Scientists Test Turbid Waters in Debate Over Origin of Life

By JOEL ACHENBACH

Scientists test turbid waters in debate over origin of life

In the beginning, God created the heavens and the Earth. And He said: Let there be Chemistry.

And He looked upon the Chemistry and He saw that it was good. And then He said: Wait, we need more carbon. Also more water. Tap is fine.

Soon there was something new upon the waters of the Earth, this thing called Life. It oozed, multiplied, diversified. It learned to swim, crawl, even fly. Eventually a new form of life appeared, a creature large of brain, compulsively inquisitive, with an obsession for asking the really big, hairy, gnarly questions, such as: Where did I come from?

Thats when things got really complicated.

A definition of science

There is a tendency to think of science as a series of established facts and consensual theories a bunch of things we know, to be memorized, in the words of Robert Hazen, the science popularizer and researcher into the origin of life.

What Hazen will tell you is that science is actually a very human enterprise. Its full of unknowns and uncertainties, of raging controversies, of passions and prejudices. Of all the great unknowns, the origin of life is particularly daunting. Direct evidence of the origin is essentially nonexistent: It happened too long ago, in too subtle a way. Theres no fossil of the First Microbe. If there were, some skeptical scientist would surely raise a ruckus, saying: Thats just a blob of mud.

The field has attracted people with strong personalities. They argue. They grumble. They snipe. Their debates are much more intense, and more grounded in the rules of science, than the much- hyped debate about evolution and intelligent design.

They are wrestling with basic questions: What is life, exactly? Does it always require liquid water and those long Tinkertoy carbon molecules? Does life require a cell? Did life begin with a hereditary molecule or with some kind of metabolic chemical reaction? Where did life begin on Earth? Was there a single moment that could be described as the origin of life, or did life sort of creep into existence gradually?

All that is very much in play. In the words of George Cody, an origin-of-life researcher, No one knows anything about the origin of life.

At the risk of absurdly oversimplifying, there are two prominent schools of thought in the origin-of-life (OOL) community: The Millerites and the ventists.

The Millerites follow in the footsteps of Stanley Miller, the mastermind of the most famous experiment in the history of the field. In 1952, working under Harold Urey at the University of Chicago, Miller created a laboratory analogue of the young Earth. One five-inch-diameter flask held water, mimicking the primordial ocean, heated by a gentle flame. A larger flask held a mixture of gases methane, ammonia and hydrogen representing a hypothetical early atmosphere. Miller zapped the atmosphere with electricity (lightning). The next day he discovered that his clear ocean water had turned yellow, and a brown gunk had appeared around the electrodes. The simple experiment, repeated over many days, produced organic molecules, including amino acids, some of the building blocks of life.

This was a long way from making life in a test tube the simplest organism is vastly more complicated than anything in the Miller- Urey experiment but it set a template for the field of prebiotic chemistry. Miller made chemistry look like a powerfully creative force.

The ventists are apostates. They are blasphemers. Perhaps life didnt begin at the surface of the Earth, they say, but rather deep beneath the sea around a hydrothermal vent. Such geysers form along mid-ocean ridges, spewing hot water into a dark, cold, pressurized realm that teems with bizarre organisms, like giant clams and 6- foot tube worms. The ventists say the disequilibrium between the hot and cold water is a natural driver of interesting chemical reactions. This would be a good place to cook up organic molecules from which life could emerge and evolve, they say. Moreover, the deep hydrothermal environment would have been protected from harsh ultraviolet sunlight and the meteor bombardments common at the surface of the young Earth.

In other words, its where we humans live, on the surface, that might be the truly exotic environment. Perhaps lifes miracle is not that it learned to live at the bottom of the sea, but somehow in the sunshine.

On a knoll of bedrock on the edge of Rock Creek Park, tucked on a back street called Broad Branch Road in Washington, D.C., is a little scientific fiefdom called the Carnegie Institution. On the third floor of the Geophysical Lab youll find the aforementioned Robert Hazen a proud ventist.

You may have read one of his 19 books (such as Science Matters, written with James Trefil), or taken one of his science classes at George Mason University. Or maybe youve seen him play classical trumpet in a symphony orchestra. Hes somewhat all over the place as scientists go. About a decade ago, after years as a crystallographer, studying rocks, he turned his attention to the origin of life.

