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.

The surprising strategy employed by weaver ants has left scientists stunned, as their unique approach to teamwork could potentially transform the field of robotics. A recent study published in Current Biology reveals that individual weaver ants actually increase their contribution to tasks when working in larger groups, defying the long-standing problem of declining performance with team size.

This phenomenon was first observed by French engineer Max Ringelmann in 1913, who found that human teams’ total force increased as more people joined in, but each individual’s contribution decreased. In contrast, weaver ants (Oecophylla smaragdina) have evolved to form super-efficient teams where individuals actually get better at working together as the group gets bigger.

Lead author Madelyne Stewardson from Macquarie University explains that each individual ant almost doubles their pulling force as team size increases. The researchers set up experiments enticing weaver ant colonies to form pulling chains to move an artificial leaf connected to a force meter. They found that the ants split their work into two jobs: some actively pull while others act like anchors to store the pulling force.

The key to this mechanism lies in the “force ratchet” theory developed by co-lead author Dr Daniele Carlesso from the University of Konstanz. Ants at the back of chains stretch out their bodies to resist and store the pulling force, while ants at the front keep actively pulling. This method allows longer chains of ants to have more grip on the ground, better resisting the force of the leaf pulling back.

The discovery has significant implications for robotics, as current robots only output the same force when working in teams as when alone. Dr Chris Reid from Macquarie’s School of Natural Sciences says that programming robots to adopt ant-inspired cooperative strategies could allow teams of autonomous robots to work together more efficiently.

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The discovery of the Denisovans has revolutionized our understanding of human evolution. In 2010, scientists uncovered the first draft of the Neanderthal genome, confirming that early humans had interbred with these extinct relatives. Just months later, a finger bone found in Denisova Cave revealed the presence of another unknown hominin group, the Denisovans. Like their Neanderthal counterparts, researchers have found evidence of interbreeding between modern humans and Denisovans.

According to Dr. Linda Ongaro, Postdoctoral Researcher at Trinity College Dublin’s School of Genetics and Microbiology, this phenomenon is not unique to a single event but rather the result of multiple interbreeding episodes that shaped the course of human history. “It’s a common misconception that humans evolved suddenly and neatly from one common ancestor,” she notes. “The more we learn, the more we realize interbreeding with different hominins occurred and helped shape the people we are today.”

Despite the limited Denisovan fossil record, scientists have managed to uncover significant evidence of their genetic legacy. By leveraging surviving segments in modern human genomes, researchers have identified at least three past events where genes from distinct Denisovan populations were incorporated into the genetic signatures of humans.

These events reveal varying degrees of genetic similarity to the Denisovan remains found in the Altai region, suggesting a complex relationship among these closely related groups. In their review, Dr. Ongaro and Professor Emilia Huerta-Sanchez highlight evidence that Denisovans lived across a vast territory stretching from Siberia to Southeast Asia and from Oceania to South America. Different groups appear to have been adapted to their own specific environments.

Moreover, scientists have detailed several Denisovan-derived genes that provided survival advantages in different parts of the world. For example, one genetic locus confers tolerance to hypoxia (low oxygen conditions), which makes sense in Tibetan populations; multiple genes confer heightened immunity; and one gene impacts lipid metabolism, providing heat when stimulated by cold, giving an advantage to Inuit populations in the Arctic.

Dr. Ongaro emphasizes that there are numerous future directions for research that will help tell a more complete story of how the Denisovans impacted modern humans. These include more detailed genetic analyses in understudied populations and integrating more genetic data with archaeological information, which could reveal currently hidden traces of Denisovan ancestry.