Humans Interesting Facts

here are some interesting facts:

• Humans were first infected with the HIV virus in the 1930s.
  
• If left alone, 70% of birthmarks gradually fade away.
  
• Grapefruit scent will make middle aged women appear six years younger to men. The perception is not reciprocal and the grapefruit scent on men has no effect on women's perception.
  
• Women blink twice as many times as men do.
  
• Intelligent peoples have more zinc and copper in their hair.
  
• There are 550 hairs in the eyebrow.
  
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