The result is a new book, genesis: The Scientific Quest for Lifes Origins, a rambling tour of a controversial field. We learn about the theory of A.G. Cairns-Smith, that life began as clay. We learn about the Iron-Sulfur World of the German patent attorney and chemist Gunter Wachtershauser, described as quick to fire off an angry letter on legal stationery. We learn about the Protenoid World, championed by the late Sidney Fox, who cooked up in a lab tiny spheres that he thought possessed rudimentary consciousness.

Amid all the chemistry are scenes of scientific rancor, as when Hazen describes a face-off between two scientists, Martin Brasier and William Schopf, over some alleged 3.5-billion-year-old fossils:

As Brasier calmly outlined his arguments, the scene on stage shifted from awkwardly tense to utterly bizarre. We watched amazed as Schopf paced forward to a position just a few feet to the right of the speakers podium. He leaned sharply toward Brazier and seemed to glare, his eyes boring holes in the unperturbed speaker.

Hazen writes that the origin-of-life field is at times tarnished by questionable data, contentious debates, or even outright quackery.

Now you can see how all this might get a bit delicate given the current debate about intelligent design. Hazen knows that by exposing the backstage bickering on the origin of life, he may give ammunition to the critics of the scientific community: Anything I say that shows any uncertainty or doubt, they will use as evidence that scientists are baffled.

But Hazen has a broader agenda, which is to make science accessible to ordinary people. And perhaps, he seems to be saying, making it more human will help that cause. He doesnt flinch, unlike many scientists, from engaging in verbal battle with the proponents of intelligent design.

He doesnt apologize for putting out a book with a title that, except for the fact that its lowercase, is the same as a much more famous book by a much more revered Author.

The word genesis has a more generic content. Its everybodys word, Hazen said. We have just as much ownership over the genesis story as they do, and wanted our story to be heard.

He believes the universe is hard-wired for the emergence of life. Emergence is his buzzword, much more than evolution. What he sees is inevitable progress from the simplest elements to more complex chemistry, then to life, then to consciousness, and finally to creatures who can comprehend the cosmos. And if that isnt meaning and purpose, I dont know what is.

Is there a God who hears the prayers of human beings? Science cannot say yea or nay to that, he said. Science cant answer questions about faith and the nature of God.

But can religious people accept the scientific take on the cosmos?

If you wanted to know if the universe has meaning and purpose, wouldnt you be better off studying the universe?

Two camps, zero common ground

Hazen is, at first glance, a prime candidate to represent the scientific view of lifes origins. Hes good-looking, articulate, passionate and has collaborated in origin of life experiments. He puts interesting samples into contraptions called hydrothermal bombs, and squeezes them at 4,000 atmospheres of pressure at 1,000 degrees Celsius.

But hes also a relative newcomer to a highly contentious field. Some of the old guard, the Millerites, have not welcomed Hazen any more than theyve embraced the deep-sea-vent idea.

As Hazen writes, Miller and his scientific cohort had staked their claim to a surface origin of life, and they seemed determined to systematically head off dissenting opinions.

The Millerites, Hazen reports, relentlessly attacked the theory that life could have begun at ocean vents, saying high temperatures would have destroyed amino acids. Miller called the vent hypothesis a real loser.

To this day, the Miller camp wont budge.

This whole hype on hydrothermal systems and everything is just bogus, said Jeff Bada, professor of marine chemistry at Scripps Institution of Oceanography at the University of California at San Diego and the most prominent protege of Miller. I think he oversells this.

Bada questions an experiment that Hazen and his colleagues conducted in which they managed, in mimicking deep-sea pressures and temperatures, to create an important biomolecule called pyruvate: I have some strong questions about whether that experiment is even valid. We havent been able to repeat it.

Nothings ever dull in the OOL world.

Hazen says, Ultimately the truth comes out. But some questions are harder than others. Life began on Earth a long time ago, maybe as long as 4 billion years ago. Someone can always show how it could have happened, but as Harold Morowitz, another prominent origins researcher, puts it, Will we ever know what happened historically 4 billion years ago? No.

And so the debate over the beginning will probably never come to an end.