The authors of the target article present a new definition of innovation, and a dichotomous key, shown in Figure 2, allows researchers to decide whether innovation exists, without conducting long-term field studies. However, longitudinal field studies may still be necessary to monitor the properties of the behavior and its changes over time. Thus, it appears that the key pertains largely to species whose behavior is either already well studied under field conditions, or to species for which future fieldwork is possible. Field studies under naturalistic conditions are the focus, although they may be impossible to carry out with many species. Innovations occurring after humans have altered or disrupted the environment may be equally important, and are becoming of increasing significance. The possibility of experiments in the field or experimentation with captive animals has been downplayed, although such studies can quickly yield far more testable data than traditional field studies can. Furthermore, experiments in the field or captive studies allow a depth of examination that may never be possible with conventional field studies.
Innovation and faithful transmission of innovations are crucial components of human culture. It is therefore not surprising that humans would assume the inevitability of transmission. An innovation that is not transmitted dies aborning. However, data cited in this article for nonhuman primates indicate that the reasons for transmission failure would be a productive area of study. The data presented here found only a 16% transmission rate to at least one other individual, out of the 606 reported cases of innovations. Granted that adaptive significance, relevance, duration of performance, and status of the innovator are important factors, there must also be additional reasons for such a massive failure to spread innovations. I suggest that hierarchical social structure in nonhuman primates hinders this spread by focusing the attention of conspecifics on details of rank and dominance interactions. Novel behaviors become associated with the social persona of the individual animals who first exhibit them and so are then not recognized as adoptable by others. For example, experimental studies of tool behavior in primates often demonstrate a lack of transmission to conspecifics, in spite of the fact that they have observed the behavior, and will even benefit from it (Cachel Reference Cachel2006).
Innovation is a learned behavior, because an animal must be capable of recognizing novelty as well as perpetuating it. Consequently, a memory of past events and preparation for future events is necessary for the occurrence of innovation. The authors discuss the Baldwin effect, which indicates how a novel behavior can become a species-specific behavior. However, given the definition of innovation used here, is it possible for animals considered to be of lesser intelligence or of low cognitive capacity to be capable of innovation at all? Must novel behaviors in these animals arise only by accident or improvisation before they become fixed in a population? If one considers the repertoire of very complex behaviors that occur in social insects (e.g., nest or hive construction, individuals linking together to bridge a spatial gap, fungus farming), does this article imply that such behaviors, which are formed from a series of complex actions, could never be classified as innovations, because they arose as a concatenation of individual accidents or improvisations? The origins of new behavior in animals with little individual behavioral plasticity, but with possible social transmission of novelty, is an interesting theoretical question.
The target article rightly argues that innovation is fundamentally related to questions of animal culture and intelligence. The authors focus largely on higher primate examples, and emphasize the interaction of culture and innovation. That is, culture represents a compendium of innovations, but it also preserves innovations from extinction by spreading novelty through observation and social learning. An innovation that is spread widely enough is then preserved from local extinction. Practitioners of the behavior are then saved from the necessity of reinventing it.
However, one could argue that an individual capacity for innovation might be more useful in long-lived solitary animals, or animals that live in small groups. Innovative species should also be found in cases where sociality is low or absent. This is because of the likelihood that an innovation can easily be lost through the death of an individual practicing it, or the deaths of several members of a small group. In this case, individuals that were capable of innovation could invent or reinvent solutions to problems that they encounter. One would expect that these species would exhibit high levels of exploratory behavior, and would demonstrate neophilia or novelty seeking. Attributes such as curiosity and play might also be present. Otters are an example of this type of species. Among primates, orangutans exemplify these traits, because they are long-lived and fit the classical definition of being a solitary species. Innovative species are not necessarily species with complex sociality; sociality may, in fact, be absent. On the other hand, insect societies with complex sociality may be composed of individuals with low behavioral plasticity and yet show an ability to innovate.
