combined age

Newspapers love the idea of the "combined age" of a group of people, you see it all over:

• "Scottish family emerges with combined age of 854 in race to be..."
  
• "Siblings combined age is nearly 700"
  
• "The world's oldest family, with a combined age of close to 500..."
  

Of course it's not very useful if you don't know how many people are in the group. But it got me to thinking, what's the combined age of the human race at the moment?

Using the CIA world fact book we can estimate it at 224 billion years. Interestingly, the age of the universe is 13.75 billion years, so collectively the people living on Earth right now have lived more than 16 times the age of the universe.

Image source

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This post was originally on LiveJournal.