The evolution of intelligence is linked to sexual selection.

Researchers focused on evolution have uncovered a number of surprising patterns. For instance, recent studies suggest that toothed whales, which experience menopause, live longer than whales of similar size but from different species. Additionally, children's interest in risky play is part of an evolutionary strategy that allows them to learn more about their environment and assess their own abilities.

Experts from the Australian National University (Australia), the German Primate Center, Göttingen University (both in Germany), and Stellenbosch University (South Africa) have identified one possible reason why male mosquitofish (Gambusia holbrooki) have developed relatively high cognitive abilities. The findings of their study were published in the scientific journal Nature Ecology and Evolution.

The mosquitofish is a tiny fish resembling a guppy. It inhabits Central America and is now found worldwide. According to researchers, male mosquitofish possess impressive problem-solving skills. For example, they can navigate mazes, circumvent transparent barriers, and remember and distinguish colors.

The authors of the publication conducted an experiment involving mosquitofish and demonstrated that the evolution of intelligence may be linked not only to natural selection, where higher cognitive abilities aid in finding food and avoiding dangers, but also to sexual selection. According to the scientists, smarter males are more attractive to females or are better at achieving mating success.

The researchers measured the intelligence levels of male mosquitofish through a series of underwater tests (transparent barriers, color spot differentiation, etc.) and then observed their search for females and reproduction for two months. Over 2000 paternity tests revealed that the more intelligent males—those who performed better on the tasks—mated with a greater number of females and produced more offspring.

“The evolution of cognitive abilities may have been driven by sexual selection favoring males who had more opportunities for mating. Something about these males seems to give them an advantage. Females may have recognized and preferred smarter males, or smarter males may have been better at pursuing females and compelling them to mate,” the authors of the scientific article explained.

Scientists plan to continue their research to clarify the observed pattern. They suggest that it is important to closely observe mosquitofish to understand how the behavior of smarter males differs from that of less intelligent ones.