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Author Topic: What are the limits on the size of a human?  (Read 9723 times)

Offline Anthony31209

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What are the limits on the size of a human?
« on: 13/05/2011 04:58:04 »
In theory is it possible for a man to grow to a large size...using current or future technology? By tweaking genes and/or using drugs? And also adjusting food intake. Lets say a size of...gigantopithecus blacki, 1000lb. Or african elephant[5 to 9 tonnes].


If possible could you give detailed answers?

Thanks.
« Last Edit: 13/05/2011 09:07:04 by JP »


 

Offline RD

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What are the limits on the size of a human?
« Reply #1 on: 13/05/2011 15:29:25 »
... it possible for a man to grow to a large size...using current or future technology? By tweaking genes and/or using drugs? And also adjusting food intake. Lets say a size of...gigantopithecus blacki, 1000lb.

Can be achieved with diet and plenty of taxpayer's money ... http://www.thenakedscientists.com/forum/index.php?topic=36244.msg338521#msg338521
« Last Edit: 13/05/2011 15:38:35 by RD »
 

Offline Anthony31209

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What are the limits on the size of a human?
« Reply #2 on: 13/05/2011 18:13:38 »
Aha thanks, what I meant was a proportioned(not obese)composition, say a bodyweight of 900lb and 160-180lb is bodyfat.
« Last Edit: 13/05/2011 18:25:28 by Anthony31209 »
 

Offline RD

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Offline Anthony31209

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What are the limits on the size of a human?
« Reply #4 on: 14/05/2011 21:13:07 »
Thanks...nice to read. Could extreme growth hormone manipulation, alone or in combination with something else, produce the body sizes/proportions I was talking about? Is it theoretically possible?
« Last Edit: 14/05/2011 22:34:15 by Anthony31209 »
 

Offline Supercryptid

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What are the limits on the size of a human?
« Reply #5 on: 15/05/2011 04:11:29 »
Technically, a civilization that has perfected genetic engineering could produce about any size human that the laws of physics and chemistry will allow. Of course, we are far from such a state. It's also more difficult to do than scaling up a normal human proportion-wise.

Andre the Giant, who was billed at 7'4" and 500 or so pounds, had joint pain that was debilitating at times due to his size. I suspect that hormone abnormalities such as the gigantism he had do not promote the proper growth for the healthy, fully-functional giant that you are searching for. We would need to tailor growth of the bones and tissues to be the correct proportions to deal with the weight more suitably.

Scaling laws are an important aspect of biology. When you take a particular object (such as a human being), and make it twice as tall (while keeping the proportions the same) its weight will not increase 2-fold. It will actually increase 23-fold (8-fold)! A 6-foot person weighting 160 pounds, if doubled in height, will therefore be 12 feet tall and weigh 1,280 pounds if you kept the proportions the same.

There is a problem with this.

Although weight increases 23-fold, the strength of the bones would only increase 22-fold. It means that the strength-to-weight ratio of the bones is half that of a normal person. A giant with these proportions would stress their skeletons more easily and be at greater risk for injury if they fell down. In order to fix this problem, you would need to make the bones wider in proportion to their length so that the weight of the person produces less pressure on the bone.

A well-proportioned giant would therefore be a rather wide, burly-looking person with thick arms and legs.
 

Offline CliffordK

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What are the limits on the size of a human?
« Reply #6 on: 15/05/2011 06:57:49 »
Potentially your bones could generate more compact bone, and less marrow, and would compensate reasonably well.  But, one's muscles, tendons, and etc would also have to compensate.  The knees, ankles, and hips would also take a beating. 

Perhaps when the moon is colonized, we'll see Lunar Giants.
 

Offline Anthony31209

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What are the limits on the size of a human?
« Reply #7 on: 15/05/2011 19:05:05 »
Thanks for both replies. I find it all really interesting to read about.

I know this is really stretching it, but would it be actually possible for this person to be the same size and proportions of say...King Kong? Wouldn't a person that big have to eat about 20,000 calories per day?
 

Offline CZARCAR

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What are the limits on the size of a human?
« Reply #8 on: 15/05/2011 20:11:19 »
how tall would NAPOLEON be today?
 

Offline Supercryptid

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What are the limits on the size of a human?
« Reply #9 on: 16/05/2011 07:23:59 »
Quote
I know this is really stretching it, but would it be actually possible for this person to be the same size and proportions of say...King Kong? Wouldn't a person that big have to eat about 20,000 calories per day?
Possibly. Think about large theropod dinosaurs like Tyrannosaurus rex. Those creatures demonstrate that bipedalism is possible for very large animals.

In order to reach that size (5-7 tons), a lot might have to be changed about human physiology. A better cooling system might be needed (surface area does not increase as quickly as volume does, so the heat-generating tissue of a large mammal has less surface area to release that extra heat from). Might such giant humans require elephant-sized ears for temperature regulation? More sweat glands? Or perhaps a lower average body temperature? Larger or more efficient lungs would be needed too (the diffusion of oxygen and carbon dioxide gases is limited by the surface area of the alveoli in the lungs).

I calculated my basal metabolic rate to be around 1,730 calories a day, so if you were to scale my mass up to that of a T-rex, my metabolic rate would would increased by a similar amount (~112,000-156,000 calories per day). If you went for the "lower the body temperature" solution to the heating problem you'd get less calorie burn than that, though. In fact, warm-blooded creatures expend around 90% of their caloric intake just warming their own bodies up. A cold-blooded giant might not be so bad!
 

Offline CliffordK

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What are the limits on the size of a human?
« Reply #10 on: 16/05/2011 22:56:44 »
Larger or more efficient lungs would be needed too (the diffusion of oxygen and carbon dioxide gases is limited by the surface area of the alveoli in the lungs).
The lung volume should be ok due to the fractal space-filling nature of the lungs, unless your creature panted like a dog as part of its temperature regulation.

Ignoring the Great Blue Whale which has different physiology demands than a human would, we have animals of all sizes including the African Elephant that is as big as 6 tons, and I believe is capable of supporting its weight on 2 feet, but even on 4 feet, that would be 1.5 tons per foot.

Mammoths would have even been bigger, perhaps 10 tons, or about 2.5 tons per foot.

Humans vary in height from around 4 feet to about 7 feet with relatively "normal" physiology, although perhaps head size varies less than other parts of the body. 

The record for the shortest adult (ever), Gul Mohammed at 1'10.4" appears to be more awkward proportioned than some of the taller people.  The shortest living adult, Khagendra Thapa Magar at 2'2½" appears to have very "normal" proportions, although his arms look quite slender.


The tallest man was Robert Pershing Wadlow at 8'11". 
http://www.guinnessworldrecords.com/records/human_body/extreme_bodies/tallest_man.aspx



According to Guinness,
Wadlow's greatest recorded weight was 222.71 kg (35 st 1 lb) on his 21st birthday and he weighed 199 kg (31 st 5 lb) at the time of his death. His shoe size was 37AA (47 cm, 18½ in long) and his hands measured 32.4 cm (12¾ in) from the wrist to the tip of the middle finger. He wore a size 25 ring. His arm span was 2.88 m (9 ft 5¾ in) and his peak daily food consumption was 8000 calories.

The cause of death is very telling...

Wadlow died at 1:30 a.m. on July 15, 1940, in a hotel in Manistee, Michigan, as a result of a septic blister on his right ankle caused by a brace

The current record holder, Sultan Kösen at 8'3" is often photographed with crutches.  However, since there are many basketball players over 7', perhaps the leg problems are not always found with tall individuals.
 

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What are the limits on the size of a human?
« Reply #10 on: 16/05/2011 22:56:44 »

 

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