Why Variety is the Spice of Life When it Comes to Our Evolved Moral Sense

8 08 2010

Here’s the riff (developed from the paper I delivered at the recent AAP conference): because the success* of behavioural strategies – including moral strategies – depends on the environmental conditions in which the agent is situated, and because that environment includes the strategies employed by other agents, it pays to Mix It Up A Bit in terms of the strategies employed by the population.

As a result, you’d expect to see a diversity – or a ‘pluralism’ or ‘polymorphism’ – of strategies employed in a population. Some will be ‘nice’, some will be ‘suspicious’. That’s what I call Lesser Moral Diversity. Some will be ‘nice’, some ‘suspicious’, some ‘nasty’. That’s what I call Greater Moral Diversity. Details below:

Some adaptive problems are relatively static against the background environment; how to transport energy between cells is a relatively static problem, and it has been more or less solved with the evolution of the astounding ATP molecule. Discovering the solution to problems such as these is modelled by decision theory – which looks at ‘single player games’, where one agent is working to find a solution to a problem against some static (if imperfectly known) background conditions.

However, some adaptive problems aren’t situated against a static background. In these cases the success of a particular solution depends on the solution chosen by other agents or aspects of the environment that changes depending on the agent’s chosen solution. For example, consider the arms races that take place between certain predators and their prey: one side evolves a new defence mechanism, the other evolves a way around it. These problems are modelled by game theory, a favourite of this blog.

As another example of a dynamic adaptive problem, consider the immune system, and the major histocompatibility complex (MHC) in particular. The MHC is a large region on our genome – and the genomes of almost all other vertebrates – that is central to our adaptive immune system, which is the part of our immune system that identifies and reacts to invaders and pathogens that enter our body. The MHC provides a mechanism for our immune cells – primarily killer T cells – to identify friendly ‘self’ cells produced by the body from potentially harmful ‘nonself’ cells.

Interestingly, the MHC region on the genome is incredibly polymorphic, meaning it varies tremendously between individuals of the same species. This is interesting because most parts of our genomes are drastically less polymorphic – meaning there’s less variation – because evolution has slowly gravitated towards one, or a small set of, solutions to a particular problem. Or, when it comes to traits that have little adaptive significance, such as eye colour, there’s little selection pressure to encourage the evolution of more alleles, such as yellow or orange eye colours.

But with the MHC it appears as though something has actively been driving the high polymorphism – something has been encouraging new mutations to stick around and join in the big pool of alleles. There were a number of theories proposed to account for this polymorphism, such as overdominance selection – which is where heterozygotes have a greater adaptive advantage compared to homozygotes, thus encouraging polymorphism in that trait. The paragon example of overdominance is that of sickle-cell anaemia versus malaria.

But it seems the most important force is frequency-dependent selection. This is where the selective benefit of a trait is dependent on the frequency of other traits in a population. To take a fairly banal abstract example, consider a gene that encourages an animal to seek out the lowest fruit on a tree. Seems to be plenty of advantages to such a strategy. But if that gene is rife in a population, all the lowest fruit on trees will be subject to fierce competition. In such an environment it might be more fruitful (no pun intended) to seek out fruit higher up the tree, with the cost of picking that fruit compensated for by less competition with other members of your species. But, if this second gene raises in frequency sufficiently, then there’ll be increased competition over the higher fruit. And on it goes.

Likewise our immune system, is constantly adapting to the evolving threats in our environment, such as new mutations of viruses like influenza. As viruses mutate and adapt to the more common genotypes, it’s the more novel or rare genotypes that are likely to survive infection or a widespread epidemic. High polymorphism in a population thus reduces the likelihood of a devastating pandemic that kills most or all of the population. And because the pathogens are constantly adapting, so too does our immune system have to keep adapting.

Now consider our moral sentiments that motivate moral behaviour. The more ‘nice’ people there are in your population, the more benefit you’ll get from employing a ‘nasty’ strategy. Yet a sufficient number of ‘nice’ strategies working together will out-compete ‘nasty’ strategies. Ultimately, there is no one solution that will dominate in every environment, so you’ll end up with a polymorphism of strategies.

We know that genes influence an individual’s moral sentiments – although environment and culture also have a great influence. So we’d expect there to be a polymorphism in the genes that influence moral sentiments. This polymorphism might only result in a small variation in the emotional responses of one individual compared to another, but this small variation might be amplified by cultural forces and experience to produce a more pronounced difference in personality: for example, someone with a higher empathy response might be drawn to ideologies that favour cooperation over competition, and that might amplify their empathy strategies.

Lesser Moral Diversity is the thesis that we’d expect to see a polymorphism within a population of ‘nice’ (or, coarsely, ‘liberal’) strategies and ‘suspicious’ (or ‘conservative’) strategies. Greater Moral Diversity just extends this slightly to include strategies that we’d consider immoral, or ‘nasty’, such as are employed by psychopaths, and suggests that we’d expect a certain percentage of these strategies within a population as well. Equilibrium is found dynamically rather than gravitating to a single ESS, like with the MHC.

