For some lizards it’s easy being green. It’s in their blood. Six species of lizards in New Guinea bleed lime green thanks to evolution gone weird.
It’s unusual, but there are critters that bleed different colors of the rainbow besides red. The New Guinea lizards’ blood — along with their tongues, muscles and bones — appear green because of incredibly large doses of a green bile pigment. The bile levels are higher than other animals, including people, could survive.
Scientists still don’t know why this happened, but evolution is providing some hints into this nearly 50-year mystery.
By mapping the evolutionary family tree of New Guinea lizards, researchers found that green blood developed inside the amphibians at four independent points in history, likely from a red-blooded ancestor, according to a study in Wednesday’s journal Science Advances.
This isn’t a random accident of nature but suggests this trait of green blood gives the lizards an evolutionary advantage of some kind, said Christopher Austin of Louisiana State University.