WHY???

I would guess that as a teacher and a physician, not to mention father and grandfather, I have heard this question more often than any other. I also suppose that H. sapiens is the only species that asks it. "WHY?" is cosmic, contextual, value-laden, and usually philosophical. It can be the basis for some interesting late night ruminations. It is also a question that often has no "real" or satisfactory answer, particularly if the questioner is under the age of 21.
Often the real question, however, from a practical and scientific perspective, is HOW?? This question often can be answered and become the basis for significant learning and more productive questioning.
Sometimes, though, the answer to WHY can be found. The photo above shows IRON. Iron is an essential element in the production of hemoglobin. Metals carry oxygen in a way that allows it to be readily transported and released. But why iron? Because it is the most abundant metal in the universe. If copper were similarly abundant and iron rare, it is likely our blood would contain it instead. And WHY blood is red is that when oxidized iron turns into a reddish oxide (like rust!). If our blood metal were copper then our blood would be green, like Lady Liberty! Wouldn't that be cool?
Take care of your iron this weekend--eat some spinach!