Metabolism is a measure of the rate at which we live life. The higher the rate, the more food is required and, generally, the shorter the life span. Warm-blooded mammals and birds have high metabolic rates, necessary to keep body temperatures elevated—it takes fuel to produce heat, whether you're talking about a stove or a living body. Not surprisingly, it takes a higher metabolic rate for a warm-blooded animal to live in a cold climate than in a warm climate, just as it takes more fuel to keep a house warm in Michigan than in Florida.
We've long known that members of the same species living under
different temperature regimes differ in their metabolic rates. We've generally
assumed, though, that this was a matter of individual acclimatization, rather than
something genetic. We may have to adjust our thinking. A recent study of birds from
different populations raised under identical conditions reveals genetically controlled
metabolic rates. Just possibly those of us with a long history in our hot desert may be
more genetically fit for it than are recent arrivals.
Contributor: Arthur H. Harris, Laboratory for Environmental Biology, Centennial Museum, University of Texas at El Paso.
Desert Diary is a joint production of the Centennial Museum and KTEP National Public Radio at the University of Texas at El Paso.