Out of the Blue
Was life the fortunate accident of physics and chemistry right here on Earth? Or was it the outcome of an extraterrestrial event, even a purposeful plan from beyond?
According to the picture drawn by modern science, the ancient Earth was an angry place. In its early days, likely more than 4.6 billion years ago, our planet was in its volcanic youth: the sea steamy, its floor laced with boiling vents; the oxygen-free sky streaked by a bombardment of meteors. Even so, most biologists believe the first cells—life itself—formed incredibly early in this hellish crucible.
The evidence? Although the entire geologic record of that time has been lost to erosion and tectonic recycling, some of the oldest rocks we’ve found contain fossils of bacteria-like cells.
This is an enigma. How could they have evolved in situ under such horrific conditions? Charles Darwin once suggested that life might have begun in a “warm little pond,” but these early conditions seem far too extreme. The timing seems just too sudden for natural selection to have worked out the intricate details of the living process. Although we have tried, we have never observed the spontaneous generation of chemicals into compartmentalized metabolism, genetics and reproduction, aka cells. Not even under the best conditions in the best labs, chock-full of all the necessary chemicals, has a scientist ever been able to create a cell from scratch. New genes might be engineered and inserted to make a cell with a created genome, but the formula always starts with a preexisting cell.
Beating the Odds?
Even building the basic precursor molecules of life—amino and nucleic acids, lipids, and carbohydrates—requires intricate chemical recipes. If that can be accomplished, they still must jigger each other into functional membranes, passageways and energy-harvesting pathways; then, on top of all that, they must innately configure the heritable information needed to do it again, and again. And all of this, from the materialist perspective, must self-organize without forethought or purpose. It’s an idea known as abiogenesis, the theory that life sprang from nonlife at some point in the distant past.
Although it carries much gravitas as a scientific hypothesis, abiogenesis is actually a kind of “just so” story, a conclusion that seems plausible but is based more on speculation than on fact. One could say that believing this origin story requires no less faith than believing that “God created the heavens and the earth.” In fact, the idea of an intelligence creating the living process makes greater logical sense to many people, including some scientists.
Philosopher of science and one-time geophysicist Stephen Meyer noted in a 2005 article in Canada’s National Post that expecting proteins to self-organize is “like saying that a newspaper headline might arise as the result of the chemical attraction between ink and paper.” When Vision asked Meyer to elaborate, he said, “The information—the major innovations—necessary to build the first life and subsequent forms of life provide evidence of the activity of a designing intelligence of some kind in the history of life. Information is a mind product, the result of an intelligent cause.”
The math supports that conclusion. The chances of building the functional amino acid sequences within a simple cell, according to one study, is statistically highly unlikely at best, the odds falling between 1 in 10100 and 1 in 1040,000. That’s a 1 with anywhere from 100 to 40,000 zeros after it. (For contrast, the odds of winning the grand prize in the Lotto America lottery are a mere 1 in 2.6 x 107, or 1 in 26 million.)
“Even assuming the lower value in this range, the probability of abiogenesis leading to life remains truly minuscule.”
“The improbability argument stated here has its critics of course,” concede researchers Carl Gibson and Chandra Wickramasinghe. They admit that “scientific arguments for abiogenesis remain ill-defined to the extent that no processes have been identified that can lead from prebiotic chemistry to life. The enormous probability hurdle needs somehow to be overcome.”
Yet here we are, along with millions of other species. How might this have happened? The principle of Occam’s Razor—that one should seek the simplest solution—is a useful lens through which to examine the possible solutions to life’s origin on Earth.
A Warm Little Pond Somewhere
Since the 1870s, when Charles Darwin speculated (in a letter to a colleague) about the chemistry of life beginning in “some warm little pond” on the early Earth, biologists, geologists and astronomers have searched for that incredibly lucky spot. Science writer Michael Marshall recounts the stories of that pursuit in The Genesis Quest: The Geniuses and Eccentrics on a Journey to Uncover the Origin of Life on Earth. “This book is the story of the scientists who have attempted to explain how and why life arose on our planet,” he writes.
