Researchers at the Max Planck Institute for Biology have produced intriguing evidence of how environmental factors and genetic adaptation can lead to evolution of novel and aggressive traits and behaviours in nematodes. The discovery of genome duplication and a new cannibalistic morph in Allodiplogaster sudhausi raises questions about how these genetic changes impact social dynamics, intra-species interactions and resource competition within nematode populations. Their findings are reported in Science Advances.