Alice robots at work.
What’s the News: The diminutive, unassuming Alice robot has helped a Swiss research team test a core tenet about the evolution of altruism, called Hamilton’s rule. The researchers’ new study shows that even simple robots operating with simple evolutionary rules can recreate evolution’s complex interplay of selfishness and selflessness.
How the Heck:
- Each Alice bot is a trundling cube equipped with two wheels and 33 “genes” that reflect the make-up of its artificial nervous system. These genes control how well they can move around and push small disks that represent food into their nests. Because researchers wanted to do the study on a big scale (500 generations of 1,600 robots each), they actually carried out most of the action in a computer simulation of the robots, where it could be done faster and cheaper. (Previous work showed that the software version of Alice evolution was a good model of the hardware version.)
- At the beginning of the simulation, each robot was randomly assigned a value for each of its genes. Then survival of the fittest took over: The robots that couldn’t gather food effectively didn’t have their genes passed on to the next generation, which the researchers created by recombining successful genomes, just as would happen in an animal population.
- The researchers wanted to see how the robots would behave when given a chance to collaborate with robots closely related to them. So they gave the robots the option of sharing their food equally among all the others in their group. They found that when robots were around robots with similar genes, they gradually evolved altruistic behavior, choosing more frequently to share the bounty than hoard it.
- The question at the heart of the simulation was whether robotic evolution of altruism followed Hamilton’s rule, an inequality that connects the fitness cost to the altruist, the fitness benefit to the beneficiary, and their genetic relatedness. They tested out 25 different combinations of these values, and found that the transition to altruistic behavior always occurred at the point predicted by the rule.
What’s the Context:
- Kin selection is a theory that attempts to explain why, if we evolved through a system of survival of the fittest, we take care of others instead of ruthlessly brushing them off. It holds that because we share genetic material with our family, helping them out is really just a way of helping ourselves (or, more accurately, our genomes) and thus doesn’t conflict with goal of passing our genes on.
- The idea is not without controversy: E.O. Wilson, the scientist who popularized it, announced last year that it failed to hold up to close mathematical scrutiny. But it has consistently offered one of the few convincing possible explanations for altruism and still a subject of much study.
- The group has previously published studies using the Alice bots as model organisms. A 2010 paper has a detailed description of their earlier work with evolving altruistic Alices, which involved getting them to cooperate on collecting food disks too large for a single bot to push (as in the top image).
Reference: Waibel M, Floreano D, Keller L, 2011 A Quantitative Test of Hamilton’s Rule for the Evolution of Altruism. PLoS Biol 9(5): e1000615. doi:10.1371/journal.pbio.1000615
Image credit: EPFL