[_ Old Earth _] Common Heat Reduction Techniques within Differing Species

[Blue-Lightning]

I have been thinking lately about the use of sweat by humans and by horses (other animals use sweat but only abnormally) to cool themselves. You see, both creatures have sweat glands developed to release about 15% of their heat overload and both do it in a strikingly similar way - only they are not strikingly close in proposed ancestory.

Think about it this way, here we have two species which (under DToE) are no more closely related than being within the mammal criteria and yet both organisms use the exact same technique for heat reduction. Yet when we look at their ancestor's we do not see this technique at all. Most of you already know where this is going; how odd is it that the same biological method would be developed in two species where the method could not be passed on (keep in mind the complexity of sweating and all of the neurological/physiological demands).

More still is that when I researched heat reduction among animals, I found that this commonality in uncommon species is almost rampant. Camels and hamsters both have the ability to extract an insane amount of moisture from their digesting food. Once again, this is not an easy extension of a common trait, but a very complex process. And once again, the two are not closely related* as far as I am aware.

Another form of heat protection is migration - and two types of animals (granted not species) which follow in a very similar migratory style for a similar purpose are very, very different: birds and butterflies. Now this one may seem silly at first, but what we must remember is that both butterflies and birds are cold blooded and as such, both must avoid temperatures which would make their bodies unstable. Thus, both migrate. But what is interesting is that they don't just migrate, they actually migrate to fairly specific locations without ever having performed the action before. And though the means are different, the result is not.

Interesting quandry for evolutionists, I would think...

BL

 

[SyntaxVorlon]

Evolutionary traits can develop in parallel. There's nothing stopping birds from migrating just because they're not related very closely to butterflies. And I'm not an animal behaviorist so I can't say how butterflies and birds migrate.

Flight itself is developed in parallel, though through different means.

What would be particularly astonishing would be if the genetics of it were the same.

 

[Rogue 9]

Birds are not cold-blooded. Far from it in fact, especially for smaller birds; their metabolisms work at an insane rate just to provide the energy necessary for flight. This produces a lot of body heat.

Migratory birds do so because of the lack of food that occurs when the ground is covered in snow and frozen solid, not because they would slow down in the cold like reptiles. Still, the other points are quite interesting.

 

[Barbarian]

There's another point. Physiologists have found that birds tend to use up more calories resting and trying to stay warm in cold weather, than they use up flying for an equal amount of time, when they generate a huge amount of metabolic heat.

And all mammals have some sort of sweat glands. Dogs have them on their feet, for example. To be effective, sweating must not dehydrate the animal. This means that animals that sweat must be fairly large. Horses, humans, and bears sweat, among others. They have a good supply of glands. Cats, squirrels, and other small mammals don't. They would dehydrate too easily.

So it's just a case of profuse sweating being found in larger mammals. Some larger mammals don't sweat much, BTW.

 

[Rogue 9]

Elephants do not have large amounts of sweat glands, if they have any at all. :P So much for large mammals.

 

[Barbarian]

Elephants have evolved a slightly different approach. When they are hot, their system opens up blood vessels in their ears and they fan them, radiating heat rapidly.

They also head for water and splash and spray each other. The point is that small mammals do not sweat. We only find that cooling method in large animals. That some animals do not sweat just means that different cooling adaptations have occurred in different animals, after they became larger. Since the ancestors of horses, cattle, men, and elephants were small creatures, we would not expect sweating or any particular method of cooling to be common for all of them; it had to evolve in response to the decrease in realtive surface area, after they diverged from a common ancestor.

 

[Blue-Lightning]

Birds are not cold-blooded.

Oh good grief... what a terrible goof on my part. :

Horses, humans, and bears sweat, among others. They have a good supply of glands. Cats, squirrels, and other small mammals don't. They would dehydrate too easily.

Actually, you're incorrect, Barbarian, to the best of my knowledge. Cats actually do have sweat glands and quite a lot of them - more so than dogs even (which you comment on later [and no, dogs dont' just have sweat glands on their feet, they have a few on their skin, but just don't use them normally]). But as with both cats and dogs, sweating only occurs in extreme situations - normally only as a last defense against overheating. Cats are actually have a very unique way of keeping cool in that they just bathe themselves... it performs the exact same function as sweating but conserves water loss (unless it's a jaguar in which case just jumping in the nearest stream is the best idea).

Elephants have evolved a slightly different approach. When they are hot, their system opens up blood vessels in their ears and they fan them, radiating heat rapidly.

This is actually the same technique that humans have except that instead of widening vessels in our ears, we widen ours' in our cheeks (think about red cheeks and that tingling sensations when we get hot and exercise). The major difference is that elephants use it as their primary heat cooling techniqe and thus, they need a huge amount of area to cool the amount of blood they have (so they get ears only Ross Perot would want). Whereas we only use our cheeks when sweating and normal radiation won't do (and bounce our radiation up by about 10%), elephants use it all the time.

That some animals do not sweat just means that different cooling adaptations have occurred in different animals, after they became larger.

