Mystery of mole's second thumb solved
Scientists have discovered how one of the world's best diggers got its "extra thumb".
Comparing the mole's digits with those of its close relative, the researchers looked for molecular clues to the anatomical oddity.
The results show that the mole's second thumb is not a real digit but starts out as a wrist bone, the scientists report in Biology Letters.
The extra appendage helps propel the mole through its subterranean world.
BBC News - Mystery of mole's second thumb solved