It should be clear that the vast majority of biological interactions are largely indifferent to others, while there is also a high degree of cooperation as necessitated by the evolution of sexual reproduction. It is this level of cooperation that has also given rise to many animals living in groups or participating in group arrangements.



While there are many animals that are asocial, there are also a significant number that regularly interact and form groups of varying sizes. It should be clear that the formation of such groups is a cooperative effort, but more importantly it also gives rise to an additional consideration since there is often a “cost” associated in belonging.



In the simplest cases, groups may consist of collections of animals such as herds whereby there is no specific organization, instead the animals benefit by simply having large numbers around to provide warnings and cover as necessary. Protection from predators would improve by probability alone, since the more animals a predator has to choose from, the greater the likelihood that others will escape. This is contrasted by the opposite situation in which a single prey animal confronts a predator, where the probabilities will shift to favor the predator.



The significance of this change is that instead of animals needing to be faster or more agile to escape predators, the existence of the group dramatically increases the likelihood of survival for individuals. Instead of selection pressures causing phenotypic changes in an organism, the evolutionary pathway shifts to that of the group itself. In other words, there is now a selection pressure that ensures greater probabilities for survival in those animals that adapt to the group hierarchy which will tend to produce higher levels of cooperation among members.



As such social groups take on increasing importance to individual survival, the group itself will become subject to evolutionary selection pressures and give rise to adaptations and the “rules” mentioned previously.



As we’ve seen from earlier posts, it is important that no species become too successful, lest that success translate into competition between its own members. Therefore an equilibrium point needs to be reached to maintain the survival of individuals and the group without overwhelming their environment with offspring.



Considering a herd of wild horses as an example, we see a matriarchal social group where the females are under the control of the herd mare and mating occurs with the dominant male stallion. The division of labor requires the male to maintain the basic security of the herd and driving off the young fillies and stallions. This has been theorized as a mechanism to avoid inbreeding with the stallion’s own female offspring. Competition between males will ultimately result in the lead male being replaced, but in general, the hierarchy is preserved between all the bands that make up a herd.



We see similar behaviors in animals like elephants, which are also matriarchal societies. Although the reproductive “rules” aren’t quite as strict, the males also tend to be kept apart from the primary group unless they are mating.



It would appear that these groups offer a significantly better chance of survival for individuals and their offspring than would exist if each animal lived in isolation. In addition, it would also seem that the strategy of driving off the young males will tend to ensure that only the most successful survivors would return to compete for the role of a leading male.



In effect, the adaptation into a cooperative group will create a selection pressure to ensure that all members of the group comply with the “rules” and enforcement being provided by the group at large (by their specific behavior towards interlopers). We can easily see how such a strategy might’ve evolved in a particular direction. Using the specific example of the horses, the females are the determining factor in the size and general behavior of the herd bands. It is their selection (or cooperative agreement) regarding the male that will determine who will breed the next generation. In addition, it promotes a very narrow genetic exchange very much like that practiced in animal husbandry.

Of significance, is that the genetic contribution of one male is distributed over the much larger field of females, despite the fact that these females can readily choose any other male for breeding. In addition, it appears that the “bachelors” follow the rules, which is also enforced by the mares themselves.



The point to consider is that some males may never breed, which clearly indicates that their cooperation within the group context is much more important to their survival than passing on their own genes. This is another example of how the group promotes the survival of individuals and also affects the selection pressures on those individuals.



Other adaptations may include “part-time” groups where only certain activities gain the cooperative support of individuals, but in general the same principle applies. The survival advantage of cooperation far outweighs any conceivable benefit the organism would have by being isolated.



Without exploring all the details and nuances of various group behaviors, the general trend is clear regarding the benefit conveyed, but it is also worth noting that there are at least two other characteristics of individuals that play a role in maintaining the cohesiveness of such a grouping.



The two characteristics that will affect cooperation are; trust and personality. These two attributes are often ignored when attempting to model the results of selfish and cooperative interactions. It is presumed that the cooperative group is naively cooperative while the selfish group simply takes advantage. In truth, it’s much more complicated than that.



Trust is implicit in any group and is a requirement for the “rules” of the group to function properly. It is no coincidence that many groups involve kin that are all part of the same family and it is this requirement that would determine how successfully an outsider could be introduced into the group. It is the role of trust between individuals that provides the cohesive to act as a unit and to follow the designated leadership. Invariably a new potential group member is scrutinized and assessed in proportion to how tightly knit the group is.



The role of personality may seem unnecessary, but actually represents the range of behaviors that an animal may display, whether it is easy-going or aggressive, passive or assertive. While genes will ultimately determine what traits an animal possesses, it is equally important to recognize that genes don’t determine explicit behaviors but rather provide a range of possible behaviors which we call personality. This allows for variation in the social interactions with some being “rewarded” while others may be “punished”. In this way, the social group also evolves based on the evolution of the individuals in it. Such a mechanism ensures that animal behaviors are not “hard-wired” but capability of changing with the circumstances.



These issues are routinely at work when captured animals are to be returned to the wild. Perhaps one of the most dramatic examples relates to Keiko, the Killer Whale, and the basic problem that he had no group social skills, so even a proximal contact with a killer whale pod failed. In fact, Keiko had been specifically socialized for his role in human society and not killer whale society. Similarly the phenomenon of male gangs in elephants (after adults were separated from youths), clearly illustrates how the social group provides instruction and promotes the orderly management of the group.



In examining the ideas of group selection, or multi-level selection it is important to recognize that the animal groups do not operate on simplistic “hard-wired” levels as being all-cooperative, or all-selfish. Instead we see a dynamic that suggests that we see more cooperation among individuals that “trust” each other. This actually makes it highly unlikely for a selfish member to have much opportunity for exploitation.



In addition, it is this level of trust and commitment to the group that will ultimately give rise to another phenomenon; altruistic behavior.