Yawns are more contagious among people with closer relationships.
163
On average, there's 100 billion neurons in the human brain.
83
The human brain is very soft, having a consistency similar to soft gelatin or firm tofu.
13
In 30 minutes, the average body gives off enough heat (combined) to bring a half gallon of water to boil.
198
The average person's skin weighs twice as much as their brain.
131
You forget 90% of your dreams.
256
Modern humans first appeared about 200,000 years ago, but record keeping didn't begin until about 6,000 years ago. That means about 97% of human history is lost.
21