Human Gland Probably Evolved From Gills

The human parathyroid gland, which regulates the level of calcium in the blood, probably evolved from the gills of fish, according to researchers from King's College London. Professor Anthony Graham and Dr Masataka Okabe suggest that the gills of ancestral marine creatures, which were used to regulate calcium levels, were internalised rather than lost when land-living, four-limbed animals the tetrapods evolved.

Guesser: Professor Anthony Graham and Dr Masataka Okabe, King's College London