Field of Science

On the origin of life

First of all, you may have notied something a little different here. I am now a member of Field of Science, a new network of science blogs. You can investigate the other blogs in this network through the links at the top and bottom of this page. All the content from the original blog has been imported here (including your lovely comments), and the original address redirects here, so no need to update your links. At the moment, we're looking a little plain in the visual department, but some massive redecoration plans are in the works.

On to today's topic: life. How exactly did a collection of random chemicals give rise (eventually) to sentient beings? Where did it start?

This question supposes that at some point, a collection of chemicals that were "not alive" found a way to organize themselves into an entity that was "alive." But we immediately run into another, more fundamental issue: what, exactly, is life? How can we distinguish life from whatever came just before it?

Some researchers (see this Wikipedia article, for instance) consider chemicals such as DNA or RNA to be the distinguishing feature of life, and reduce the question of life's origin to looking at how these chemicals were synthesized.

But this perspective, in my opinion, misses the point. Life is a process, not a chemical. The distinguishing feature of life is not what it's made of but what it can do: namely, it can reproduce itself. More precisely, we can define the process of life by this picture:

Or in words:

An entity is alive if it can produce copies of itself using the free energy and materials that are available in its environment.

There are other caveats we may want to add, such as that living entities can tolerate a certain amount of mutation or environmental change without losing their reproductive ability. But self-replication is a good starting point.

Now the question becomes, how could such a process have arisen? Scientists have managed to synthesize a few self-replicating molecules, but the sponaneous formation of such molecules from inorganic matter seems highly unlikely.

On the other hand, nature is full of chemicals that do this:

In this diagram, A plays the role of a catalyst, helping to synthesize B from other chemicals in the environment. The ubiquity of catalysts led Stuart Kauffman to hypothesize that life may not have started with a single self-replicating molecule, but with a collection of catalysts, each catalyzing another in a cycle:

or in a more complex network:

Kauffman called such collections autocatalytic sets. If such a set of chemicals were able to surround themselves with a membrane, and eventually produce enough of themselves so that the membrane would split in two, we could have our very first example of a living cell.

This idea has a number of interesting implications, which I intend to explore in the very near future. In the meantime, enjoy the new site!

Why Darwin?

Charles Darwin turns 200 today. His birthday is the occasion for worldwide celebrations by scientists, and also a few protests by those who still dispute the theory of evolution. 150 years after this theory was published in "Origin of the Species," it remains the primary flashpoint of what some call a war between science and religion. I'd like to take this day to explore exactly why evolution has sparked such a passionate debate, and why even those of us who have no use for the concepts of creation or God might find value in considering the philosophical implications of evolutionary theory.

First, why is Darwin such a hero to the world of science? Before Darwin, biologists could only describe the "what" of nature. Evolutionary theory provided them with the tools to ask "why?" The whole nature of biological inquiry was changed. Beyond that, he showed how every living thing on Earth is connected by a common heritage. Evolutionary ideas have found application in almost every other area of science. An argument could be made that no other single idea has had such an impact on the history of science.

Secondly, why exactly is evolutionary theory so threatening to those who take the Bible literally? It's hardly the only scientific theory to contradict the literal truth of the Bible: scientists knew for decades before Darwin that the earth must be much older than 4000 years. The Big Bang theory has generated much less controversy than evolution, despite its obvious differences from the biblical creation story.

I think that the hidden thread underlying the evolution/creation debate is the question of meaning. Genesis doesn't just give a story for how the earth started, it gives humans a special place and purpose on the earth. It tells us that we are made in God's image, and that we are to fill the earth and be its stewards. Evolutionary theory upends this picture, saying instead that we are the product of a random process, following our genetic impulses, whose only purpose is to ensure the survival of our species.

Of course, it is not the role of science to provide meaning in people's lives. But I do think scientists should ackowledge the philosophical implications of their work, if for no other reason than that it significantly affects how that work is recieved. Having deflated the Judeo-Christian idea of meaning in life, can scientists, in their alternate roles as human beings, help provide an alternative?

My life partner is taking a class at Harvard Divinity School, taught by complex systems guru Stuart Kauffman and theologian Gordon Kaufman, exploring this very idea. Kauffman holds that notions of the "sacred", and even "God" itself, can and should be reclaimed without any reference to the supernatural, that the natural word itself can be our source of spirituality and meaning.

I won't say any more now about Kauffman's ideas because I haven't read his book yet. But I will over the course of the semester, and I'm sure I'll have much more to say about it soon.