The 6 Ways Altruism Could Have Evolved: Part 2, Commitment & Sex

In my first post in this three part series I focused on the first 2 of 6 ways – reciprocity and kin selection – that evolution by natural selection without any divine interference could have produced altruistic creatures.

Now of course Evolutionary Altruism, as I discussed before, is both easily observed and easy to account for.  Take a look at ants and other hive creatures that easily sacrifice their individual biological fitness for the sake of others.  But the purpose of this series is to account for Psychological Altruism in humans.  Here we’re interested in the motivations and emotions one has.  Specifically those that place another’s well being and interests above our own.  This is instead a set of moral characteristics, emotions, and concerns that we have.


Sexual Selection: Ever wonder why the peacock has such a ridiculous tail? It makes it easier for predators to spot it and snag it. Shouldn’t evolution have selected it to be smaller and less colorful? Well with many birds colorful feathers meant a good immune system. So lady peahens had reason to mate only with the most colorful. After the men got wise to this, natural selection favored those that were ever more colorful.  This eventually started an arms race with males trying to becoming more and more colorful since only the most colorful got to mate and pass on their genes.

In my last article I discussed how kin selection and reciprocal altruism could select for a full blooded psychologically altruism in humans.  In this second part of my little series I want to focus on two more possibilities I think likely had a much stronger selective pressure than these first two.

First, there is what Robert Franks calls the Commitment Problem in his amazing book Passions Within Reason.  And second, I want to address what evolutionary biologists back to Darwin have called sexual selection.

3. Overcoming the Commitment Problem

Passions Within Reason

Click Here to Check Out the Book

The Commitment Problem, very much related to the Paradox of Egoism, is fascinating and, honestly, it’s hard to give it any justice in the small space I’ve given myself here.  That being said, let me try anyway.

To give a sneak peak, let with start with the conclusion: it’s often rational to be irrational, defined in terms of desires and self interest, that is.  Philosopher Derek Parfit discusses this phenomena as being indirectly self-defeating.  In other words, to achieve what is in our interests we often need to act counter to them, or at least indifferently.

Here’s one of my favorite examples which Frank gives himself.  Imagine two neighbors, Farmer Fred and Rancher Rick, whose large properties border each other.   Now Fred has always grown grain while Rick has newly decided to herd cattle.  Unfortunately, there is no fence between their property and Rick’s cows every so often wander over and eat in Fred’s fields.  Naturally, Fred knocks on Rick’s doors and asks him politely to build a fence to keep his cows in.

But here’s the catch: Rick knows that Fred only acts rationally, i.e. in his self interest.  So, because it will cost Fred much more money to sue him (given lawyer fees and the time it takes) compared to the small amount his cows eat, Rick knows Fred will choose to suffer the cost or build his own fence.  Since Rick knows Fred is rational, Rick can ignore Fred and save money by not building a fence.

If Tom think's Fred is rational and acts only in his self interest, then he won't build the fence since a lawyer will cost him more than to build his own fence. But if Tom thinks Fred is irrational and will act out of pure spite, then Tom will build the fence to avoid being sued.

If Rick think’s Fred is rational and acts only in his self interest, then Rick won’t build the fence since a lawyer will cost Fred more than to build his own fence. But if Rick thinks Fred is irrational and will act out of pure spite, then Rick will build the fence to avoid being sued.

But what if Fred were not systematically rational?  What if out of anger, burning indignation, a sense of justice, and other emotions Fred has he will undoubtedly sue Rick even though he himself loses out all things considered?  Well, if he isn’t self-interestedly rational then Rick will build the fence himself to avoid being sued.  Rick knows that Fred will commit to his threat.

Being irrational and taking on costs solely to spite others or serve justice here means that Fred actually ends up more well off than if he were a rational and self-interested person.

But this is about justice and vengeance, not helping others?  What about altruism?  Well, there are a slew of other commitment problems.

