The United Nations says that sometime around Halloween the seven-billionth person will be born into this world — most likely in India, which is on track to overtake China as the most populous nation in just 16 years.
This latest milestone may not come as a surprise. But it is remarkable nonetheless. It took Earth 50,000 years to reach the one billion mark. By 1960 there were three billion souls. Since then we've added another billion every decade, or less.