[mommylady28]

It is safe to say that animals when put in a new eco. system, will change or die out. I have notested the size of newborns in small scale humain races have ben getting larger, and is this ocuring in random places or in places where the magnetic feald has changed? . Also, could their dencety be greater not just the size increse? I know i would have to match up my findings on a global scal,and find out the change patterns of birth wheght, and gravity. I don't know where to start my search, thank you for you'r help.

[CliffordK]

I would imagine that there are birth weight statistics available someplace.

I haven't been around the neonatal wards much, but I would guess there could be a few issues that would be related to birth weight.

Better Nutrition.
Some new treatments to prevent premature births.
Less Smoking?
Fatter Society?

I doubt subtle things like the fluctuating magnetic pole will affect birth weights.  However, there could be changing natural selection.  While mothers with heavy babies may induce labor early now, 100 years ago, a 10+ lb baby might have posed a significant risk to both the mother and the infant.  Perhaps a historical search would show greater survivability of both the very heavy, as well as very light babies now than in the past.  So, genes that would be related to issues that could put the mother of baby at risk would now be survivable, and passed onto the next generation.

[Airthumbs]

I have notested the size of newborns in small scale humain races have ben getting larger, and is this ocuring in random places or in places where the magnetic feald has changed? .

Hi Mommylady, Where has the magnetic field changed?

[CliffordK]

The magnetic poles apparently always have moved somewhat,  with magnetic North more or less moving northward towards true North, and Magnetic South also moving North, away from the South Pole.

http://www.greatdreams.com/spinaxis.htm

Earth's magnetic field also goes through periods of weakening and strengthening, and even periodic reversals. 
http://en.wikipedia.org/wiki/Earth%27s_magnetic_field#Magnetic_field_reversals

It may or may not go through a reversal over the next few centuries, but it has weakened in the past, only to get stronger later. 

These events are unlikely to have a significant impact on human genetics , unless somehow they are related to greater UV or cosmic rays getting to the surface of the Earth. 

[mommylady28]

if you look up the magnetic feild a some sights will show that over the last 15 years or so the feild has changed the modle i saw shows blue on top (north and red on botum (south)  over time the north started to show red splotches and the southern shows blue splotches allmost merorring each other on the globe. i am tring to find the show i saw it on i think discovery ch?

Hi Mommylady, Where has the magnetic field changed?
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[mommylady28]

(I doubt subtle things like the fluctuating magnetic pole will affect birth weights.  However, there could be changing natural selection.  While mothers with heavy babies may induce labor early now, 100 years ago, a 10+ lb baby might have posed a significant risk to both the mother and the infant.)

  :Xty i like the addvice i won't pretend im well educated lol but i love science. and you are right if not for modern med. my doughter and i would have probly died  B)

[Sprool]

I'd put it down to better nutrition and health care. I can't imagine how fluctuations in the position of the magnetic poles could affect the birth weight of a human baby.