Shark corneas are used in eye transplants and shark bone marrow can be used to graft human bones.
132
The oldest stone tools found are dated from 2.7 - 2.9 million years ago. The species that made these tools is unknown.
13
Enamel is hardest substance in the human body.
61
Pain occurs when sounds are above 130 db.
124
There are glasses which allow a red-green color-blind person to see colors the way everyone else does.
22
Only 12,000 years ago there was a species closely related to modern humans called Homo floresiensis that had been living on an Indonesian Island. They used fire and rather advanced tools, yet were only about 3 feet tall and weighed around 25kg.
15
The human brain is more active during sleep than during the day.
28
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