The cornea is the only tissue in the human body with no blood supply — it gets oxygen directly from the air.

The Earth's outer core is liquid metal.

Fact #250 · Human Body

The Thirty Years’ War affected much of Central Europe.

Fact #1171 · Human Body

The human heart pumps blood through the circulatory system.

Fact #99 · Human Body

The Olympic Games are held every four years.

Fact #923 · Human Body

Some birds have hollow bones to reduce body weight for flight.

Fact #889 · Human Body

The dragonfish has bioluminescent organs along its body.

Fact #1404 · Human Body

The Earth's inner core is solid despite extreme heat.

Fact #217 · Human Body

The human brain continues to develop into early adulthood.

Fact #83 · Human Body