"We had asked, 'Can we look at the evolutionary origins of the synapse?' " said Kosik. He explained that the marine sponge is called the most basal of all animals because the sponge ancestor probably branched off first from the original animal, before any other existent lineage.
"You had some ancestral animal that is long-since extinct, and its descendants became these modern-day sponges that we have, and there were other descendants that became the rest of the animal kingdom from jellyfish to baboons," said Kosik. "We speak of the sponge as being this earliest branching phylum, or group of animals. What distinguishes the sponge from all the other animals is that it does not have any nervous system or synapses."
He explained that the conclusion of that early work the finding that genes that encode a synapse are present in the sponge has important implications. "The conclusion of that paper said that what evolution did was exaptation," said Kosik. "This is a very important technical word. Evolution takes something that was evolved for one purpose and uses it for something else. Nature used this still-mysterious sponge structure to make the synapse, an exaptation of certain genes, which then became a key part of the nervous system."
Kosik said that another reason the discovery was important is that one of the ways that some anti-evolutionists have criticized evolution as an idea is by using the term "irreducible complexity." In other words, they say that the biology of certain organs is too complex to have developed through evolution. "How do you evolve an eye?" asked Kosik. "An eye is very complex, you can't have half an eye. You need a whole eye to function. If you are missing a piece, it is no
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| Contact: Gail Gallessich gail.gallessich@ia.ucsb.edu 805-893-7220 University of California - Santa Barbara Source:Eurekalert |