When you kiss someone for the first time, you get a spike in the neurotransmitter dopamine, making you crave more.
23
By weight, Bone is five times stronger than steel.
417
The world's shortest man measures only 21.5 inches.
73
Only 12,000 years ago there was a species closely related to modern humans called Homo floresiensis that had been living on an Indonesian Island. They used fire and rather advanced tools, yet were only about 3 feet tall and weighed around 25kg.
15
In one day, adult lungs move about 10,000 litres of air.
11
On average, there's 100 billion neurons in the human brain.
83
It took 200,000 years for humans to reach 3 billion in number. It took 40 years for the next 3 billion.
11