Ben Bova: On Earth, the search for life’s origins

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Last week we talked about astronomers’ search for Earth-like planets among the stars. This week we’ll stay right here at home and look at research that has produced the first step in creating life out of non-living chemicals.

The quest to find other worlds on which life exists is closely tied to the question of how life began here on Earth. Is there life elsewhere in the universe? Did life on Earth arise spontaneously out of non-living chemicals?

Or are we, and the world we live in, the act of a supernatural power who built this planet, seeded it with life, and created the human race?

The argument between religion and science is mainly about this question. Were we created by a special and unique act of God? And, by extension, was the whole universe also thus created. Or can we show that it all came about from natural, not mystical, forces?

Many religious faithful find fault with Charles Darwin and his concept of evolution precisely because it seems to remove God from the explanation of who we are and how we came to be.

A century and a half since Darwin’s work was first published has seen mountains of evidence amassed by scientists of many different specialties. That evidence clearly shows that humankind evolved from earlier ape-like predecessors. We are not the result of some special act of creation, separate and apart from all forms of life on this planet.

Ah, but where did life come from originally? The same old question still awaits an answer. Can science show how life arose out of non-living materials? Or must we conclude that life was created by forces beyond scientific explanation?

Researchers at the University of Manchester, in England, have successfully produced a unit of RNA out of non-living chemical ingredients. They have duplicated steps that probably happened in nature nearly 4 billion years ago, steps that led to the creation of life in Earth’s early history.

RNA is ribonucleic acid. It is a vital part of the machinery inside every cell of every living creature.

Living creatures must be able to accomplish two functions: metabolism and reproduction. Whether a single cell or a giant blue whale, living organisms must be able to take in the energy they need to drive their life processes (metabolism) and they must be able to make new copies of themselves (reproduction).

To accomplish these two goals, life on Earth consists of proteins and the nucleic acids DNA and RNA. The proteins handle the metabolism and the nucleic acids take care of reproduction.

In the nucleus of every cell lies the double-helix molecule of DNA (deoxyribonucleic acid). Strung along the intertwining spirals of DNA are the genes that contain the information for making the proteins your body requires. RNA is a single-stranded molecule that takes the information for building new proteins from the DNA and carries it outside the cell’s nucleus to units in the cell that actually manufacture the proteins.

You can think of living cells as a sort of factory. The DNA has the master blueprints, the RNA is the messenger that carries the information from the blueprint to the factory floor, where the proteins are built.

For several decades some biologists have thought that RNA actually came into being before DNA arose. They have postulated an “RNA world,” where RNA carried the cell’s blueprint and directed the manufacture of the cell’s proteins, as well. Only later did DNA come into being and take over the task of maintaining the cellular blueprint.

So RNA could be the key to how life arose on Earth out of inert chemicals.

The Manchester researchers combined chemicals such as cyanamide (which chemists call a “base”) and glycolaldehyde (a sugar). Both these chemicals very likely existed in Earth’s early seas, or mixed with the clays of seashores.

According to one of the team’s leaders, John Sutherland, “We took half a base, added that to half a sugar, added the other piece of base, and so on.” It was an intricate process, “like making a soufflé,” Sutherland said.

The process produced a complete nucleotide, one of the “bricks” that makes up the long molecular chain of RNA. Put enough of those “bricks” together and you have a molecule of life.

Since 1953, scientists have been able to synthesize amino acids in their laboratories. Amino acids are the building blocks of proteins. Now they have created a building block of RNA. What the scientists have done in months of work, in lab flasks, nature apparently did in the vast oceans and shores of Earth over millions of years.

This is powerful evidence that life arose on Earth quite naturally. Opponents of this explanation for life’s origin claim that it’s ludicrous to expect inert chemicals to just happen to randomly combine in such a way as to produce life. The probabilities strain belief, they say.

But chemicals don’t combine at random, as anyone who has suffered through high-school chemistry will remember. Chemicals are rather choosy about how they combine. Scientists have shown how simple chemicals tend to build up into more complex molecules, producing an “organic soup” in which all the ingredients for life were present.

Now they have produced the building blocks both for proteins and RNA. No special outside force needed: ordinary organic chemistry does the job.

In time, researchers will produce living cells out of non-living chemicals. Test-tube life. Not a Frankenstein monster but a single cell that lives, eats, moves and reproduces.

Religious faithful need not be dismayed, though. If you believe that God created life on Earth (and on other worlds, too) all the scientists are doing are showing the steps involved in the creation.

As Galileo put it, “I do not feel obliged to believe that the same God who has endowed us with sense, reason and intellect has intended us to forgo their use.”

Naples resident Ben Bova is the author of 120 books, including “The Immortality Factor,” his latest novel. Bova’s Web site address is www.benbova.com

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