A human being loses an average of 40 to 100 strands of hair a day.
133
Enamel is hardest substance in the human body.
61
The average person's skin weighs twice as much as their brain.
131
Only humans shed emotional tears.
331
The oldest stone tools found are dated from 2.7 - 2.9 million years ago. The species that made these tools is unknown.
13
The human brain is more active during sleep than during the day.
28