For instance, marriage and love is another classic example.  How will I know that you really mean you’ll stay with me when I’m old, ugly, and disabled and not run off with someone better when you first have the chance?  Well, because of love.  As humans we have these irrational emotions that make me do irrational things and view others, the object of our love, as more important than our own happiness or anything else in the world – including someone ‘better’.

The same kind of commitment problems come up again and again with friends, devotion to groups (like family, states, and religions), ethical norms like promises and justice, and so on.  If we really are committed to something outside ourselves, if we are guided by irrational emotions instead of methodical self interest, then we can be trusted by others to fully commit ourselves.  And since in so many cases it pays to be irrational instead of rational and to have these non-self interested emotions and inclinations, natural selection will preference those individuals who have them over those that do not.

4. Sexual Selection & Fitness Signals


Just as excessively colorful feathers signal health, altruism may signal greater devotion to family or the financial ability to even be so generous.

Studies already are beginning to show that nice guys not only often finish first, but are also considered sexier doing it.  Now at first glance it might seem obvious.  It is always to my advantage to choose those who will selflessly help me out.  But here I want to make a stronger claim about altruism.  What evolutionary benefit is there to picking a partner that is altruistic and selflessly helps complete strangers?

Now the article above, and other resources, give two alternatives for how sexual selection may select for psychological altruism.  Dr. Freya Harrison, a Research Fellow in The University of Nottingham’s Life Sciences Centre for Biomolecular Sciences, explains that

We’re not sure whether [1] being helpful to others signals that you’re more likely to be a good parent who helps your partner with the work involved in raising children, or [2] whether it might be a signal that you carry ‘good genes’ that will produce healthy children — having the energy and ability to help others might be a show of vigour, rather like a peacock’s tail.

In other words, first, it could be that one sex is signaling they’re a caring person.  Though of course not consciously, altruism and selfless giving towards those unrelated is a great indicator of a tendency to give even more selflessly to one’s own family and children.  Those who preferred genuinely altruistic partners were more likely to have mates that cared intensively for their offspring.  Those that were altruistic, therefore, were more likely to get mates, since everyone was looking for altruistic mates themselves.

Second, selection pressure could have been so that one sex is signaling they’re a wealthy person.  Similarly, altruism is a great indicator of having excess resources, whether in terms of time, energy, food, skills, or whatever.  Those that give away much of their wealth freely are those that have so much wealth that they can selflessly give it away, even without any expectation of return.  Charity is an activity only of those that don’t need it themselves.  

Further Possibilities for the Evolution of Altruism

Now as I’ve said before, this isn’t an either or decision.  It could be that altruism was (and is) a signal to the other sex in both of these ways.  It is also, I think, likely that every one of the possibilities I have given so far – kin selection, reciprocity, the commitment problem, sexual selection – and will give are all involved in the evolution of psychological altruism to at least some degree.

To read the other possibilities for how psychological altruism could have evolved, check out the other posts in my series.

Part One

1. Old Heuristics and Kin Selection
2. An Extra Aid to Reciprocal Altruism

Part Three

5. Social Selection and Keeping up With Norms
6. Group Selection, Cooperation, and War

Paul Chiariello (Chief Editor, Rutgers & Yale University)
DSC_0484Paul Chiariello graduated from Rutgers in 2009 after studying Philosophy and Anthropology and has been running around the world ever since. Currently he is on the Board of Directors of the Rutgers Humanist Community, Co-founder of the Yale Humanist Community, and Director of the Humanism & Philosophy Curriculum for Camp Quest, Inc.  Paul has a MSc in Comparative Education from Oxford, completing his field research in Bosnia on ethno-religious identity and conflict, and has spent a year studying philosophy of ethics and religion at Yale on a PhD fellowship.  He has also worked with research organizations at the UN and in DC, as well as schools abroad in Uganda, Kenya, India, Indonesia and Germany.

2 responses to “The 6 Ways Altruism Could Have Evolved: Part 2, Commitment & Sex

  1. Pingback: The 6 Ways Altruism Could Have Evolved: Part 1, Kinship & Reciprocity | Applied Sentience·

  2. Pingback: Evolution and altruism | SelfAwarePatterns·

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