That’s evolved moral diversity.

* By “success” I mean, in evolutionary terms, reproductive fitness – i.e. the number of related offspring (and grand offspring) and individual can produce. Not that reproductive fitness is the goal of morality today, of course…




6 responses

8 08 2010
Sixteen links « Evolving Thoughts

[…] Julian Baggini explains why I won’t read your earthshattering manuscript. Tim Dean explains why moral variety is the spice of life (hint: it’s just like MHC molecules). Sebastian Lutz […]

9 08 2010
Mark Sloan

Thanks for pointing out that polymorphism that produces a range of biological structures responsible for moral emotions, conscience, and so forth could be an adaptation that increases reproductive fitness of a population. It was apparent there were such variations, but it had not occurred to me that such variations in a population could increase the population’s reproductive fitness.

It’s a bit scary that rational psychopaths (people who are incapable of feeling empathy and have no conscience but are otherwise rational) might be included in that ‘adaptive’ mix for our ancestors. Unfortunately, this reinforces a concern I already had – that the anonymity and mobility of modern civilizations favor the reproductive fitness of rational psychopaths more than was the case for our hunter-gatherer ancestors.

An ideal secular morality would be the rational choice (the choice expected to best meet needs and preferences) not only for people with normal abilities to feel empathy and guilt, but also for rational psychopaths. It will be difficult to come up with such a morality. One way to make accepting the burdens of a morality more of a rational choice for rational psychopaths would be to reduce anonymity in our social interactions and thereby make social penalties for bad behavior more certain. This would at least in part compensate for rational psychopath’s lack of emotional penalties for bad behavior.

9 08 2010
Tim Dean

Hi Mark. Interesting idea that mass society favours the psychopath – perhaps it does in a reproductive fitness sense – but it’d be interesting to see some empirical studies on this notion.

Also, I don’t think a secular morality need bend itself too much to accommodate psychopaths. A secular morality that is geared towards promoting the interests of a population on aggregate would be about promoting cooperation, compassion, empathy, reciprocation etc. If a psychopath behaved counter to these principles, they’d be censured. That censuring might be different to accommodate their psychology, but it wouldn’t be allowed willy-nilly.

A secular morality is not the only way that we advance interests – to define morality as the general strategy for making decisions in every aspect of life is to define it too broadly. Morality is about that part of our lives that manages social interaction. In that area, psychopaths’ intuitive tendencies are destructive. Doesn’t mean they can’t advance their interests, but if they do so at the expense of others, that’s immoral. Hope that makes sense.

9 08 2010
Mark Sloan

Yes, that makes sense. But I expect morally censuring law abiding rational psychopaths would have to include more than “shame on you” in order to be effective. (Based on game theory, how a morality is ‘morally’ enforced is a critical part of every morality that I think doesn’t get nearly the attention in moral philosophy that it should.) Perhaps the most practical moral censuring of law abiding psychopaths would be to make their immoral deeds widely knowable in a way that would reduce the number of people they can exploit. This would compromise everyone’s privacy, but something like it might be needed at some point.

Robert Hare developed the test used in the United States for psychopathy and has suggested that 1) rational psychopathy has a genetic component, 2) at least male rational psychopaths behave in ways that should increase their reproductive fitness (they like sex as well as anyone), and 3) most rational psychopaths are never convicted of a crime. In fact, their psychology can make them very successful in business, religious, and government organizations. He has two light read books on the subject “Without Conscience” and “Snakes in Suits”.

In important ways, an effective morality for rational psychopaths might be very similar to an effective morality for intelligent computers, which is also of interest. Of course that assumes these hypothetical intelligent computers would not feel empathy or guilt.

10 08 2010
Alan Cooper

I have a minor quibble re your definition of “success” in this context as “in evolutionary terms, reproductive fitness – i.e. the number of related offspring (and grand offspring) and individual can produce.”

Actually “success” for a gene (or gene complex) is to maximize the number of its copies in future generations. Often this is done by contributing to reproductive success of the host or the host’s immediate relatives, but for behaviours dependent on a “moral sense” the situation is more complicated. It may serve the genes for such behaviour better to have their host recognize and support others of the same “moral” type than that host’s own immediate relatives who lack those genes – and even to identify and destroy “immoral” offspring! (I have commented in the past that this makes genes for conscious altruism actually the most “selfish” genes of all, as they can be prepared to sacrifice their chromosomal neighbors in favour of those carried by another “moral” host.)

29 01 2012
From Genes to Politics: How Biology Influcences the Way You Vote « Ockham's Beard

[…] in all this is to explain how and why our genes got to be this way. I’ve written about that before, and I’ll add more as I continue to write it into my […]

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