Abstract
Eusociality, where largely unreproductive offspring help their mothers reproduce, is a major form of social organization in social insects and other animals. An increasingly documented feature of eusociality is that mothers induce their offspring to help by means of hormones, pheromones, or behavioral displays, with evidence often indicating that offspring help voluntarily. The co-occurrence of widespread maternal influence and voluntary offspring help may be explained by what we call the converted helping hypothesis, whereby helping originally arising from maternal manipulation subsequently becomes voluntary. This hypothesis requires that parent-offspring conflict is eventually dissolved—for instance, if the benefit of helping increases sufficiently over evolutionary time. Here we show that maternal manipulation of offspring help enables the mother to increase her fertility to such extent that parent-offspring conflict is transformed into parent-offspring agreement. Such conflict dissolution mechanism requires that helpers alleviate the total percent life-history trade-off limiting maternal fertility, and results in reproductive division of labor, high queen fertility, and honest queen signaling suppressing worker reproduction, thus exceptionally recovering diverse features of eusociality. This mechanism is widely applicable, thus suggesting a general explanation for the origin of eusociality, the prevalence of maternal influence, and the offspring’s willingness to help. Overall, our results explain how a major evolutionary transition can happen from ancestral conflict.
Competing Interest Statement
The authors have declared no competing interest.
Footnotes
Introduction, Results, and Discussion expanded; Figures 1, 2, and 3 revised; Figure 4 added; Supplementary Information updated.
