Fundamental Laws of Biology

We generally think of laws in terms of physics (Newton's laws, e.g.) or chemistry (gas laws, e.g.) but we have our laws in biology too, sometimes expressed mathematically but often not. On a biology teacher's listserv, I followed a recommendation to watch a video of E.O. Wilson and James Watson interviewed by Charlie Rose (December, 2005). The occasion was that both had recently published anthologies on the life and work of Charles Darwin. Worth a watch, and raises many of the interesting social/philosophical question that I tend to be drawn to, sometimes overly so.

I particularly liked Wilson's enunciation of two fundamental concepts in modern biology, and in light of the recent discussion of terminology, I was delighted that he applied the term "laws" to these statements:

Two Fundamental Laws of Modern Biology

1. All living processes are ultimately obedient to the laws of physics and chemistry.

2. All living systems and processes evolved by natural selection.

The work of Watson & Crick in discovering the secrets of DNA was seminal (DNA, seminal - get it? Oh never mind!) in providing proof of the first law and of course Charles Darwin gave us the second one.

So how exactly are they laws? Well, they postulate a general description of how certain things "behave under stated circumstances." Living things obey the laws of physics - there is no special "life force" distinct from other laws of physics that apply to non-living systems. Anything that appears to be beyond the laws of physics, the "miracle of life" for example, only appears miraculous because the physical processes happen at the microscopic level or inside a black box, so to speak (the womb), or because we haven’t yet worked out all the specific pathways. The statement is beyond a mere fact because it is generalized to ALL situations involving any living process at any time.

But aren't laws supposed to be proven to be true, kind of like facts in that sense? And if so, how do we know that all biological processes can be explained by physical laws when there are still biological processes that we can't fully explain, like how the mind works, or consciousness? Well, actually no. Laws are not "proven" in the sense that they have been tested in every possible circumstance in every possible location at every point in time - that would be impossible. Instead, laws (and hypotheses and theories, for that matter) are arrived at in science inductively: We make observations about how the things behave and if a pattern emerges we generate rules, or "laws." Further observation can strengthen our confidence in the law or force the law to be revised or discarded.

In that way the process of arriving at laws is not unlike the process of arriving at theories, but theories are generally broader and more explanatory than descriptive, although sometimes the distinction is rather blurry. Another reason not to get too hung up on terminology. Still, the first statement stands as a "law" and no known exceptions to the law exist and every new discovery of how a particular process works has supported the law. Any argument against the law must therefore show positively some process that disobeys the laws of physics - it isn't enough to simply point to processes that haven't yet been explained and say, "Aha! Your law is invalid because you can't explain human consciousness!"

I think that last point is particularly important when we start talking about the second law. Opponents of evolution are fond of saying things like "well, no one was around to see the beginning of life or the appearance of disnosaurs/mammals/humans/whatever, so you can't know that these things evolved." Well, no one was around to see the formation of the planets in our solar system but invoking the laws of gravity to explain it is noncontroversial. We do know for a fact that evolution happens now. We see it in the field, we observe it in the laboratories, our entire agricultural way of life is built around it. We know for a fact that species change over time. We know for a fact that the flora and fauna of earth today are different from the flora and fauna of past periods of earth's history. We know how evolution happens. I could go on. Every piece of evidence in biology points to common descent.

In the absence of conflicting evidence, it’s fair to generalize that all living things, all living processes, evolved. The law is not invalidated by pointing to specific cases that we do not yet fully understand. Find evidence of an alternative mechanism for generating new species, or find a species that does not use the universal genetic code, or a dog that is genetically closer to a snake than a cat, and you might have a starting point for a case against evolution. Argue that no one was around to see it happen or that it cannot explain “X” (blood clotting, bacterial flagellum, etc.) and you have no place at the table – that’s not an argument, it’s covering your ears and saying “blah blah blah blah.”

Finally, this statement (paraphrased) would probably raise a lot of eyebrows, to say the least, if anyone actually watched Charlie Rose:

Charles Darwin was the most important individual to have lived on Earth. Ever.

Watson said it, Wilson agreed. I'll leave it at that.