Does Earth's Gravitational pull increase with time? Gravitational field depends on mass ($g = \frac{GM}{r^2}$) and every year many outside cosmic objects like asteroids or tiny object are hitting earth. So I think may be in a very microscopic amount the mass of Earth is increasing. But does it increase the Gravitational Pull or Gravity on Earth?
And also, does it result in decrease in height of organisms in each century? Because some older people say that people in their time or in ancient times were taller and more aged. I am just curious if it is the reason or not.
 A: Actually the opposite is true.
Quoted from Gizmodo - Did You Know That Earth Is Getting Lighter Every Day?:

  
*
  
*Earth gains about 40,000 tonnes of dust every year,
  the remnants of the formation of the solar system,
  which are attracted by our gravity and become part
  of the matter in our planet. Our planet is actually
  made from all that starstuff.
  
*Earth's core loses energy over time. It's like a giant
  nuclear reactor that burns fuel. Less energy means less mass.
  16 tonnes of that are gone every year. Not much.
  
*And here's the big mass loss: about 95,000 tonnes of hydrogen
  and 1,600 tones of helium escape Earth every year.
  They are too light for gravity to keep them around,
  so they get lost. Gone into space.

So, summing all these effects mentioned above,
you get a mass loss of 57,000 tonnes per year.
But this is still much too small to have a measurable effect on gravity
($g = GM/r^2$) even after millions of years,
because the mass of the earth is $M = 6\cdot 10^{24} \text{ kg}$
(i.e. 6,000,000,000,000,000,000,000 tonnes).
