Life Built to Order
Los Alamos scientist Steen Rasmussen plans to one-up nature by cobbling together a brand-new creature that reproduces and evolves. Is he making a biotech marvel that will do our bidding, or a test-tube-size Frankenstein monster?
One morning last fall, a dozen or so government scientists shuffle into a small conference room on the sprawling grounds of Los Alamos National Laboratory to kick off an unusual research project. The room, tucked away in the basement of an old physics building known as SM-40, has paint-flaked cinderblock walls and a tangle of exposed plumbing overhead. The only decorative touch, a cheap potted floor plant, is slumped half-dead in the corner. Eventually a tall man with a sculpted Scandinavian jawline hurries in. Steen Rasmussen apologizes for running late. He shakes a few hands and then cues the team’s lead chemist, Liaohai Chen, to begin. Someone flips off the lights, and a PowerPoint slide flashes onto a projector screen.
The slide reads: “We are not crazy.”
For an instant the scientists seem unsure how to react. Some laugh, others look uneasy. And who could blame them? Los Alamos, famed birthplace of the atomic bomb, has just awarded Rasmussen nearly $5 million to attempt an experiment as bold as the one that drew scientists to this pine-dotted New Mexico mesa back in the 1940s: He intends to create a brand-new life-form. If any scientific enterprise demands a sanity check at the outset, surely this is it.
Flipping though slides thick with chemical equations, Chen explains how Rasmussen’s team of chemists and physicists, who are gathered together here for the first time, will build their bug. They aren’t going to simply transform an existing organism by tweaking its DNA. No, Chen explains, they’re going to create their being from scratch, literally breathing life into a beaker full of inanimate molecules. It is a Frankensteinian vision-though, granted, one that will unfold on the nano scale. The team’s “protocell” will be thousands of times as small as a typical bacterium and far more primitive. But if all goes as planned, it will possess the defining characteristics of life: It will spawn offspring, generate its own energy, even evolve. Left unspoken was this: If Rasmussen, who first started contemplating protocells seven years ago, and his colleagues succeed, they will have crossed a threshold, bestowing on humankind powers that now belong exclusively to nature (or to God, depending on your beliefs).
The desire to create life is nothing new. In the Renaissance, scientists would put a hunk of raw meat in a jar, set it aside, come back in a few weeks, and observe the “spontaneous generation” of life-maggots and the like. In the 1790s, Italian physician Luigi Galvani observed movement when he jolted the severed legs of frogs with electricity; his experiments inspired Mary Shelley in the writing of Frankenstein nearly three decades later. In 1953 Stanley Miller and Harold Urey of the University of Chicago conducted a landmark investigation: They tossed together
molecules thought to have been present in the Earth’s early atmosphere-methane, ammonia, hydrogen and water vapor-and arced a spark of electricity through them to simulate lightning. In a week, amino acids, the building blocks of proteins-and thus life-appeared. It was evidence that haphazard chemical interactions could lead to living things.
Chen finishes his presentation, and Rasmussen leans forward. “If we can just make a system that’s able to replicate a few times,” he says gravely, “we’re going to change the world.” It’s the kind of boast few scientists would dare make aloud, especially when their grant check has only recently cleared. Several of the veterans in the room chuckle and shake their heads-there he goes again.
But Rasmussen’s team isn’t the only one attempting to create new organisms. By some estimates, more than 100 labs are chipping away at the problem, including one
headed by superstar biologist Craig Venter, whose innovative DNA-sequencing technology led to the decoding of the human genome four years ahead of schedule. Last April the European Union launched the $10-million Programmable Artificial Cell Evolution project, and when I visited
Rasmussen in October, he had caught wind of a Japanese effort about to get under way. “There’s no doubt that this is going to happen,” he says. “It’s no longer a question of “if,’
but of who is going to do it and when.”
Many of these scientists are trying to solve the oldest
puzzle in science: How did we get here? What combination of inanimate molecules led, four billion years ago, to the first microscopic creature, and from there to the riot of diversity that is life on Earth? “One of the major questions [this work] could answer is, Was life an accident or inevitable?” says Peter Nielsen, a chemist at the University of Copenhagen who is collaborating with Rasmussen.
Still other investigators are betting that custom-built organisms will spark a biotech boom. Already genetic-
engineering techniques such as gene splicing have made it possible to create everything from fungus-resistant corn to cows that churn out medicines in their milk. But some researchers would rather not limit their handiwork to the raw materials around them. They want to make completely new creatures. “You want more than a plumper pig. You want something outside the realm of what nature can ever conceivably provide,” says University of Florida biophysicist Steven Benner.
