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New animal family tree raises questions about the origin of nervous systems
New animal family tree raises questions about the origin of nervous systems [arstechnica.com]
A recent study challenges the idea that evolution always leads to increased complexity in animals. By analyzing gene arrangements on chromosomes, researchers sought to understand the evolutionary relationships between species. The study found that sponges, which lack muscles and a nervous system, are more closely related to humans than comb jellies, which possess both traits. This contradicts the assumption that complexity determines evolutionary proximity. The research suggests two potential explanations: either sponges and other simple animals lost nerves and muscles over time, simplifying their body plans, or nerves and muscles evolved independently in different lineages. Further investigation, such as studying the nerve and muscle cells of comb jellies in a lab, is needed to differentiate between these possibilities. The study underscores the complexity of animal evolution and challenges existing notions of evolutionary relationships based on traits and complexity.
Journal Reference:
Schultz, Darrin T., Haddock, Steven H. D., Bredeson, Jessen V., et al. Ancient gene linkages support ctenophores as sister to other animals [open], Nature (DOI: 10.1038/s41586-023-05936-6 [doi.org])
