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Quest for Fire Began Earlier Than Thought - Comments

Zeuglodon's Avatar Comment 1 by Zeuglodon

Fire has almost a mythic status among many people. Notice how often, in fantasy works, the four-elements view of the Ancient Greeks (fire, earth, water, air) is taken up? Pity there isn't a 92-element view instead. A hydrogen wizard (as opposed to a generic "fire wizard") would be awesome.

This article is interesting. I'm unimpressed by the suggestion that it could be bat guano - it's less probable than the idea that it was evidence of human activity, as human fires were much more common and mundane and thus had more opportunities to leave traces. If they found evidence of bat remains in the cave, that would make that suggestion (of guano combustion) more plausible.

I wonder what the invention of fire would have been like. Perhaps humans originally saw it caused by lightning storms or droughts, and occasionally picked it up for use. Then our ancestors and their contemporaries began to collect and store such fires, feeding them for long-term use. Then, they created "spawn" fires by taking burning branches from the original fires, and so pass it on. Finally, they learned how to make their own. After that, perhaps we had a long technological history experimenting with different fuels. Maybe there were thousands of kinds of fires recruited for a variety of purposes.

I feel almost guilty when I flick on the gas stove and think how easily and thoughtlessly I can just use the fire. Sometimes, I think we give our forebears too little credit.

Sat, 07 Apr 2012 17:33:32 UTC | #932911

Sjoerd Westenborg's Avatar Comment 2 by Sjoerd Westenborg

Comment 1 by Zeuglodon :

I feel almost guilty when I flick on the gas stove and think how easily and thoughtlessly I can just use the fire. Sometimes, I think we give our forebears too little credit.

I've never been able to imagine how a relatively primitve human brain could come up with a way to recreate fire without a burning coal from an earlier fire. It must have been the Einstein of it's time.

(Maybe he used guano? ;P )

Sat, 07 Apr 2012 17:49:41 UTC | #932915

Narvi's Avatar Comment 3 by Narvi

@Zeuglodon: I don't know if you know this, but the webcomic "Order of the Stick" features a very intelligent (but evil) cleric that uses the periodic table in his elementals. There has been a few chlorine elementals and the like.

Sat, 07 Apr 2012 18:19:53 UTC | #932920

Stafford Gordon's Avatar Comment 4 by Stafford Gordon

These findings, even before they're ratified, give me a distict feeling of empathy with my antecedents, in that I'm made aware of what a wonderful period I'm living in; how out of place would I and my computor be in that cave at that time? What would the reaction have been of those people to hearing or seeing an aeroplane fly overhead?

Sat, 07 Apr 2012 19:12:45 UTC | #932926

Stafford Gordon's Avatar Comment 5 by Stafford Gordon

Further to my last, what would our reaction be to what we'd find if we were able to return in another million years or so?

Sat, 07 Apr 2012 19:18:01 UTC | #932927

Neodarwinian's Avatar Comment 6 by Neodarwinian

Gives Wrangham's cooking hypothesis much needed support.

Sat, 07 Apr 2012 19:24:14 UTC | #932928

Alan4discussion's Avatar Comment 7 by Alan4discussion

It is quite probable that early man ate naturally cooked food (as animals do today) from those burned in natural bush fires in dry areas.

It is also probable that in selected volcanic locations fires would start naturally or could be started simply by putting dry sticks into hot volcanic ground, as in the 4th photo on the link.

After you arrive at the visitors Car Park you will witness several demonstrations of 'how hot' the area is (temperatures just a few metres below the surface reach between 400°C and 600°C). Dry brush thrown into a hole in the ground catches fire immediately, while water poured into a bore hole erupts seconds later in the form of steam - like a mini-geyser.

Sat, 07 Apr 2012 20:22:04 UTC | #932937

Katy Cordeth's Avatar Comment 8 by Katy Cordeth

Comment 7 by Alan4discussion :

It is quite probable that early man ate naturally cooked food (as animals do today) from those burned in natural bush fires in dry areas.