To accomplish this, though, most scientists are sticking close to nature’s script. They’re trying to create cells much like the ones that exist today-cells, that is, that are
surrounded by double-layered membranes and stuffed with genetic material in the form of DNA or RNA. Not
Rasmussen. For most of his 49 years, the Danish-born
theoretical physicist has been obsessed with understanding what makes life possible. In attempting to make his own version, he tossed aside biology textbooks and asked himself, What’s the simplest living system I can imagine? The result is that his protocell looks like no life-form anyone has ever seen. “I’m sort of out in the extreme,” he confesses.
Howard Hanson, who oversees a Los Alamos grant program for high-risk research, says Rasmussen’s proposal is one of the most radical his office has ever bankrolled. According to chemist David Deamer, an origins-of-life researcher at the University of California at Santa Cruz, Rasmussen is one of the gutsiest and most original scientists in the field. “He’s willing to stick his neck out,” Deamer says. “Once in a while it gets chopped off, but he just picks it back up and screws it on again.”
On a warm Saturday last June I gave Rasmussen a lift to Santa Fe in my rental car to meet up with his wife, Jenny, a German-born painter who often spends weekends at an outdoor market space in the state capital selling her abstract landscapes. As we drove past weather-sculpted rock outcroppings and dry arroyos dotted with pion and juniper, it struck me that New Mexico is a pretty good place to contemplate the origins of life. Staring out at the stark, rocky landscape, I began to imagine primitive, prebiological molecules dancing in some murky primordial puddle off the side of the road-until the neon glow of an Indian casino on the horizon broke the spell.
Rasmussen was apparently thinking similar thoughts, because as he looked out at the landscape rolling past he mused, “All your experiences completely contradict the ability for us to be here. You see the mountains crumble, the landscape erode. If you don’t maintain your house, it falls apart. Your car has to go in for repair all the time.” He turned to face me. “So how did we come about? What is it in nature that creates complexity? That has sort of been my driver.”
Rasmussen grew up in Munkerup, a small coastal town that’s a 45-minute drive from Copenhagen. One of his earliest memories is dragging his father, a mason turned entrepreneur, out into the evening air so that he could scramble atop his shoulders and “be closer to the stars.” There the future scientist and the former bricklayer debated cosmic questions: Was there an end to the universe? If so, what lay on the other side? Rasmussen was four years old.
Later, as a physics student in the late 1970s at the Technical University of Denmark, Rasmussen’s interest in life’s origins led him to the papers of Belgian physical chemist Ilya Prigogine and German biophysicist Manfred Eigen, Nobel laureates known for their pioneering work on self-organizing systems. Perched at the crossroads of physics, chemistry and biology, self-organization is a phenomenon visible everywhere, from the undulating grains of sand dunes to the synchronized gyrations of schools of fish. In each case, order and pattern arise seemingly spontaneously from chaos and randomness. Rasmussen became transfixed by these phenomena and how they might apply to inanimate organic molecules bobbing in the early oceans, molecules that somehow organized themselves into increasingly complex living systems-eventually resulting in us.
He began spending long hours in the computer lab modeling lifelike processes, much to the dismay of department elders. “My physics professors said, “These are computer games! What are you doing?’ ” he recalls. They gave him an ultimatum: Keep fiddling with origins-of-life research, and you can forget about getting a job as a physicist. But by then Rasmussen was hooked. When it came time to choose a dissertation topic, he announced that he would tackle the problem of how and when genes arose. His advisers threw up their hands, but Rasmussen couldn’t stop thinking about these questions. (“There is no “off’ button,” his wife told me with a playful eye roll after we met up with her in Santa Fe.)
In 1987 Rasmussen was finishing a postdoc at the Technical University and feeling conflicted about whether to stay in science. Then a friend and colleague handed him a flier for a conference in the U.S. on a new interdisciplinary field called artificial life, or A-life. “I read it three or four times,” Rasmussen says. “Then I grabbed the telephone.”
His call led to an invitation not only to attend the conference-which was held at Los Alamos-but to give a talk about the various computer simulations he had
created to predict when the first genes and other early biomolecules may have emerged. A year later he had landed
himself a full-time job at Los Alamos studying self-
organizing complex systems, which over the years has led him to investigate topics as seemingly far from the origins of life as urban sprawl and the dynamics of traffic jams.
