Galef, B.G. 1995. Why behaviour patterns that animals learn socially are locally adaptive. Anim. Behav. 49:1325-1334

Laland, K.N. 1996. Is social learning always locally adaptive? Anim. Behav. 52: 637-640.

Galef, B.G. 1996. The adaptive value of social learning: a reply to Laland. Anim. Behav. 52: 641-644.

(Tim Wright)

This series of papers debates the extent to which behavioral traits learned socially by animals are locally adaptive. The debate is started by a polemic from Galef on the supposed inadequacies of theoretical models by Rodgers (1988) and Boyd and Richersen (1988) that predict that socially-learned traits can sometimes be maintained in a population even if they are maladaptive. Galef insists that such maladaptive social traits never occur (although the empirical evidence to support either position is pretty scant.) He states that the problem with these models is that they do not allow modification of socially learned traits by individual learning based on rewards (psych term) or selection (bio term) from the environment, and that such rewards are ubiquitous. Laland later points out that while this is true of the Rodgers model, it is an incorrect interpretation of the B & R model and several others that were ignored by Galef. Thus this criticism is moot, although Laland points out that some models do assume an inverse relationship between the amount of social and individual learning for an individual, which is probably not often valid.

Galef goes on to make a few interesting points. One is that the origin and maintenance of behavioral traits should be considered differently, and we know little about how new traits are introduced into a repertoire. Second, he draws attention to the Staddon-Simmelhag (1971) learning model which makes the unusual proposition that the absence of reward for a given behavior will lead to its elimination from a repertoire rather than requiring presence of a reward to strengthen. I’m not sure that this is an important distinction, but it makes sense to me when I think of social interaction reinforcing learned vocalizations in birds, rather than there being stronger selection for certain types of vocals. He ends by citing some examples of social learning (rats and pigeons on food preferences and songbird song learning) and states " stable, socially learned behavior patterns that do not garner disproportionate rewards from the environment . . should be rare and ephemeral, rather than common and persistent" because socially learned traits that are not rewarded are either eliminated or changed through individual learning.

In addition to pointing out Galef’s misunderstanding of the models, Laland describes three situations in which it seems social learning might propagate traits independent of their fitness consequences. First is when learned traits may be functionally equivalent and selectively neutral, perhaps in an ESS-type equilibrium. Second is when a trait is maintained through social learning is adaptive but not the most adaptive of all possible choices. An example is when a circuitous route to food is maintained through fear of predation even when shorter, more profitable routes exist. Third is when maladaptive social traits exist because the consequences of a behavior are not fully perceived; an example is cannibalism by the Fore of New Guinea that maintained the disease kuru. For all of these it remains an open empirical question how common these situations are in animals.

Galef responds weakly but insistently on his main point. One is left with the suspicion that some of his insistence derives from his focus on rats and their eating patterns, which are traits that are strongly selected and have a strong component of both individual and social learning.

My own thoughts: Neither author treats other factors that might potentially introduce or maintain maladaptive traits in a population, such as (by analogy to genetic processes) dispersal, drift, or inbreeding for populations or fluctuating selection, epistasis, hitchhiking, or pleiotropy for specific traits. It seems worth considering whether such factors could theoretically play a role in maintaining maladaptive cultural traits or if there is any empirical evidence from animals.