CAN HAMILTON’S RULE EXPLAIN COOPERATION IN NON-HUMAN ANIMALS
Cooperation is a trait found in a variety of animals. We, humans, share the capacity to cooperate with members of our species with Meercats, elephants, lions, geese, gorillas and many other social creatures. These animals poses the ability to and often practice helping others when they can directly get something on return and even when they cannot. From a Darwinian perspective, this is irregular. Survival for the fittest is the fundamental law of Darwinian evolution. It alludes to competition between the animals with different traits to winnow out the unfit and leave only the animals with the best fit. Therefore, benevolence is unexpected in this evolutionary view, yet it exists in abundance throughout the world. This paper examines whether Hamilton’s rule can explain cooperation in non-human animals
Hamilton’s rule describes an animal’s altruism and cooperation in relation to kinship. William Donald Hamilton was an evolutionary biologist who codified this relationship Hamilton defined inclusive fitness as “the animal’s production of adult offspring stripped of all components due to the individual’s social environment leaving the fitness he would express if not exposed to any of the harms and benefits of that environment and augmented by certain fractions of the harm and benefit the individual himself causes to the finesses of his neighbors. The fractions in question are simply the coefficients of relationship“. The rule is expressed mathematically as, “RB > c”. Where ‘C’ is the cost to the actor, ‘R’ is the genetic relatedness between the actor and recipient, and ‘B’ is the benefit (Oli, 2003). The equation means that if the costs of helping is less than the benefit, then it pays to help or be altruistic.
The conflict between altruism or cooperation and the traditional Darwinian idea of evolution is apparent. The latter proposed that only the fittest survive. That species and individuals with different traits are in a state of continuous competition against one another. Those who are best adapted to their niche or environment survive and thrive while those who are not, die out. Cooperation disrupts this ideology. When animals cooperate, they help the weaker ones survive. Meercats, for instance, are small mammals that would find it hard to feed and watch out for predators, but since they cooperate, while some look for food, others look out for predators. Therefore, whereas a single member would be easily picked off by an eagle or hawk, collectively, they can avoid such a death.
Cooperation is, however costly, and this is addressed in Hamilton’s law. Altruistic acts often take a toll on the actor (Taylor, 2016). For instance, in the meerkat illustration mentioned earlier. The individuals that stand guard bear the opportunity cost. The opportunity cost, in this case, is that they miss out on an opportunity to feed as they look out for threats. The individual member could instead be gorging himself on food like the rest of the group. Hamilton’s law explains this choice. Meerkats are social creatures that live in groups of up to thirty individuals. These packs are comprised of individuals from related family units. Dominant meerkats breed while the rest take turns taking care of the offspring and other roles in the pack. Therefore, these packs are made of very closely related individuals. According to Hamilton’s relatedness of an individual actor to the recipient of the action determines how likely they are to cooperate. In these families, the meerkats are very cooperative with one another, regardless of personal cost. However, interactions with other packs are extremely aggressive and can lead to injuries and even fatalities. In this manner, these creatures demonstrate that the cost of the benefit of being altruistic to one’s own family far outweighs the cost. However, the cost of being altruistic to strangers is far too great to bear, and thus they’d rather fight than cooperate.
Hamilton’s law, however, cannot explain all animal cooperation. For example, the relationship between an oxpecker and a rhino (Plotz and Linklater, 2020). The two have almost no relation to each other; therefore the ‘r’ in the formula approaches zero. However, the woodpecker will risk its personal safety to pick parasites off the animal. The benefit to the rhino of having a handful of ticks picked off its body multiplied by a number approaching zero is not greater than the risk the bird exposes itself to. Therefore, not all cooperation can be explained by Hamilton rule. Other criticisms have been made of the rule. For instance, these cooperative gestures may just be steps taken by family units to maximize its progeny. Therefore they are not altruistic but at all since they directly favour the actor or group (LEIGH Jr, 2010).
In summary, Hamilton’s rule cannot completely explain non-human animal cooperation. Some of these actions are taken by animals to give themselves a competitive advantage over rivals by improving their progeny’s likelihood of survival. Others are mutually beneficial relationships, with almost no relationship between the animals involved. However, cooperation has a clear advantage and does indeed improve the likelihood of survival.
Reference list
LEIGH Jr, E.G. (2010). The group selection controversy. Journal of Evolutionary Biology, 23(1), pp.6–19.
Oli, M.K. (2003). Hamilton goes empirical: estimation of inclusive fitness from life-history data. Proceedings of the Royal Society of London. Series B: Biological Sciences, 270(1512), pp.307–311.
Plotz, R.D. and Linklater, W.L. (2020). Oxpeckers Help Rhinos Evade Humans. Current Biology, 30(10), pp.1965-1969.e2.
Taylor, P. (2016). Hamilton׳s Rule in finite populations with synergistic interactions. Journal of Theoretical Biology, 397, pp.151–157.