Agriculture and cultural ecology

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Large brains evolved because hunting and gathering is hard and requires intelligence? Think about this. Rats, birds, whales, lizards, spiders... all hunt and/or gather. It is the de facto standard means of subsistence for the animal kingdom. If it required giant brains, wouldn't all animals have huge brains like ours? Yes, indeed-ie. But that isn't we see. There must be another reason for our brain.

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Human foraging is efficient, not hard. Don't confuse the two. It takes training. It's also not just large, it has many specialized regions that allow certain functions to develop in a cultural context. Those animals are able to function without training and survive quite well without it. Their behavior is instinctual. Humans on the other hand have to be taught.

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I am not sure if there is a consensus in the field, but the theory I favor for the initial push to big-brains involves where are ancestors lived and how they survived. Our ancestors lived in a very hot and sunny part of Africa. Animals in this environment become quite sluggish during the middle of the day. This includes the hunters-- the cats. Humans are very good at keeping cool. We have little hair and sweat a lot. Body proportions are such that heat escapes rapidly. In other words, we could function during the middle of the day when other animals, both prey and predator, are at their weakest. It was adaptation to this niche that provided the initial push for brain size. How? Our brains are huge, but we don't actually need all it to survive. There is a lot of redundancy. This is easily demonstrated by investigating modern brain trauma cases. Some people loose large parts of their brain and still function relatively normally. Heat kills brain cells. Since we were operating in a very hot niche, there was a need for redundancy, for backup brain cells-- hence, brain size increased.

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I'm supposing that you are assuming the old myth about humans using only 10% of their brains. Most brain cells are not neurons with 90% of them being mostly glial cells. The brain has many specialized features, the loss of any one of them may make the individual incapable of functioning normally. It is not a general purpose organ. Many people lose small portions of their brain and never function normally again.Even after hominids left the hot confines of Africa, the brain continued to increase in size with Neanderthals attaining cranial capacity in excess of 1500 cc. They were a cold weather hominids as well. Then you have to consider the surface area to volume ratio in that with increased volume, the area available to cool the interior decreases in proportion to the volume. A big brain would be a liability in a hot environment.Your friends experience is not anything close to a conclusive or objective point about foraging. It's like saying smoking cigarettes is safe because you heard some 90 year old guy smokes 2 packs a day.------------------
Bringer of fire, trickster, teacher.

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Human foraging is efficient, not hard. Don't confuse the two. It takes training.

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You are drawing a distinction that isn't there.Sentences one and three contradict one another.

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It's also not just large, it has many specialized regions that allow certain functions to develop in a cultural context.

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"It" being the brain, I take it. What is the point?

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Those animals are able to function without training and survive quite well without it. Their behavior is instinctual.

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Yes. That is what is so foolish about your position. Everything else manages to forage but humans require what you make out to be graduate degrees to survive in the same way. It is silly.

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Humans on the other hand have to be taught.

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Primates in general are very heavy on training and low on instinct. Monkey and ape children learn most of their behaviors. They all forage just fine, and do so without inordinate amounts of higher education. Just growing up in a foraging lifestyle is adequate training. But humans, arguably the smartest kids on the block, can't pull it off?

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I'm supposing that you are assuming the old myth about humans using only 10% of their brains.

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No. I am not. And I said so in my previous post. Is this intentional misrepresentation or can you not read?

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The brain has many specialized features, the loss of any one of them may make the individual incapable of functioning normally. It is not a general purpose organ. Many people lose small portions of their brain and never function normally again.

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The traumatic loss of whole features would be a problem in the absence of modern medicine but the fact that people can suffer immense brain trauma and recover does quite dramatically prove that we don't need all of the brain we have. Luckily, however, I did not posit traumatic injury as a driving force. The driving force I propose is heat. This isn't local but effects the whole brain somewhat the way alcohol effects the brain.

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Even after hominids left the hot confines of Africa, the brain continued to increase in size with Neanderthals attaining cranial capacity in excess of 1500 cc.

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Yes, by that time the brain had been co-opted for other things.

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Then you have to consider the surface area to volume ratio in that with increased volume, the area available to cool the interior decreases in proportion to the volume. A big brain would be a liability in a hot environment.

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The brain is cooled by its blood supply, not by evaporation from its outer surface. You are complaining that the engine block cannot cool itself but you are forgetting about the radiator.The variant of the theory I posted came directly from an anthropology/primatology professor named Glassman. It is one of several theories. Others being the climatic change theory and the shellfish theory. One variant of the theory I posted, and a variant that I am starting to like, is that an adaptation to the heat-- a cranial blood vessel structure change-- allowed the increase in brain size rather than the increase itself being an adaptation to the heat.