It is also probable that in selected volcanic locations fires would start naturally or could be started simply by putting dry sticks into hot volcanic ground, as in the 4th photo on the link.

After you arrive at the visitors Car Park you will witness several demonstrations of 'how hot' the area is (temperatures just a few metres below the surface reach between 400°C and 600°C). Dry brush thrown into a hole in the ground catches fire immediately, while water poured into a bore hole erupts seconds later in the form of steam - like a mini-geyser.

Isn't it quite probable that the first cooked food that early man ate on a regular basis would have been prepared by immersing raw meat into hot springs - boiling it rather than broiling it?

Naturally occurring volcanic springs would have provided a much more reliable and permanent source of heat and wouldn't have required him to sit around twiddling his opposable thumbs waiting for a forest fire or a lightning strike to occur.

By the time our primitive ancestors (a relative term, I know) finally learned how to harness fire, they may already have been eating cooked food for thousands of years.

Sat, 07 Apr 2012 21:15:36 UTC | #932944

Helga Vieirch's Avatar Comment 9 by Helga Vieirch

What Michael Chazan et. al. are suggesting is that the use of fire was associated with the species Homo erectus from quite an early stage; which is extremely suggestive, since it is this species that showed the first really significant increase in brain volume.

Homo erectus was -probably- the first human species that migrated out of Africa, and it was successful in adapting to extreme variations in environment and climate all over Eurasia. This new evidence that this species used fire before leaving Africa is significant, since use of fire has long been associated with this species elsewhere, but evidence that it dates from the period prior to the migration out of Africa has been fairly tenuous until now.

Wrangham's cooking hypothesis is just the tip of the iceberg as far as the analytical implications of fire control and use among humans is concerned. This includes its significance in understanding our cognitive evolution.

You have to remember that hunter-gatherers use fire not just for cooking, heat, and defence, but also for environmental management. Controlled burning to keep ecosystems in a mosaic of stages of secondary growth was used by humans on every continent to increase ecosystem diversity and biomass, and to manage it in ways conducive to human food preferences.

A nontrivial degree of mental sophistication is implied. Just imagine the mind that can integrate knowledge of

a) variation of ecological zones and species diversity within each,

b) large data bases about plant succession communities over many decades,

c) together with information on animal behaviour and reproduction, as well as

d) detailed knowledge of both long and short term animal and plant response to burning at varying times of year, (for instance, how many people even today still know that plant growth in a grassland will be stimulated by a fire, and so show a flush of green even in the absence of rain at the end of a dry season, thus attracting grading animals?).

The kind of mind that can do this could certainly figure out how to hit two specific kinds of stones together to spark a fire (they were making stone tools anyway, so this would have been blindingly obvious to them), and even how to create enough heat through friction applied to dry sticks to start a fire (something every 10 year old child knows how to do among the hunter-gatherers I lived with).

The thing that gets my imagination fired up, (smiles) however, is the degree to which the use and control of fire was one of the critical technologies that set up new and fairly severe selection pressures, pressures which served to drive up brain size in our ancestors. Conceivably it also drove the evolution of a bigger and more effective pre-frontal cortex, so that strategic thinking and long term planning became essential if a human group was to leave as many survivors as groups that were also learning to manage their environments. Mere use of fire for cooking and keeping warm shrinks in significance compared to the use of fire to enhance ecosystem productivity.

It is a burning question. One might even say, incendiary!

Sat, 07 Apr 2012 21:25:32 UTC | #932947

strangebrew's Avatar Comment 10 by strangebrew

I am reminded of the scene in 'Quest for Fire' when the clan are chasing one of the principal characters across a shallow stream bed in a festive spirit party mood and he has the only fire in the clan camp in his hand and was just dancing around with it showing off...when he slips in the shallow stream the inevitable happens and the torch goes out...the look on the rest of the clans faces is absolutely priceless...it was the only bloody fire they had and them without a clue as to how to relight it.

