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Sponges are more closely related to us than some animals with a nervous system:
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)
(Score: 2) by Spamalope on Friday May 19, @02:47AM
Exactly. 'Old' lineages have survived multiple mass extinction events, and those filter out organisms wasting calories on unneeded function. We see many instances of losing function, just not these two core ones that require an extreme adaptation to lose.