The fruit fly species whose connectome was mapped and used in the simulation.Drosophila is a genus of small flies, and one species in particular — Drosophila melanogaster, the common fruit fly — has become one of the most important laboratory animals in biology. It is a few millimetres long, lives on fermenting fruit, and completes its entire life cycle from egg to adult in about ten days at room temperature. That short generation time, plus the ease of keeping thousands of them in small bottles, made it a practical subject for studying inheritance long before anyone could sequence DNA. The fly's genome contains roughly 14,000 genes packed into just four pairs of chromosomes, and a large fraction of those genes have recognizable counterparts in humans, including many involved in development and in cancer. Because the animal is small and its wiring is finite, it also became the first creature whose full brain wiring diagram — its connectome — was reconstructed in detail, which is why it appears in simulations of neural circuits.
Thomas Hunt Morgan began using Drosophila in his Columbia University laboratory around 1910, and his group's discovery of sex-linked inheritance and of mutations carried on chromosomes established the fly as a model organism. The full connectome of the adult fly brain was published in 2024 by the FlyWire consortium.
The fruit fly develops through distinct stages: embryo, three larval stages, a pupal stage in which the body is rebuilt, and the adult. This metamorphosis means the same set of genes is reused in different contexts, which is part of why the fly is informative about how genes control body shape. Its nervous system is built from a fixed and countable number of cells, so individual neurons can be identified and traced from one animal to the next. That reproducibility is what makes a complete wiring map meaningful: the same cell in two different flies occupies the same place and connects to the same partners.
Drosophila is used in genetics, developmental biology, neuroscience, and drug testing, and its connectome serves as a testbed for simulating how a real nervous system produces behaviour.
About 60 percent of Drosophila genes have a human counterpart, and roughly 75 percent of the genes known to cause disease in humans have a recognizable match in the fly.