The human brain doesn't stop developing until about 25 years old.
102
It takes twice as long to lose new muscle if you stop working out than it did to gain it.
127
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
The average person's skin weighs twice as much as their brain.
131
There's 100 trillion good bacteria living in your body.
17
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
You can hear the blood flowing through your ears if you find a quiet place and cover them tightly.
17