Sat, 07 Apr 2012 21:28:47 UTC | #932949

Pete H's Avatar Comment 11 by Pete H

Naturally occurring volcanic springs would have provided a much more reliable and permanent source of heat and wouldn't have required him to sit around twiddling his opposable thumbs waiting for a forest fire or a lightning strike to occur.

Lightning strike can be sufficiently reliable.

Australian human history is more recent, around only 80,000 years, but similar conditions would have occurred elsewhere and much earlier in human history. Lightning ignited bushfires are extremely common in Australia. And many animals are too slow moving to escape these bush fires. E.g. Snakes, koala,and wombat and the megafauna of the era. So cooked meat from carcasses is easy to find. Just follow the pillars of smoke, visible from over 30km away. The prehistoric equivalent of McDonalds yellow arches.

Humans can travel a very long way on meal of protein and saturated fat. And we have the ability to rapidly stock up tremendously on belly fat – enough to last for months. Internally consuming 20kg of accumulated body fat could keep a man fully energised for 6 months or so, despite otherwise eating only lettuce and a few other scraps. Possibly this instinctive expectation to eat hot food every 30 km or so is why we now have truck stops and McDonalds restaurants at 30 km intervals along major Australian highways. Plus it also explains the typical Australian long distance truck-driver’s natural inclination to acquire 20kg of accumulated belly fat as quickly as possible. Most of us are aware of the ‘problem’ of obesity, but few are aware of the evolutionary advantages of obesity as a solution in a scavenging lifestyle.

It would have only been a small step from this natural scavenging to deliberately triggering artificial bush fires, based on the observation that the charred vegetation opens up clearings in the bush and encourages new grass growth which attracts browsing megafauna while making them very much easier to catch. (Including catching them by starting a fresh bush fire and burning them to death.)

It’s known as fire stick farming. There’s a theory that pretty much the ecology of much of the entire continent of Australia was transformed into a giant tinder box and the original megafuana were entirely extinguished around the time that humans first became established in Australia. So this process may have happened very quickly.

The innovative technology of the spear thrower may be relevant. Spear throwers enable much more effective killing of larger animals, plus they get very hot and possibly smoulder and ignite from the abrasive rubbing when spear throwers are being shaped during manufacture. Same principle applies to the bow and arrow and its application to fire bows. Once human groups have acquired one of these technologies then the associated approach to fire making also exists by default. Perhaps it’s also possible to start fires by rubbing tiny twigs dipped in a mixture of bat guano.

Sat, 07 Apr 2012 23:22:33 UTC | #932966

Steven Mading's Avatar Comment 12 by Steven Mading

I wonder if, when fire was relatively hard to start but highly valued and cherished once started, there might have been a sort of early economy formed in the trading of fire. Imagine a fire merchant, who has found a way to carry portable fire, perhaps a series of torches where a new torch is lit when an old one gets low, and goes to villages saying "I will use this to light a campfire for you in exchange for....."

The interesting thing about selling fire would be that it multiplies naturally and isn't a limited quantity (once you have one fire, you can use it to create fifty others fairly easily) and this means it would behave economically more like software or music and less like manufactured widgets. The infinite "copy ability" of it means that the more popular it becomes, the cheaper it gets, breaking the assumption behind supply and demand economics that popular things get more expensive. It would be like software, where if you want to buy something for which there's only a few hundred customers in the world, you pay thousands of dollars for it, but if you buy something for which there's millions of customers for it, you pay like $40.

Sun, 08 Apr 2012 01:20:23 UTC | #932999

Lapithes's Avatar Comment 13 by Lapithes

"Evidence may be found that human ancestors made campfires 1 mya" is not equal to "Quest for Fire Began Earlier Than Thought"

Why bother with having titles if they're not going to have much relation to the content of the articles?

Sun, 08 Apr 2012 07:39:39 UTC | #933019

JuJu's Avatar Comment 14 by JuJu

Comment 12 by Steven Mading

Imagine a fire merchant, who has found a way to carry portable fire, perhaps a series of torches where a new torch is lit when an old one gets low, and goes to villages saying "I will use this to light a campfire for you in exchange for....."

