Press Release
28 Jan 2026 at 20:21
To the Point
How do new behaviors evolve? A study in predatory nematodes shows that hunting emerged by repurposing sensory systems originally used for threat avoidance. By combining genetics, neuroscience and machine learning, the researchers reveal how touch and smell were rewired to turn a harmless feeder into an active predator.
Understanding how new behaviors arise is a central question in evolutionary biology. Animals often share similar sensory building blocks, yet use them in strikingly different ways. In a new study, researchers show how evolutionary changes in sensory systems enabled the emergence of predatory behavior in the nematode Pristionchus pacificus.
Unlike its close relative Caenorhabditis elegans, which feeds exclusively on microbes, P. pacificus can actively hunt and kill other nematodes. To uncover how this behavioral shift evolved, the researchers systematically examined genes involved in mechanosensation and analyzed how changes in sensory processing affect behavior. They identified the gene Ppa-mec-6 as a crucial factor for prey detection. While several genes are required for general touch sensitivity, Ppa-mec-6 plays an additional role in recognizing prey. Therefore, animals lacking this gene not only responded less to touch but also showed severe deficits in hunting behavior.
The study also demonstrates that predation does not rely on a single sense. Instead, P. pacificus integrates mechanical and chemical information to detect and attack prey. Disrupting both sensory modalities caused far stronger impairments than disabling either one alone, highlighting the importance of multisensory integration. At the neural level, both sensory pathways converge in the same set of environmentally exposed IL2 neurons. These neurons form the first point of contact between predator and prey and act as a sensory hub that translates combined signals into attack behavior. Silencing these and other Ppa-mec-6 expressing neurons was sufficient to strongly impair predation. To capture the full complexity of hunting behavior, the researchers used automated tracking combined with machine learning. This approach allowed them to distinguish subtle behavioral states such as predatory searching and biting from non-predatory movements.
Together, the findings show how evolution can repurpose existing sensory circuits to support entirely new ecological functions. Neural systems that once helped animals avoid danger were reconfigured to also actively detect and pursue prey. By linking genetic changes to neural integration and behavior, the study provides a detailed example of how complex behaviors can emerge through evolutionary rewiring.
About the research group
The Lightfoot Lab led by James W. Lightfoot investigates how new behaviors evolve by comparing two nematode species with contrasting lifestyles. Using genetics, neuroscience and quantitative behavior analysis, the group studies how sensory systems and neural circuits were repurposed to enable predation and kin recognition.
About the institute
The MPI for Neurobiology of Behavior – caesar (MPINB) in Bonn focuses on basic research in neuroethology. International researchers at the institute study how the collective activity of vast numbers of neurons gives rise to the plethora of animal behaviors. The interdisciplinary research spans from imaging neural circuits at the nanoscale to analyzing neural activity in a freely moving and naturally behaving animal. The MPINB works closely with the University of Bonn and other local research institutes to train the next generation of young scientists in a joint graduate school.
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