Effect of gravity on height of a person My physics teacher told us (while teaching the topic gravitation) that gravity has a effect on height of human body, he gave us following examples:


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*The height of astronauts after coming back to earth is found to be increased slightly.

*The people living at equator (such as in west indies) are usually found longer than people living in polar countries (as value of $g$ differ at pole and equator). {This example seems quite interesting and I have a doubt in it}.
His examples were quite interesting and also confusing (as I am unable to get the reason behind them), but I suppose I can get the answer here. I hope for an answer  which may describe the relation between gravity and height of a person.
 A: The human body is somewhat elastic (a good property to have, otherwise we would break bones more frequently) and as with any elastic body it will tend to stretch or compress when subjected to a force. Gravity is such a force. When we stand upright, the force of gravity compresses us and makes us a little shorter. If we measured our height while hanging by our heels, the effect would be opposite and we would be somewhat taller.  
As for the observation that people living at or near the equator tend to be taller than those living near the polar regions, I would doubt that that (if true) is due to gravity.  The gravitational effect is probably too small to dominate over other factors such as genetics and nutritional effects.
A: Astronauts experiencing microgravity in space have indeed been found to return to Earth a few centimeters taller than when they left. Some studies conducted have indicated that microgravity affects the spinal vertebrae, allowing them to expand and relax more easily than when under the effect of the Earth's gravity (where the greater gravitational force of the Earth pulls the spine downwards, compressing the vertebrae). It is worth noting that these changes in height quickly dissapear upon return to Earth as the spine becomes once again compressed.
As for people around the equator, as far as I know they have grown taller primarily through natural selection, with weaker gravity playing a small or negligible role (although I may be proven wrong!). Typically people living in areas around the equator - many African people for example - have diets high in animal proteins, allowing them to grow taller, whereas animal proteins in the north and south pole are scarce!
See this link for further information on the effects of microgravity on the spine:
http://www.space.com/19116-astronauts-taller-space-spines.html
A: Consider and extremely simplified model of a human as say a spring with a mass at the top, where the spring is some representation of your muscular joints/backbone etc. that keeps you up. Because of a gravitational force, the equilibrium height of the mass of the spring will be somewhat lower than the natural length of the spring. This deviation will increase in an increasing gravitational field.
In the same way, being in a weaker gravitational field will allow your backbone etc to stretch out a little more because there isn't as much of a force opposing it.
That being said, I highly doubt that there would be any measurable difference in the average height of people living at the equator and people living near the poles. The astronaut example I believe, and I'm quite sure is true, but I would be very skeptical of the equator vs polar country example being attributed to the difference in the effective gravitational field.
A: The differences are very small but being in the presence of stronger gravity will compress your body a little more than what weaker gravity would do. The body isn't a completely rigid structure (ie. diamond) so like the other poster mentioned it's kind of like a spring. The more force you apply to the spring the shorter it will be.