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Your friends experience is not anything close to a conclusive or objective point about foraging.

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Sure it is. You say it can't be done. Someone did it. You are wrong. Case closed. But I can't support the claim. It is personal experience. I don't have records.How about the Texas Macaques? Japanese macaques, native to snow covered mountains, were introduced to the Texas desert in 1972. They are still getting along just fine. The monkey's weren't taught to forage, and and avoid novel predators, in the Texas desert. They made it up. Humans are not capable of this kind of innovation? I'm afraid that we are.------------------
No webpage found at provided URL: www.hells-handmaiden.com

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The brain is cooled by its blood supply, not by evaporation from its outer surface. You are complaining that the engine block cannot cool itself but you are forgetting about the radiator.

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So since the brain is cooled by the blood supply, there should be no lost cells with adequate blood flow. There would be no need to have spare cells hanging around and metabolizing food you could put to good use like pumping blood around. You would also benefit by having a smaller brain in any event.------------------
Bringer of fire, trickster, teacher.

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So since the brain is cooled by the blood supply, there should be no lost cells with adequate blood flow.

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This is completely insane. The brain is cooled by blood supply, but no system is perfect. Any mammalian brain, really, is cooled by its blood supply. It is enclosed by the skull. It can't very well evaporate or radiate its heat away directly. Human brains are better at it that most though. Still, it doesn't mean the system is perfect or that there is no need for redundancy. If this were the case you'd only have one kidney, one lung, half your liver, one testicle... Get it? Your body is full of fail-safe systems. We shouldn't need them if everything works perfectly. Things do not work perfectly all the time. High stress conditions call in the reserves and that makes the difference between a successful hunt or escape and death.Tell you what, Speel, take a trip to the equator and run around for awhile during the middle of the day. Then come back and tell me if you started to feel dizzy and confused. It won't take long for this to happen. At 114 degrees it can happen in minutes. Trust me. That effect is due to brain damage. You'll recover because your brain is very redundant. Can you honestly tell me that you'd prefer that that redundancy did not exist? And that you'd rather rely completely on the primary systems-- sweat?------------------
No webpage found at provided URL: www.hells-handmaiden.com

I can do better than going to the equator, I can just step into a suana and get over 140 F easily and still not have my body core temp exceed 98 degrees.Getting dizzy is not a sign of brain cell death. You can achieve the same thing by hyponatremia, people do this all the time in America.

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I can do better than going to the equator, I can just step into a suana and get over 140 F easily and still not have my body core temp exceed 98 degrees.

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And you were in there how long? Ten? Twelve hours at over a hundred with several hours in the middle over 120? And there was a hole in the roof so that the sun could shine directly down onto your head as it would out on a savannah? Was your water supply nearby, say, within a few steps? Or did you have to walk half a mile to get to it? How much food did you collect during that stay in the sauna? Did you chase down a bunny and club it death, or did you just sit on your butt? There is a big difference between sitting on your ass in a sauna for twenty minutes and living on the damned grasslands. That you think this is a rational comparison is amazing.

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Getting dizzy is not a sign of brain cell death.

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In association with heat stress it does signal neural damage. You really need to work on relevance.

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You can achieve the same thing by hyponatremia, people do this all the time in America.

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See what I mean? Irrelevant crap is just... well, irrelevant.------------------
No webpage found at provided URL: www.hells-handmaiden.com

John,people running around in hot climates do not have their brains lose brain cells. I have never seen any reference to this at all. If you can find a citation, use it.------------------
Bringer of fire, trickster, teacher.

heat stroke can cause brain damage...check out webmd------------------
Asgara
"An unexamined life is not worth living" Socrates via Plato

Heat stroke is not all that common in hot climates. People survive quite well and never suffer heat exhaustion or stroke.However, some drugs will increase the likelyhood that brain damage will occur if heatstroke occurs. High levels of serotonin and dopamine may help induce apoptosis in brain cells.http://www.annalsnyas.org/cgi/content/abstract/813/1/572------------------
Bringer of fire, trickster, teacher.

True, as far as it goes. However, it is very much a question of acclimation. Even those, like myself, whose recent genetic legacy owes more to northern/central Europe (Scots, English, German) find little difficulty in living in the tropics after a certain amount of time (in my case, it took about six months). However, without that acclimation period the risk of heat prostration is quite high. This probably has to do, as John has been noting, with our remote ancestors all having evolved in a hot climate. Even then, it depends on what other adaptations have taken place. I think an Inuit, for instance, would have great difficulty living/surviving in the tropics, regardless of the amount of time spent acclimating, as they have phenotypical cold adaptations that are exactly the opposite of the requirements for a hot climate (Allen's and Bergmann's Rules).

