Prosopagnosia — face blindness — affects about 2% of the population and is often undiagnosed.

Lake Baikal in Russia holds about 20% of the world's unfrozen fresh surface water.

The Earth's continents were once joined as Pangaea.

The Black Death originated in Central Asia and wiped out roughly half the population of Europe in under a decade.

More people live in Tokyo than in the entire country of Canada.

The Alaska Purchase in 1867 added territory to the United States.

The entire population of Earth in 1 AD was around 300 million — roughly equal to the current population of the United States.

The ocean contains structures larger than mountain ranges.

Around 90% of the world's population lives in the Northern Hemisphere.