Almost every individual recognizes that humanity is a part of the web of life on this planet. People want to know where life came from, in order to have a better sense of place in the universe. The search for life’s origins thus becomes no dispassionate journey but a pilgrimage filled with significance. This trek draws each person onward with the nagging need to answer the ultimate question: What is the meaning of existence?
In search of answers for life’s origin, there are two general directions from which to choose—evolution and creation. Each of these concepts raises a multitude of questions. The goal of this book is to bring the answers to some of these questions into clearer focus and to let the known scientific facts determine which theory better solves the mystery behind life's beginnings. The ultimate purpose is to discover the truth.
Evolution, derived from naturalism (the belief that the physical universe comprises all reality), is the better known and preferred theory in many circles. To some, it seems the only possible pathway to knowledge of life’s start. And certainly this concept has a long and distinguished history, counting among its advocates many of modern history’s greatest thinkers. But whether this idea makes the most sense, based on what is known about the initial appearance of life, remains to be seen.
Can evolution's theory of abiogenesis (the birth of life from nonlife) be demonstrated as true? If abiogenesis lacks scientific support, then evolutionary theory stands by blind faith alone. For biology to be framed in naturalistic terms, scientists must demonstrate the continuum from a prebiotic mixture of chemicals through the most complex life forms. However, if something more than nature, namely the supernatural, was involved in life’s origin, then the door is open for viewing biological phenomena from a creation perspective.
The history behind the current state of origin-of-life science begins the investigation.
Scientific explanations for the origin of life have a colorful history over the last 150 years. Along the way, this discipline has taken a number of remarkable twists and turns.
Darwinism. Biology moved with full force into the materialistic arena in the late 1850s with the publication of Charles Darwin’s The Origin of Species. Darwin and those who accepted the essence of his ideas no longer regarded species as the fixed product of divine creative activity. Rather, Darwinists viewed species as evolving from one form into the next strictly through natural mechanisms—inheritable variation operated on by natural selection. They believed that all life throughout Earth’s history stemmed from a single form or a few original forms.
Darwin did not address the origin of life directly until more than a decade after publication of his now famous book. His theory dealt only with life’s transformation once it existed. In 1871 he advanced the bold idea that life could have emerged on Earth through chemical processes involving ammonia, phosphates, and other inorganic materials.
Darwin’s contemporaries, such as T. H. Huxley and Ernst Haeckel, suggested similar pathways to the first life form. Haeckel, one of Darwin’s leading German supporters, proposed the existence of ancient creatures that occupied an intermediate position between life and nonlife. Haeckel called these predecessors to life “monera” and thought them to be formless lumps of gel with the capacity for reproduction. Shortly after Haeckel advanced his hypothesis, Huxley provided observational support for the idea. He detected gelatinous lumps in ocean-floor mud and interpreted them as moneran remains.
The protoplasmic theory of the cell—the idea that the cell consists of a wall surrounding a nucleus and homogeneous jellylike protoplasm—made the early naturalistic explanations of abiogenesis seem plausible. As early as the 1830s biologists Matthias Schleiden and Theodor Schwann, working independently, advanced the theory that all life is composed of units called “cells.” Observational capacity at that time limited biologists’ view of the cell to three features: the cell wall, the nucleus, and the protoplasm.
When biologists and chemists focused attention on the protoplasm in the 1850s, they began to envision chemical routes that could possibly produce what they believed to be the single ingredient of the cell’s protoplasm. For example, German chemist Edward Pflüger suggested that simple carbon- and nitrogen-containing compounds on early Earth underwent a series of transformations to produce the single complex molecule comprising cellular protoplasm.
By the end of the nineteenth century, with the rise of the new field of biochemistry, the protoplasmic view of the cell waned. Scientists recognized that the cell’s protoplasm is a chemically complex system. This complexity became apparent with the discovery of enzymes in the cell’s protoplasm, capable of catalyzing a large number of chemical reactions. With the demise of the protoplasmic model, the earliest ideas about abiogenesis came to an end. At the same time, chemical studies indicated that Huxley’s “moneran” remains were simply chemical artifacts—calcium sulfate precipitate caused by alcohol addition to mud samples.
Panspermia. In the late nineteenth century, an entirely different approach to the origin-of-life question became popular. Many scientists began to regard life, like matter, as eternal. This idea left no room for a creator. It embraced materialism and circumvented the question of a beginning by regarding life as always present in the universe. Scientists referred to this concept as panspermia—“everywhere life’s seeds.”
Proponents of this theory viewed life as qualitatively different from matter, yet considered it an inherent part of the universe. Panspermia gained legitimate support from the prevailing view that the universe is eternal and infinite. Also integral to the concept was the recognition that biological organization is far too complex to emerge by the random processes that comprise abiogenesis.
