The Gombe Chimpanzee War: A Fight Of Non-human Clans
One of the biggest impediments to studying animal behavior is, paradoxically, the human mind itself. It is a fact that we tend to humanize other living beings: if we see a cat run over in the street and another moving its paws over the corpse, we automatically think that it is trying to revive it and feels sorry. In any case, there is also the possibility that he is arranging a warm space to lie down to rest, in order to take advantage of his partner’s body heat.
The same thing happens when observing almost any living being interacting with the environment, but the reality is that the “feeling” is limited to very few animal species. Living beings experience basic short-term emotions (fear and disgust, for example), as these are adaptive behaviors that maximize the long-term survival of the community. In any case, it is difficult for us to believe that a lizard is capable of loving its offspring or that an insect feels pain the way a human does.
Ethology, the branch of biology that studies animal behavior, encounters a big wall every time it tries to explain a behavior or hierarchy in the animal kingdom: is the exhibited character a product of natural selection and does it serve a specific purpose or is it Is it a trait of the individual, not adaptive, but personal? Based on these very interesting premises, we tell you from a biological perspective what happened in the Gombe chimpanzee war
The Gombe chimpanzee war was a conflict between two communities of chimpanzees (Pan troglodytes), which occurred in the Gombe Stream National Park of Tanzania, between 1974 and 1978 The groups involved in this conflict remained at the time in the Kasakela community, the study population of the famous primatologist Jane Goodall. Due to its monitoring since the 60s, this has become the animal population with the longest study history in the entire history of biology.
It all started with the split of the main group. Six males, three females and their offspring separated from the established population, receiving the baptism of the “Kahama community.” The Kasakela nucleus was left with a total of eight males, 12 females and their offspring. Later we will delve into the possible reasons for this division, but for now it is enough to keep the name of both nuclei.
First blood took place on January 7, 1974, when a group of six males from the Kasakela core ambushed and murdered one of the Kahama males while being fed.
This was the first time that the murder of a chimpanzee by another of its relatives has been recorded. Brawls are common between populations of the same species in many taxa, but ending the life of an individual that shares genetic load is completely counterintuitive.
We will spare you details, as it is enough to know that each of the Kahama males fell over the years. In the end, The Kasakela population completely conquered the land of their murdered former relatives, although stability was not possible until quite some time later Other chimpanzee populations bordered the Kahama terrain, so the division of territories was irregular.
The chimpanzee war and kin selection
As we have seen, the fact that two different populations attack each other is nothing new, even though they may belong to the same species. The biological unit that must always be kept in mind is the population since two nuclei of specimens separated by an ocean, no matter how much they belong to the same species, will never exchange genes nor will they be exposed to the same environmental impositions.
The most interesting thing about the Gombe chimpanzee war is that what happened challenges, to some extent, ideas of kin selection According to this theory (Kin selection) some living beings favor the reproductive success of their most direct relatives, although this means a decrease in the biological fitness of the individual in the process.
Kin selection could be confused with altruism, since it seems that one individual helps another in a selfless way, but this is not the case: the more similar the genome is between both individuals (for example, siblings), the more likely it is that this behavior will occur. “altruistic”. This theory is based on the concept of “inclusive fitness”, or in other words, that not only the children that an individual produces matters, but also those conceived by their relatives.
Hamilton’s rule explains this interaction R refers to the relationship between the recipient of aid and the donor, B represents the “benefit” of the donor by acting as an altruist, and C refers to the biological cost of the donor. If helping a relative has more benefits than costs, sociality and community life may be encouraged.
The war already described challenges this idea, since we can assume that the chimpanzees in conflict were inbred. By killing a male from the same population (at least it was a few months ago), the killers are “shooting themselves in the foot”, since part of their inclusive fitness (genes in the form of relatives) is being destroyed without an apparent reason.
So why did this confrontation between animals happen?
At this point, it is necessary to explain the concept of “population fission”. It is more than documented that, andIn many species of mammals (including humans), population splits occur when living in groups is no longer beneficial This happens when the following parameters are met:
When any of these parameters are met (or all at once), it is postulated that a population may be at risk of splitting, regardless of how strong it was in the past. For example, imagine that in a field where there is a population of 200 chimpanzees there is a fire and half of the foraging areas are lost. If there is no food for all the members, There are two options: kill the weakest or allow them to leave
To date, there are multiple subsequent studies that have tried to explain the reason for the population fission of the Gombe chimpanzees. Some professionals argue that the Kasakela population could have been composed of two different groups at its conception and, therefore, the genetic relationship between specimens was not as great as was believed. According to this postulation, the fatal outcome was only a matter of time, since Maintaining a hierarchy between unrelated individuals is complex to say the least
However, other sources argue that there is no evidence to believe in this dual community theory. According to them, all those involved were members of the same population, but the first signs of fission began to be evident in 1971, three years before the first bloody conflict.
It is believed that the trigger for this event could have been the lack of established dominance between males from the same population or, alternatively, the increase in males in the population with respect to the total number of females. If the operational sex ratio is greatly disrupted, the population is in danger: Given the excess of males, some have to leave or be expelled.
Summary
What this tour shows us is that the Gombe chimpanzee war is an extremely interesting event, but less “poetic” than its name might suggest. In the process of humanizing the rest of living beings, we forget that they They have a concern that goes far beyond hatred, resentment or the lust for power: survival
In nature, everything is a matter of genes and adaptations: if something endangers the population, it is discarded, no matter what the cost. Therefore, the most plausible explanation for this conflict is the lack of females in the Kasakela population, which began to take effect in 1972. If the sex ratio becomes unbalanced, some of the surpluses must leave the nucleus, since their chances of having offspring are drastically minimized.
