Tuesday, September 16, 2014

Chemical Faithfulness, Part 3: Natural Laboratories for the Origin of Life

In the past two parts of this series I described how liquid water is living water, its special chemistry shaping geology and biology to give us the world today. Water’s life-giving power extends even deeper than this, as deep as a few billion years back in time. We saw how liquid water’s chemical power created the Puget Sound and sustains deep-sea ecosystems today. Likewise, water could have participated in creation long ago.

The chemical ingredients life needs come together at the deep ocean vents: carbon, sulfur, hydrogen, iron, nickel, and especially energy from within the earth.  Long ago, water’s chemical power may have brought these ingredients together to shape the first life forms.

I once avoided these ideas because I felt that a chemical bridge from non-life to life threatened God’s creative sovereignty. But now I’ve changed my mind. If God came up with the ideas, then they actually convey God’s creative sovereignty. The more I appreciate the dynamic elegance of water’s chemistry, the more I think that God appreciates dynamic elegance, too. All origin of life experiments have an important role for the chemical power of flowing, liquid water.

For example, some deep-sea vents form rocks with holes that look suspiciously like small cells. These cavities naturally stockpile and separate chemicals, like natural laboratories with billions of chambers. They are lined with iron and nickel atoms that react with the sulfur and hydrogen streaming out of the earth like Champagne bubbles.

One of the central molecules in all metabolism, pyruvate, forms spontaneously in these vents, as well as other related molecules that look like the breakdown products of pyruvate found in every cell. It’s as if a biochemical network is budding from the rocks. The holes in the rock can hold different mixtures of chemicals in place, like the 96-well plates scientists use to run 96 experiments at once. In the rock, simple circular chemical cycles could have formed and started to turn, fed by gas bubbles.

Or maybe the heat was more gentle, the toasty temperature of a hot spring at the earth’s surface. This makes a different kind of natural laboratory, where holes in the rock act as gas condensers, collecting steam and letting it drip down in a purifying cycle. Every organic chemistry lab contains complex glass sculptures built to condense and distill. Some hot springs have rocks that do the same chemistry.

Experiments in a similar environment found conditions where simple 4- or 5-atom molecules naturally rearrange into the complex, three-part nucleosides that make up DNA. In an elegant flourish, this fascinating set of reactions is catalyzed, not by a rare element or molecule, but by the very common bio-molecule, phosphate. DNA has phosphate in it, meaning this important molecule may incorporate its own catalyst.

Origin of life chemistry as a field is full of successes like these but also its fair share of failures. One major failure is summed up by Steven Benner as “the asphalt problem”: undirected reactions tend to make tar. What’s interesting to me is where the failures may come from. I think most experiments were too simple, too purified, and too dilute. If the experiments are made dirtier, in many cases with actual “dirt,” they work better. The deep-sea experiment above can’t make pyruvate without the iron and nickel from rocks. In the DNA-making experiment, the DNA nucleosides are not made from a sequence of reactions, but by mixing everything together in one pot and running thousands of reactions at once. The more the experimental conditions mimic the geological complexity of the early earth, the more the resulting chemicals look like biological complexity (that is, pyruvate or DNA nucleosides).

This experiment is run with chemical ingredients provided by the periodic table and the physical forces of mixing and geology, which are mediated by liquid, living water. If God gave the chemical laws, then God gave water this power, and this could be how God created. God works with me patiently and through the world around me – perhaps he did the same at the creation of life.

If we can imagine God giving his power to God’s creation, then origin of life chemistry experiments have no necessary conflict with a strong theology of creation. The first biochemical cycles would have obeyed the rules of chemistry, and we know Who made those rules. Even the deepest part of the sea at the far extent of Earth’s history is part of God’s creation and ordered by God’s Word.

Water is the medium of life-giving grace, and we can see through it to the one who ordered the atoms with the rules of chemical bonding (and the math that sets those rules). In Greek, such rules would be called the logos -- the wisdom and Word by which worlds were created. As a chemist, I am called to seek out the subset of those rules called chemistry, and to understand that God is at work providing and upholding them.

The world looks different if flowing, living water is seen as a chemical gifted with the potential to create life. We know water is powerful enough to carve landscapes, form gemstones and ores, and support fantastic microbes. Now to these powers is added the ability to make life by reacting with rocks, and the story of creation becomes that much more amazing.

The length of this story is incomprehensible to our small experience. Our experiments show that Earth held an ocean of life-sustaining water on its surface for 4 billion years, not boiling it into steam like Venus or losing it to a barrage of asteroid impacts, like Mars. The word for that duration of constancy is faithfulness. Through eons, God has cared for us by upholding a universe with constant chemical laws, rules that convey the simple grace of living water.

I am writing a book that recounts the story of these chemical laws, this logos, that shaped the world around us. Water is so important to that story that I changed the book’s title halfway through to give water a place of honor – now it is called River of Life: How Chemistry Shaped Biology. A river is living water, and water, despite its small size, is the chemical cornerstone of life.

The angle of science and the angle of theology fit together and co-illuminate in the story of “living water.” The creator who emptied himself of power and became so small at Christmas also made the small but powerful molecule H2O, then gave us oceans of it. The more things we discover about that molecule, the more we can delight in the hand that gave it yesterday and continues to give it today.

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