Many prominent scientists of the time, such as Lord Kelvin, Hermann von Helmholtz, and Nobel laureate Svante Arrhenius, argued vigorously for panspermia. Research efforts involved identifying mechanisms that could transport life throughout the universe. Life’s origin on Earth equated to life’s first arrival under survivable conditions. Kelvin and von Helmholtz thought that meteorites transported the first life forms to Earth. Arrhenius suggested that naked bacterial spores, or spores associated with dust particles, prevailed throughout the universe. He proposed the idea that radiation pressure from stellar systems propelled the spores through interstellar space.
Panspermia lost its appeal in the early twentieth century as cosmologists began to recognize from Einstein’s theory of general relativity and Edwin Hubble’s observations of space’s expansion that the universe had a beginning. Other experiments showed that ultraviolet radiation kills bacterial spores. Because this deadly ultraviolet radiation permeates interstellar space, this implied that bacteria could not have survived interstellar journeys. The evidence seemed to be turning against panspermia.
Neovitalism. Given the vast complexity of life and the complicated problems with abiogenesis and panspermia, most scientists of the early 1900s gave up trying to discover how life originated. Life’s beginning was considered a profound mystery.
Other scientists began to argue for a special “life force.” A scientific minority emerged that gave attention to this concept, termed neovitalism. One leading proponent, Hans Driesch, argued that the hypothesized life force mysteriously propagated from one generation to the next and that the origin-of-life question stood beyond reach.
The Oparin-Haldane hypothesis. Reacting to this neovitalism, Russian biochemist Alexander I. Oparin and British geneticist J. B. S. Haldane independently provided a detailed hypothesis for abiogenesis in the 1920s. Though initially rejected by much of the scientific community, the Oparin-Haldane hypothesis became the chief organizing principle in origin-of-life research through the 1970s, and in some form it persists today. Oparin and Haldane were the first to propose the mechanism for life’s origin as part of a detailed scientific model.
That model presented detailed stepwise pathways from inorganic systems on primordial Earth to the emergence of Earth’s first living entities. They postulated an early atmosphere devoid of oxygen and dominated by reducing gases—hydrogen, ammonia, methane, and water vapor. Within this gas mix, energy discharges formed prebiotic molecules that accumulated in Earth’s oceans to form the primordial soup. Chemical reactions then led step by step to the first life forms.
Oparin and Haldane differed regarding the intermediates to life. Oparin viewed the transitional molecular system as protein aggregates, whereas Haldane regarded life’s intermediate as a large self-replicating molecule.
Not until the 1950s did anyone offer significant experimental verification for the Oparin-Haldane hypothesis. Stanley Miller, a student of Nobel laureate Harold Urey at the University of Chicago, performed the now famous spark-discharge experiments, launching the origin-of-life research program as a formal scientific discipline. His experiments produced amino acids and other organics by passing an electrical discharge through a gas mixture devoid of oxygen, and his success inaugurated a series of similar experiments by other scientists. Results seemed to continually validate Oparin’s and Haldane’s ideas. Giddy with Miller’s accomplishment, many scientists predicted the origin-of-life problem would be solved in the next few decades.
Chemical analysis of a meteorite that fell in Murchison, Australia (in 1969) further fueled the optimism and sense of accomplishment within the origin-of-life research community. Scientists looked to the Murchison meteorite, and others like it, as a proxy for the chemistry operating on early Earth because they are from the era when the solar system formed. The organic compounds found in the Murchison meteorite resemble in quantity and type those formed in laboratory simulation experiments.
Excitement grew as researcher Sidney Fox achieved the next important milestone in the 1970s. Fox and his lab group coaxed amino acids to condense, forming “proteinoids.” Some of these compounds—closely related to proteins in structure—possessed the ability to catalyze, or assist, chemical reactions. Fox and his coworkers observed that under certain conditions proteinoids aggregated to form microspheres. These microspheres superficially resemble cells.
While earlier studies focused on finding chemical routes that produced life’s molecular building blocks, scientists in the mid-1980s and 1990s began to assess the operation of these chemical pathways on early Earth. Their research seemed to turn up more dead ends than fruitful avenues to study. They also started probing the geochemical and fossil records of Earth’s oldest rocks—data that establish time constraints for beginning-of-life scenarios. In addition, researchers began applying information theory to the origin-of-life dilemma and started to understand life’s minimal complexity. Problems grew increasingly insurmountable. The thrills of the early decades of research gave way to growing frustration and pessimism.
Currently, scientists stand no closer to understanding life’s beginning than they didwhen Stanley Miller conducted his first experiments fifty years ago. Though some scientists assert that the research is in its infancy, significant resources have been brought to bear on the origin-of-life question over the past five decades. To date, no real answers have emerged. Rather, a misguided approach has essentially stalled the research program.
Best-selling author Paul Davies makes this point in his book The Fifth Miracle:
When I set out to write this book, I was convinced that science was close to wrapping up the mystery of life’s origin. . . . Having spent a year or two researching the field, I am now of the opinion that there remains a huge gulf in our understanding. . . . This gulf in understanding is not merely ignorance about certain technical details; it is a major conceptual lacuna.
Davies’ statements likely surprise most people, including scientists. From popular media reports, one would think researchers have all but finalized the explanation for life’s beginning. But such is not the case.
