[neilep (OP)]

Would I be right in thinking that the strength of Gravity affects my height, and any other living growing thing ?..trees for example.....If our Gravity was half what it is, could I expect to be much taller ?...and in contrary to that, if Gravity was stronger, I presume I'd be shorter eh ?


I assume the comments will also say that if we existed with a different Gravity then our whole biology and anatomy would also be different.


I await the weight of your answers without levity, but with gravity.[]

'Men are the same as women...just inside out !'

[chris]

Neil - you grow and shrink every day due to the effects of gravity.

When recumbent at night, and gravity is no longer applied to your long (vertical) axis, you get longer as tissues swell and stretch slightly including, for instance, the gelatinous discs that sit between each of the bones in your back, and the cartilage in your joints. They are squelchy and when pressure is applied downwards they behave like a sponge - excess water is squeezed out and they get smaller. When the pressure is removed they exapnd again. So as the day goes on, you shrink...then re-expand at night (possibly alongside other things).

Your height also fluctuates during the day (together with your weight) in a lift, or on an aeroplane. That momentary heaviness or lightness you experience when ascending (or descending) is an increase (or decrease) in your weight when you accelerate (or decelerate). This weight change will momentarily translate into changes in height for the reasons outlined above.

If you were subjected to a different gravitational field strength there wouldn't be a sudden change in height. We have evolved to be the size that we have over millions of years. This involves many factors including how well your heart can push blood around your body, the ability of your joints to be stable over a range of heights etc.

One thing that space scientists have been interested to know more about is the ability of embryos to develop under different gravitational conditions. Obviously if we plan to populate distant worlds we'll need to be able to reproduce - yet no one knows if this is possible - or even if sperm can swim correctly - under conditions of weightlessness. With this in mind, NASA recently tested sea urchin sperm aboard the space shuttle :
http://www.thenakedscientists.com/HTML/shows/2001.10.28.htm#sperminspace

And the Chinese have been sending developing hens' eggs into orbit and then hatching them out back on earth :
http://www.thenakedscientists.com/HTML/Shows/2002.07.07.htm#2

Chris





"I never forget a face, but in your case I'll make an exception"
 - Groucho Marx

[neilep (OP)]

Thanks Chris.....yes, I should have put my thinking hat on for a little longer before asking that question (well it was almost 3am).....I certainly knew about the gaining height  (length)as you lie down etc but really appreciate the explanation........and, gosh, yes I can see there could be procreation problems ahead, who knows, if and when we establish colonies on other planets or in space, sex may become redundant (apart from a recreational point of view !!) and perhaps we'll only be able to procreate in a lab.....

Lets hope the sea urchin sperm are helpful, presumably there must be a very good reason why sea urchins in particular are used. Thanks for the links which I'll now check

Thanks

'Men are the same as women...just inside out !'

[bezoar]

And I remember reading that giants (people over 7 feet) are prone to heart problems, and it was theorized because the heart had so much further to pump.  Anyone know anything about that?

[chris]

I think it is actually a bit more subtle than that in the sense that the metabolic syndrome that causes the gigantism also leads to cardiac problems. For instance, individuals with too much growth hormone (acromegaly) invariably develop hypertension and all of its attendant vascular risks.

Chris

"I never forget a face, but in your case I'll make an exception"
 - Groucho Marx

[Exodus]

Are there any characteristic health aspects at the other end of the spectrum i.e. for midgets?

[OmnipotentOne]

Yeah i remember reading somwhere that the tallest man in the world died of heart problems....I'm glad im short.

To see the world through a grain of sand.

[Exodus]

yeah, us shorties do alright... i always think of myself as a bit more stable!!