Hot and Cold critters

[Aussie Pete]

One of my main objections to evolution is the divide between warm blooded and cold blooded creatures. I know something about closed loop temperature control. Anyone with an air-conditioned office or home is aware how hard it is to regulate temperature exactly.

"Creation Evolution Headlines" has produced this article on the same subject.

Warm-Bloodedness Not Explained by Evolution – CEH

 

[The Barbarian]

One of my main objections to evolution is the divide between warm blooded and cold blooded creatures. I know something about closed loop temperature control. Anyone with an air-conditioned office or home is aware how hard it is to regulate temperature exactly.

It's not as complex as some make it out to be. And some mammals are rather casual about the exact temperature they keep.

It's not just dinosaurs, birds and mammals. Tuna, for example, keep a constant body temperature.

The data suggest that homeothermy in mammals was a gradual development:

Standard Metabolism of Monotremes and the Evolution of Homeothermy.

• January 1979
• Australian Journal of Zoology 27(4)

The standard metabolic rates (SMR) of species from all extant monotreme genera were determined together with body temperatures. The echidnas, Zaglossus bruijni and Tachyglossus aculeatus, of the Family Tachyglossidae, both had an SMR 25-30% of predicted eutherian levels. The platypus Ornithorhynchus anatinus, however, had a much higher SMR. The weight-independent values (watts, kg*-075) were 0.86, 0.98 and 2.21 respectively for Z. bruijni, T. aculeatus and 0. anatinus. Body temperatures were similar, however, with means in the range 31.3-32ºC. The data are suggested to support the idea of a gradual evolution in metabolic capability rather than marked jumps in metabolic levels.

 

[Aussie Pete]

It's not as complex as some make it out to be. And some mammals are rather casual about the exact temperature they keep.

It's not just dinosaurs, birds and mammals. Tuna, for example, keep a constant body temperature.

The data suggest that homeothermy in mammals was a gradual development:

Standard Metabolism of Monotremes and the Evolution of Homeothermy.

• January 1979
• Australian Journal of Zoology 27(4)

The standard metabolic rates (SMR) of species from all extant monotreme genera were determined together with body temperatures. The echidnas, Zaglossus bruijni and Tachyglossus aculeatus, of the Family Tachyglossidae, both had an SMR 25-30% of predicted eutherian levels. The platypus Ornithorhynchus anatinus, however, had a much higher SMR. The weight-independent values (watts, kg*-075) were 0.86, 0.98 and 2.21 respectively for Z. bruijni, T. aculeatus and 0. anatinus. Body temperatures were similar, however, with means in the range 31.3-32ºC. The data are suggested to support the idea of a gradual evolution in metabolic capability rather than marked jumps in metabolic levels.

It still does not answer the question. It's just observations. The difference between cold blooded and warm blooded are not just physical. A cold blooded creature somehow knows that it has to keep warm. That in itself is amazing. A warm blooded creature has all the necessary systems in place to maintain its body temperature. I know how hard that is to do. A gradual transition from cold blooded to warm blooded is impossible in my view. Obviously there are variations between warm blooded species. That does not explain the origin of warm blooded creatures in the first place.

 

[The Barbarian]

It still does not answer the question. It's just observations. The difference between cold blooded and warm blooded are not just physical. A cold blooded creature somehow knows that it has to keep warm.

So does the Texas spiny lizard living in my front garden. It suns itself or finds shade as necessary. So does my dog. As you now see, the evolution of precise homeothermy was a rather gradual affair, with early mammals being only somewhat able to regulate their temperatures.

A warm blooded creature has all the necessary systems in place to maintain its body temperature.

Well, some do. Others, like monotremes, aren't so good at it, and their temps vary more than in other mammals.

I know how hard that is to do.

I'm open to your evidence that God was unable to make the world so that this kind of thing couldn't evolve. What do you have? God is a lot smarter and more effective than some creationists are willing to let Him be.

A gradual transition from cold blooded to warm blooded is impossible in my view.

Since there are still transitional forms living today, reality is much more convincing than your feelings. Since we know that dinosaurs and pterosaurs and likely therapsids (ancestors of mammals) were homeotherms, it's not at all surprising that birds and mammals retain that adaption.

But tell us what steps in the evolution of homeothermy do you think are impossible to evolve. List the biological mechanisms for homeothermy and then explain why you think they couldn't evolve.

What do you have?