Today Rasmussen’s office is a short walk from where that first A-life gathering took place. It was a watershed moment. Eighteen years ago, artificial life was fringe science; some of the people who traveled to that first meeting to discuss everything from life’s origins to how one could create lifelike robots, computer viruses and even biological entities kept their participation hidden from scientific colleagues. Today all that has changed, and now Rasmussen and other founding fathers find themselves tackling questions that are among the most cutting-edge in science. One day Rasmussen leads me across the campus to a small, bland building called the J. Robert Oppenheimer Study Center. Once inside, we climb the stairs to the second floor. “This is it,” he says. It’s not much to look at-your basic carpeted ballroom with a podium in front. But for Rasmussen and a handful of other true believers, it might as well be the Vatican.
From the earliest days of A-life, people have contemplated its wider implications. In 1999 ethicist Mildred Cho of Stanford University headed a panel to weigh the risks of emerging efforts to create synthetic life-forms. The panel backed the research but cautioned that such an organism had the potential to “wreak ecological havoc” or become the engine for a fearsome new biological weapon. Rasmussen agrees. “Let’s be clear,” he says. “There are clouds on the horizon. We don’t want to pollute either ourselves or our environment with renegade processes.” But, he thinks, in the end the technology may wind up being safer than the genetically altered crops being created today. His protocells would probably die if they strayed from the environment for which they were designed. Initially they’ll be lucky to survive even inside the carefully controlled conditions of the lab. “Just shake the beaker,” he says, “and they fall apart.”
I ask him if he worries about a backlash from people who might condemn these efforts as overreaching, playing God. Rasmussen, who studied philosophy for three years before committing to physics, quickly dismisses the notion. “I think there’s no contradiction whatsoever in being spiritual or religious and the work we’re doing,” he says. “We’re peeling the onion, taking layer by layer off and figuring out how the world is put together. We’re just puny humans that are trying to understand.”
There are two main approaches to creating artificial cells, dubbed “top down” and “bottom up.” Genome guru Craig Venter is the most prominent top-downer. Starting with the simplest known bacterium on the planet, a harmless 517-gene organism called Mycoplasma genitalium that inhabits the human genital tract, Venter’s team at the Institute for Biological Energy Alternatives in Rockville, Maryland, is attempting to replace the organism’s natural genetic code with a stripped-down synthetic one.
That, of course, requires knowing which genes are essential to keeping the bug alive and which aren’t. By pruning genes from the bacterium one at a time, the team has already determined that as many as 215 genes might be extraneous. The next step, which the group is sweating over now, is constructing an artificial, Cliffs Notes version of the original genetic code, installing it in an organism stripped of its DNA and then seeing if they can coax this new creature to life.
Even Venter, a scientist accustomed to mega-challenges, has admitted that getting his synthetic bug to “boot up” will be no small feat. So far, the record for a scratch-built genome is 7,500 chemical bases, assembled in 2002 by researchers at the State University of New York to create a polio virus. Venter’s bug will require a synthetic DNA strand 40 times as long. Even if his team succeeds in constructing it, nobody knows whether it’s possible to swap the entire genetic code of a living creature for an artificial version without killing the organism. Still, Venter and his colleagues are making headway. In 2003 they reported that they had sewn together a harmless virus known as phi-X (although some scientists derided the feat as little more than a publicity stunt). In the months since, Venter has been tight-lipped about his group’s progress but not about the potential promise of the Energy
Department-funded project. One possibility: loading his synthetic organism with genetic instructions to convert atmospheric carbon dioxide to methane for use as fuel.
As ambitious as Venter’s plans are, they hardly compare with what Rasmussen and other bottom-uppers are trying to accomplish, building an organism from scratch. Sitting in the living room of his adobe-style house, Rasmussen and I discuss his protocell. An impressive variety of creatures roam the grounds-horses, chickens, mosquito fish, a dog, a cat, two kids, and who knows what else. As we talk, Rasmussen’s 13-year-old son Leif appears, plucks a parakeet from a nearby cage, and places it on his dad’s shoulder. But Rasmussen is too wrapped up in the notion of creating life to pay heed to the life-form twittering into his ear.
When he began this project, he compiled a list of the minimum necessary parts for an artificial organism, then pruned it to three: a metabolism to generate energy, a DNA-like molecule to store operating instructions, and a membrane to serve as sausage casing and hold all the parts together. But he soon realized that he needed to simplify further. Even primitive single-celled organisms are works of sophisticated engineering, their membranes studded with channels for transporting nutrients in and waste out. These natural structures would be tough to duplicate.
