“Ants reduce investment per worker in one of the most nutritionally expensive tissues, for the benefit of the collective,” Matte explains. “They are shifting from self-investment to a distributed workforce.”
The power of the collective
The researchers think the pattern they observed in ants reflects a more universal trend in the evolution of social complexity. The transition from solitary life to complex societies mirrors the transition from unicellular organisms to multicellular organisms.
In a single-celled organism, a cell must be a 'jack of all trades', performing every function necessary for survival. In a multicellular animal, however, individual cells often become simpler and more specialized, relying on the collective for protection and resources.
“It's a pattern that reflects the evolution of multicellularity, where cooperative units can be individually simpler than a solitary cell, but collectively capable of much greater complexity,” Matte says. Still, the question remains open as to whether under-investing in individuals to boost the collective makes sense for creatures other than ants, and it's most likely less about nutritional economics than about sex.
Replaceable servants
The research focused on ants that already have a reproductive division of labor, in which workers do not reproduce. This social structure is probably the most important condition for the cheap worker strategy. For the team, this is why, at least so far, we haven't found similar evolutionary patterns in more complex social organisms like wolves, which live in packs – or humans with their astonishingly complex societies. Wolves and humans are both social, but retain a high degree of individual self-interest regarding reproduction. Ant workers could be made expendable because they do not pass on their own genes – they are essentially extensions of the queen's reproductive strategy.
Before looking for signs of ant-like approaches to quality versus quantity dilemmas in other species, the team wants to take a closer look at ants. Economo, Matte and their colleagues are trying to extend their analysis to other ant tissues, such as the nervous system and muscles, to see if the cheapness of individuals extends beyond the exoskeleton. They also look at ant genomes to see which genetic innovations made the shift from quality to quantity possible. “We still need a lot of work to understand the evolution of ants,” says Matte.
Scientific progress. 2025. DOI: 10.1126/sciadv.adx8068
