Do scientists understand the origin of life?

Introduction

Both creationist and intelligent design writers assert that science has yet to understand the origin of life, and further claim that this is a fatal flaw in evolutionary theory [Behe1996; Dembski1998]. More importantly, creationist-minded members of the public have, in numerous cases, attempted to capitalize on this perceived weakness to persuade school boards and teachers that the prevailing theory of evolution is seriously flawed. For example, in the 2005 Dover case, the Dover Area School Board passed a resolution saying that “The Theory [of evolution] is not a fact. Gaps in the Theory exist for which there is no evidence. A theory is defined as a well-tested explanation that unifies a broad range of observations.” It continued, “Intelligent Design is an explanation of the origin of life that differs from Darwin’s view.” [Lebo2008, pg. 62].

So what are the facts here? To what extent does modern science understand the origin of life, and what difference does it make?

It is undeniably true that scientists do not yet fully understand biogenesis (as the origin of life is often termed). In particular, the origin of the first self-reproducing biomolecules, on which evolutionary processes could operate to produce more complicated systems, remains unknown. What’s more, unlike bony structures that leave fossil records, the early stages of biological evolution on the planet very likely have been completely erased, so that we may never know for sure the full details of what transpired.

But research in biogenesis is fundamentally no different than in any other field. Even in areas of science that one would think are extremely well established, both theoretically and experimentally, research continues to be done. In other words, claims by creationists that unknowns in the origin of life arena “prove” that scientists do not have all the answers are only met with puzzled stares by real research scientists. Of course scientists do not have all the answers — exploring unknown, unanswered questions is what science is all about.

Biogenesis from 1950 to 2000

The first major result in the field of biogenesis was a 1953 experiment by Stanley Miller and Harold Urey. In this experiment, the researchers tested an earlier hypothesis that conditions on the early earth may have favored the synthesis of organic compounds from inorganic compounds. They placed water plus some gases in a sealed flask, then passed electric sparks through the mixture to simulate the effects of sunlight and lightning. Over the next week or so, the mixture in the flask slowly turned a reddish-brown color. Upon analyzing the resulting “goo,” they discovered that it contained several amino acids, which are the building blocks of proteins [Davies1999, pg. 86-94]. The Miller-Urey experiment firmly established that basic biochemical building blocks such as amino acids can spontaneously form given the right conditions. Nonetheless, researchers have more recently pointed out that in current models of early earth’s atmosphere and oceans, carbon dioxide and nitrogen would have reacted to form nitrites, which quickly destroy amino acids. Thus the Miller-Urey experiment might not be truly representative of what really happened on the early earth.

Going beyond the synthesis of basic amino acids, one leading hypotheses is that ribonucleic acid (RNA) played a key role. For example, researchers recently found that certain RNA molecules can greatly increase the rate of specific chemical reactions, including, remarkably, the replication of parts of other RNA molecules. Thus perhaps a molecule like RNA could “self-catalyze” itself in this manner, perhaps with the assistance of some related molecules, and then larger conglomerates of such compounds, packaged within simple membranes (such as simple hydrophobic compounds), could have formed very primitive cells [NAS2008, pg. 22].

21st century developments

Even with these developments, until quite recently a sober view of the biogenesis field is that researchers have not yet found the central key to a complete or near-complete scenario for the origin of life. However, a series of very interesting new results have been published in the field just in the past few years, and there is a sense in the field that progress is accelerating.

Perhaps the most notable recent development came in May 2009, when a team led by John Sutherland, a chemist at the University of Manchester in England, solved a problem that has perplexed researchers for at least 20 years (see above), namely how the basic nucleotides (building blocks) of RNA could spontaneously assemble. As recently as a few years ago, the appearance of these nucleotides on the primitive earth was thought to be a “near miracle.” In the 2009 study, Sutherland and his team used the same starting chemicals that have been employed in numerous earlier experiments, but they tried many different orders and combinations. They finally discovered one order and combination that formed the RNA nucleotide ribocytidine phosphate. What’s more, when the mixture was exposed to ultraviolet light, a second nucleotide of RNA was formed [Wade2009].