Along with chemist Chen, who works at Argonne National Laboratory, Rasmussen pared down his design,
creating computer simulations to test his ideas as he went. “We turned things completely upside down,” he says. Or, to be precise, inside out. For starters, Rasmussen and Chen put some of the molecular machinery on the outside of their
synthetic cell, thus doing away with the need for a fancy
channel-studded membrane. Instead the protocell is glued together by a clump of fatty-acid molecules (“kind of like
a used wad of chewing gum,” Rasmussen explains). This molecular blob-known in the chemistry trade as a micelle -is about as primitive a membrane as you can make.
The beauty of the plan is that the micelle should assemble itself. When I ask how, Rasmussen bolts up. “Let me show you something,” he says, scurrying off barefoot into the kitchen, where he bangs around before returning with a sloshing glass of water, a stainless-steel dish-soap dispenser, and an unreadable glint in his ice-blue eyes. I realize that he’s about to perform an impromptu experiment-and I briefly wonder if I should duck for cover. Rasmussen has confessed that he’s more comfortable at a computer than a chemistry bench. Years ago Peter Nielsen, the Danish chemist who is collaborating on the protocell project, invited Rasmussen to his lab to “get his hands wet,” as experimentalists like to
say. Rasmussen did, and then some. Neither man will reveal precisely what happened, just that it involved the accidental spilling of a certain radioactive substance and the ruining of an experiment. In fact, when Rasmussen first asked Nielsen to help with the protocell, Nielsen agreed, but only after joking that Rasmussen must promise not to touch anything.
Back in Rasmussen’s living room, I watch him pump a few shots of soap into the water glass, cup his hand over the rim, and shake as if he were mixing a cocktail. Liquid erupts from between his fingers, splattering his shirt. Rasmussen curses under his breath, then holds out the glass for me to inspect. Delicate bubbles swirl in the cloudy water. OK, so?
So, he explains, looking slightly deflated that his Mr. Wizard bit didn’t suffice, soap is what chemists call a surfactant. On a sheet of paper, he sketches something that looks like
a sperm. The head of the soap molecule, he explains, is attracted to water, the tail repelled by it. Spritz enough of these part-hydrophilic, part-hydrophobic structures into water, and the molecules automatically ball up into micelles. Rasmussen and his team won’t use dish soap, of course, but some other surfactant; like many details of the protocell’s design, they will know which one only after intensive experimentation. But the basic recipe for protocells starts with throwing a fatty-acid surfactant into a beaker of water. In the blink of an eye, there should be, as Rasmussen puts it,
“zillions” of blobby micelles swirling inside.
Next, the genetic material. Most organisms operate with DNA or RNA. But Rasmussen and his group plan to try a man-made nucleic acid called PNA, or peptide nucleic acid. Synthesized by Nielsen and his colleagues in the early 1990s, PNA looks and acts much like DNA-same double-helix shape, same four chemical bases. But rather than a backbone composed of sugar-phosphate molecules, PNA has one made of peptides, the building blocks of proteins.
Rasmussen’s PNA-based protocell might help solve a long-standing riddle: What was the ur-gene? One leading theory is that the earliest organism relied on a self-replicating version of RNA. But in 2000, Stanley Miller, the father of
origins-of-life research, suggested that PNA ingredients were also present on the early Earth. Could the first life-form
have been weirder than we thought, a PNA-based creature? Rasmussen’s protocell will test that notion.
The main advantage of PNA, though, is that it is electrically conductive, so in addition to acting as genetic material, it jump-starts the protocell’s metabolism. In the initial blueprint, a photosensitive molecule-the alcohol pinacol is one option-and short PNA strands are thrown into the mix [see illustration]. After running a series of simulations in November, Rasmussen and Chen conceived of attaching the pinacol to the ends of PNA strands before throwing it into the beaker. When light strikes the pinacol, it will cause the compound to throw off an electron, which will streak down the PNA bases. When it reaches the other end, scientists expect it to trigger a chemical reaction with the final ingredient they plan to throw into the mix: food.
