According to Darwinian theories, nature is locked in a vicious cycle for the survival of the fittest. This cycle involves the evolution of behaviors and adaptations that allow a species to survive and reproduce over time. A process known as natural selection. However, by strictly following these theories, one would not be able to address the question, “If animals, such as the young and old, play, what benefit does this provide to the survival of the species?” It is a question that has challenged behavioral ecologists for quite a long time.
At La Selva Biological Station, a group examined this phenomenon within a band of coatis; a species known to exhibit infanticide behavior. Infanticide is the act of killing an infant who may or may not be biologically related. In this exceptional experiment, the group was able to study the social structure of coatis ranging from infanticide behavior to highly affiliative interactions with juveniles.
The white-nosed coati is a member of the Procyonidae family (the same family as raccoons) and is considered to be the most social of the group. The social structure consists of a band of adult females with juveniles of both sexes. During the mating season, some bands permit one or two males to travel with them until the end of the breeding season, after which the band of juveniles is left to travel on their own.
At the end of two years, the sexually matured males will leave the group becoming solitary, reaching sexual maturity at three years old. It is at any point in the first three years of age that older male coatis may target bands with juveniles. However, throughout the course of this study, no males were observed to commit infanticide, instead they found an extremely high percentage of play (22% of the time spent together).
Play bouts were defined as spontaneous and voluntary. These bouts were identified by contexts not contributing to their survival; exaggerated/awkward movements, relaxed states (not hungry, engaged in intense competition, or not overly stressed). Play fighting was the predominant form of play and it involved biting, rolling, chasing, tackling, kicking, jumping on top of each other, squeaking, among various others. Of the 24 play bouts exhibited over the 12 days by the juveniles, adult males were present for 22 of the occasions; much more than expected, while adult females did not exhibit any play bouts with the juveniles. For one of the first times documented, coatis showed an extremely high percentage of friendly encounters with juveniles.
It is still unclear what drives the adult male behavioral interactions with juveniles. The benefits of infanticide are still not well understood on a broader scale, especially in a species that exhibits so much active affiliation (play). However, the high variation of behavior in coati species would be an excellent model system for investigating the benefits of infanticide. Future studies should focus on prevention mechanisms through long term studies in which genetic relationships are also studied.