In February 2010 scientists at the Scripps Research Institute in San Diego announced that they have synthesized RNA enzymes, known as ribozymes, that can replicate themselves without the help of any proteins or other cellular components. What’s more, these simple molecules can act as catalysts and continue the process indefinitely. The researchers began with ribozymes that occur naturally, and put these in a growth medium, where subsets “competed” with others. Eventually more successful (and more complex) ribozymes came to dominate the culture. As researcher Gerald Joyce noted, “The key thing is it replicates itself, and passes information from parent to progeny down the line. … Some functions are more fit than others, and those that are more fit ‘breed’ more, and are perpetuated more efficiently, and so it goes Darwinian.” [DaSilva2010].

A number of other recent developments are summarized at Origin.

Summary

It is undeniably true that scientists do not yet have a fully-developed theory of the origin of life — no knowledgeable scientist has ever claimed otherwise. Numerous scenarios have been explored, but there are still significant gaps in these theories. For these reasons, some religious-minded writers have suggested that God created life. On one hand, this proposition is consistent with scientific knowledge, because no natural explanation is yet known. Such a notion is much more reasonable than, say, asserting that the entire process of creation completed in six days or 6000 years.

Nonetheless, given the remarkable progress that has occurred in the biogenesis arena just in the past few years, it would be utter folly to presume that no additional progress will be made. Hundreds of scientific papers and experimental studies have been published on these topics, and several previous show-stopping obstacles, such as the formation of certain building blocks of RNA, have been overcome. Almost certainly even more remarkable results will be published in the next few years.

Given these developments, most observers, including the present author, believe that it is extremely unwise to base one’s religious or philosophical creed on the presumed impossibility of scientific research eventually discovering a natural process that could satisfactorily explain the origin of life on earth. That would be a premier example of a “God of the gaps” theological error. Along this line, it may well be the case that all traces of the first self-reproducing systems and the earliest unicellular life may have been destroyed in the chaotic chemistry of the early earth, so that we may never know for certain the precise path that actually was taken. But even if scientific research eventually demonstrates some plausible natural path, this would already defeat the claims of creationists and others that only a supernatural force could initiate life. And, frankly, such a discovery could be announced at any time.

It must also be kept in mind that the process of evolution after biogenesis is very well attested in fossils, radiometric measurements, DNA, and numerous other lines of evidence, completely independent of how the first biological structures formed. In other words, those unknowns that remain in biogenesis theory have no bearing on the central hypothesis of evolution, namely that all species are related in a family tree, having proliferated and adapted over many millions of years. Thus there is no substance to the creationist-intelligent design claim that unknowns in the origins area are a fatal flaw of evolutionary theory. Indeed, to the extent that creationist and intelligent design writers continue to emphasize the biogenesis issue as the premier flaw of evolution, they risk being discredited, even in the public eye, as new and ever-more-remarkable developments are publicly announced.

One fundamental difficulty with both the creationist and intelligent design approaches to the origin of life can be seen by considering the following “thought experiment.” Suppose a major international society announced that it had received a communication from a super-intelligent Entity, and the authenticity of this communication could not be denied because it included, say, solutions to mathematical problems that are utterly beyond the present level of human knowledge and computer technology. Suppose also that this communication disclosed that this Entity had initiated or created life on earth. The next day inquisitive humans would then ask questions such as “What time frame was required for this creation?,” “What processes and steps were involved?,” “Can we replicate these processes and steps in a laboratory?,” “Why was earth appropriate for life?,” “Was life similarly initiated or created elsewhere?,” “Who created this Entity?,” “Who created the universe?,” etc. In other words, virtually all of the fundamental questions of existence that have intrigued scientists and theologians alike for centuries would remain unanswered. In this light, the creationist-intelligent design approach of merely asserting “God did it,” and resisting deeper investigation, is tantamount to a “thinking stopper,” reveling in ignorance instead of thirsting for knowledge. Surely there is a more productive approach to harmonize science and religion.

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