Weight of numbers: if unchecked, self-replicators such as these monarch butterflies can multiply exponentially. Photo by Frans Lanting/Gallery Stock
Why does life resist disorder? Because ever since the first replicating molecules, another kind of stability has beckoned
by Addy Pross
(Addy Pross is professor of chemistry at Ben-Gurion University of the Negev, Israel. His latest book is What is Life? How Chemistry Becomes Biology (2012).)
Biology is wondrously strange – so familiar, yet so strikingly different to physics and chemistry. We know where we are with inanimate matter. Ever since Isaac Newton, it has answered to a basically mechanical view of nature, blindly following its laws without regard for purposes. But could there be, as Immanuel Kant put it, a Newton of the blade of grass? Living things might be made of the same fundamental stuff as the rest of the material world – ‘dead’ atoms and molecules – but they do not behave in the same way at all. In fact, they seem so purposeful as to defy the materialist philosophy on which the rest of modern science was built.
Even after Charles Darwin, we continue to struggle with that difference. As any biologist will acknowledge, function and purpose remain central themes in the life sciences, though they have long been banished from the physical sciences. How, then, can living things be reconciled with our mechanical-mechanistic universe? This is a conceptual question, of course, but it has a historical dimension: how did life on Earth actually come about? How could it have? Both at the abstract level and in the particular story of our world, there seems to be a chasm between the animate and inanimate realms.
I believe that it is now possible to bridge that gap. But before I explain how, it is worth mentioning how modern biology has generally dealt with it. Bluntly, it has dropped the problem into the ‘too hard’ basket and looked the other way. This has meant fencing off biology from physics and chemistry, and developing a separate philosophy of science. One of the leading evolutionary biologists of the 20th century, Ernst Mayr, openly argued for the ‘autonomy of biology’. Physics and chemistry deal with inanimate matter, he insisted, biology deals with living systems, and, at least for the time being, that’s that.
But this is not good enough. Nature is one. Science seeks to generalise, to unify. The purpose-driven character of life stands as a challenge to our understanding of the material nature of the universe. We can’t leave it there. And happily, we don’t have to.
I am a theoretical chemist drawn to a new field, systems chemistry. That means I’m interested in replicating molecules and the reaction networks they establish. Some recent research in this field appears to show us just how biology can be restored to the mechanical world. These replicators cross Mayr’s great disciplinary divide with impunity. In the laboratories of my colleagues, the living and dead realms bleed into one another.
And so the conceptual unification of biology with physics and chemistry is now underway. New insights are steadily coming into view. The first important one, in fact, concerns precisely that question of how life on Earth might have begun…