Two comments in response to Jennie Brand's recent post on cold climates
and body fat:
1. I think the idea that seals and whales live in one of the coldest
climates might be challenged by oceanographers and climatologists. The
whales are obligate ocean dwellers, the seals facultative, but in either
case the ocean is nowhere close to the terrestrial temperatures in the
polar regions. The penguins of Antarctica would be a better species
choice. And they go IN and OUT of the water in addition to surviving
brutal temperatures. But I think the focus should be on conditions
affecting HEAT loss rather than TEMPERATURE. Whatever the temperature,
the conductivity of water is the crucial factor compared to air. I
believe people have succumbed to hypothermia in the summer in the Sierra
Nevada after falling into a cold mountain stream and coming out with
soaking wet clothing just as a serious (though not necessarily cold) wind
comes up.

2. While penguins probably have fat layers I doubt they compare with whale
blubber. But most animals adapted to cold do have less exposure of their
extremities. In hot climates the reverse is functional, e.g., the large
ears of elephants which serve as cooling surfaces, esp. important for
large animals like elephants since body surface expands as the square of
body dimensions while  mass (and therefore metabolic heat capacity)
expands as the cube of linear dimensions. Whatever their body fat content,
I suspect that modern penguins are descended from species with much
greater wing surfaces (relative to body mass) than the extant penguins.

An analogous argument has been presented in regard to human evolution,
i.e., the tall thin Masai have a greater surface to mass ratio than short
stocky Aleuts, Eskimos, or Yakuts--but how good is the data unless it
reflects a comprehensive view of many ethnic groups over a wide geographic
range?

John Martinson   Facilities Planning  Univ of Nevada-Reno