A new study says that moles can no longer open their eyelids after adapting to an underground lifestyle, but they have still managed to retain the basics of vision.
"What we think we''re seeing in the mole is the very start of a breakdown in the eye. I think the moles would have no problem seeing light and dark," New Scientist magazine quoted Martin Collinson, a developmental biologist at the University of Aberdeen, UK, as saying.
For their research, Collinson and his colleague David Carmona studied eye development in Iberian moles, whose eyelids are glued shut thanks to their adaptation to subterranean life.
The researchers found a gene called PAX6, which tightly controls a host of other genes important for normal eye development, to be active in mole embryos.
They say that PAX6 stays on too long in moles, and loses its tight grasp on the genome, thereby causing a breakdown in the choreography of eye cell development.
According to them, the skin of their closed eyelids is thin enough to let some light shine through.
"Moles do have use for their eyes: they come to (the) surface and they have some sort of circadian rhythms," Collinson says.
He believes that congenital eye diseases in humans may also result from the same genetic changes as observed in the moles.
The study has been published in the journal BMC Biology.