why r we a limited size?

[TimbaLanD]

I was thinking why our body is the standard size it is!! Why are we not so big or not so small? The standards size is around 6ft and 80kg?? We could reserve our resources if we are small by say 50%? Is there a reason why we are the size we are?

[SkepticLance]

Talk about complicated questions!

There are ten million factors in determining how big we are.

 

Some is sexual selection. The lady prefers a big guy as mate. The kids end up big.

 

In equatorial Africa, some tribes grow tall and thin. High surface area to volume ration means good cooling through sweat.

 

In high Arctic regions, some tribes grow short and wide. Small surface area to volume ratio means good heat conservation.

 

Evolution works through all these factors and more, to end up with a compromise average size.

[Klaynos]

One of the factors I'm aware of is, the increased pressure the heart would have to pump at to raise blood to a higher elevation, would mean it would have to be considerably bigger for just a small height increase...

[GutZ]

As far as I know we are not really a standard size, it changes alot if you look at it from a longer time frame.

 

http://researchnews.osu.edu/archive/medimen.htm

[swansont]

Scaling is not a simple matter. Certain physical mechanisms can only scale through a certain range (on both extremes) and still remain functional, because length, area and volume scale with different powers of length. So if you scale something up it may not e.g. support weight properly (and scaled down it's wasted if it's too strong), and e.g. heat dissipation attributes change with surf/vol ratio, as SkepticLance noted. Outside of a certain range you may need to radically alter the attributes in queston in order for them to work (e.g. exoskeleton vs endoskeleton), and whether a pathway is open to that much change needs to be addressed. Lots of things to consider.

[Tartaglia]

Here is one of the most famous scientific essays is on this subject "On being the right Size" by J. B. S. Haldane, the great British mathematical biologist and Communist party member

 

http://irl.cs.ucla.edu/papers/right-size.html

[swansont]

J. B. S. Haldane' date=' the great British mathematical biologist and Communist party member

[/quote']

 

 

Is mention of the latter merely irrelevant, or is it an intentional ad hominem (attempt to poison the well)? (or even, perhaps, an attempt to glorify communism)?

[scicop]

Interestingly enough its well known that humans have generally grown taller over the past 2000 years or so. A male was considered tall in ancient roman times if he was 5'5". I learned this at a trip to one of the Smithsonian Museums a few years back. Prior to that, whenever I visited a museum with garments from antiquity (such as roman gladitor uniforms) I would get disappointed with the small sizes!! The armor looked as though it was made for hobbits.

[Tartaglia]

Not at all Swansont, but if you read the essay (written 1928) you need to know the context in which it is written to understand the references to socialism. Thus the mention of his affiliation is not irrelevant. Perhaps you should read the whole essay before you put up ill advised posts

J. B. S. Haldane was one of the great characters of science and a true original. He was rather more famous as a public face of the CPGB at the time though

[swansont]

Not at all Swansont' date=' but if you read the essay (written 1928) you need to know the context in which it is written to understand the references to socialism. Thus the mention of his affiliation is not irrelevant. Perhaps you should read the whole essay before you put up ill advised posts

[/quote']

 

I know that paper was written in 1928, as it states that in the preamble. I see a mention of democracy and of socialism in the last two paragraphs, but nothing that points to the author necessarily having a particular political/socioeconomic viewpoint. What I failed to see was any relevance to Haldane's communist views. Couldn't a capitalist have come up with the same conclusions?

[Tartaglia]

Swansont - I tend not to compartmentalise my knowledge and I was not making any suggestion that Haldane's scientific contributions would have been different had he been a capitalist. That neither of us can know. What I do know is that Haldane was not only one of most important scientists of the 20th century and one of its most successful popularisers of science. Many of his famous essays appeared first in his column in "The Daily Worker" and in the period he was writing many intellectualy gifted people were attracted by both science and communism. Indeed I was once privileged to meet John Maynard Smith, who did his PhD for Haldane while moving through the CPGB. He ofcourse made important contributions to evolutionary biology himself.

 

On a personal note, although Haldane died the year I was born, he had a great effect on my career. About a week after I was appointed to my first University lectureship (age 25) a friend of mine who was appointed on the same day as me gave me Haldane's book of essays "On being the Right Size". This led me on to Ronald Fisher's work and ultimately I became a statistician. For me it was one of those pivotal moments.

[Martin]

...

J. B. S. Haldane was one of the great characters of science and a true original. He was rather more famous as a public face of the CPGB at the time though

 

 

Hello Tartaglia' date='

In my opinion the culture of science has benefited from its great characters, who with all their peculiarities have given zest and energy to it. People like Kepler and Galileo and Darwin (and that peculiar fellow Niccolo Fontana nicknamed "the stammerer") all help to make science an exciting human STORY.

 

the essay was written in 1928 while Haldane joined the PARTY in 1937 according to Wikipedia.

 

Perhaps he was a socialist in 1928, many of the educated class in UK were at that time.

 

My interest in this discussion is that SFN needs every bright one it's got. Including you. Including Swansont.

Including JBS Haldane, if he could join us, regardless of his political affiliation!

