Blue eyes are a genetic mutation. Before the mutation occured, all humans had brown eyes.
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In one day, adult lungs move about 10,000 litres of air.
11
When you get goosebumps and your hair stands, the hair helps to trap air, making you feel warmer by keeping in your body heat.
46
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
After age 30, the brain begins to lose about 50,000 neurons per day - shrinking the brain .25% each year.
55
There are about 1,400 different species of bacteria in your belly button.
10
The human brain doesn't stop developing until about 25 years old.
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