A person will create enough saliva to fill two average size swimming pools during his lifetime.
191
Our eyes are always the same size from birth, but our nose and ears never stop growing.
266
Tigers can see 6 times better at night than humans.
305
The human brain doesn't stop developing until about 25 years old.
102
It took 200,000 years for humans to reach 3 billion in number. It took 40 years for the next 3 billion.
11
It takes about 20 seconds for a red blood cell to circle the whole body.
102
Babies crawl an average of 200m a day.
212
