Yawns are more contagious among people with closer relationships.
163
After age 30, the brain begins to lose about 50,000 neurons per day - shrinking the brain .25% each year.
55
Your thumb is about the same size as your nose.
124
One human hair can support 3 ounces.
191
It would take about 1,200,000 mosquitoes to fully drain the average human body of blood.
217
Enamel is hardest substance in the human body.
61
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
Dogs can be trained to identify the scent of lung cancer long before symptoms develop.
190