NationStates Jolt Archive


Natural Selection and Human Height

Jitia
06-12-2006, 03:05
Just a silly debate I've gotten into with some people. One group says that the average height of a population is determined by the nutritional level of the population and natural selection plays a only a minor role - if any. The other group(which I'm siding with) says that the average height of a population is determined equally by natural selection and nutrition. The basic argument of the first group is: Humans are getting taller purely because of increased nutrition. Second group: Humans are getting taller because of nutrition, but the fact that taller humans are normally considered more attractive has also contributed to height increases over the past several centuries.

I recognize the fact that in modern society nutrition plays a much larger role. Mainly because we know more about nutrition than we ever have, and in modern societies shorter people are able reproduce at the same rate as taller people. But back when life was grimmer, when people barely made it to their 30s, I’d argue that the taller person was much more likely to produce offspring than the shorter person.

Your thoughts? Some links would be nice.
Sylvontis
06-12-2006, 03:07
I'm 16 and currently 5'7/5'8 range. If this means I'll die a virgin then I'm going to be very unhappy. :(
Tech-gnosis
06-12-2006, 03:10
After nutrition height is mostly determined by temperature of the local environment. Where its hot organisms will be tall and skinny. This helps bleed waste heat most efficiently. Where its cold organisms will be short and stocky. This helps retain heat. Note this is in the long term.
Cybach
06-12-2006, 03:10
I'm 16 and currently 5'7/5'8 range. If this means I'll die a virgin then I'm going to be very unhappy. :(

Lol, dwarf. :D
Tech-gnosis
06-12-2006, 03:11
I'm 16 and currently 5'7/5'8 range. If this means I'll die a virgin then I'm going to be very unhappy. :(

You're dying a virgin has nothing to do with your height. :p
Gorias
06-12-2006, 03:11
a study in england said that thier was increased proportional to the invention of the bike. people were able to get other more.

so maybe its to mixing of genes.
The Psyker
06-12-2006, 03:11
Well, considering what I know of the historical record, at least in Europe, and how height took drops in periods where crop production was suposedly poor, I'd say nutrition for the most part. Genetics would play a small role.
Gorias
06-12-2006, 03:11
You're dying a virgin has nothing to do with your height. :p

maybe he should but some mints?
Tech-gnosis
06-12-2006, 03:12
maybe he should but some mints?

Plastic surgery might help. And acne cream!
Ladamesansmerci
06-12-2006, 03:13
maybe he should but some mints?

Wait, you hate hippies? :(

We're not going to get along then.
Jitia
06-12-2006, 03:14
5'7-5'8 is just the low end of average. I'm thinking more along the lines that the margins(Like 5'2-5'4 in males) will be pushed out because of natural selection.

After nutrition height is mostly determined by temperature of the local environment. Where its hot organisms will be tall and skinny. This helps bleed waste heat most efficiently. Where its cold organisms will be short and stocky. This helps retain heat. Note this is in the long term.

But wouldn't this just be the result of several generations of one type of organism reproducing less often than the one who has a better chance of surviving in the specific environment?
NERVUN
06-12-2006, 03:17
Nutrition seems to be the most important factor. The Japanese have gotten a lot taller since their diet switched from only rice, veggies, and fish, to include more red meat.

Though, yes, I have read that women tend to be attracted to taller men (within a certain range) so there might be a natural selection component there.
NERVUN
06-12-2006, 03:18
After nutrition height is mostly determined by temperature of the local environment. Where its hot organisms will be tall and skinny. This helps bleed waste heat most efficiently. Where its cold organisms will be short and stocky. This helps retain heat. Note this is in the long term.
Uh, how do you explain bushmen in Africa (who are usually short) and how tall many Northern Europeans are then?
Jitia
06-12-2006, 03:20
Well, considering what I know of the historical record, at least in Europe, and how height took drops in periods where crop production was suposedly poor, I'd say nutrition for the most part. Genetics would play a small role.

