Researchers at Oregon State University have discovered, for the first time in any animal species, a type of “selfish” mitochondrial DNA that is actually hurting the organism and lessening its chance to survive -- and bears a strong similarity to some damage done to human cells as they age. The findings, just published in the journal PLoS One, are a biological oddity previously unknown in animals. But they may also provide an important new tool to study human aging, scientists said.