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Why evolution wouldn’t favour Homo economicus

By Peter E. Earl

Economists traditionally have assumed that all decisions are taken by weighing up costs and benefits of alternative courses of action. In reality, people seem to make their choices in at least three ways, and which way they use depends on the kind of context in which they are choosing. They can choose in a programmed manner; they can exercise free will after thinking carefully about the potential consequences of choosing one action rather than another; and they can simply delegate their choices to others and go with the social flow without really considering alternatives or where what they are doing might lead.

There seem to be good evolutionary reasons why humans have ended up with more than one way of choosing.

By being able to deliberate rather than merely follow existing decision rules, humans have been able to come up with innovations that enable them to thrive and reproduce, adapting to new environments as they do so.

But the capacity to deliberate is also potentially disastrous if a person can become immersed in a problem that cannot be solved rapidly. While attention is concentrated on one problem, the person may be overwhelmed by unnoticed external or internal threats. It is therefore vital that people have programmes that will kick in — as unmet basic needs do — to over-ride deep thought and ensure they make choices swiftly enough to avoid disaster.

Such choices may not involve consideration of alternatives — either in detail, or even, at all — but merely the application of a very simple rule. Prejudices and check-lists may enable people to make choices swiftly rather than become ending up paralysed as they try to consider the pros and cons of alternative possibilities. In a social setting, acceptance of suggestions from others enables the group to make something happen in the limited time available, so it is no wonder that those whose deliberative tendencies threaten to cause their peers to ‘lose the moment’ get labelled as ‘party-poopers’.


The capacity of humans to engage in deliberation is potentially disastrous for their reproductive success. Others species reproduce by following their instincts, in other words, by operating in a programmed manner. Humans are in a position to reflect on the costs and benefits of engaging in sexual activity, so their free will potentially can overcome any primitive programmed sexual urges. Cool reflection could lead to decisions to abstain: birth is dangerous for women, and the short-run burden of having children may vastly outweigh their long-run potential to provide support for elderly parents.

For humans to populate the planet as successfully as they have done, they needed to evolve something that would get in the way of such a view of sex and reproduction. That ‘something’ seems to have been the almost uniquely human ability to experience sexual pleasure. This had to be of an intense but fleeting kind that could not be stored in the memory and replayed in the imagination but was only available by repeating the sexual act.

Intelligence and the ability to experience intense sexual pleasure are, in evolutionary terms, a winning combination for the human race. The former makes it possible to cope with the Malthusian pressures that follow from the latter frequently overwhelming cool logic. Evolutionary fitness is also helped by inherited dispositions to find children cutely alluring while, in terms of social evolution, we should not be surprised that the societies that thrived in primitive times were patriarchal ones. The risks of childbirth would give women greater pause for thought than men about whether to allow sexual urges to be turned into action.

An evolutionary perspective on choice does not merely point towards a plurality of ways of choosing and to why humans are equated to enjoy sex rather than viewing it as at best a ridiculous activity and at worst as potentially disastrous in its consequences. An evolutionary perspective also provides reasons for doubting that humans would end up having the kinds of preference orderings that economists commonly assume. Being willing always to make tradeoffs is not conducive to survive if one’s body has a set of basic physiological needs that are hierarchically ordered. Moreover, when people are in a position to meet their basic needs, being unwilling to consider many kinds of goods (as in’I don’t like …’) gives them identities that facilitate social and economic coordination as well as reducing the choice problem to manageable proportions.

Peter E. Earl is Associate Professor of Economics at the University of Queensland, Brisbane, Australia. His Cambridge PhD was on behavioural economics but was completed long before it became fashionable to mix economics with psychology, and he coedited the Journal of Economics from 2000-2004. His research focuses mainly on how people and organisations try to cope with problems of information and knowledge. He has just finished co-authoring a book about the work of GLS Shackle and is currently engaged in a major project on how Australian consumers choose their mobile phone connection services. He is the author of the paper ‘The robot, the party animal and the philosopher: an evolutionary perspective on deliberation and preference’ in the Cambridge Journal of Economics.

The Cambridge Journal of Economics, founded in 1977 in the traditions of Marx, Keynes, Kalecki, Joan Robinson and Kaldor, provides a forum for theoretical, applied, policy and methodological research into social and economic issues.

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Recent Comments

  1. Brendan

    ” That ‘something’ seems to have been the almost uniquely human ability to experience sexual pleasure”

    You should talk with a zoologist, quite certain that numerous other mammals, like dolphins or species of monkey, also enjoy sexual experiences.
    Some undertake it just for the sake of pleasure, not for reproductive pruposes

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