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Lack of load on growing bones helps them to grow stronger.
The osteoporosis (bone loss) which develops in microgravity is one of the greatest hurdles to an extended human presence in space. A recently published study of International Space Station crewmembers found that, on average, they lost bone density in the hip at the rate of 1.6 to 2.7 percent per month, a serious and unacceptable consequence for a crew during transit to Mars. Earth-based human and animal studies have demonstrated that extremely low magnitude mechanical loading, if imposed at a high frequency, can inhibit bone loss in the load-bearing skeleton.
My guess is better nutrition, easier lifestyle. It has been shown that the nutritional habits of pregnant women reflect on their unborn baby's health later in life. I would suggest that height is probably linked, though more likely nutrition at birth and on has more of an effect. We (collectively the western world) are never short of a drop of milk to give to our kiddies, making strong healthy bones. Do children in countries where milk is harder to obtain show the same strength in height? We also don't load them (children) up with grains and water to carry home (well, I do that on weekends and race them, but that's another story) Lack of load on growing bones helps them to grow stronger and longer.
Quote from: JnA on 25/11/2008 22:33:46Lack of load on growing bones helps them to grow stronger. Not according to NASA ...QuoteThe osteoporosis (bone loss) which develops in microgravity is one of the greatest hurdles to an extended human presence in space. A recently published study of International Space Station crewmembers found that, on average, they lost bone density in the hip at the rate of 1.6 to 2.7 percent per month, a serious and unacceptable consequence for a crew during transit to Mars. Earth-based human and animal studies have demonstrated that extremely low magnitude mechanical loading, if imposed at a high frequency, can inhibit bone loss in the load-bearing skeleton. http://www.nasa.gov/mission_pages/station/science/experiments/VIBE.html
I think it has alot to do with genetics. If your parents have 29" inside leg jeans and you have 31" inside leg jeans then you must be taller than your parents or your jeans will drag along the floor.In the instance you have shown above, it may have more to do with trousers (US pants) than jeans.Ahhh! I seem to have got my jeans and my genes in a bit of a muddle......
Hmmm odd, I read somewhere that the average height of Americans is now 2.5 in. taller than at the end of the civil war.