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people running around in hot climates do not have their brains lose brain cells.

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Yes, they do. Brain cells die all the time, for many different reasons. Smack your head against a wall moderately forcefully; you kill brain cells. Drink yourself into a stupor; you kill brain cells. Heat also kills brain cells. One rarely notices because the brain is so damned redundant. This redundancy, as per the theory I have been trying to describe, and hence brain size was initially an adaptation to heat stress. In other words, those individuals who had a few more brain cells faired better under the hot conditions wherein we all evolved. Heat, Hair, Sweat, and MarathonsYou stated to Asgara: [qs]Heat stroke is not all that common in hot climates. People survive quite well and never suffer heat exhaustion or stroke.[/b][/quote]Right. Because circa 2 mya we started developing some good adaptations to the climate.------------------
No webpage found at provided URL: www.hells-handmaiden.com

Brain cells do not die when you hit your head unless there is some bleeding in the blood vessels. If neurons die, they release a toxic amount of glutamate and this in turn will cause other neurons to die. With the advent of drugs known as glutamate antagonists, a great deal of this secondary damage is blocked and the damage is decreased. This is one reason why many people recover so well from stroke and brain trauma these days, they receive treatment as soon as possible that stops this secondary damage.The brain is comprised of 90% non-neuronal type cells, by and large these are referred to as glial cells. These cells will continue to replicate throughout the life of the brain, they die, they are replaced as needed.(The myelin sheath surrounding neuronal axons is comprised of glial cells.)Neurons by and large are nearly immortal they do not die and are resistant to apoptosis (Pronounced A-POE-toe-sis).The hunting technique that you are referring to is known as persistance hunting and it has been postulated that the need for remembering which animal was being stalked and the need to hunt with others was a driving force for the enlargement of the brain. Brain cell death is not the reason to increase brain size. It just doesn't happen. When you drink yourself into a stupor, most of the cells that die are the glial cells and since they comprise 90% of the volume of the brain, the brain will shrink in alcoholics. Long before most alcoholics die of brain damage, they die from liver failure. If an alcoholic stops drinking, the glial cells can recover but in severe cases, they may take years to regain proper function.------------------
Bringer of fire, trickster, teacher.

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Re: A brief primer on the brain

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LOL... Ignorance and arrogance! A winning combination! It is almost too incredible to believe.Seriously, do you research any of this stuff before you post? Or do you just make up what need?Browsing a site concerning brain injury might help. Page not found - Brain Injury Association of AmericaEspecially... Page not found - Brain Injury Association of America

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Brain cells do not die when you hit your head unless there is some bleeding in the blood vessels.

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Every wonder why football players are at risk for brain injury? Page not found - Sports Injury BulletinBoxers? BBC - 404: Not Found Soccer players? Vision Problems May Occur After a ConcussionEver wonder why one should never ever shake a baby? No webpage found at provided URL: http://newsbureau.upmc.com/medsurg1/Kochanek.htmAnswer: Physical impacts cause damage.Are you so desperate that you are willing to make idiotic statements like this? That impacts to the skull do not cause damage?I'm not sure why you are focusing on bleeding. I suspect it is so that you can pretend you have a valid objection. Not many injuries are bloodless. Practically any cell damage will cause some bleeding, even if minor.

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If neurons die, they release a toxic amount of glutamate and this in turn will cause other neurons to die.

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This is hardly news. Are you implying that neurons don't die because if they did the resulting cascade would kill ALL the nuerons in the brain? It sure looks that way. It is also a silly point. Dying cells do not start an unstoppable cascade, unless the initial trauma is past a critical threshold in the first place. Heat related trauma that is past that threshold would, out on the plains, kill the individual thus selecting against the individual's brain, removing it from the system. This is exactly the process for which I am arguing.Babies with shaken baby syndrome, by the way, have elevated glutamate levels.

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With the advent of drugs known as glutamate antagonists...

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And this is relevant to our prehistoric hunters in what way?

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The brain is comprised of 90% non-neuronal type cells, by and large these are referred to as glial cells.

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Lets take a moment to note how you are spinning what I've said. I have made no statements specific to neurons, nor to glial cells. I have very consistently refered to brain size and brain cells, yet someone reading your response would get a very different impression. Both neurons and glial cells are in the brain are they not? Damage to either the glial cells or the neurons would be damage to the brain would it not? Damage to glial cells, in fact, can cause consequent damage to nearby neurons. Neurons do fair well without them.So once again you've demonstrated your very dishonest debating tactics.