Davies explains why this mismatch persists between public perception and stark reality:
Many investigators feel uneasy about stating in public that the origin of life is a mystery, even though behind closed doors they freely admit that they are baffled. There seems to be two reasons for their unease. First, they feel it opens the door to religious fundamentalists and their god-of-the-gaps pseudoexplanations. Second, they worry that a frank admission of ignorance will undermine funding.
So scientists are keeping quiet and searching for new directions in which to proceed. Their behind-the-scenes frustration became evident (to these authors) at the combined meetings of the International Society for the Study of the Origin of Life and the International Conference on the Origin of Life, held both in 1999 at the University of California, San Diego, and in 2002 in Oaxaca, Mexico (hereafter referred to as ISSOL 1999 or ISSOL 2002). This joint scientific meeting, held every three years, attracts leading origin-of-life investigators from around the world and serves as a platform for them to share and discuss their latest findings.
The atmosphere at such gatherings typically crackles with anticipation as participants gather to hear about new discoveries and breakthroughs. However, at both of these last two ISSOL events, a grim mood laced with desperation prevailed. Participants acknowledged that some fifty years of well-funded investigation have led to one barricade after another. The old intractable problems remain as new ones come to light.
Origin-of-life investigators have successfully discovered many plausible chemical routes, from simple compounds to biologically important compounds. Yet for other critical biomolecules no pathways are knownin fact, they may not exist. For those molecules with identified synthetic routes, in many cases their chemical pathways would likely be blocked by early Earth’s conditions. Origin-of-life researchers cannot identify any location on primordial Earth suitable for production of prebiotic molecules. Those studying the problems cannot explain how the uniform “handedness” (homochirality) of amino acids, nucleotides, and sugars could emerge in any so-called prebiotic soup.
Data from the geological, geochemical, and fossil records all place impossible constraints on naturalistic scenarios. Life arose rapidly and early in Earth’s historyas soon as Earth could possibly support it. Origin-of-life researchers recognize that life had no more than tens of millions of years to emerge. Life also appeared under amazingly harsh conditionsconditions that would not allow life to survive, let alone originate.
Earth’s first life was complex chemically, though simple morphologically (that is, in its form). Consistent with this, investigators have discovered that life in its most minimal form requires an astonishing number of proteins that must be spatially and temporally organized within the cell.
History seems to be repeating itself. Just as the first Darwinists gave up on the earliest versions of abiogenesis, so scientists today are abandoning long-cherished pillars of the naturalistic origin-of-life paradigm. Many now speculate that life may have originated somewhere other than on Earth.
In the face of this challenge, the science community is turning once again to the panspermia idea to explain life’s first appearance on Earth. However, the panspermia of the twenty-first century differs from that of the nineteenth. Originally, panspermists viewed the universe as eternal and viewed life as qualitatively different from matter. Today scientists consider the universe to have had a beginning in time and they see life and matter as indistinguishable at a chemical level.
Some neopanspermists merely transfer the life-origin problem to another body in the solar system (Mars, for example). They posit that materials ejected from the surfaces of these other solar system bodies could have served as the vehicles that delivered life to Earth, or perhaps life originated in a nearby star system and traversed interstellar space as spores or on interstellar dust grains, similar to Svante Arrhenius’s mechanisms.
A few researchers, influenced by astrophysicists such as the late Fred Hoyle and Chandra Wickramsinghe, adopt a form of panspermia virtually identical to that of the nineteenth century. They reject big-bang cosmology and regard the universe as eternal. Also, they see biological complexity as too great for abiogenesis. Infinite time, infinite matter, and infinite life become the only way around this dilemma. Yet—amazingly—most panspermia proponents today view life’s beginning as a reasonably likely occurrence.
The appeal to panspermia offers only a short reprieve for the naturalistic paradigm. Mounting scientific evidence underscores the unlikelihood that life could emerge on any planet (or other body) in Earth’s solar system or travel through interstellar space. As today’s panspermists rediscover the obstinate problems associated with panspermia, they will likely be forced to abandon these ideas again.
Recognizing the problems with origin-of-life scenarios on Earth and with both interplanetary and interstellar panspermia, some scientists have begun to espouse a radical version of the conceptdirected panspermia. First suggested by Nobel laureate Sir Francis Crick and origin-of-life researcher Leslie Orgel, this approach explains life’s first occurrence on Earth as the work of aliens who sent an unmanned ship to Earth, seeding it with life.
Like the neovitalists of the early 1900s, other scientists recognize the problems of chemical evolution and panspermia and appeal to a yet-undiscovered law of physics or life principle to explain life’s beginning. But another alternative may make more sense.
The dead ends that continually stymie researchers need not yield the same confusion and frustration experienced by scientists at the beginning of the last century. A radical new approach based on new findings may begin to provide solutions to the intractable problems.Excerpted from Origins of Life, 2004 by Fazale Rana & Hugh Ross. Used by permission of NavPress/Pinon Press. All rights reserved.