Your thumb is about the same size as your nose.
124
The average sperm cell swims at 8 inches per hour.
76
The human brain is very soft, having a consistency similar to soft gelatin or firm tofu.
13
Enamel is hardest substance in the human body.
61
Quick naps not only improve your alertness, but they also help in decision making, creativity and sensory perception.
149
The human brain doesn't stop developing until about 25 years old.
102
Dogs can be trained to identify the scent of lung cancer long before symptoms develop.
190
Cracking your knuckles does not actually hurt your bones or cause arthritis. The sound you hear is just gas bubbles bursting.
18