Those researchers have explored numerous ideas and taken many paths, as Marshall outlines, but so far they haven’t found the answer. Because a viable process has not yet been found in our laboratory recreations of the presumed conditions of the early Earth, suspicion is growing that life may have originated on other worlds, perhaps on one of Saturn’s or Jupiter’s moons, and then migrated here. It appears that “little ponds” exist below the frozen surfaces of some of those outer worlds.
The first step in evaluating this possibility is to find life on another planet. Does life exist beyond Earth? And if so, how does it compare to Earth-life? Is it cellular? Does it use DNA? The purpose of a search for other life is to assess its relatedness to life on our planet—a kind of planetary ancestry.com.
The most Earthlike place to look for relatives has become Mars. For almost five decades since the Viking landers of the 1970s, NASA has pursued a “follow the water” strategy. Now that ample evidence of past water has been found, the mission is to “seek signs of life.” Perseverance is there now, scooting around a crater that has all the appearance of having once been a river delta. The rover is built to extract drill cores that may one day show fossil evidence (or even spores?) of microorganisms. But don’t hold your breath; that final reveal will probably be decades in the future. Perseverance can only dig out the cores; it can’t examine them. The little rock cylinders will need to be collected by a sample return mission that is still on the drawing board.
And now Venus is getting a second look. It, too, may have been watery in the past, so the discovery of odd organic molecules in its atmosphere has sparked new questions about the possible evolution of life there. NASA is planning new missions by 2030 that “aim to understand how Venus became an inferno-like world when it has so many other characteristics similar to ours—and may have been the first habitable world in the solar system, complete with an ocean and Earth-like climate.”
Seeds of Life
Ironically, although we have no evidence of abiogenesis, or spontaneous generation, many seem to expect to find life springing up everywhere, independently, on different planets. This seems to fail the simplicity test.
So what if, rather than having to overcome the odds on each planet, life came from space itself? The idea that life was seeded on Earth from space is called panspermia. In this theory of origins, life began beyond our solar system and then, like seeds drifting on a breeze, traveled through the galaxy to take root wherever conditions allowed. Could those meteors that rained down on the early Earth actually have carried bacteria cells? Could these be the ancestors of today’s extremophile bacteria that continue to populate deep-sea vents, rock fissures and other highly acidic or saline environments? Maybe such early migrants became the root of Darwin’s tree of life?
The Champagne Vent—a mile-deep hydrothermal vent in the western Pacific’s Mariana Arc—spews bubbles of carbon dioxide at temperatures above 100°C, as well as cold droplets of liquid carbon dioxide. Researchers wonder whether the vent’s abundance of chemicals and energy could provide clues to the origin of life on Earth.
Source: NOAA (via Wikimedia Commons)
Marshall doesn’t give much credence to panspermia in The Genesis Quest. Pushing the origin of life away from Earth isn’t solving the origin problem, he writes. “The philosophical problem with panspermia is that it is cheating. Instead of devising a process by which life could have begun on Earth and testing it, advocates of panspermia evade the challenge by saying that the formation of life was extremely unlikely, only happened once in the galaxy, and cannot be repeated. This is not an explanation, but an admission of defeat.” You might as well say “God did it,” he adds. “Better, [most origins researchers] say, to face the difficulties head on.”
But we have and we are. And although we know much more and have run many more experiments, as Marshall chronicles, the best answer still seems to be “God did it.”
As a hypothesis to explain the origin of life, panspermia has been around since ancient times. Greek philosopher Anaxagoras coined the word from pan (universal) and sperma (seed) to describe his view of origins. In 1871, William Thomson (better remembered as Lord Kelvin) brought the idea into the modern era in a speech to the British Association for the Advancement of Science. This coincided with Darwin’s warm-pond speculations and continuing discussion of On the Origin of Species. While many recognized that existing species may diverge and adapt to new conditions by natural selection, questions of ultimate origins were, as they are today, still debated. But the simplest answer, most argued, was that the First Cause was God.
