The evolution of empathy, and the altruism and cooperation it encourages, is a bit of a curly problem. It’s well known that groups that employ a particular minimal threshold level of altruism can potentially outcompete groups that are less cooperative. The problem is, beneath this threshold level, it’s difficult to see how empathy and altruism can gain a foothold without being drowned out by self-interest.
This is a problem that even Darwin acknowledged, and there have since been proposed a number of possible solutions, including kin selection and reciprocity. Here’s one of my own – although it’s more than likely it’s been proposed before, but I haven’t stumbled across any explicit references to it to date:
Mirror neurons and social learning.
Yeah, mirror neurons – they’re well known for their involvement in empathy, and could well be one of the physiological adaptations that underpins empathy and altruism. So, what if there was a way that mirror neurons could have evolved such that they performed their empathy-inducing function, but the selection pressures that produced them weren’t themselves prone to the threshold problem with empathy and altruism mentioned above?
Maybe there’s way. Because mirror neurons are also instrumental in social learning, particularly through imitation, and social learning is arguably one of the pivotal features in our cognitive explosion that has occurred over the past several million years. Social learning enabled the horizontal transmission of adaptive information and skills, allowing far more flexible and plastic behaviour in response to a complex and changing environment, and doing so far quicker than old fashioned genetic change from one generation to the next, driven by mutation and selection.
Cultural evolution is a force multiplier. Behavioural traits can emerge quickly, change, bounce back, and be transmitted to others and spread quickly, and each individual doesn’t have to re-invent the wheel. And mirror neurons play a central role in the whole process.
So, maybe the selection pressure driving the evolution of mirror neurons was based on social learning, and the useful ability to automatically imitate the actions of others, including their minor gestures and facial expressions. Add to this a burgeoning theory of mind, and the ability to intuit intentional states in others – which may have been driven by the selective demands of an increasingly complex social environment – and mirror neurons could easily have started mirroring emotional states along with physical gestures.
And bam: empathy.
It might have only been a small nudge in the direction of empathy, and perhaps highly restricted in terms of its strength, or which other individuals triggered it, but it might have just reached that threshold level to allow altruism to increase and the new selective pressure of promoting cooperation take over in driving empathy to even higher levels.
I’m sure there are reams of details to be filled in, and there may be many alternate and superior explanations for the beginnings of empathy and altruism, but I suspect that mirror neurons and imitative learning could be a piece in the empathy puzzle.