Animals that help others care for their young, whether or not they are relatives, do so as a result of natural selection: they generate an evolutionary advantage for the entire group, favoring the chances of survival and expansion of the entire herd, according to one research carried out at the University of Bern of which the Spanish scientist Irene García Ruiz is the main author.
Irene García Ruiz is currently a PhD student in Behavioral Ecology and Evolution at the University of Bern, where she arrived in 2018. She previously studied Biology at the University of Valencia and Animal Behavior at the University of Exeter (England). She has also been a researcher in the Department of Zoology at the University of Cambridge, in the Kuruman River Reserve, South Africa.
In his doctorate he studies the mechanisms involved in the evolution of cooperative breeding, using both theoretical models and empirical experiments. In particular, he studies the rent-paying hypothesis (when individuals help out as payment in order to stay in the dominant’s territory) and group augmentation in relation to kin selection.
The journal Science Advances published last week an investigation led by Irene García and Professor Michael Taborsky, both from the Institute of Ecology and Evolution of the University of Bern, which we reported on in another article, according to which altruism is an expression of natural selection because it provides a survival advantage.
In this interview with T21, Irene García explains the advantages of cooperative breeding in the animal kingdom, as well as the mathematical model she uses in her research. She also discusses the selfish benefits of altruistic behavior and concludes that our species has achieved greatness due to our ability to be social and cooperative.
What is the advantage of cooperative breeding?
From the perspective of the dominant breeding pair, the advantages are very clear. Assisting in rearing increases its reproductive success, that is, how many offspring it produces and the survival of those offspring.
What is not clear is what benefit helpers get, since helping is expensive. One possibility is that it increases the reproductive success of individuals with whom they share a kinship and, therefore, they may also pass on their genes indirectly through their relatives.
However, we also observe cooperative reproduction between unrelated individuals. In our research, we show that individuals can gain survival benefits from living in larger groups, and therefore it pays to help the dominant breeding pair produce more offspring because this in turn will increase the size of the group. This helps explain phenomena observed in nature such as kidnapping of offspring from other groups.
What does the mathematical model applied in your work consist of?
The model is basically a computer program where we simulate natural selection on specific behaviors. In the model we then have “individuals”, these individuals must make certain decisions and the decisions that lead individuals to pass on their genes further dominate the population. In this case the behaviors we are interested in are the propensity to leave their group or stay, and the propensity to help others raise their offspring. Together, we model different environments and let natural selection choose which individuals survive and reproduce over many generations.
In the end, we can see which behavioral strategies are selected in the different environmental conditions. Furthermore, we also allow individuals to display flexibility in their behavior according to their probability of becoming breeders. So we can see how individuals adapt to different environmental and social conditions.
In this model, different ecological scenarios are defined: what do they consist of?
In our model we have different ecological scenarios. We have benign environments with low mortality and harsh environments with high mortality rates. What we found is that the selective pressures that select for cooperative breeding are different in different ecological environments.
In benign environments, where there are limited opportunities to breed independently, helpers primarily help increase the reproductive success of related breeders, while waiting in the group to inherit territory in order to breed.
In harsh environments with high mortality due to poor habitat quality or due to high predation, however, it is important to help increase group size because this offers benefits in terms of increased defense against predators or because they increase efficiency in obtaining food, for example by hunting together.
Can we still talk about altruistic behavior if it’s all about “saving skin/genes”?
This depends on the definition of altruistic behavior. We say that a behavior is altruistic when it benefits others at an immediate cost to the donor. However, true altruism cannot be evolutionarily stable in the long run.
Natural selection will only select for behaviors that ultimately help us pass on our genes, either directly through our offspring or through the offspring of family members. The question we are trying to answer is, what are the selfish benefits of seemingly altruistic acts?
How is the altruistic behavior observed in the animal world reflected in human beings?
First of all, when we talk about adaptive behaviors, we must think that most of human evolution occurred in prehistory when we were still hunter-gatherers. Therefore, we must think about what was good for us back then, which may be different from today’s needs.
In any case, the most obvious reason for altruism to evolve in our species is cooperation between family members. This includes the surprisingly long period of survival after menopause, which can be explained by the fact that grandmothers often help raise their grandchildren and thus indirectly pass on their genes.
Our research also shows the importance of cooperative group formation in harsh environments, such as those our ancestors faced, as they offer the opportunity to cooperate in dealing with environmental challenges.
Another reason to cooperate is the “quid pro quo”, which is another hypothesis about the evolution of cooperation and that seems important in our species, maintained by lasting bonds such as friendship.
All these reasons that select for altruistic behavior are carried out subconsciously, of course, mediated for example by feelings of compassion and empathy.
In short, our species has achieved greatness because of our ability to be social and cooperate. And apparently different evolutionary forces act in unison for altruistic acts to happen.