Yeah, I'm aware the fact that heights tend to go up and down. But when height does drop, does it drop as low as it was before the initial rise? For example: one population starts out around 5'3 and gradually moves up to 6'0. There's a series of famines, wars, etc. and nutrion drops back to the level it was before. Wouldn't the population most likely drop to around 5'5 or 5'6 instead of the previous average of 5'3?
Free Soviets
06-12-2006, 03:22
Uh, how do you explain bushmen in Africa (who are usually short) and how tall many Northern Europeans are then?

i think you mean the mbuti and pals - the pygmies.
NERVUN
06-12-2006, 03:25
Yeah, I'm aware the fact that heights tend to go up and down. But when height does drop, does it drop as low as it was before the initial rise? For example: one population starts out around 5'3 and gradually moves up to 6'0. There's a series of famines, wars, etc. and nutrion drops back to the level it was before. Wouldn't the population most likely drop to around 5'5 or 5'6 instead of the previous average of 5'3?
Actually, it does. During WWII, nutrition was so poor in Japan that the average height actually dropped down lower than it had been before Japan opened up.
The Psyker
06-12-2006, 03:26
Yeah, I'm aware the fact that heights tend to go up and down. But when height does drop, does it drop as low as it was before the initial rise? For example: one population starts out around 5'3 and gradually moves up to 6'0. There's a series of famines, wars, etc. and nutrion drops back to the level it was before. Wouldn't the population most likely drop to around 5'5 or 5'6 instead of the previous average of 5'3?

Why would it do that? If new genetic material were playing a small part, as I said it could, then yes I could see how it might suposeing the introduction of genetic traits that cause greater growth, but if the increase was solely due to increased nutrition I would think it would return to the previous level.
NERVUN
06-12-2006, 03:26
i think you mean the mbuti and pals - the pygmies.
Yes, them. Sorry, my bad.
Helspotistan
06-12-2006, 03:27
Just a silly debate I've gotten into with some people. One group says that the average height of a population is determined by the nutritional level of the population and natural selection plays a only a minor role - if any. The other group(which I'm siding with) says that the average height of a population is determined equally by natural selection and nutrition. The basic argument of the first group is: Humans are getting taller purely because of increased nutrition. Second group: Humans are getting taller because of nutrition, but the fact that taller humans are normally considered more attractive has also contributed to height increases over the past several centuries.

I recognize the fact that in modern society nutrition plays a much larger role. Mainly because we know more about nutrition than we ever have, and in modern societies shorter people are able reproduce at the same rate as taller people. But back when life was grimmer, when people barely made it to their 30s, I’d argue that the taller person was much more likely to produce offspring than the shorter person.

Your thoughts? Some links would be nice.

Given that the average height of a japanese man has grown by a foot since WWII its got to be pretty much diet that is doing most of the work in that situation. However it is leveling off now at about 170 cm. Which is about 8cm shorter than the average here in Australia.

So looks like nutrition is likely to play a large part... but you are right genetics can't be discounted..
The Psyker
06-12-2006, 03:28
Uh, how do you explain bushmen in Africa (who are usually short) and how tall many Northern Europeans are then?

I've heard about what he is talking about as well. Suposedly it is because longer limbs provide more surface area to shed heat, while a compact build makes it easier to conserve heat. Don't know the particulars about the groups you mention
Helspotistan
06-12-2006, 03:30
Yeah, I'm aware the fact that heights tend to go up and down. But when height does drop, does it drop as low as it was before the initial rise? For example: one population starts out around 5'3 and gradually moves up to 6'0. There's a series of famines, wars, etc. and nutrion drops back to the level it was before. Wouldn't the population most likely drop to around 5'5 or 5'6 instead of the previous average of 5'3?

I don't think selection is biased to the increase of height only... like someone pointed out there are advantages and disadvatages to being tall.. In some situations selection will actually select for people who are shorter.

So your situation seems pretty unlikely....
Tech-gnosis
06-12-2006, 03:35
Uh, how do you explain bushmen in Africa (who are usually short) and how tall many Northern Europeans are then?

Either they have some kind advantage outweighing their disadvange, other environmental factors make their height an advantage, or not enough time has past for natural selection to have done its work.
Jitia
06-12-2006, 03:37
Why would it do that? If new genetic material were playing a small part, as I said it could, then yes I could see how it might suposeing the introduction of genetic traits that cause greater growth, but if the increase was solely due to increased nutrition I would think it would return to the previous level.

