A new study led by researchers at the University of Chicago offers insight on how a “zombie” gene plays a key role in protecting elephants and other large animals from developing cancer. “Peto’s Paradox”, the lack of correlation between body size and cancer risk has intrigued and confounded cancer researchers for decades. In basic terms, big animals (think elephants, blue whales) should equal more cancer, simply because their bodies contain more cells and undergo more cell divisions.

Slower metabolic rates and slower growing tumors may play a role, but the University of Chicago researchers point to another factor – extra “zombie” LIF genes, including LIF6 (a leukemia inhibiting factor pseudogene), which is up-regulated by the master tumor suppressor gene p53 in response to DNA damage. When activated by p53 these “zombie” genes respond to damaged DNA by killing the cell.