From: Andy Soos, ENN
Published March 14, 2012 10:16 AM

Cats and Sweets

Cats, along with many other carnivores, are unable to taste sweets at all. Yes there are always exceptions but the typical cat like animal cannot taste sweets. Now why is this? Lions, hyenas and other pure carnivores have lost the ability to taste sweet foods. Omnivores (like humans) can taste sweets. A team of researchers from the Monell Chemical Senses Center in Philadelphia studied 12 different mammals who subsist mainly on meat and fish, and focused on their sweet taste receptor genes. Some mutation along the way changed how sweets are perceived.

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It is widely believed that most mammals perceive five basic taste qualities: sweet, umami (savory taste), bitter, salty, and sour. The receptors for
sweet, umami and bitter tastes are G protein-coupled receptors(GPCRs) Sweet taste is mediated largely by a heteromer of two closely related Tas1r (type 1 taste receptor) family GPCRs.

For decades, scientists have known that cats show no real preference for sweets. Then in 2005, researchers at the Monell Chemical Senses Center in Philadelphia published research showing that domestic cats have a mutation rendering their taste receptors unable to bind to sweet molecules. The same was true of their wild cousins, including lions, tigers and jaguars.

Seven species, all exclusive meat eaters, have lost the sweet taste receptor according to the new research. Some of those species inhale their food without even chewing. The list included bottlenose dolphins, sea lions, and spotted hyenas.

Sweet taste buds still work in mammals that need fruit and carbs, like raccoons and red wolves, showing that diet has played a part in their recent evolution. Animals who were already skipping the sweets never missed the ability to taste them.

What does that mean for cats showing a penchant for melons, or an obsession with cake? Probably that another aspect of their taste perception is attracting them, like bitter or savory flavors.

When the researchers looked more closely at the genes, they saw that, for the most part, different mutations independently disabled sweet receptors in different species.

An animal's diet, it appears, determines whether a taste tasting mutation will disappear or stick around.

What we eat affects ultimately how we may change or evolve when a random mutation pops up.

For further information: http://www.pnas.org/content/early/2012/03/06/1118360109.full.pdf+html

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