Some also argued, however, that in God’s omnipotence He had spread life throughout the universe. Panspermia might describe a means of populating all the universe, not with other humans, of course, but with the potential of life according to the prevailing conditions. Life itself is “good,” so if God filled the “formless void” of Earth, He could do the same across the cosmos.
“Because we all confidently believe that there are at present, and have been from time immemorial, many worlds of life besides our own,” Kelvin said, “we must regard it as probable in the highest degree that there are countless seed-bearing meteoric stones moving about through space. If at the present instant no life existed upon this earth, one such stone falling upon it might, by what we blindly call natural causes, lead to its becoming covered with vegetation” (Kelvin’s emphasis). His pejorative reference to natural causes indicates his belief that God would actually be directing such a scheme in contrast to the Darwinian view of mindless, random chemistry. Citing another colleague at the time, he argued that natural selection “did not sufficiently take into account a continually guiding and controlling intelligence.”
In 1908, Svante Arrhenius (1903 chemistry Nobel laureate) returned panspermia to the limelight. Although he was skeptical that living cells could survive the hostile environment of space, he concluded that if the theory proved true, all life in the universe would be interrelated. Thus this remains an open question.
“We perceive that, according to this version of the theory of panspermia, all organic beings in the whole universe should be related to one another, and should consist of cells which are built up of carbon, hydrogen, oxygen, and nitrogen.”
Recent studies actually support the concept of life sustaining itself on a trip across the universe. The condition that Arrhenius suggested a century ago (regarding the need to survive the tortures of space) has apparently been met, at least in a short-term way: Research aboard the International Space Station has confirmed that a little ball of bacteria could form “an ark for interplanetary transfer of microbes.” Earlier studies showed that bacteria within rocky material survived years in space.
And there is plenty of that material. One estimate is that 5,000 tons of cosmic dust drifts down to Earth each year.
Photos of cosmic spherules and micrometeorites, captured by means of Scanning Electron Microscopy (SEM). Such particles are typical of the cosmic dust that falls to Earth. From left to right: glassy cosmic spherule, stony cosmic spherule, partially melted micrometeorite, unmelted fine-grained micrometeorite.
Source: J. Rojas et al., “The Micrometeorite Flux at Dome C (Antarctica), Monitoring the Accretion of Extraterrestrial Dust on Earth” (under Creative Commons license)
All things considered, if panspermia is really happening, we might expect to find evidence of life wherever we look: Earth, Mars, Venus, or anywhere that once had warm, watery conditions to support its germination. But if we did, would that be evidence of chemistry’s ability to produce life, or of God’s hand? And what if we never discover other life? The simplest answer to the question of First Cause will still be God.
Scientists, of course, seek definitive answers and continue to put forward more complicated hypotheses. In 1973 Francis Crick and Leslie Orgel even suggested that panspermia might be directed, a way for extraterrestrial civilizations to colonize the universe. Their answer to “God did it” was alien intelligence. “Could life have started on Earth as a result of infection by microorganisms sent here deliberately by a technological society on another planet, by means of a special long range unmanned spaceship?” They found the evidence inconclusive but didn’t rule out alien intervention and noted that we, in our own space travels, need to be wary of contaminating other worlds with our microorganisms—a suggestion that various space agencies, including NASA, have taken to heart.
Cometary Panspermia
Chandra Wickramasinghe is one of the founders of astrobiology, which he defines as “a synthesis of astronomy and biology.” While he doesn’t agree with the idea of God nor aliens, he contends that the accepted scientific model of origins is stifling. “In the context of a continuing failure of laboratory experiments to show that small-scale abiogenesis is a viable scientific theory, with superastronomical odds against the transition from organic chemicals to life,” he says, “the requirement for life’s origins requiring a cosmological setting is growing fast.” Many criticisms, he told Vision, “are polemical expressions of cultural prejudice.”
“The adherence to the standard ideas of abiogenesis, without any proof, is more a religion than our rival ideas.”
