Did Sweating Evolve To Keep Us Cool Or Expell Excess Salt?

What's your answer to the problem of how early humans managed to evolve a profuse sweating mechanism, which requires a large quantity of fresh water in near constant supply, in increasingly arid conditions when they would have been prey to many open flatland predators and unable to defend these all important water sources?

 

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Clearly your premise is flawed, our sweating is not profuse, people do not require large quantities of fresh water, as they are able to live in arid areas, and sweat, and cool themselves.

But to clue you in, we used our intelligence, and tools. That separates us from many other species, and helps us survive in inhospitable environments, and prevail against predators.

 

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It IS compared to all other savannah animals, we are one of the hottest and sweatiest creatures on land.

It still wouldn't have been easy in those scary early days. The predators were much more formidable than today remember. The semi-aquatic ape hypothesis where a heavy sweating mechanism evolved in a coastal environment is a good fit of the facts. It's an undeniable contender at least.

 

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You've clearly never ridden at horse.

Were they? How did we get to become apex predator, if they were better than us?

No it's not a good fit at all. It's cherry picking factoids and building a straw man around them.

 

Wrong on all three counts.

 

Er, the 2nd was a question, how can a question be wrong?

Comprehension FAIL.

 

Do tell more. I've continued watching this forum in hopes that somebody might have something new to say about this argument.

 

Incidentally, I think that it was combination of the expelling of excess salt and a cooling mechanism based on a sea breeze due to a semi-aquatic ape existence that had a sudden increase in salt intake due to drinking semi-salt water and seafood.

 

And why do horses sweat? Did they have aquatic ancestors too?

 

Well, maybe horses evolved sweating to cool, but that doesn't mean humans did. Convergent evolution, anyone?

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We've already covered this in post #11;

And another thing; horses have a grazing technique which is especially suited to seaweed, due to the yanking action. I've worked with horses and remember being surprised when they suddenly take a mouthful of leaves and twigs from overhanging trees along the road. Is this a characteristic of picking seaweed from boulders and rock egdes in the distant past? The more I think about it, the feasible a river delta existence seems to be. Also sweating is a poor cooling mechanism in not only humid conditions (which it is in the Congo basin) but also in cold conditions! Just on TV last night I saw how farmers shave the backs of the dairy cows so that they don't suffer from pnuemonia due to the sweat!

Seaweed eating ponies

 

OK, but horses walk on all fours, which totally diminishes the argument for apes becoming bipedal to exploit the same terrain.

Sorry, but it just doesn't add up.

 

No, you've got it wrong again. I'm saying that it was just our ancestors that exploited the coastal river estuary terrain, and developed their 'throwing arm' from the use of sea-rounded rocks. Bipedalism came before this, their protection being from the use of wooden clubs and branches.

 

Nonsense. Mammals, including humans, with excessive salt intake don't sweat profusely. They urinate profusely. Our kidneys are well adapted to expelling excess salt -- to a point. Consume too much salt and you don't sweat profusely. You die.

Urine can contain up to 2.2% salt concentration. Blood plasma contains less than 1% salt. Sweat contains even less salt than does plasma when our sweat glands are functioning properly. The sweat gland mechanisms that act to retain salt in our bodies can be overwhelmed by profuse sweating, making the salt concentration in our sweat at most equal to that of blood plasma. Our sweat glands are a very poor mechanism for eliminating salt compared to our urinary system.

If anything, human perspiration is evidence against the aquatic ape conjecture rather than for it. Our sweating is a very good adaptation for life in savannah-like environments but is a maladaptation for life in hot and humid coastal environments. People who have lived for generations away from a savannah-like environment who then move to such an environment acclimate within a week or so. They begin sweating earlier, sweat more profusely, and produce less salty sweat.

Compare this to a hot, humid coastal environment. Our sweat glands malfunction. We succumb rather than acclimate to such an environment. We learn to do everything slower because our system is ill-suited to such an environment. A savannah-like climate is ideal for us.


Bottom line:

To the contrary. You've come up with yet another incredibly stupid idea. The evidence speaks for itself.

 

Please read post#62 from DoubleD. He DOES sweat when he eats salty food!

Could the sweat mechanism have been different in our evolutionary past though? Ans = yes.

