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The Imitation Factor: Evolution Beyond The Gene

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Lee Alan Dugatkin has spent the last ten years studying imitation in guppies and in "The Imitation Factor" he explains his research and summarizes numerous other examples of imitation found in nature. His conclusion: even low intelligence animals like guppies can engage in the non-genetic transmission of behavior through imitation, and that transmission can have an impact on genetic evolution.

In carefully controlled experiments using guppies Dr. Dugatkin explores how the tendency to imitate other females in mate selection can override other mate selection preferences. Female guppies of a certain species prefer bright orange males over drab gray ones. Dugatkin places a female and a dull male in one corner of a tank and a bright male in the other and then allows a second female to observe the guppy groupings. Then the first female is removed and the observer female is allowed to choose which male to go to. The observer female shows a greater tendency to select the male she saw with the first female (Yes there is a control to make certain that the observer is not just going to the side of the tank where there were two guppies). Further, after repeated exposure to females associated with drab males, the observer female shows a preference for drab males in general.

Beyond his own research Dugatkin also details the research of others on imitation in animals. Examples include some very carefully controlled experiments with pigeons poking open boxes to get food, blackbirds learning which animals are predators, numerous studies of chimpanzees and rats who learn which foods are edible from their presence on other rat's whiskers. In addition to those examples he also discusses when imitation is likely to a useful survival strategy, and points towards other researchers who have developed mathematical models for when imitation is more likely to occur and what affect it will can have on the evolution of a species.

Dugatkin is clearing attacking the idea proposed by others such as Susan Blackmore that humans are different from other animals because of the ability to imitate. If behavioral imitation is as common place as Dugatkin's evidence shows, these arguments are certainly erroneous. With his numerous examples and carefully controlled experiments Dugatkin does a very credible job of proving his point. I have just a few quibbles with this book. Dugatkin's definition of culture is a bit too loose for my preference. I would only count the guppies as being cultural because they can develop a general preference for drab males that can be transmitted, whereas Dugatkin would consider it culture even if the preference only applies to one male at a time. I am not certain under his definition whether a distinction can be made for fleeting imitation examples like observer animals moving when they see another member of their species fleeing something the observer can not see. I would hesitate to call that culture because their is nothing to pass from generation to generation. Similarly, while a general preference for drab males learned by observing females mating is something that could pass along indefinitely, a specific preference for a single male can only be passed along until while the male still lives.

In addition, although he does an excellent job with his own specialization he unwilling to fill the gap left if the concept of human as super imitator idea is incorrect. Early on in the book he suggests that there might be two types of cultural evolution, that which he describes for guppies and other animals and a sort of 'runaway' cultural evolution which develops its own rules independent of genetic evolution, but he never really explains this distinction in any detail. Of course this is not the main thrust of his work anyway.

Overall though this book should be valuable reading for anyone interested in cultural evolution. Highly recommended.

This is a wonderful book - clearly written, authoritative, up-to-date, and fun. I recommend it to all people interested not only in the study of animal (and human) behavior, but also to those who want a good read about what researchers are up to. Dugatkin is a first-class biologist and a great writer with a good sense of humor.

Lee Alan Dugatkin is a first-rate animal behavior experimentalist whose specialty is the guppy, as well as a game-theoretic modeler. Most welcome is Dugatkin's talent for popular exposition of animal behavior research.

This book is a very general exposition of animal behavior theory for the general public, with a special emphasis on epigenetic transmission of information, which Dugatkin equates with cultural transmission. He does quite a good job, and I would recommend this book to curious newcomers to the field. Dugatkin is especially good at weaving general themes (e.g., the various explanations of mate choice) with the specifics of particular
experiments.

My concern here will be as an animal behaviorist whose specialty is human beings. Humans come into the picture in the first sentence of Dugatkin's book: "We desperately want to think of ourselves as somehow distinct from other life forms on our planet...Currently there is the sense that we are unique because

"culture" is found only in humans...As we shall see, culture is not humanity's gift to the universe." (p. ix). There is no doubt but that Dugatkin is correct, and indeed, it is impossible to understand human culture as divorced from the broad sweep of cultural phenomena across species. The attempt to do so is a major flaw in sociological and anthropological approaches to human culture--but that is another story to tell.

