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
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.
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There are times when you're walking that the pressure on your feet exceeds your body weight, and when you're running, it can be three or four times your weight.
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If Earth's life was compressed into 1 year, then humans would have been around for only 2 seconds.
15
A third of the human population sneezes when they look at the Sun. Light can signal the ocular nerve near the sinuses and triggers a sneeze.
18
Due to the angle at which the optic nerve enters the brain, staring at a blue surface during sex greatly increases the intensity of orgasms.
252
The average person's skin weighs twice as much as their brain.
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Oxygen, carbon, hydrogen and nitrogen make up 90% of the human body.
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