While I was imagining your "fire Merchant" I suddenly imagined a gang of fire torch robbers, lying in wait to steal the fire. Like wild west train robbers after the gold.

Sun, 08 Apr 2012 07:44:59 UTC | #933020

hellosnackbar's Avatar Comment 15 by hellosnackbar

I've often wondered if the discoverer of fire made his discoverry during a flint knapping exercise; possibly setting fire to the dry grass on which he was sitting?

Sun, 08 Apr 2012 09:45:23 UTC | #933037

Alan4discussion's Avatar Comment 16 by Alan4discussion

Comment 8 by katy Cordeth

Isn't it quite probable that the first cooked food that early man ate on a regular basis would have been prepared by immersing raw meat into hot springs - boiling it rather than broiling it?

It is possible to use hots springs, but there are serious limitations.
1. They are often heavily contaminated with chemical minerals.
2. A flowing spring washes away the nutrients.
3. A small fixed pool cannot be cleaned after earlier meals.
4. Hot water is difficult to transport without modern containers, and cools rapidly.

Naturally occurring volcanic springs would have provided a much more reliable and permanent source of heat and wouldn't have required him to sit around twiddling his opposable thumbs waiting for a forest fire or a lightning strike to occur.

Where there are hot springs, there are usually volcanic sources of fire, which will start natural fires, and from which burning material can be moved to a safe distance.

On the link I give @7 they actually run a barbecue directly from the volcanic heat, without combustible material being used at all.

Sun, 08 Apr 2012 09:46:23 UTC | #933038

mmurray's Avatar Comment 17 by mmurray

Comment 15 by hellosnackbar :

I've often wondered if the discoverer of fire made his discoverry during a flint knapping exercise; possibly setting fire to the dry grass on which he was sitting?

Makes sense. Blokes with their tools are still starting fires.

Michael

Sun, 08 Apr 2012 10:06:34 UTC | #933042

CEVA34's Avatar Comment 18 by CEVA34

On the subject of portable fire, my impression has always been that it means glowing embers in a pot, rather than a torch, which could too easily be dropped, or blown out by the wind. By the way, the National Film Board of Canada, which has always been great on animation, some years ago produced a very funny cartoon called "Hot Stuff" about the origin of fire, as part of a campaign to encourage fire safety. I don't know if it's anywhere on DVD, but it should be.

Sun, 08 Apr 2012 11:46:15 UTC | #933056

Alan4discussion's Avatar Comment 19 by Alan4discussion

Comment 18 by CEVA34

On the subject of portable fire, my impression has always been that it means glowing embers in a pot, rather than a torch, which could too easily be dropped, or blown out by the wind.

Embers on the end of a thick stick or bunches of dry grass work reasonably well. A breeze makes large embers burn brighter.

Comment 11 by Pete H

It would have only been a small step from this natural scavenging to deliberately triggering artificial bush fires, based on the observation that the charred vegetation opens up clearings in the bush and encourages new grass growth which attracts browsing megafauna while making them very much easier to catch. (Including catching them by starting a fresh bush fire and burning them to death.)

In Chaparral or savanna environments, dry combustible material simply builds up until some human or natural form of ignitions sets the wildfires away.

Sun, 08 Apr 2012 12:10:46 UTC | #933060

Katy Cordeth's Avatar Comment 20 by Katy Cordeth

Sun, 08 Apr 2012 12:37:16 UTC | #933063

Reckless Monkey's Avatar Comment 21 by Reckless Monkey

What interests me about fire and early hominids is that it must mark an ability to recognise something that would normally be a source of terror (ask a bush fire survivor) and see it as a useful thing to carry around. It suggests quite a good imagination, ability to plan and guts so to speak. Most animals flee at the first sight of fire and for good reason. I suppose a number come in after and clear up dead animals that's already been suggested above. I saw video somewhere possibly TED sorry can't recall, where a chimp had been taught to build a fire and light it (with a lighter). Having seen footage of Australian Aboriginals lighting fires using their hands and sticks (no bows like the American Indians) and trying it as kid for some hours I can tell you it's bloodly hard work just get something warm let alone hot enough to ignite something. So I take my hat off to my smaller brained predecessors.

