Don't listen to what Charles Darwin says — "survival of the fittest" might be old news. Researchers at the University of Kansas have theorized that species that use more energy on a daily basis are actually more likely to go extinct, compared to ones that use less. Their study, published in the journal Proceedings of the Royal Society B, analyzed more than 300 million species of mollusk in order to determine that species with a high metabolism were at a higher risk of going extinct than low-metabolism species. Why mollusks?