“Rewired for Romance: Scientists Give Gift-Giving Behavior to Singing Fruit Flies”

Rewired for Romance: Scientists Give Gift-Giving Behavior to Singing Fruit Flies

In a groundbreaking study published in the journal Science, researchers from Japan have successfully transferred a unique courtship behavior from one species of fruit fly to another. By activating a single gene in insulin-producing neurons, the team made Drosophila melanogaster, a species that typically sings “courtship songs,” perform a gift-giving ritual it had never done before.

The study reveals that the reason for this difference lies in the connection between insulin-producing neurons and the courtship control center in the brain. In gift-giving flies (D. subobscura), these cells are connected, while in singing flies (D. melanogaster), they remain disconnected. This discovery highlights that the evolution of novel behaviors does not necessarily require the emergence of new neurons; instead, small-scale genetic rewiring can lead to behavioral diversification and species differentiation.

The researchers inserted DNA into D. subobscura embryos to create flies with heat-activated proteins in specific brain cells. They used heat to activate groups of these cells and compared the brains of flies that did and did not regurgitate food. The study identified 16-18 insulin-producing neurons that make the male-specific protein FruM, clustered in a part of the brain called the pars intercerebralis.

“Our findings indicate that the evolution of novel behaviors does not necessarily require the emergence of new neurons; instead, small-scale genetic rewiring in a few preexisting neurons can lead to behavioral diversification and, ultimately, contribute to species differentiation,” said Dr. Yusuke Hara, co-lead author from the National Institute of Information and Communications Technology (NICT).

This study demonstrates how scientists can trace complex behaviors like nuptial gift-giving back to their genetic roots to understand how evolution creates entirely new strategies that help species survive and reproduce.

The research was conducted with support from KAKENHI Grant-in-Aid for Scientific Research and has been published in the journal Science on August 14, 2025.