Sun, 08 Apr 2012 13:05:36 UTC | #933067

mmurray's Avatar Comment 22 by mmurray

Comment 21 by Reckless Monkey :

Having seen footage of Australian Aboriginals lighting fires using their hands and sticks (no bows like the American Indians) and trying it as kid for some hours I can tell you it's bloodly hard work just get something warm let alone hot enough to ignite something. So I take my hat off to my smaller brained predecessors.

Did you see the comment from Helga above

how to create enough heat through friction applied to dry sticks to start a fire (something every 10 year old child knows how to do among the hunter-gatherers I lived with).

Maybe you were just bought up in the wrong part of the world :-) . I used to try with a magnifying glass as a kid but could never get a flame. Lots of charred holes in the paper. I assume our ancestors shared the fascination we all seem to have with fires.

Michael

Sun, 08 Apr 2012 13:15:20 UTC | #933069

Helga Vieirch's Avatar Comment 23 by Helga Vieirch

Comment 19 by Alan4discussion Comment 11 by Pete H

It would have only been a small step from this natural scavenging to deliberately triggering artificial bush fires, based on the observation that the charred vegetation opens up clearings in the bush and encourages new grass growth which attracts browsing megafauna while making them very much easier to catch. (Including catching them by starting a fresh bush fire and burning them to death.)

In Chaparral or savanna environments, dry combustible material simply builds up until some human or natural form of ignitions sets the wildfires away.

Most larger grazing animals in the African savannah actually will easily evade a fire, as in grassland, you can simply step or jump over the advancing line of burning material. A number of antelope species, notably the Sable antelope. actually calve on fresh burns.

Animals are also attracted to recently burned areas in order to lick ash and chew charred sticks, as a source of minerals and other nutrients.

The Kua used to set snares for ostriches around old campsites that had been burned down deliberately after someone had died and been buried there. There were enough odd bits of bone (of game previously consumed at the site) exposed by this process to attract the big birds. Ostriches are always on the lookout for such objects, since they need them to grind up food effectively in their gizzards. (This being the origin of the myth that ostriches will swallow tin cans and all kinds of other small bits of junk.)

Ash, of course, is a natural fertilizer. The productivity of certain wild nut bushes and bean fields in the Kalahari was enhanced by burning, sometimes remarkably so.

I was interested in your remark about how in certain environments like chaparral the dry material in deadwood builds up to the point where a lightning strike (or careless human) can set off a huge wildfire. We have witnessed a number of these in California every summer.

It was not so in before, when these areas were managed by the Amerindians. LIke foragers on every other continent, they kept wildfires from happening by setting up a schedule of smaller controlled burns annually that kept the amount of burnable debris down. Thus wildfires which might have threatened their own camps, as well as burning so out of control as to actually endanger the wildlife, were not allowed to happen.

The Kua, in fact, made explicit statements to this effect, when questioned about their management of veld fires in the Kalahari.

It is interesting to note that many kinds of valuable trees, like lodgepole pine, are in fact dependent upon fire for reproduction, and are highly adapted to thrive under conditions of light annual low-level grass fires.

Sun, 08 Apr 2012 14:55:58 UTC | #933076

Premiseless's Avatar Comment 24 by Premiseless

I imagine the observation of tinder, to nearby hot volcanic rock, may have piqued the ancients intellect and made them more prone to replicate a smaller version to fall asleep alongside on a cold night? More a case of "What's for breakfast?" receiving more appetising replies rather than "Maybe me."

Sun, 08 Apr 2012 15:13:28 UTC | #933081

Pete H's Avatar Comment 25 by Pete H

@Comment 23 by Helga Vierich

I don’t know anything about the chaparral, but we have more or less the same situation in Australia.

