The assumption that mothers are more driven by altruism with regard to their children than fathers is more complex than once thought. This is the conclusion of an article published by experimental economists from Radboud University in the journal PLOS ONE. The results add qualifications to an important evolutionary theory.

When economists conduct research on decisions in families, their models include assumptions about parental altruism. They relate these assumptions to choices having to do with jobs, education, fertility, etc.. Based on evolutionary considerations, economists assume that parents are altruistic towards their children and that mothers are more altruistic than fathers.

Altruism under conditions of scarcity

The evolutionary-biological Assymetric Parental Altruism (APA) Hypothesis predicts that mothers are more altruistic with regard to their children than fathers, because mothers are certain that their children are their own, while there is always some uncertainty on the part of fathers. From an evolutionary perspective, it is thus more advantageous for mothers to invest in their children than it is for fathers.

Nevertheless, this assumption had not yet been experimentally tested under conditions of scarcity, in which it is most relevant. For this reason, researchers Jana Vyrastekova, Jeroen Smits and Janine Huisman of Radboud University (Economics/Development Studies) collaborated with a Tanzanian colleague to conduct experiments in rural Tanzania to investigate the altruism of mothers and fathers under a variety of conditions.

Mother and father, mother or father

'The results of our experiment indicate that mothers are indeed more altruistic', explains Vyrastekova, 'but only if they bear complete responsibility for the decision. The difference between men and women disappears when the partner is involved in the decision. The addition of a social element thus affects the asymmetry in altruism between fathers and mothers. We are the first researchers to draw this connection between the traditional biological theory concerning altruism, the influence of the social context and the process of taking economic decisions'.

Sandals, sugar or cash

In the experiments designed by Vyrastekova and colleagues, Tanzanian parents with small children received rewards that they had earned previously in another experiment. The parents could choose between something for themselves (money or sugar) or a pair of sandals for their children. The sandals were of relatively high value, and the experiment took place in a region where most children must walk long distances to school or to work in the fields, either barefoot or in worn-out sandals.

One or two parents

In the one-parent condition, fathers and mothers were asked to participate without their partners being involved in the experiment. In the both-parents condition, both partners participated in the experiment. When selecting the reward, the participants did not know what their partners had chosen.

In the one-parent condition, the mothers were clearly more likely to select the sandals than the fathers were. This difference disappeared, however, in the situation in which the partner was also involved. The frequency with which the men selected the sandals was approximately the same in both situations. The reason for this outcome will require further study.