In both studies, the researchers turned to elephant genes. They analyzed the DNA of African and Asian elephants and discovered that both species had 20 copies of P53, a gene known to have tumor-suppressing qualities. The team from the University of Utah School of Medicine looked at the DNA of 60 smaller organisms, including humans, and found that most have only one copy of P53. The authors of the other study, led by researchers from the University of Chicago, analyzed the genes of elephants’ smaller ancestors, discovering that they contained fewer copies of P53. That implies that, as elephants evolved to be larger, their genetic code developed more copies of P53. When cancerous mutations occur, the genetic mutation causes them to quickly die, making them less likely to proliferate and form tumors.