She See Synapses in the Sea Sponges
Lab Notes : ‘Irreducible Complexity’ is Reducible After all
The intelligent design camp also argues that some biological structures are just too darn sophisticated to have evolved through random mutation and natural selection. They must therefore have been designed by an intelligent agent. In particular, since complex structures have lots of components, how could the components have been just hanging around for eons waiting for the final component to emerge? Think of it this way: if you don’t already have all the other components of a mousetrap, why would you keep a spring around? A spring is only useful if you also have the base, the bar and the rest. This is the argument called “irreducible complexity,” and it has proved very persuasive to the public.
Which brings us to the latest discovery in evolution: DNA needed to make synapses, the sophisticated junctions between neurons, in none other than the lowly sea sponge. Considered among the most primitive and ancient of all animals, sea sponges have no nervous system (or internal organs of any kind, for that matter), notes Todd Oakley, assistant professor in the Department of Ecology, Evolution and Marine Biology at the University of California, Santa Barbara. But, he adds, they “have most of the genetic components of synapses.”
The first neurons and synapses appeared something like 600 million years ago, in a group of animals called cnidarians which, today, include hydra, sea anemones and jellyfish. Sea sponges are even older.
Sponge spicules
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