Penguins may be immaculately tailored but it seems they may be a bit tasteless in other areas; specifically that of, erm, taste.
This is according to new genetic research which indicates that the smartly turned out flightless birds of the Antarctic have the genes to detect only two of the five tastes (which are sweet, sour, salty, bitter and "umami" - all others are your sense of smell, according to science). Penguins only have the DNA to pick up sweet and sour, apparently.
"Penguins eat fish, so you would guess that they need the umami receptor genes, but for some reason they don't have them," says Jianzhi (aka "George") Zhang of the University of Michigan. "These findings are surprising and puzzling, and we do not have a good explanation for them. But we have a few ideas."
One theory goes that penguins' Antarctic ancestry may lie behind the loss of the flavour-pickup genes. Abilities based on these flavours wouldn't have been much use on the chilly austral continent, and may have died out as global cooling set in there long ago.
We are told:
Unlike receptors for sour and salty, the taste receptors required for detecting sweet, umami, and bitter tastes are temperature sensitive. They don't work when they get really cold anyway. In other words, even if penguins had those taste receptors, the receptors wouldn't be much use to many of them.
Indeed it seems that the waddling birds may have completely dispensed with all sense of taste, despite still having the genetics to use sour and salty. Zhang says their tongues don't seem to have taste receptors, and in all likelihood, penguins - despite being dressy - have no taste at all.
"Their behavior of swallowing food whole, and their tongue structure and function, suggest that penguins need no taste perception, although it is unclear whether these traits are a cause or a consequence of their major taste loss," comments the prof.
Zhang and his colleagues have published their research in full boffinry detail here, in the learned journal Current Biology. ®