Biological science tells us that up to 98% of our genetic make-up as human beings is identical to the genetic make-up of chimpanzees. There seems to be no good reason to dispute this scientific claim (notwithstanding attempts by some fundamentalist thinkers to suggest that we do not share 98% of our genetic make-up with chimpanzees). But it is worthwhile to note that approximately 60% of our genetic make-up as human beings is identical to the genetic make-up of the fruit fly; and approximately 40% of our genetic make-up as human beings is identical to the genetic make-up of lettuce. It does not follow, of course, that fruit flies are 60% human, or that lettuce is 40% human; nor does it follow that chimpanzees are 98% human. Another way of making the point is to say that 100% of our genetic make-up as human beings is identical to the genetic make-up of our gluteus maximus muscle (that’s because almost every cell in the human body — including a typical muscle cell — contains a full copy of the human genome); but of course, it does not follow that a human ass is the same as a human being (though the reverse is very often true, metaphorically-speaking). What is crucial in determining what a thing is, and why it is what it is, is not just the genetic make-up (what Aristotle would have called the material cause), but rather the formation, the organization, the structuring, and the expression of that genetic make-up (what Aristotle would have called the formal cause). Two different things can be made out of almost the same — or even exactly the same — constituents or components, and yet nevertheless remain two very different kinds of things. Consider the fact that 100% of our sub-atomic make-up as human beings is identical to the sub-atomic make-up of a bowling ball; the human being and the bowling ball are made up of the very same sub-atomic constituents: protons, neutrons, and electrons. It does not follow, however, that a human being and a bowling ball are the same kind of thing; indeed we have good reason — in most cases — to hold that human beings and bowling balls are different kinds of things, and have rather different natures and capacities.