Being the giants that we are, our minds boggle when we stop thinking on a big scale and go for the small. Everyone knows that humans are made up of a lot of small units known as cells. Of course, as impatient beings, we usually don't spend years counting things, especially when results are going to vary between individuals because big people have more cells than little people and because we're constantly having some cells die while others divide. Some ballpark estimates range from around only 10 trillion to as many as 100 trillion (that's a hundred with 12 zeros trailing behind, folks).
"Trillions" don't really mean much to us, except in
regard to national debts. "Miles", though, we understand. How many miles of
blood vessels would you think a human body has? One? Five? 100? If you're thinking
along these lines, then once again you're not thinking small enough. A reasonable
estimate seems to be somewhere around 60,000 miles. Loosen up people: you really need
to think small to get the big picture!
Contributor: Arthur H. Harris, Laboratory for Environmental Biology, Centennial Museum, University of Texas at El Paso.
Desert Diary is a joint production of the Centennial Museum and KTEP National Public Radio at the University of Texas at El Paso.