Pet dogs and elephants are the only animals that seem to instinctively understand human gesture.
14
If Earth's life was compressed into 1 year, then humans would have been around for only 2 seconds.
15
Shark corneas are used in eye transplants and shark bone marrow can be used to graft human bones.
132
The average sperm cell swims at 8 inches per hour.
4
The oldest stone tools found are dated from 2.7 - 2.9 million years ago. The species that made these tools is unknown.
13
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
The human body contains over a billion miles of DNA.
147