Any alert readers of this site (ha, as if there are any readers…) might have noticed that I am gradually working my way thorugh some recent back issues of New Scientist highlighting a few interesting articles along the way. Something that intrigued me from New Scientist Issue 2697 (28 February 2009) was the response to a letter from a parent asking a question on behalf of their daughter (age not given). The daughter wanted to know why humans have evolved to have two systems to excrete waste products (“poo” and “wee”). I’ve never thought about this before, but the responses indicated that in fact we only have one real excretion system, “wee”, as this takes waste products from inside our bodies and ejects them to the outside. It turns out (and this is the good part) that really our bodies can be thought of as having an elongated annular shape, by which I mean that we are a chunk of connected organic matter that surrounds a long tube. We feed by drawing material in through our mouth, squashing it about a bit, squirting acid on it, sucking the good bits into our interior and leaving what is left to drop out of the end of the tube. This is certainly a very different view of things, but clearly it is not wrong. Now I keep thinking of humans as being quite like some ultra-mobile and (presumably) ultra-intelligent worms, roaming through space enveloping food, and leaving a trail of waste behind us… What a great question.
Tim O'Hare 