The food consists of precursor molecules that the protocell’s PNA-pinacol metabolism will convert into new fatty acids and PNA molecules. Without the addition of these precursors, Rasmussen explains, the protocells “would pretty much just sit there doing nothing.” The newly created fatty acids will be incorporated into existing micelles, causing them to grow until they become unstable and pinch in two-protocell procreation. An adult protocell will measure merely five to 10 nanometers across; in comparison, M. genitalium, the organism Venter and his team are working with, is between 200 and 250 nanometers. “We couldn’t imagine anything that’s simpler,” Rasmussen says.
With only three basic parts, the protocell itself may be simple, but the chemistry that brings it to life is wildly complex. On paper, at least, the micelles should soak up the precursor molecules, providing a ready store of “food” for the light-powered metabolism to act on.
Single-stranded PNA molecules, meanwhile, should cling to the micelle’s
exterior and pair with complementary strands of PNA that have been created by the organism’s own metabolism. But who knows? Rasmussen says it remains to be seen how all these molecules will actually behave in solution. “If we really knew ahead of time how to do this,” notes William “Woody” Woodruff, a Los Alamos chemist on Rasmussen’s team, “we would have created life already.”
Some of the experts who have seen Rasmussen’s blueprint have serious doubts that this Rube Goldbergian organism will work. When Rasmussen talks about his protocells at astrobiology conferences and other such gatherings, his work isn’t always warmly received. The words “abstract” and “weird” pop up a lot. “It’s too far-fetched,” argues chemist Pier Luigi Luisi of the University of Rome. Luisi says he wants to see experimental data before he buys into Rasmussen’s approach: “You cannot convince anybody with calculations on a blackboard.”
Other scientists emphasize that it’s not yet clear what route-top-down, bottom-up or something in between-may ultimately lead to artificial life, so it would be premature to dismiss Rasmussen. Biophysicist Andrew Pohorille of the NASA Ames Research Center in California contends that Rasmussen has as much chance of creating life as anybody-maybe more, since few researchers out there have put as much thought into it: “He is definitely way ahead of the curve.”Rasmussen thinks his critics exaggerate. “It sounds mind-boggling,” he says, “mostly because we have a pretty rigid idea of what life is.” He won the three-year Los Alamos grant in part because of computer models he devised showing that the protocell could work. More important, he and Chen have been able to show in the lab that their primitive light-sensitive meta-bolism can create the chewing-gum-like membrane molecules.
Meanwhile, Rasmussen is exploring other opportunities. He and several scientists from the European artificial-cell effort have formed a Venice, Italy-based startup called ProtoLife. Last June, Rasmussen flew to Silicon Valley with two partners to speak with potential investors. One commercial possibility
Rasmussen envisions is turning protocells into drug-delivery
vehicles. The protocell, he says, could be designed to sense when it encounters a particular type of tissue in the body and then to dump its cargo. Rasmussen also imagines making protocells that could withstand high toxicity levels. Such “Terminator” cells could be used to sop up nasty contaminants such as perchlorate, something existing remediation systems don’t do well.
If you really get Rasmussen going, he’ll rhapsodize about far-out stuff like self-healing coatings for aircraft. And why not? All organisms have evolved mechanisms to repair themselves, and Rasmussen thinks that protocells should ultimately be capable of doing the same, opening the door to all kinds of exotic applications. True, a more practical approach to such problems would be to fiddle with the DNA of existing organisms-as many scientists are already doing. But Rasmussen says that the option to build entirely new creatures will give scientists a
fresh palette. Nevertheless, it seems premature to be articulating applications. The venture capitalists whom Rasmussen
approached apparently agreed; they declined to cut a check.
One day when Rasmussen was busy, I asked someone in the Los Alamos public relations office to show me the lab where the first artificial life-form might be created. Driving on a private road, my guide, Nancy, and I passed TA-55, the place where
plutonium is sculpted into grapefruit-size bulbs for thermonuclear bombs. Nancy remarked that it’s the most heavily guarded complex on the mesa. Then she looked in her rearview mirror and saw that a white SUV with government plates was driving close behind. Not until we pulled into the driveway of the lab where the protocell work would take place did it peel away.
Even when you’re not being followed, it’s impossible to
wander Los Alamos, where street signs carry names like Bikini Atoll Road and Trinity Drive, without pondering the double-sided nature of novel technologies or the irony that a place identified with the most fearsome killing machine in history might one day spawn a new kind of life. For now, though, Rasmussen says he’s just concerned with getting something to happen inside his team’s shiny glass beakers.
“Just one fricking life cycle,” he tells me later, sliding his hand through his hair, “would be wonderful.”