obscure a full appreciation of human psychological plasticity and the intricacies
of development. To borrow a phrase from David Hull (1987) we need to re-
member that human beings are genealogical actors in ecological roles, and a
large portion of this work constitutes a consideration of ways in which we should
perceive the contribution of genes and ecology to our evolved psychology. How
then should we conceive of ‘evolutionary psychology’? What concepts and de-
bates characterise this field? How does it relate to other disciplines? What does
it have to say about psychiatric classification and mental illness?
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To provide a coherent framework within which to analyse conceptual disputes in
psychiatry it is an indispensable prerequisite to evaluate competing perspec-
tives on human evolution (and evolutionary biology in general) and perspectives
in the history and philosophy of science. Although this can often seem a highly
circuitous route to an understanding of mental illness, recent work in these ar-
eas does allow us to clarify and refine some of the concepts and theories that
provide the foundation for the profoundly antagonistic debates that impede the
exploration of human nature. Consequently, chapter two ‘The Separation of
Contradictory Things’ considers the origins and consequences of the arbitrary
allocation of causal co-determinants to mutually incompatible schemes of ex-
planation and advocates the developmental systems approach to evolution and
the causal homeostatic theory of natural kinds as frameworks capable of avoid-
ing damaging dichotomies. Chapter three ‘The Problem of Classification in Psy-
chiatry’ provides an overview of the recent history of biological psychiatry and
examines the failure of the principal neurochemical hypotheses of mental disor-
ders it has produced. Psychiatric classification is examined from a number of
perspectives and a distinction is drawn between arbitrary concepts and pro-
jectable categories as the foundation for explanation and induction. Chapter
four ‘Evolution and Human Nature’ examines the development of sociobiology
and evolutionary psychology. Chapter five ‘The Society of Mind’ commends the
modular view of psychological faculties within the developmental systems per-
spective, and finally chapter six ‘Evolutionary Developmental Psychopathology’
demonstrates how the ideas advocated within this work can provide novel in-
sights into the nature of mental disorders. These insights allow us to re-organize
research findings into an alternative scheme (or schemes) of investigation and
classification.
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Chapter 2

The Separation of Contradictory Things

Since the genome represents only a part of the entire develop-
mental ensemble, it cannot by itself contain or cause the form that
results. But then, neither can its surroundings. As is frequently the
case in these matters, people in some way know this perfectly well
and say so. The reason they often end up belying their own good
sense seems to be their tendency to view a lack of variation
(within the organism if focus is on individual nature and within the
species if focus is on species nature) as evidence of inherent,
necessary qualities.
(Oyama, 1985, pp. 19-20)

The word ‘dichotomy’ is derived from the Greek dikhotomia, which means liter-
ally ‘cutting in two’. In this chapter I will discuss the arbitrary separation of vari-
ables and argue that the allocation of causal co-determinants to opposing ex-
planatory schemata undermines our understanding of the natural world and
human nature. The pervasive influence of three pivotal dichotomies on scientific
enquiry and on therapeutic intervention: those of mind versus body, cognition
versus emotion and nature versus nurture, will be a recurrent theme throughout
this work. Although scholars in the natural and human sciences usually disavow
belief in distinct material and immaterial substances contemporary debates are
phrased largely in terms that would have been familiar to the Greek philoso-
phers, and which still divide human characteristics into divine or transcendent
attributes2, in modern terminology the surrogate terms include ‘rational’, ‘cogni-
tive’, ‘discursive’, ‘autonomous’ and ‘unrestricted’, and animal or corporeal at-
tributes, the surrogates being terms such as ‘emotional’, ‘instinctive’, ‘deter-
mined’, ‘immutable’, and ‘bounded’. The three dichotomies are all inspired by
this essential dualism and each term evokes one or more of the properties as-
sociated with each category. Viewed in these terms many contemporary scien-
tific, political, and cultural debates often have an unacknowledged quasi-

2 It can be extremely enlightening to keep in mind some synonyms for divine: heavenly, sublime,
ineffable, numinous, supernatural, supramundane; and for animal: brutish, bestial, subhuman,
mindless, unthinking, intemperate, sensual.
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theological dimension, and it is this dimension that is responsible for some of
the greatest impediments to the understanding of human nature.

I will argue that we should attempt to employ a rigorously mechanistic approach
to the natural world. This does not imply a commitment to unrestrained and un-
realistic reductionism, or to the arbitrary exclusion of phenomena that are
clearly characteristic of the human condition, such as emotional experience or
the moral sentiments – traits that are often considered to fall outside the domain
of scientific enquiry. This standpoint can be achieved through a synthesis of two
key perspectives: the developmental systems approach to evolution by natural
selection, and the causal homeostatic theory of natural kinds.

