Enamel is hardest substance in the human body.
61
An average heart beats 100,000 times a day, pumping some 2,000 gallons of blood through its chambers. Over a 70-year life span, that adds up to more than 2.5 billion heartbeats.
73
On average a woman has 4 sexual partners in her lifetime.
-143
A third of the human population sneezes when they look at the Sun. Light can signal the ocular nerve near the sinuses and triggers a sneeze.
18
When you kiss someone for the first time, you get a spike in the neurotransmitter dopamine, making you crave more.
23
The human brain doesn't stop developing until about 25 years old.
102
Gorillas can catch human colds and other illnesses.
205
You can't tickle yourself.
29