People in their language recognize basic tastes - salty, sweet, sour and bitter. And thanks to specific receptors can recognize and fifth taste, umami called. The body transmits the information that the right to enjoy a substance with a higher content of glutamic acid, ie that consume meat. Although the existence of this "meaty" flavor was not until 2000 scientifically described, today it is considered that it normally sees most animals. Penguins between them does not, however, despite the fact that consumers are almost exclusively fish. As noted Jianzhou Zhang of the University of Michigan: "It's kind of an evolutionary puzzle, which still do not find an appropriate answer."
Many birds, such as chickens or finches perceive sweet taste. Still have receptors that allow them to detect the presence of acidic or umami taste. Beyond Discovery tapered flavor spectrum of penguins standing genetic research that on penguins and imperial ring conducted Zhang colleagues in China. "Repeatedly sequenced part of the genome, and could not find functional genes for taste receptors," says Zhang. "When we looked at their DNA in more detail, we found that it was not a mistake. Penguins really lack a functional gene groups for the development of receptor sweet, bitter and umami taste. "
To explain why, in the course of evolution penguins impoverish their range of tastes, are the University of Michigan scientists have only theories. It is worth noting, for example, the initial occurrence of penguins in extremely cold environments. And while the full development of taste sweet, bitter or umami is tied to a specific temperature is felt to salty or sour sufficient and frost. "So we can assume that the penguins on the evolutionary path not taken anything extra than what they need in the chilly environment," says Zhang . "Which might not have the joy of their contemporary descendants, who went from cold Antarctic closer to the equator." What did it was for scientific theory if it had existed alternative hypothesis.
The second option is that penguins through specific construction of their language have developed taste buds. Whether first lost mouthfeel, and only then taste buds, of course, is not certain. Their language is short, covered with solid surface horny layer. Its primary purpose is to enjoy, but hold twitching fish in the direction polykajícího esophagus. "Penguins swallow whole fish, and maybe not at all about enjoying some interest," says Zhang. "At what stage of development actually lost three of five flavors but not yet really do not know. "
Source: Ekolist.cz
Author: Radomír Dohnal
