More on evolutionary psychology and morality

I have been reading work by the evolutionary psychologists Peter Descioli and Robert Kurzban. Kurzban gave a great talk I saw last week at a conference proposing that the reason people have Kantian rule-based systems of morals is because morality serves as a way for bystanders to collectively coordinate which side to join in a conflict. As an illustration, imagine that you and I live in a communal house with ten people. Our housemates Adam and Bob get in a dispute. Adam is hungry, so he takes and eats Bob’s lunch. A fight breaks out. Because we tend to look to form alliances when in disputes, both Adam and Bob look to the other 8 members of the household for support. This dispute can potentially threaten us all. It could lead to a larger conflict or a war among all ten of us. Kurzban argues that morality evolves as a way for all 8 bystanders to pick the same side. The best way to do this is to use some clear rule that everyone can see. It can’t be a rule that is based on the participant’s identity or their relationship with bystanders. It must be something everyone can see objectively. Did Adam steal? Then Adam is wrong. Because stealing is wrong. This places the entire group on the side of Adam and the dispute is settled quickly and efficiently. People who fail to conform to this moral rule will be on the wrong side of the argument with less support, so it behooves everyone to be on the majority side.

This kind of “collective decision-making” is common in nature. For instance, it’s the way bees in a colony and brains make decisions. In social evolution, you can model the effects of these kinds of coordinated actions by considering how individual decisions feedback on individual inclusive fitness, or by partitioning the effects into individual and group fitness (multi-level selection). This sheds light on topics such as the evolution of society and multicellularity. The basic point here is that sometimes interests are aligned and it benefits everyone to do the same thing.

The more I think of it, the more I feel like a lot of what we know about how humans condemn others is consistent with this model of morality. It also explains some oddities in moral reasoning.

In another study, Kurzban posed the old classic Trolley moral dilemma to a sample of people. You probably know this already:



Version 1: There’s a trolley out of control. It’s going to kill 5 people. If you throw a switch it will change tracks and only kill one person. Do you throw the switch? Most people say yes.

Version 2: There’s a trolley out of control. It’s going to kill 5 people. But you can push a large fat man in front of it to stop it (your own body is too small). It will kill him but save 5. Do you push the person? Most people say no.

There’s a lot people have said about this finding. One basic point is that most people are Kantian in their moral reasoning. They follow moral rules like “Do not kill others” which is why the decision flips based on the action (flipping switch/pushing person) rather than the outcome. To a utilitarian, all moral actions should be based on outcome only.

Some people even find the utilitarian moral decision (killing 1 to save 5) offensive. It can seem cold and calculating rather than "human-hearted".

Some people even find utilitarian moral reasoning offensive. “Killing one to save the many” can seem cold and calculating rather than “human-hearted” approach of  following moral norms  like the Golden Rule or “Never kill anyone”

Kurzban gave both versions a novel twist. He posed the same problem but in one version he said the 5 saved and 1 person killed were all siblings. In another version he said they were friends and in another they were strangers. So what effect did this have?

People were significantly more willing to sacrifice 1 friend to save 5 other friends or to sacrifice 1 sibling to save 5 siblings. They were much less willing to sacrifice a stranger.

When people are dealing with kin and friends, they think more about welfare maximization (How many lives can I save?). But when dealing with strangers they worry more about following moral rules (Do not kill people.) This makes sense, if we think that the driving force for moral decisions dealing with strangers has more to do with how other people might judge us. By contrast, decisions to help or harm friends and relatives are treated differently in our brains. There is a different kind of moral calculation that goes on. Specifically, we have adaptations for true biological altruism with relatives (just like a mother would give up her life to save her children). And because of the importance of reciprocal cooperation to human social life, we also care directly about the welfare of friends, because they are valuable to us and their wellbeing feeds back on ours . With strangers, our moral calculation has more to with what decision is most consistent the moral rules, i.e. what is socially acceptable. It is not socially acceptable to kill a person by pushing them in front of a trolley.

In Kurzban’s view, the trolley problem pits altruism systems (maximize welfare) against moral systems (Kantian rule-based ethics). Surprisingly, he found that almost half of subjects
reported that they would not kill 1 stranger to save 5 siblings. This shows that moral systems might be able to over-ride evolved altruistic tendencies, which is a hallmark human pecularity. I would bet however that in an actual real situation most people would kill 1 stranger to save their close family. They just don’t think they would when answering a survey.

The main point here is that Kurzban’s ideas are not a mere just-so story. They lead to a novel unique prediction: that people will be more likely to switch from utilitarian to Kantian moral reasoning when switching from kin/friends to strangers. It’s hard to explain this using past explanations of moral behavior.

A lot of people I know don’t like evolutionary psychology. Many folks associate evolutionary psychology with bad scientific justifications for conservative political worldviews or simplistic posthoc just-so story explanations for gender stereotypes: “girls like pink because ancestral females used to gather fruits and flowers, and boys like math because men were hunters had to count mastodons”. This is an unfair characterization to be sure. I’ve heard evolutionary biologists sometimes say that evolutionary psychologists get evolution wrong. And I’ve heard clinical psychologists say that evolutionary psychology researchers doesn’t have a real purpose: how does this work help anyone?

In my view, the basic theoretical approach taken by evolutionary psychology is exactly how we study animal behavior (that is adaptationism– testing the extent to which biological traits have a functional design). This has been one of the most successful paradigms in biology. People study function of a trait and this helps us to understand when it evolved, how it develops during the lifetime, and how it works.

It’s often harder to study the evolution of human social behavior because it’s so easy to bring our own intuitive baggage to bear on the problem, including our own introspections and political world views. It’s also easy to slip between talking about the design on behavior (e.g. “evolutionary altruism”) and the actual thoughts and behaviors that people have (e.g., “psychological altruism). This happens often when we talk about things like “strategies”. It’s clear what we mean when we say that root allocation in a plant is a strategy for competing less with kin. But this becomes a bit more ambiguous when we talk about a strategy in a human or vampire bat. People mistakenly think you mean conscious planning.

Basically, “anthropomorphism” is possible even for humans. We falsely believe that other humans think the way that we think we think (which is often wrong).

Ultimately, psychology has to be based firmly in biology (and that means evolution), just like biology has to be based in chemistry and physics. Of course physics doesn’t explain everything about how cells divide, what causes species to go extinct, or why mammals but not reptiles have milk. But everything in biology can be understood as going back to physical and mathematical laws. The greatest leaps forward in biology occurred when abstract concepts (such as disease, genes, mind)  were routed in real physical things made of atoms and molecules (viruses, DNA, and neural circuits).

So to with psychology as it develops into a mature science with links to neuroscience and evolutionary theory. Many of evolutionary psychology’s controversial ideas are completely accepted in animal behavior—  that minds are composed of modular functional adaptive specializations, that learning is not a general associative process but based upon instinctual rules about what to learn and when,  and that all the complex traits of human nature at some point increased inclusive fitness in the environments in which they evolved. These ideas will soon be completely uncontroversial among all disciplines within my lifetime (I hope).


About Gerry Carter

I study the behavioral, sensory, and social ecology of vampire bats.
This entry was posted in About cooperation. Bookmark the permalink.

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s