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Neurons by and large are nearly immortal they do not die and are resistant to apoptosis (Pronounced A-POE-toe-sis).

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Neurons do not die? Just above you were explaining how glutamate levels kill neurons? Something isn't adding up. Resistant to apoptosis? A big problem with head injuries is that neurons are prone to apoptosis. Page not found | Psychiatrist.comAnd lets not forget necrosis.

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The hunting technique that you are referring to is known as persistance hunting...

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Yes it is. Proposed, originally, by Grover Krantz, I believe. But I am not talking only about hunting. The ability to function during the hottest periods of the day would give you an edge in other areas as well, primarily because the other predators are at their weakest. Foraging in general would be safest while the predators are hiding from the heat.

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... it has been postulated that the need for remembering which animal was being stalked and the need to hunt with others was a driving force for the enlargement of the brain.

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Indeed, this has been proposed. Several other ideas have also been proposed. I mentioned a few in an earlier post. People like to go for the theories that stress intelligence and cognitive abilities. We like to think we are smart. Frankly, chasing an animal does not take a hell of a lot of brain power. Remembering what you are chasing does not take a hell of a lot of brain power. That memory is the key does not make sense. Some animals, with proportionally smaller brains than ours-- squirrels, or birds, for example-- have phenomenal memories for certain things. Squirrels remember where they stash their food, for example. And birds keeps tabs on stash robberies. No webpage found at provided URL: http://news.nationalgeographic.com/news/2003/08/0822_030822_tvanimalmemory.htmlCooperative hunting isn't it either. Chimps are extremely social and hunt cooperatively. They have big brains, but nowhere near the size of ours. Dogs and wolves also hunt cooperatively. We don't see a trend to big brains.

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Brain cell death is not the reason to increase brain size. It just doesn't happen.

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What doesn't happen? Brain cell death? Sorry. It does happen. And it happens under exactly the conditions I have been describing. Try again. And try harder.

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When you drink yourself into a stupor, most of the cells that die are the glial cells and since they comprise 90% of the volume of the brain, the brain will shrink in alcoholics.

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First, drinking does kill neurons. Secondly, I wonder why you specically mention alcoholism. A binge kills brain cells immediately. No webpage found at provided URL: http://www.csam-asam.org/binge_drinking_and_neuron_.htmBut here again you are trying to spin my argument. Neurons don't have to die to have their functions impaired. This latter part is the important bit.

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Long before most alcoholics die of brain damage, they die from liver failure.

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Irrelevant.

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If an alcoholic stops drinking, the glial cells can recover but in severe cases, they may take years to regain proper function.

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The brain can heal but neuronal structure is permanently altered, much like a liver will heal though its structure is permanently changed by alcoholism. Strangely, the answer given in the above article for the question "Does alcohol kill brain cells?" is "Not in the cerebellum." This is strange because the cerebellum isn't the whole brain. Alcohol does most of its damage in the frontal lobe. No webpage found at provided URL: http://home.iprimus.com.au/rboon/ALCOHOLBRAINSHRINKAGE.htmNow, to bring this back around to the topic. I brought up impacts and alcohol as examples of means other than heat that can kill brain cells. I did this because you seemed to be having such a hard time understanding that brain cells die.Brain function is effected by heat. The following isn't about cell death but it does demonstrate a link between temperature and brain function. No webpage found at provided URL: http://www.sfu.ca/mediapr/Releases/News/2000/March2000/Violence.htmlParesthesias, a neurological disorder, is associated with heat exhaustion.More info... remember, redundancy reduces the effects of the damage. A man named Falk proposed something very similar. In Falk's radiator hypothesis, brain size is a side effect of an adaptation to heat, rather than a direct adaptation. I rather like this theory as well. ------------------
No webpage found at provided URL: www.hells-handmaiden.com

John,Having actually taken courses in the neurosciences, I do have a bit of knowledge about the subject at hand. (That being brain cell death via apoptosis.)I suggest you run your theory by some neuroscientists sometime to see if it flies.------------------
Bringer of fire, trickster, teacher.[This message has been edited by Speel-yi, 10-09-2003]

Having seen the quality of your posts and witnessed the string of dishonest debating tactics, I know that you are full of sh*t. Your lame appeal to "I took some classes" only confirms the conclusion.Those classes wouldn't have any relationship to that 'field work' you claim to have under your belt-- a claim you unceremoniously dropped when asked that it be substantiated?
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No webpage found at provided URL: www.hells-handmaiden.com[This message has been edited by John, 10-09-2003]