The Shape of Life . Origins

I'm obsessed with learning where we came from. And what I mean by that is not who your mother and father are, or your grandparents, but rather where do the organisms come from that gave rise to complex animals like us? -- Mitch Sogin

Dr. Sogin picking up sponge

Video: Sogin studies sponge DNA

Molecular Biologist Mitch Sogin, of The Marine Biological Laboratory at Woods Hole, Massachusetts, recently sent shock waves through the scientific world when his genetic research supported the placement of sponges at the base of the animal kingdom.

Sogin made this discovery by extracting DNA from a sponge and investigating one gene common to all animals. After painstakingly sequencing this gene, he compared its nucleotide sequence (represented by letters) to that of the same gene in other animals like worms, mammals, insects and more. Little variation of this gene in different animal groups would signify the groups were closely related while large variations would represent a more distant relationship. After comparing all the groups, Sogin traced out an evolutionary family tree, knowing that the animal at the base of the tree would be our oldest ancestor. He discovered that sponges indeed, were the most basal group that must have laid the foundation for all animal life to follow. "The sponge was the first animal with the genetic blueprint for living large," Sogin says. "All animals are based upon that same blueprint."

Woods Hole, MA
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