Don't many rodents have a modified sweating mechanism? I know it doesn't occur in desert rodents, but I'm fairly certain that others sweat near their posterior when extremely hot so as to cool off. I've heard that it's because then the water falls on to their tail which, already acting as their major radiator, is boosted up a couple of notches in its effectiveness. That's why if you've ever seen a pet rat expired from being in a hot car (so I'm told) that it is sitting in a pool of water.

...it had to evolve in response to the decrease in realtive surface area, after they diverged from a common ancestor.

I think though that it is the commonality that some of these animals have which is amazing. I mean, you would think that if different species developed sweating at different times, that they would have developed it in different ways - but that's not the case. These species which don't have a common ancestor* with sweating techniqes usually have almost exact sweating physiological structures and psychological responses.

Let me know if I'm wrong on any of this, Barb - I know you've got a little bit of experience on me... to the tune of a few decades.

BL

 

[Rogue 9]

Well, my only pet rodent is a guinea pig. No tail. :wink: Actually, they're not technically rodents, more closely related to rabbits. But its close enough. No sweating that I ever saw. When the room got hot, she'd get under her water bottle and ram up the ball bearing to soak herself. :

 

[Blue-Lightning]

Guinea pigs are most closely related* to beavers and porcupines I believe. But seeing as they do not use the barren tail for radiation like mice, rats, etc., I wouldn't think that they would cool off in the manner discussed. Of course, I try to abstain from discussions about guinea pigs since the topic of coprography eventually comes up!

BL

 

[Rogue 9]

? I'm not sure what that is, and why would it come up?

 

[Blue-Lightning]

I'll just PM you :wink:

BL

 

[Barbarian]

Guinea pigs are indeed rodents. Technically, they are known as caviomorph rodents.

Lagomorphs are related to rodents, and include rabbits, hares, and pikas. The easiest way to tell the differnce is the teeth; lagomorphs have an extra set of incisors behind the main one.

 

[Rogue 9]

And my brother lies to me yet again. One of these days I'll learn not to trust him...

 

[Admiral Valdemar]

Another example of parallel evolution when one species discovers a trait that another one has at the same time or before it but was never in contact with it.

It's nothing strange at all, bats found how to use sonar as well as dolphins and neither are related.

 

[Barbarian]

Actually, almost all mammals have a primitive sort of echolocation. Go into a large, empty open building, like a warehouse, and walk about, with your eyes closed. You will discover that you can know when you are getting close to a wall, by he sound of footsteps. With a little practice, you can detect a lower ceiling, too.

 

[M82A1]

Guinea pigs are most closely related* to beavers and porcupines I believe. But seeing as they do not use the barren tail for radiation like mice, rats, etc., I wouldn't think that they would cool off in the manner discussed. Of course, I try to abstain from discussions about guinea pigs since the topic of coprography eventually comes up!

BL

But you don't believe that animals are 'related', because that is a reference to common descent. :roll:

 

[M82A1]

Actually, almost all mammals have a primitive sort of echolocation. Go into a large, empty open building, like a warehouse, and walk about, with your eyes closed. You will discover that you can know when you are getting close to a wall, by he sound of footsteps. With a little practice, you can detect a lower ceiling, too.

I can tell if somebody is talking directly at me by the pitch of their voice.

 

[Blue-Lightning]

Another example of parallel evolution when one species discovers a trait that another one has...

I hope you're not saying that one species sees another one with something they want so they decide to develop it... Sorry, I just had - the wording made me think of it right away! :

It's nothing strange at all, bats found how to use sonar as well as dolphins and neither are related.

Well, I think that's a poor example in relation to the near mirror-like process of sweating in certain mammals since the dolphin and bat techniques of sonar/radar (take your pick) are so dissimilar.

But you don't believe that animals are 'related', because that is a reference to common descent. :roll:

Don't you roll your eyes at me, young man... or lady.... or elderly person... oh, you get the idea.

Actually it's more complex than that - I don't like the ill-defined classification of species because there're discrepencies and disagreements regarding them among scientists.

BL

 

[SyntaxVorlon]

Another example of parallel evolution when one species discovers a trait that another one has...

I hope you're not saying that one species sees another one with something they want so they decide to develop it... Sorry, I just had - the wording made me think of it right away! :

Strawman, don't twist my wording. I'm saying they developed parallel to one another, not intersecting, they didn't mix genes.

[quote:95456]It's nothing strange at all, bats found how to use sonar as well as dolphins and neither are related.

Well, I think that's a poor example in relation to the near mirror-like process of sweating in certain mammals since the dolphin and bat techniques of sonar/radar (take your pick) are so dissimilar.
[/quote:95456]
Since dolphins' ancestors which lived on land didn't have sonar this means they developed it on their own, no help from bats. Sweating exists in rodents so it's possible that it has developed in some of the same ways. You could confirm this by studying the genetics of horses and humans.

 

[Blue-Lightning]

Strawman, don't twist my wording.

It was a joke, hombre. Un chiste.

Sweating exists in rodents so it's possible that it has developed in some of the same ways.

I think Barbarian already sufficiently dismissed this.

You could confirm this by studying the genetics of horses and humans.

Really? I would think that if common ancestors lacked the sweating mechanism and yet humans and horses had mirrored genetics regarding that process then it would give quite a bit of credence to ID.

BL