“Artificial life, the stuff of dreams and nightmares, has arrived.” So proclaimed The Economist on May 20th, after a team of scientists headed by J. Craig Venter  announced that it had replaced the natural DNA in a bacterial cell with DNA they had artificially synthesized.
According to University of Pennsylvania philosopher and bioethicist Arthur Caplan, “Venter and his colleagues have shown that the material world can be manipulated to produce what we recognize as life. In doing so they bring to an end a debate about the nature of life that has lasted thousands of years. Their achievement undermines a fundamental belief about the nature of life that is likely to prove as momentous to our view of ourselves and our place in the Universe as the discoveries of Galileo, Copernicus, Darwin and Einstein.”
Whoa! Wait a minute!
What Venter and his team did was to determine the sequence of the DNA in one of the world’s simplest bacteria, use the sequence information to synthesize a copy of that DNA from subunits sold by a biological supply company, then put the synthetic copy of DNA into a living bacterial cell from which the natural DNA had been removed.
As Nicholas Wade pointed out in The New York Times, Eckard Wimmer and his colleagues did something similar in 2002 by synthesizing poliovirus RNA. Wimmer and his colleagues then used that synthetic RNA to make functioning polioviruses. But viruses are not living cells. No one has ever been able to make a living cell from its DNA–not even Craig Venter.
A virus is just RNA or DNA in a protein capsule. The viral RNA or DNA can’t make more of itself, nor can it make the capsule. Viral RNA or DNA must first be put into a living cell (or, in the case of Wimmer’s experiment, into an extract carefully prepared from living cells), because only the cell (or its extract) contains the complex molecular machinery needed to make more RNA or DNA and to manufacture the protein capsule.
By themselves, however, RNA and DNA are biologically inert. Only a living cell is alive, and in our experience, life always comes from life. That’s why spontaneous generation doesn’t happen. That’s why origin-of-life researchers have not even come close to solving their problem. And that’s why Venter and his team couldn’t create life; they had to start with it. There is much more to living cells–even relatively simple cells–than is dreamt of in Arthur Caplan’s philosophy.
In contrast to Caplan’s exaggerated claims, CalTech biologist and Nobel laureate David Baltimore said that Venter has “overplayed the importance” of his results, which represent “a technical tour de force” rather than a scientific breakthrough. Venter “has not created life, only mimicked it,” Baltimore said.
Boston University bioengineer James Collins called Venter’s work:
an important advance in our ability to re-engineer organisms, not make new life from scratch. Frankly, scientists don’t know enough about biology to create life. Although the Human Genome Project has expanded the parts list for cells, there is no instruction manual for putting them together to produce a living cell. It is like trying to assemble an operational jumbo jet from its parts list–impossible. Although some of us in synthetic biology have delusions of grandeur, our goals are much more modest.
These realistic assessments probably wouldn’t impress the anonymous author of The Economist article. “Pedants may quibble,” the writer complains, that “the researchers had to use the shell of an existing bug to get that DNA to do its stuff.”
Shell? But oh, what an amazing shell it is! And from that shell of life, what discoveries may come? Ay, there’s the rub.