Archive for January, 2013

This week involved many introductions- after introducing ourselves and our backgrounds, we jumped into basic evolutionary theory. We discussed how replicating populations evolve and the criteria for biological evolution. There are three main criteria: some trait is variable in a population, this trait value affects an individual’s reproduction, and this trait is heritable to a parent’s offspring. From a classical perspective of evolution we need only track organisms. We can also look at evolution from a Hamiltonian perspective, which focuses more on selection for genes than selection for organisms. It’s important to remember that these are alternative, non-conflicting, frameworks for viewing biological evolution.

As well, we introduced the concept of relatedness between individuals as the probability of two individuals sharing the same genes. Thus your relatedness to your mother is r=0.5, your relatedness to your sibling is r=0.5, and your relatedness to your cousin is r=0.125. This is the source of JBS Haldane’s quip “I would [give my life] to save two brothers or eight cousins.”

We introduced several terms:

Kin selection: when an organism acts with personal cost to the evolutionary benefit of closely related members. Example: JBS Haldane jumping into a river to save two of his brothers.

Group selection: when individuals form groups and selection is operating on the group. This occurs in special cases where some groups may reproduce. Example: loss of virulence in Myxoma virus infecting Australian rabbits.

Multi-Level Selection: the idea that genes, organisms, and groups may all be the locus of selection.

Reciprocal altruism: when an individual acts with immediate personal cost with expectation (implicitly or explicitly) of returned benefit later. In the long run, individuals thus exchange benefits  Example: blood feeding among vampire bats.

Prisoner’s Dilemma: game theory problem where two individuals compete. Due to the specific pay-offs of cooperating and cheating, the rational choice of each player is to cheat, regardless of whether the other person cooperates or cheats. However, mutual cheating is a worse outcome for each player than mutual cooperation.

Tragedy of the Commons: the multiplayer version of the Prisoner’s Dilemma where each player is tempted to overuse a common good; however, this may lead to exploitation of the common good. Example: fisheries population.

Operational altruism: behavior that appears to include immediate costs to the actor and benefits to a recipient, setting aside questions of whether it was intentional or has long term benefits.


Lastly, we discussed the difference between biological altruism and ethical altruism. If we define ethical altruism as “intending to act without benefit to self”, then altruism seen in biological circumstances may or may not fulfill this definition. Evolutionary explanations always refer to what we’ve termed ‘operational altruism’. So organisms sometimes display behaviors that appear ‘altruistic’ in the ethical sense but actually aren’t. Thus operational altruism may be explained as ethical altruism AND/OR explained by evolutionary processes such as the ones above. Interesting areas we will explore in ethical altruism include self-sacrificial will and the ability to promote normative ethical principles.

As we wrapped up our class, we mentioned several questions that will come into play in the future.


  1. How do genes produce (or influence) behavior?
  2. How can we identify which model of altruism fits an observed phenomenon (particularly interesting in group selection versus kin selection discussions)?
  3. What human behaviors can we explain using a discussion of altruism?


Read Full Post »