Well, in my scenario the height increase was coming from both nutrition and selection. I was assuming that when the nutritional factor is removed, then only the genetic factor would remain. Basically, genetics raised both the lower and upper limits, but because of nutrition the average person was getting closer to the upper limit.
The Psyker
06-12-2006, 03:52
Well, in my scenario the height increase was coming from both nutrition and selection. I was assuming that when the nutritional factor is removed, then only the genetic factor would remain. Basically, genetics raised both the lower and upper limits, but because of nutrition the average person was getting closer to the upper limit.That would require new genetic info wouldn't it? In the form of either new mutations or new taller members coming into the mix?
Poliwanacraca
06-12-2006, 05:43
I think the influence of any selection for more "handsome" tall people is likely to be negligible - for one thing, while 5'3'' men may have a bit more trouble getting a date than 6'3'' men, I rather suspect it's the other way around for women, who also pass along height-determining genes to their offspring.
Tech-gnosis
06-12-2006, 05:58
There is the fact that relatively tall men do better than relatively shorter men.
Iztatepopotla
06-12-2006, 06:43
Nutrition. During WW1 the well fed Australian troops were much taller than the British ones. By WW2 and thanks to better food, they were almost the same height.

Taller men are generally considered more attractive, but that's not necessarily true for women.

And there's a limit to how tall human anatomy can be without breaking down. I think it's about 2.4m - 2.5m, although I could be remembering wrong. There have been people over that height, but they suffer all kinds of problems.

EDIT: Although, yes, genetics plays a part. If you have "short" genes you're not going to grow up to be 1.85m no matter how well you eat, but good nutrition can be the difference between ending up at 1.60m or at 1.70m.
Laerod
06-12-2006, 07:45
Your thoughts? Some links would be nice.The nutrition you get while in your growing phase will have a major effect on your growth, possibly more so than your genes, but possibly not. I didn't manage to outgrow my dad and by brother is barely smaller than I am. Nutrition just lets you meet the full potential of your geneticly possible height.
Helspotistan
06-12-2006, 07:54
The nutrition you get while in your growing phase will have a major effect on your growth, possibly more so than your genes, but possibly not. I didn't manage to outgrow my dad and by brother is barely smaller than I am. Nutrition just lets you meet the full potential of your geneticly possible height.

Its not just your nutrition either.. your mother's nutrition will also effect your height while she is pregnant and breast feeding. So even if you eat really well as a teenager you may never grow to your full (genetic potential) height.
Mentholyptus
06-12-2006, 08:07
You've all got it wrong. The actual reason for the observed increase in human height over history is deeply related to the actual cause of gravity. See, the force holding people to the ground, far from being caused by the mutual attraction of massive objects, is in fact the effect of the Noodly Appendages of the Flying Spaghetti Monster touching human beings, whom He loves. As the population has grown, the FSM has had to touch each person less and less, having as He does only a finite number of Noodly Appendages. So, as the population has increased, the average height of people has gone up since they are touched less (and thus pushed down less) by the FSM. It's all in the Gospel of the Flying Spaghetti Monster. And I'm seriously disappointed that it took this many pages before someone posted this.
Free Randomers
06-12-2006, 10:31
Things we know:

1. Your (personal) genetics affect the height you have the potential to grow to. This is why children of tall parents tend to be tall, and children of short parents tend to be short.

2. Poor nutrition hinders growth, and if nutrition is poor throught childhood and adolescence then growth will often be permanently stunted. Protien is key to this, however other nutrition plays a part too.


It is then obvious (to me at least) that a persons maximum potential height is determined by their genetics, and that the level of nutrition they recieve determines how much of that potential they achieve.

Two other things we know:
1. Ethnic populations tend to share genetic traits and trends. See hair colour, eye colour, ability to produce melanin for example. This does not mean that everyone in the population has that trait, but there is a tendancy to have it.

2. Ethnic populations tend to share similar diet - even given access to any food, diets between different cultures (which closely approximates to different races) are not the same. Often chinese people in the west stick to (real) chinese food for example


So the question becomes a bit more complex as when you look at average heights across races as there is obviously genetic variation, but this is almost always combined with variation in diet - and hence often with protien intake.

Personally my gut feeling is that average potential height does vary with race, but that the only way to really confirm how height and race correlerate would be to carry out a large study on adopted children where the child adopted is a different race from the adoptive parents. But also making sure the parents all had similar ideas on what makes up a good healthy diet. Such a study I doubt will happen.
Letila
06-12-2006, 15:52
I'm 16 and currently 5'7/5'8 range. If this means I'll die a virgin then I'm going to be very unhappy.

I'm 19 and I'm only 5'6", so I'm almost certain to die a virgin.