I read a great book by Tim Flannery: ‘The Future Eaters’ where he discusses that natural fires in Australia were once less frequent. (Apparently they can measure these things.) The vegetation was once more resistant to fire, but since the time when humans are believed to have first occupied Australia large areas have become more fire prone and the vegetation has adapted. E.g. trees drop small dry branches and oily leaves which easily burn every few years or so, with the effect of killing off competing saplings and other plants but not seriously damaging the mature trees. Plus there are much more fire-dependent plants around, like those which only cast off seeds in the heat of a bush fire.

In the preceding conditions it’s possible that larger animals hadn’t needed to escape bush fires. It’s different now, and affects the size of the animals. Smaller mammals can hide in holes and hollow logs. But even large Australian animals driving cars now have difficulty in getting away from bush fires. It wasn’t until the invention of the helicopter monsoon bucket that people have felt safe enough to live in the Australian bush without building fire resistant houses and having fire shelters in their houses. (Though they may need to rethink that owing to some recent disasters.)

One factor is that natural fires plus the fires started by the early aborigines were so frequent that the average fuel load in the bush didn’t accumulate significantly. Now that humans have evolved religions like environmentalism, the green movement, property development, and house flicking, routine burn offs are forbidden or discourage by the authorities because they temporarily impact the visual appeal and reduce property saleability for a couple of years. (This exceeds the investment time preference of city council officials, who tend to be heavily involved in property development and house flicking).

More recently most Australian city council budgets have been severely impacted via massive malinvestments in the US sub prime mortgage market. (Council financial controllers were like lambs to the slaughter for the American bank sales reps.) Consequently few bushfire prone Australian city councils can now afford routine burn-offs, even if their environmental protection policies allowed them. (I think that burn-offs mostly now depend on volunteers in the SES and rural fire service.) If anything councils are more desperate to encourage new replacement local taxpayers to establish themselves within their domain. Which requires cheaper housing standards. This all results in more people living in less fire resistant houses, at greater risk of huge fuel loads and extraordinary fire storms that kill everything, including the smaller mammals, larger trees, and some environmentalists. (City councillors are less affected because they tend to live out of the danger area, generally on the coast where they can anchor their ocean going launches.)

Australian aborigine fire stick farming may have been a response to the declining availability of easy meat, following the extermination of the mega fauna. A little like the NZ Maoris developing fishing nets in response to declining food following the extinction of the Moa. (Maori long net technology was later imported to northern Europe by sealers, which enabled the European fishing industry - now extinct I think).

But I think my main point is that once people start working with wood it becomes obvious that wood gets hot with friction. Our ancestors have been using wooden and stone tools for longer than they’ve been human. And as soon as people develop wood working crafts they automatically have fire starters, the simplest and easiest being the fire plough.

There are skilled people around who can use a fire plough to start a fire quicker than an unskilled person can use a match. But there’s much more to staring a fire even than just striking a match. Most of the effort is in the preparation. Gathering firewood, making feather sticks, kindling, etc. is hard work. Smoking up the fire plough is easy in comparison. So there’s no real advantage in transporting fire or any dependency on finding natural sources of combustion.

The evidence of wooden tools used by our earliest ancestors would not be preserved. So the focus tends to be on the stone hand axes etc. But tools like hand axes would have been involved in much more than just butchering meat. E.g. shaving sticks for kindling, shaping fire plough implements, and splitting branches for dry wood in the rain etc. Plus forming spear tips, shelters etc. Where there are stone tools there would be all kinds of wood working going on. And wood working implies hot wood which implies fires. Plus, with the right kind of stone, you can generate sufficient sparks to burn just about anything. It’s reasonable to assume that such technology and stones would have been traded over a very wide area.

