Our series on evolutionary psychology continues with the basic ‘nuts and bolts’ of natural selection and its impact upon speciation, survival and behaviour (flight, hiding, sexual attraction etc). This necessarily brief overview sets the scene for the rather more complex work on evolved psychology to come. These selection pressures have been the drivers that led our species to become fully human and to develop the enigmatic set of behaviours and attitudes we call ‘human nature’.
What do we mean by ‘selection pressure’? Doesn’t evolution just happen anyway?
What do we mean by EEA?
The acronym ‘EEA’ stands for the ‘Environment of Evolutionary Adaptation/Adaptiveness’, otherwise known as the ‘Evolutionary Environment’ or the ‘Ancestral Environment’. Originally coined by John Bowlby it has come to mean the conditions in which a species adapts because of strong naturally selective pressures. (Schore 2012)
Badcock (2000) estimates that for around 99% of its existence the human species lived in small groups of hunter gatherers. The bulk of human adaptation took place during the pleistocene (beginning around 1.8 million years ago) and continuing until around 12,000 years ago (10,000 BCE). The first human (homo) species arrived on the scene around 2.5 million years ago. Our adaptation during that time, whilst well-suited to primitive societies, isn’t always helpful in the modern world of the last 10,000 years or so.
The figure of 10,000 years isn’t arbitrary by the way. That’s the time when humans first began to form larger societies – a change that our evolved psychology still seems to struggle with. We know that middle-eastern cities such as Jericho were founded around 7,000 years ago and that other cities such as Ur were founded sometime earlier.
The fact is humans didn’t evolve to live in large towns and cities with national identities and we certainly didn’t adapt through the ages to spend our lives surrounded by strangers. But why not? To answer this we need to consider a few fundamental points:
- Evolution is slow;
- Evolution occurs on ‘islands’;
- Evolution isn’t concerned with individual comfort unless it aids procreation.
Evolution is slow
Although 10,000 years seems like an almost unimaginably long time for humans it’s actually a very short period in evolutionary terms. The process of evolution by natural selection, even in ideal conditions takes millions of years. For example a recent article estimates that the most recent common ancestor linking all the great apes lived some 18/9 million years ago.
The process relies more on numbers of generations than years passed & we’re really only talking about around 2000 generations over that time. So one answer to the question ‘why not’ is simply that our species hasn’t had enough time to evolve past hunter-gatherer societies.
Evolution occurs on ‘islands’
Evolution by means of natural selection happens most rapidly when survival pressures are most prevalent and life is so hard that new adaptations create genuine procreative advantages. It’s also important that any new adaptation isn’t ‘swamped’ by too much competition as it (and the human being that carries it) competes for survival/procreative advantage. In short natural selection works best when life is short and the breeding population is small. Otherwise genetic changes get lost before they can establish a foothold.
This is what we mean by ‘islands’. An evolutionary island doesn’t need to be surrounded by water but it should be isolated. This isolation could be the result of a natural barrier (a desert or mountain range, for example) or just the result of a small population, rarely coming into contact with other human groups. In these circumstances small, adaptive genetic variations can take hold and thrive. In large, modern, industrial societies adaptive mutations (for example keener eyesight) have much less impact on the population as a whole. My own short-sightedness is easily corrected by my glasses in modern UK whereas in the EEA of a million years ago it would have been a major handicap that may well have resulted in death long before I had a chance to breed.
At this point it’s worth pre-empting one of the more superficial and tiresome objections regularly raised by creationists. We’ve already covered the ‘naturalistic fallacy’:
but I want to restate the point:
The fact that natural selection callously lets
the weakest die doesn’t mean that it is right.
The ancient evolutionary environment was hard and ruthless, in one sense that was because early humans lacked the technology we have today to make things better. Acknowledging that life was cheap ‘back then’ doesn’t mean we think that’s how it should be. But let’s be clear:
Natural selection doesn’t care what you or I might think.
Natural selection doesn’t care about anything.
Evolution isn’t concerned with individual comfort unless it aids procreation
As we will see throughout this series evolution isn’t the result of any grand design to ensure human happiness. It’s simply a ‘mechanism’ a process by which different organisms compete with each other to survive.
Personally I wish it was different. I wish there was a plan. Perhaps a divine creator would have designed a world without so much pain and suffering. But that’s not how it is – unless you believe that starvation, disease and ‘nature red in tooth and claw’ are somehow the hallmarks of a benign, intelligent designer.
Evolution has no plan, no compassion and no interest in ‘right and wrong’. Those concerns are solely human. To shirk our responsibility for creating our own moral code (whether we take our morality from nature or from Divinity) seems to me to be nothing more than intellectual and moral cowardice. If we can learn anything from either religion or the evolved natural world it’s that both are capable of creating almost unimaginable catastrophe. We accept uncritically either of these at our peril. So let’s stop pretending that Darwinism has anything to teach us about how things ‘ought to be’. Darwin’s great gift was to provide us with a way to understand how we evolved in the past. What we do with that knowledge is another question entirely.
Badcock, C. (2000). Evolutionary psychology: A critical introduction. Cambridge (UK): Polity Press.
Back into the routine with the mental health YouTube channel. Here’s the latest instalment of the evolutionary psychology series
Just because the theory of evolution by natural selection explains how we got to be the way we are, there’s no reason to imagine it can tell us how we ought to behave. There’s no particular goal-direction for the human or any species inherent in evolution. Nor is there any master plan pointing us toward perfection. Nobody is in charge and no great plan exists in a realm beyond.
Natural selection is a non-conscious, automatic mechanism that determines how likely individuals are to get their genetic material, their DNA into the next generation. That’s it. The fact that certain individuals with specific adaptations and attributes survive whilst others die off may provide the illusion of a plan, even of design but don’t be fooled.
Natural selection isn’t random because it follows some simple principles and it does so consistently. But those principles weren’t designed either. They just are.
Here you will find my developing video playlist on evolutionary psychology. It’s a long term project. Enjoy.