The world's population has reached the vicinity of 7.5 to 7.6 billion people.
Since 1960, world population has grown exponentially by about one billion every 13 years.
Humans have a large ecological footprint — we are the most populous mammal on Earth today.
But the Earth will only have capacity for the population to a point until premature death by starvation and disease balances the birth rate.
World Health Organization figures show 2.1 billion people lack access to safe drinking water, and...