As far as he’s concerned, Darwin’s idea of a recent origin of life is long overdue for admitting defeat: The theory that a primordial soup is the starting point of all life on Earth “is essentially a pre-Copernican idea, and I stress that it has no basis in logic, and it has no basis in fact, and . . . it is fatally flawed.”
As an advocate for panspermia, Wickramasinghe balks at any suggestion that the theory has religious overtones. He told Vision, “Referring to panspermia as a religion is an example of a deeply prejudiced mode of thinking about the ever-expanding set of facts that clearly accords with one particular albeit unpopular scientific theory and not with the reigning paradigm of abiogenesis.”
According to his specific theory of cometary panspermia, which he and Fred Hoyle first proposed in the 1980s, life overcame the probabilities against its spontaneous evolution in the very early universe, not the early Earth. Billions of years prior to the Earth’s formation about 4.6 billion years ago, biologically important molecules had already formed on primordial planets, which existed even before the first stars were born. Wickramasinghe writes that throughout the history of the universe, the formation of planets, comets and stars “continuously recycles these chemicals in the variety of watery environments needed to produce the organic monomers required for the origin of life. Planets make stars. Stars fertilize planets. Comets seed them.”
In this scenario, organic molecules and their chemical by-products have been circulating through the universe from a time just after the Big Bang. The theory claims that organic compounds observed in interstellar space today are not the prebiotic precursors to life; they are the remains of life, evidence of “a veritable graveyard of cosmic bacteria” and genetic fragments including viruses and viroids. The theory explains mysterious dark matter, which currently baffles astronomers, as the remnants of these early planets scattered through the galaxies.
Most scientists, however, do not believe that this theory is validated by the evidence.
The Continuing Problem of First Cause
We are now able to dissect the intricate complexity of the cell and the chemical processes of life in ways beyond the imagination of scientists of the late 1800s. Today Darwin himself would likely find it difficult to believe that life could self-create and self-build without purpose or direction. If he could see what modern biological science has revealed, he might come to agree with contemporaries who criticized his theory.
Even so, the orthodoxy of modern biology is anchored to a materialist bottom line derived from Darwin’s propositions. Like philosopher Meyer today, Kelvin would be aghast if he could witness how science has embraced this purposeless, undirected view of origins. He observed that “overpoweringly strong proofs of intelligence and benevolent design lie all around us.” It is not the idea of panspermia that necessarily supports this conclusion; it is simply the existence of life itself.
There are “perplexities, whether metaphysical or scientific,” Kelvin admitted, that sometimes distract—“recent zoological speculations” was how he described the argument over purposeless evolution.
“I feel profoundly convinced that the argument of design has been greatly too much lost sight of in recent zoological speculations.”
The products of God’s work are all around us, Kelvin concluded, and “come back upon us with irresistible force, showing to us through nature the influence of a free will, and teaching us that all living beings depend on one ever-acting Creator and Ruler.”
A century and a half later, Marshall, in The Genesis Quest, comes to a much less mystical conclusion. From his research he builds a picture of the mysterious lucky break that brought together the scattered molecular pieces from which he believes nature built the cell. But even in his materialist view, life remains an exceptional phenomenon, and our planet a special place. Because Earth and life are so integrated, “we live here, or nowhere,” he summarizes.
In the end, the question of origins is a question of faith. Some will place their faith in the idea that somewhere, somehow the incredible odds against the origin of life were overcome by natural means in that iconic warm pond. Others will reach out to the supernatural.
It’s a matter a faith because discovering a spiritual aspect to reality, or whether we owe our existence to something beyond the physical, is not scientifically possible. Researchers therefore go to extreme lengths to explain the origin of life in purely physical terms, developing scenarios that often stretch credulity to the breaking point. Such ideas highlight the simplicity of the alternative—that a nonphysical being exists and acted at some point in the distant past to create physical life-forms. As an explanation of origins, this ultimately makes more sense than materialist hypotheses that even other scientists have rejected on scientific grounds.