Agriculture and cultural ecology

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You argue that agriculture isn't an 'evolutionarily' valid strategy, but confuse 'average lifespan' with reproductive success-- the latter, not the former, being the relevant variable.

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I have no confusion about what it means. The replacement rate for people is currently 2.11 children per woman and it takes about 7 years to grow a child until they can survive without too much help from the parents. Given this, if a woman begins reproducing at age 15, she will be 22 when her first child can survive and in a forager context, she will have another child that is 3 by then and that child will be 7 when she is 26 with yet perhaps another on the way. She will probably be done having children by the time she is in her mid-30s having produced 4 children by then. One will probably have died before that time as well since infant/child mortality in this context is about 30%.When we look at the Neolithic transition, we see a greater percentage of women dying in their mid 20s. By this time with a birth interval of 2 years, she will have produced 5 children, of which 40% will have died before age 5 and of the remaining ones, if any are below the age of 5, their chances of survival are low without a mothers care. The replacement rate would not be met. There would be no increase in population unless there was immigration.Speel-yi writes:
A shorter lifespan for a woman means she has a decreased chance for producing adult children unless she decrease the interbirth interval from 4 years to 2 or so.

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Wrong. And it is a basic component of evolutionary biology that you have missed. A woman who lives to 80 has no more fertile time than a woman who lives to 40, or even 30 in most cases. That is why average lifespan is the wrong variable. Lifespan only matters up to the point where a woman can no longer become pregnant. Once a woman is infertile she could live to a thousand and it wouldn't make a damn bit of difference.

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The relevant variable is the average birth rate per woman. The key variable for birth rate is fat. Calories make babies. Agricultural based diets are high in carbohydrates relative to foraging based diets. Thus, birth rates go up.

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It doesn't matter if an organism produces more offspring, it does matter that those offspring survive to do the same themselves. There are also essential nutrients that are required to make a human. I covered this already and you can't simply supply calories and expect people to remain healthy enough to reproduce. They need essential fatty acids, essential amino acids and more. These nutrients are disproportionately low in carbohydrate laden diets. We are seeing a massive move away from the high carb "Food Pyramid" diet recently because it is so unhealthy. Not only is it unhealthy for the individual, it inhibits fertility.

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Textbooks may have incorrect information, though I am not sure how you would spot it. The term 'developing country' means 'developing a technological infrastructure.' This is not social darwinism. It is economics. Like it or not, a non-industrial country will be crushed in this world. It will be overrun.

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How I would spot it? Hmmm, another insult.Developing counties? They are not developing an infrastructure. They are presently being overrun. The United States has 5% of the world population and consumes at least 50% of the resources. There is no way a developing country will ever be developed and there is no intention to do so despite the propaganda the U.S. government claims.

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It takes no more training to learn to walk around and recognize what is edible. Agriculture is no easy thing.

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Could you survive without all the things that you have at hand? You are oversimplistic in your claim about foraging. Could you make a stone spearpoint? Where would you get the rock? Which type is best to use? When do the right plants come into season and which ones are poisonous? Can you butcher an animal after having killed it? Can you even make a fire?

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The human body will sacrifice the mother's health for the child, as long as there are calories enough. Aggriculturists have calories. What I said is that agriculture allows more people to live on a smaller plot of land than could foragers.

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Too much of a sacrifice will result in the death of the mother and then both mother and child die. There is a cost/benefit to each pregnancy. There are evolutionary benefits to delaying the first pregnancy and cultural constraints are in line with this by and large.I have a question for you John. Who will take care of you when you are 80?------------------
Bringer of fire, trickster, teacher.

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I was under the impression that slash-and-burn nomadic farming techniques pre-dated sedentary agricultural settlements. There are also various nomadic groups that forage for plant material, but bring herds of food animals with them. It seems unlikely to me that this was a historic starting point though.

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Swidden agriculture or horticulture is the term for "slash and burn" but it is not always slash and burn. They are not really nomadic, but they do have an extended range. The term for the intermediate stage between horticulture and foraging is collecting. This term was first used by Lewis Binford about 20 years ago. The ancient Natufians were most likely collectors with plants being collected and stored in central locations with foraging being employed for much of the protein intake.------------------
Bringer of fire, trickster, teacher.

No, I have been trying to point out a fallacy you tried to use earlier.

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Hunter-gatherer life expectancy at birth is 26 years
For horticulturalist — 19 years
John Bock - Division of Anthropology | CSUF

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And John added:

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Is this a long life to you? Is even 40 years long compared to our 80?

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Found in the thread:http://EvC Forum: Is Akhenaton the founder of monotheism? -->EvC Forum: Is Akhenaton the founder of monotheism?I merely pointed out that it is a mean that is heavily influenced by infant mortality. I then went on to point out that Predynastic Egypt had a life expectancy of 18 and this went to 17 in the Old Kingdom but finally recovered to 28 in the New Kingdom. Natural Selection produced a genotype that was adapted to the new environment and the culture improved to reduce infant mortality.------------------
Bringer of fire, trickster, teacher.

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It would take all of about a month to learn. That is the point.

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Then why would a large brain evolve in the first place? The costs of large brains are high. If they were not, we would expect to see many species with high encephalization quotients. The next closest species has a quotient about 1/3 that of humans.

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I've lived where I live long enough to know the plants. Foraging is not that hard. A friend of mine, born and raised in the city and kinda nuts, lived for months on stuff he found growing wild. It simply isn't that hard.

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And how many offspring did he produce during this time? Did he make clothing as well or did he carry the things he would need with him went he started this? I'd also be fairly sure that he lost a lot of weight during this period and exhibited some malnutrition symptoms. It is one thing to survive for a few months in an environment and quite another for a species to reproduce in that environment.------------------
Bringer of fire, trickster, teacher.