And one other interesting detail about our ancestor’s use of fire is that it is a means of isolating fat from animal food. Liquid fat dripping off a cooking carcass can be captured and bottled in large seed pods or leather pouches. So it doesn’t have to be eaten directly to be conveniently stored for a very long time. It’s an ideal form of highly concentrated and easily portable food energy that enables extremely long journeys, plus has other uses for rain-proofing clothes, starting fires in the rain, etc. So the adoption of fire technology by our ancestors also greatly extends their geographical range of activity, which implies more reliable access to food and other resources, plus enabling more integrated trade with all other people and the spreading of humans everywhere.

This aspect is often overlooked because of the confusion about nutrition science and the erroneous linking of fat consumption with disease. It turns out that fat is the primary source of energy fuel in humans, not carbohydrates and protein as has been erroneously (and apparently irreversibly) established. This makes sense because a mostly carbohydrate or protein diet is not compatible with prolonged endurance exercise without ready access to food.

Sun, 08 Apr 2012 23:58:32 UTC | #933153

Alan4discussion's Avatar Comment 26 by Alan4discussion

Comment 25 by Pete H

And one other interesting detail about our ancestor’s use of fire is that it is a means of isolating fat from animal food. Liquid fat dripping off a cooking carcass can be captured and bottled in large seed pods or leather pouches. So it doesn’t have to be eaten directly to be conveniently stored for a very long time. It’s an ideal form of highly concentrated and easily portable food energy that enables extremely long journeys,

This aspect is often overlooked because of the confusion about nutrition science and the erroneous linking of fat consumption with disease. It turns out that fat is the primary source of energy fuel in humans, not carbohydrates and protein as has been erroneously (and apparently irreversibly) established.

I think the sources of the confusion comes from the earlier evolved need of humans to seek out foods rich in fats and sugars, when these were scarce and valuable for survival.
The modern day pigging-out on recreational eating, of high calory foods, combined with a lack of exercise, is very unhealthy. In the industrial world, the poor diet is like the spoilt child in a sweet-shop acting on primitive urges.

Mon, 09 Apr 2012 09:09:12 UTC | #933235

Alan4discussion's Avatar Comment 27 by Alan4discussion

Comment 22 by mmurray

I used to try with a magnifying glass as a kid but could never get a flame.

If you use a big lens it is no problem.

Mon, 09 Apr 2012 09:14:38 UTC | #933239

hellosnackbar's Avatar Comment 28 by hellosnackbar

@mmurray, Thanks for that anglegrinder story.

Mon, 09 Apr 2012 09:19:09 UTC | #933240

Pete H's Avatar Comment 29 by Pete H

Comment 26 by Alan4discussion

Pigging out on unhealthy food isn’t really much of a problem for most people. At least no more than alcohol or other drug addictions. And lack of exercise is obviously unhealthy, but there’s a theory that lack of exercise is a consequence of not eating the right kind of high calorie food. It’s a symptom and rather than a cause. Eating high fat / high calorie food is always very important, even more so for our prehistoric ancestors. Some would obviously have struggled to get sufficient exercise given that gyms and personal trainers hadn’t yet been invented.

Sugar may have been scarce back then. Plus there was the bee sting factor. But animal fats would usually have been readily available, at least until human populations grew and hunting technology resulted in exterminations of the more easily harvested prey species. But that just means that other humans were at least as readily accessible as a form of prey animal. The ideal diet humans are best adapted to may be other humans. Something which might also be a source of confusion for modern nutritionists.

Mon, 09 Apr 2012 10:54:26 UTC | #933265

Alan4discussion's Avatar Comment 30 by Alan4discussion

Comment 29 by Pete H

Eating high fat / high calorie food is always very important, even more so for our prehistoric ancestors.

Central heating could be added to the modern need for less calories, - as any farmer providing winter-housing for livestock in cold climates can tell you.

Some would obviously have struggled to get sufficient exercise given that gyms and personal trainers hadn’t yet been invented.

It's good to have a sense of humour! We could make interesting comparisons with gyms, and the physical activities of bushmen hunters or chimps! (Which reminds me - I must get the big extension ladders out and cut back some of my larger trees sometime when there is no wind)

Mon, 09 Apr 2012 11:14:40 UTC | #933271