Divining the Essence: Cleaving Mind from Body

The doctrine of dualism, which holds that there are two distinct substances, one
corporeal and earthly, and the other incorporeal and transcendent, has a long
history in Western philosophical and theological thought. The Greek philosopher
Plato (428-347 BC), perhaps the most influential of all philosophers, ancient or
modern, held that the soul (or divine mind) as the source of reason, thought,
and intellect, was the essential property setting humankind apart from animals.
In The Phaedo Plato writes of the body that

…it fills us full of lusts, and fears, and fancies of all kinds, and
endless foolery, and in fact, as men say, takes away all power of
thinking from us at all… It has been proved to us by experience
that if we would have true knowledge of anything we must be quit
of the body – the soul in herself must behold things in themselves:
and then we shall attain the wisdom we desire…(quoted in Rus-
sell, 1961, p. 151).3

In the same discourse Plato employs the famous metaphor ‘depicting intellect
as the charioteer who holds the reins, with emotion and will as the horses that
draw the chariot. This triarchic model of the human psyche, comprising, intel-
lect, emotion, and will, is perhaps the most easily recognizable aspect of phi-

3 The text of The Phaedo is available on the Internet at
http://plato.evansville.edu/texts/jowett/phaedo.htm.
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losophy’s legacy to psychology’ (Jensen, 1998, p. 4) Plato’s pupil, Aristotle,
later reduced the triarchic division of the psyche to two main functions, which he
termed the dianoetic4, or what we would now call the cognitive functions, and
the orectic, which included the emotions, will, and moral sense.

Because mind and body were held to be separate, the problem of the interac-
tion between the two became one of the most intractable questions in philoso-
phy. The father of modern philosophy, René Descartes (1596-1650), believed
that the ‘thinking substance’, or mind, interacted with the ‘extended substance’,
or body, by way of the pineal gland. He saw this as the likely organ of interac-
tion because it is the only part of the brain that is not divided into two hemi-
spheres. Descartes argued that thinking was the essence of humankind, and
that the foundation for all true knowledge could be summarised in the aphorism
‘Cogito, ergo sum’ or ‘I think, therefore I am’. Although the properties of ex-
tended substances could be analysed in terms of the laws of physics, thinking
substances could be understood only in terms of the laws of thinking. Descartes
offers no coherent explanation of how extended substances and thinking sub-
stances could interact, but he contends that all conflicts are conflicts between
the soul and the body (Gaukroger, 1995, p. 402).

In the Discourse on the Method of Rightly Conducting the Reason, and Seeking
Truth in the Sciences (1637), Descartes explains how by ‘deducing effects from
their causes, and by showing from what elements and in what manner nature
must produce them’ the recent triumph of the scientific explanation of the circu-
lation of the blood had been achieved, and cautions:

…lest those who are ignorant of the force of mathematical dem-
onstrations and who are not accustomed to distinguish true rea-
sons from mere verisimilitudes, should venture without examina-
tion, to deny what has been said, I wish it to be considered that
the motion which I have now explained follows as necessarily from
the very arrangement of the parts, which may be observed in the
heart by the eye alone, and from the heat which may be felt with
the fingers, and from the nature of the blood as learned from ex-
perience, as does the motion of a clock from the power, the situa-

4 Dianoetic: rational, discursory, analytic, synthetic.
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tion, and shape of its counterweights and wheels (Discourse on
the Method, Part V).5

But lest anyone should think that the laws of mechanics could explain the na-
ture of humankind, Descartes goes on to argue that though the mechanical
properties of extended substances such as human bodies could be regarded as
no different to those of an ape or ‘any other irrational animal’, there would re-
main ‘two most certain tests whereby to know that they were not therefore really
men’. These tests are the ability to use language and the ability to reason –
abilities that could only be dependent on the properties of a reasonable soul
that

…could by no means be educed from the power of matter, as the
other things of which I had spoken, but that it must be expressly
created; and that it is not sufficient that it be lodged in the human
body exactly like a pilot in a ship, unless perhaps to move its
members, but that it is necessary for it to be joined and united
more closely to the body, in order to have sensations and appe-
tites similar to ours, and thus constitute a real man. I here entered,
in conclusion, upon the subject of the soul at considerable length,
because it is of the greatest moment: for after the error of those
who deny the existence of God, an error which I think I have al-
ready sufficiently refuted, there is none that is more powerful in
leading feeble minds astray from the straight path of virtue than
the supposition that the soul of the brutes is of the same nature
with our own; and consequently that after this life we have nothing
to hope for or fear, more than flies and ants; in place of which,
when we know how far they differ we much better comprehend the
reasons which establish that the soul is of a nature wholly inde-
pendent of the body, and that consequently it is not liable to die
with the latter and, finally, because no other causes are observed
capable of destroying it, we are naturally led thence to judge that it
is immortal (Discourse on the Method, Part V).

In proposing this substantial union of mind and body, Descartes is effectively
arguing the case for the notion of the embodied mind – a mind which has fea-
tures distinct from disembodied mind or from bodies, but he retains a commit-
ment to the idea of an indivisible and immaterial soul as the essence of human
nature. As Stephen Gaukroger points out:

5 Available on the internet at http://human-nature.com/reason/descartes/part5.html.