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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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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.

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.

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 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.

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.

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]

Your original claim:

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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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Falks theory involves cooling the brain, not having an enlarged brain to provide spare cells so you can afford to lose them. A criticism of the theory is more about how the brain can be enlarged, not why it grew larger. At any rate, your idea and Falks are two different things.

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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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Excuse me? You started out with an idea that is ludicrous from the beginning. Then post a bunch of links that only counter your own claim. (i.e. showing how brain damage is actually prevented by an efficient cooling system.)What is your obsession with my credentials? You would do better to stay with the facts at hand. I don't feel compelled to share my personal history with anyone on a public forum, nor did I realize that it was required by anyone.------------------
Bringer of fire, trickster, teacher.[This message has been edited by Speel-yi, 10-09-2003]

I see that Dr. Glassman is an archeologist, you would do well to consult with him about lithic technology. It's a little more involved than you have made it out to be.You have contradicted yourself with your posts, I have only pointed that out. The idea that you started out with is not supported by any of the links that you have spammed the thread with.------------------
Bringer of fire, trickster, teacher.

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Although it can make your child and you uncomfortable, a high fever resulting from an infection almost never causes brain damage. It's not unusual for toddlers to run a temperature of 104 or even 105 degrees F (40 and 40.5 degrees C) when they're sick. The important thing to remember is that your child's temperature will stop climbing once it reaches a certain temperature it won't keep going up and up. Fevers due to infection rarely top 106 degrees F (41.1 degrees C). A small percentage of normal children between 6 months and 6 years of age may have brief seizures when they're running a high fever, but even these "febrile convulsions" very rarely cause brain damage.

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To damage the brain, a fever has to go as high as 107 or 108 degrees F (41.6 or 42.2 degrees C). This rare kind of fever is generally the product of heat stroke or a severe bacterial infection. A temperature this high can start to break down the nervous system, and, in rare cases, may lead to brain damage or other long-term problems.

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Pretty simple to read.From the site:Page Not Found | BabyCenterThen using some simplistic argument about brain volume without addressing the complexity is ludicrous as well. Glial cells are important and any site posting rubbish about the brain being composed of neurons should have any information taken from it with a large grain of salt.Link #2: Neuroscience For Kids - glia

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The brain is made up of more than just nerve cells (neurons). Although there are about 100 billion neurons in the brain, there are about 10 to 50 times that many glial cells in the brain. But do you hear much about glia? NO! Because neurons get all the attention, you don't hear too much about glia. Although glia cells DO NOT carry nerve impulses (action potentials) they do have many important functions. In fact, without glia, the neurons would not work properly!

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And then:

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The brain is the only tissue in the body where we don't know the function of the major cell type," said Barres. Glia make up approximately 90 percent of the cells in the human brain, and yet researchers have assigned mainly passive functions to them. Some glia wrap around nerve cells and insulate them with a protein called myelin. Glia at synapses act both as a physical barrier that prevents crossed wires and as a disposal unit that mops up extra messenger molecules released by nerve cells.

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But now a particular kind of brain cell, which for decades had been passed over as relatively insignificant, has gained elevated stature. Glial cells were thought to be merely menial laborers of the brain, shuttling nutrients and removing waste. New studies are showing, however, that these cells are a major source of neurons. With a little coaxing, they may someday be veritable neuronal factories, used to produce neurons for patients in need of brain repair.

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From the site: Page not foundAll of the above demonstrate that the brain is composed of more than one type of cell. The brain also is very complex it's not a general purpose organ that simply gets filled up with information as it goes along through life. Pinker among others has been working on this for years. How this evolved is not a simple question to answer.Page Not Found | MIT - Massachusetts Institute of Technology------------------
Bringer of fire, trickster, teacher.

The first assertion I have made is that the human brain evolved to handle complex tasks such as toolmaking.John believes that there is no need for a large brain because foraging is easy, so his explanation is that the large brain evolved because hominids lived in a hot equatorial environment and a large brain meant that there would be plenty of spare cells to carry on the work after some of them had been killed off by heat.I then have pointed out that the brain does not get killed off by heat since the body strives to maintain thermal homeostasis (98 degrees for us) and the brain is cooled to this temperature.He did mention the Falk theory. This idea is that the blood supply to the skull relies on small vessels to keep the large brain cool. But Falks idea only explains how a brain can be enlarged through efficient cooling, not why it became large in the first place.John stated:

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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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I stated:

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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.

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There is the central flaw in his argument. The blood supply cools the brain, the brain doesn't need the extra cells because they don't die in the first place.In any event, it is unlikely that the brain enlarged to provide extra cells for the function for early hominids. Neural tissue is energetically expensive consuming 16 times as much energy per pound as other tissue. About 20% of modern human energy expenditure is spent on providing the electrochemical gradient for the brain to function in the first place. A reduction of any unneeded tissue would be evolutionarily favorable since an organism that needed less energy to survive, would have more available energy to produce offspring.There must be a cost benefit to the presence of a large brain and one probable benefit to the high cost of a big brain would be the commonly cited social forager model.RE: Oldowan choppers/flakes and Achulean hand axesThe limiting characteristic for making anything more complex than an Oldowan tool is the thumb of the Australopithecines, the ability to grasp items is fairly limited for these hominids. The evolution of the Erectus thumb allowed for the Achulean hand axes and these are in fact somewhat difficult to make. The point being that the limiting characteristic for making a more complex tool is the ability to grasp the raw material to make the tool as well as the chipping tool used on the hand axe.Achulean hand axes appear as cranial capacity increases, it might be a coincidence, but I don't think so.------------------
Bringer of fire, trickster, teacher.