Two number assumptions I am going to go under. 1901 the human world
population was 1 billion
and by 2008 it reached 7 billion. Now there are some facts that anyone
can find out about agriculture and I would be surprized
if noone used these facts to compute the optimal human population
size. Earth has 150 million
km^2 of land of which 20 million km^2 is arable-- that is farmable
productive in growing food.

Not counting the Oceans for protein or food then 7,000,000,000 humans
has 20,000,000
km^2 of land to grow food upon. That means 350 people per every 1 km^2
of land to live
on. Now, how many walnut trees can grow on 1 km^2 of land?

In my previous posts, I outlined a Optimal Human Population as that of
1901 where we can say
that humanity could live on this planet by using purely, and only
renewable energy and nothing
else that dirtys the air and no Global Warming and preservation of
plant and animal wild species.
So that if we kept human population with 1 and 2 billion humans, and
no more that we would each
have plenty of food and plenty of energy.

But now, let me compute the 1 to 2 billion figure from agriculture.

Archimedes Plutonium
www.iw.net/~a_plutonium
whole entire Universe is just one big atom
where dots of the electron-dot-cloud are galaxies