The human brain doesn't stop developing until about 25 years old.
102
The focusing muscles of the eyes move around 100,000 times a day. To give your leg muscles the same workout, you would need to walk 80km (50 miles) every day.
21
There are about 1,400 different species of bacteria in your belly button.
10
If you hold farts in during the day, they'll just come out when you sleep.
16
Staying awake for 17 hours is the same for your body as drinking 2 glasses of wine.
193
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