Teaching Evolution

A blog devoted to teaching evolution, both in our schools and in our communities.

Tuesday, July 26, 2005

Evolution of Taste

I've always thought the sense of taste is one of the most interesting fields of study for people who want to know more about evolution. Why do we like things that are sweet and dislike things that are bitter? Presumably because there was some evolutionary advantage to seeking out sweet foods and avoiding bitter foods.

Researchers have found new evidence that an aversion to bitter tastes has been advantageous to human evolution.

In new work, researchers including Nicole Soranzo of University College London and Bernd Bufe of the German Institute of Human Nutrition have shed light on the potential role natural selection has played in forming our present sensitivities and protecting us from harmful natural chemicals. The research team analyzed the nucleotide sequence of a human gene encoding a bitter-taste receptor that mediates recognition of a class of naturally ubiquitous, but toxic, cyanide-releasing compounds. By analyzing sequences from a large sample of individuals representing 60 human populations, the researchers found evidence that specific variants of the receptor gene have been strongly favored in the early stages of human evolution. Employing additional gene sequence analyses, the authors estimated that the favorably selected versions of the receptor gene arose prior to the expansion of humans out of Africa.

The researchers went on to show experimentally that such variants of the receptor, when expressed in individual cells, conferred an increased sensitivity toward several harmful compounds found in nature.

The work strongly supports a pivotal role for bitter-taste perception in toxin avoidance in humans, an attribute that could have come into particular play during periods of expansion into new environments. More broadly, the work contributes to the debate on the mechanisms governing the evolution of chemical sensory perception and on the role of diet as a selective force in human evolution.

The research (full study not online) is featured in the July 26 Current Biology.


At 1:24 PM, Blogger dhodge said...

I heard a piece on NPR yesterday about about some new research that has proven that cats lack the ability to taste sweetness. No hypothesies were presented that explained why cats lost (or never developed) the ability to taste sweets, however.


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