This is simply rubbish. Coastal environments are always fresher than inland due to the sea breeze.

Apart from the fact that heavy sweating requires a constant supply of fresh water. Apes and monkeys in hot humid environments don't sweat or smell like humans do. We are unique in this respect. It isn't as straight forward as you think it is..

 

Anecdotal evidence doesn't count for much for one thing. For another, he might well be allergic to what he ate. Many people have adverse reactions to eating peanuts. You need to find a medical study, not anecdotal evidence, that describes the mechanism you are proposing.

In the sense you describe, no. The adaptation would have been with a mechanism that already existed for this very purpose: Our urinary system. This exact adaptation has occurred in multiple species. Sea and desert mammals produce urine that is significantly saltier than sea water because they don't have access to fresh water. The adaptation you are talking about is nonsense. The sweat glands in all mammals are adapted to avoid expelling salt.

That is rubbish. Move to the US Gulf Coast. You will change your opinion quickly. The tropics are even worse than the Gulf Coast.

So what? You act as if this is a problem. Humans are quite capable of finding water in environments much harsher than savannah conditions. Primitive humans have lived and continue to live in primitive conditions in deserts.

Apes and monkeys live in environments where sweating is not advantageous. That we sweat so much is a sign that we evolved in a dry climate, not a humid one.

 

Oh puh-leeese.

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You’ve made a lot of unsupportable assertions in this thread, but this is one of the more absurd ones. You may be right, but that’s just the point – there’s no way to tell. The Aquatic Ape Hypothesis is not science. It’s nothing more than supposition and selective interpretations without any means of quantifiable scientific verification. It’s just one big thought experiment that does nothing to displace current accepted evidence-based theories for the evolution of hominids.

This thread is in serious danger of being moved to Pseudoscience.

 

The possibility of an allergic reaction to peanuts might be a good point. I have not experienced any other side affects (that I'm aware of) from eating peanuts, with the exception of some intestinal discomfort/gas that I get when I eat 1/2 - 1 lb at a time. I have always liked nuts and have never noticed any physical reactions to any types.

The amount of sweating also slowed somewhat after the first few days though the food intake did not change. I stopped eating both peanuts and popcorn for a couple of weeks and the profuse sweating seemed to stop at that time. I have again started eating popcorn regularly, but no peanuts for weeks now--no unusual sweating. I will make a point to buy more peanuts and add them to my diet again and see what the affect is.

For the record, the peanuts are much saltier than the popcorn I buy. Nothing else in my diet has changed, though I have reduced my already low salt intake by making further reductions of it in what I cook--trying to compensate for the popcorn.

Also, I live in Phoenix, which is an arid environment most of the time. When it is humid (happens during monsoons), I still sweat just as much in the heat, it just doesn't evaporate quickly and I do a lot of wiping to eliminate buildup.

 

I'd be interested to find if the sweating increases from saltier food intake without eating the peanuts. Then the peanut allergy proposal could be eliminated. Perhaps you could binge on potato chips for a while?? btw what are your opinions on the sea breeze of a coastal environment for heavy sweaters? How do you rate the benefits compared to inland?

D H; why is this thread so popular then if it is an open and shut case?

 

I'll try the peanuts first because I want to eat them. Whether or not I notice the same affect, and after I've run out of peanuts, I'll drink a saline solution and also report what I find. I don't want to add the extra salt to my food because I don't want to acquire a taste for it.

As far as sea breezes compared to inland, I'm not sure what you are looking for. Lower temperatures and breezes tend to remain more constant around coastal areas. Also, coastal areas are somewhat hazy, providing a sort of shade from the sun's direct glare. Inland, the combination of high humidity, heat, and stagnant air is a miserable environment. As far as sweating, I will sweat much more in the inland environment I just described because the body is trying to cool itself but the high dew point and stagnant air prevents it from doing it efficiently.

Not sure what you are looking for, but I would prefer 115 degrees in the shade in an arid environment with a small breeze over 95 degrees in the shade in a humid environment with no breeze. However, if you surround my 115 degree shade with concrete (radiating 140+ degree heat), I might change my mind. I ride a motorcycle and I have to wear jeans right now in 110-115 degree weather to insulate my legs from the much hotter heat coming off the road.