Humanity hits the eight billion mark: UN

A baby born somewhere on Tuesday will be the world's eight billionth person, according to a projection by the United Nations.

"The milestone is an occasion to celebrate diversity and advancements while considering humanity's shared responsibility for the planet," UN Secretary-General Antonio Guterres said in a statement.

The UN attributes the growth to human development, with people living longer thanks to improvements in public health, nutrition, personal hygiene and medicine.

It is also the result of higher fertility rates, particularly in the world's poorest countries -- most of which are in sub-Saharan Africa -- putting their development goals at risk.

Population growth has also magnified the environmental impacts of economic development.

But while some worry that eight billion humans are too many for planet Earth, most experts say the bigger problem is the overconsumption of resources by the wealthiest people.

"Some express concerns that our world is overpopulated," said United Nations Population Fund chief Natalia Kanem. "I am here to say clearly that the sheer number of human lives is not a cause for fear."

Since 1800, the world's population has jumped eight-fold, from an estimated one billion to eight billion.

The development of vaccines was key, with the smallpox jab particularly helping zap one of history's biggest killers.

MG