 

Don't argue with Swansont about the strict relevance or nonrelevance of haldane trivia.

Go to my thread

http://www.scienceforums.net/forums/showthread.php?t=21359

of Haldane trivia that I just started and have fun!

What else do you know about him?

 

Meanwhile Swansont I do believe that you are perfectly right Haldane 1937-1950 membership in CP is utterly [b']irrelevant[/b] to his excellent 1928 essay on the evolutionary determinants of size (although IIRC he does suggest something like that socialism might work better in a country the size of Finland than the size of US, an interesting observation)

[Martin]

On a personal note' date=' although Haldane died the year I was born, he had a great effect on my career. About a week after I was appointed to my first University lectureship (age 25) a friend of mine who was appointed on the same day as me gave me Haldane's book of essays "On being the Right Size". This led me on to Ronald Fisher's work and ultimately I became a statistician. For me it was one of those pivotal moments.[/quote']

 

that is interesting. You were born 1964.

Fisher was a great statistician. some connection with biology, or population genetics. I seem to remember there was some connection with Haldane's work.

 

Yes R.A. Fisher INVENTED MAXIMUM LIKLIHOOD statistics and the ANALYSIS OF VARIANCE!!!

 

and Fisher was ALSO a geneticist. Wonder why genetics and evolution should have been at the root of developing modern statistical methods

[Tartaglia]

Martin Politics interests me at least as much as mathematics and science.

 

I was unaware that he actually joined in 1937 but I would imagine he was a fellow traveller before then.

 

I really did not mean to stir up a hornets nest, I was just putting the information in as an interesting aside. Obviously it caught your interest if not Swansont's

[Martin]

I really did not mean to stir up a hornets nest' date=' I was just putting the information in as an interesting aside.[/quote']

 

I think all is peaceful now. there is nothing to quarrel about. but we should free associate in the Haldane Trivia thread, because there is the custom (often honored more in the breach) of STAYING ON TOPIC.

 

I would like to talk more over there. In particular I am curious how you chose the name of a 16th century mathematician who anticipated Galileo's understanding of artillery trajectories.

 

But have to exit this thread since it is about the evolution of adult body size in biology.

 

(I always thought it had to do with the brain. If you want a gallon-size skull with big brain and approx 100 watt metabolism merely to maintain the brain, then you need females to be biggish. Everything else scales accordingly. Not easy to feed that extra brain metabolism unless you are big too. And so on). Monkeys can be all different sizes, but brainy monkeys need to be fairly big.

[RichF]

Interestingly enough its well known that humans have generally grown taller over the past 2000 years or so. A male was considered tall in ancient roman times if he was 5'5". I learned this at a trip to one of the Smithsonian Museums a few years back. Prior to that, whenever I visited a museum with garments from antiquity (such as roman gladitor uniforms) I would get disappointed with the small sizes!! The armor looked as though it was made for hobbits.

 

I've always heard that was attributed to poor diets and a lack medical care...true?

 

I read a couple of studies several years ago that stated that the farther populations migrated out of Africa, the more isolated they became; this resulted in the populations being less diverse in physical structure. Basically the point was that even though the average height may be the same, the closer you get to the origin of humanity the more varied the physical build due to a more diverse gene pool......ie, a greater percentage of tall, short, fat, thin....ect

 

Edited because I mutilated the English language while trying to multitask.

[SkepticLance]

RichF

The same genetic phenomenon is supposed to be the reason why people of African origin do so well at the Olympic games. It is not that Africans are 'superior'; just more diverse. With a broader normal distribution curve of athletic ability, there will be more at the top to choose from.

 

A similar mechanism has been proposed for why humans today are taller and healthier than in Roman times etc. In times when wealth and technology were limited, so was travel. Thus, people tended to stay where they were born, and marry their neighbours. This led to a degree of inbreeding.

 

Today, people are likely to marry people from far away. Thus, less inbreeding and better genetic spread.

[RichF]

RichF

The same genetic phenomenon is supposed to be the reason why people of African origin do so well at the Olympic games. It is not that Africans are 'superior'; just more diverse. With a broader normal distribution curve of athletic ability' date=' there will be more at the top to choose from.[/Quote']

 

Exactly!

 

A similar mechanism has been proposed for why humans today are taller and healthier than in Roman times etc. In times when wealth and technology were limited, so was travel. Thus, people tended to stay where they were born, and marry their neighbours. This led to a degree of inbreeding.

 

Today, people are likely to marry people from far away. Thus, less inbreeding and better genetic spread.

 

I've always heard that the short stature was due to malnutrition but you bring up a good point! I'm not sure what impact inbreeding has but I imagine that it occurred frequently especially in colder climates where travel was difficult for part of the year. Makes since to me!

[zyncod]

Well, scicop, you live in NY. Just visit the Met if you want to see multiple examples of how small people were in times gone by.

[TimbaLanD]

Some cultures still marry their cousins to keep a close knit family! In India for example, you are allowed to marry your dad’s sister’s son/daughter but not your dad’s brother’s son/daughter. ALSO you can marry your mum’s brother’s son/daughter but not your mum’s sister’s son/daughter.