While Dugatkin's assertion is correct, and his efforts to motivate his position are quite successful, it is curious that he does not place his argument in intellectual context. John Tyler Bonner's pathbreaking The Evolution of Culture in Animals (Princeton University Press 1984) is not mentioned, nor is Eva Jablonka and Marion Lamb's ambitious Epigenetic Inheritance and Evolution (Oxford University Press 1995) are not mentioned.
Nor is the Baldwin effect, which is a major causal link from culture to genes (Baldwin, "A New Factor in Evolution", American Naturalist 30 1896).

Dugatkin is quite orthodox in taking the gene-culture coevolution definition of culture as "information", a definition anchored in the two great contributions of Cavalli-Sforza and Feldman, Cultural Transmission and Evolution (Princeton University Press, 1981), and Boyd and Richerson, Culture and the Evolutionary Process (University of Chicago Press, 1985). In brief, this view holds that culture is information concerning the organism's physical and biological environment. While the basic biological information transmission mechanism is genetic inheritance, epigenetic transmission may also be fitness enhancing, and when it is, we can expect cultural transmission in animals. I do not dispute the fact that culture includes epigenetic information transmission. For instance, as Dugatkin stresses the tendency for previously mated male guppies to be desirable to unmated females may be due to the fact that older female guppies "teach" younger females who the desirable males are (although there are other plausible explanations of this phenomenon). I do believe, however, that (a) imitation in animals is categorically distinct from the "teaching" and "learning" that typically occurs in human cultural transmission; and (b) the culture-as-information definition of culture is considerably too narrow to embrace all of human culture, and misses what is particularly unique about human culture.

On the first point, most animal behaviorists have come to accept the idea that, pace bird imitations of vocalizations, animals do not imitate complex learned behavior directly. Rather, the contiguity of an individual to a conspecific carrying out a particular learned behavior increases the probability that the individual will stumble upon the same behavior. For instance, if a chimp discovers how to use a stone to smash open a food item,
her child will be frequently in situations where stones and the food item are contiguous, and hence is more likely to discover the complex behavior. But the behavior is neither "learned" from the parent, or "taught" by the parent to the child. For more on this topic, the reader might refer to Tomasello and Call, Primate Cognition (Oxford University Press 1997), Daniel Povinelli, Folk Physics for Apes: The Chimpanzee's Theory of How the World Works (Oxford 2000), and Marc Hauser, Wild Minds: What Animals Really Think (Henry Holt, 2000).

The most distinctive characteristic of human culture, however, is the existence of ethical norms and values. A value such as "dress modestly," "work hard and do not succumb to temptations that yield only short-run pleasures," and "forgive those who transgress upon you," are deeply cultural forms, but they do not involve objective information about the world. Unlike a technique, such as how to fashion a tool, where to look for prey, or what types of things are edible, an ethical value has no scientific truth value. Of course, one might assert that if one follows a certain norm, certain material results will obtain (e.g., long life, good after-life, high fitness, happiness), but humans follow norms for their own sake, and
even when these good results are not expected. In sociology this is called the internalization of norms (see, for instance, Grusec and Kuczynski, Parenting and Children's Internalization of Values: A Handbook of Contemporary Theory, John Wily & Sons 1997). The human capacity to internalize norms is thus akin to the programmability of human goals, since the key factor in an internalized value is that people \emph{conform to the prescribed behavior for its own sake, and as a goal of action, rather than a means towards the realization of other goals. As I argue in "The Hitchhiker's Guide to Altruism: Genes, Culture, and the Internalization of Norms", Journal of Theoretical Biology 220,4 (2003):407-418, the programmability of the preference function is key to human prosocial behavior, quite on par with the accumulation and transmission of the types of cultural techniques associated with improving the ability to exploit the physical and natural environment.

I would have preferred that Dugatkin include in his analysis both the factors leading to a commonality of culture across species, and the factors involved in the special cultural position of humans, but just dealing with the first of these makes for a quite informative and interesting contribution.

Charles Darwin established a very important preceding when wrote a notable essay about the theory of emotions. Following these traces, the biologist Dugatkin analyzes the imitative behavior of the animals, since the little fishes guppies till the blackbirds concluding the imitation process is the motive force of the cultural evolution.

You will find passionate and conscientious work of fervent interest for any kind of reader.

I am sure it's a good book.... if you like to take that leap from animals to humans in a essentialist, and reductivist sense.