Is Astrobiology Research Based on a Mistake?

Caleb Scharf, director of Columbia University’s multidisciplinary Astrobiology Center, writes a wonderfully informative blog entitled Life, Unbounded. The topics of Scharf’s posts sometimes parallel those of RTB’s blog posts on Today’s New Reasons to Believe. For example, compare Scharf’s “The Fountains of Earth,” “Artificial Life: Some Assembly Required,” and “Retrograde Planets” with these RTB entries, respectively, here, here, and here.

In his post “Intelligence and Life,” Scharf expresses the opinion that humans are “freakish—an extraordinary and wonderful oddity.” He expresses skepticism about the existence of extraterrestrial life with human-like intelligence. Many biologists would agree because they appreciate the historical contingencies of Darwinian natural selection. Because of those innumerable contingencies, any particular outcome is seen as highly unlikely. Therefore, from a biological standpoint, human intellectual capabilities would not be an expected outcome of evolution any more than dolphins or cockroaches would be expected. Too many historical accidents, such as local environmental events or global mass extinctions, make it impossible and unreasonable to expect any one specified outcome, given the way evolution works.

The unpredictability of biological evolution poses problems for astrobiology research and has sparked much debate in that context. This is a downer for Search for Extraterrestrial Intelligence (SETI) enthusiasts. Evolutionary biologists pretty much throw cold water on SETI in the book Extraterrestrials: Science and Alien Intelligence¹ (a good reference for this debate).

Origin-of-life (OOL) research seems to incorporate the working assumption that the biochemical processes thought to lead to life’s origins operate within the context of natural selection, and, thus, innumerable historical contingencies occur along the way. If this is so, then no one should expect a particular outcome, such as cellular, information-rich life. Therefore, one should also expect that extraterrestrial microbial life would be rare. If life’s origins depend on Darwinian mechanisms, then NASA’s “follow the water” strategy might turn up many interesting discoveries—but as far as actually finding life as we know it, the strategy would likely have little chance of success.

In their book Rare Earth: Why Complex Life is Uncommon in the Universe,² Peter Ward and Donald Brownlee conclude that complex life in the universe is rare but microbial life is common. However, the only data they supply in support of their “microbes are common” view is that life appeared early in Earth’s history. As the name of Scharf’s blog implies, astrobiologists in general seem to assume that life is a common outcome. But if extraterrestrial intelligence and OOL both arise via natural selection, then why should one be rare while the other is common? I posted a comment on Scharf’s blog that questioned this apparent inconsistency. Scharf responded with a proposed resolution, which he acknowledged is incomplete. (You can read his response in the comments section.)

Scharf proposes that, while molecular structures allow a huge number of possible physical permutations, only a much smaller number would be allowable in viable organisms. Thus, selection influences would more quickly discard unworkable molecules and converge on those that lead to viable organisms.

A problem with this answer is that the process of natural selection does not include any mechanism for convergence.³ The system is not necessarily going anywhere; things just happen to fall out at random. Each step in a historical progression of selection is an end in itself. There is no natural next step. Compare that situation to the convergence of a numerical algorithm on a solution. For example, when computing a square root by Newton’s method, the mathematics ensures that a particular solution exists prior to the start of iterations that converge. No such situation exists with Darwinian mechanisms. If you think it does, then you have invoked a sort of teleology (which uses design as an explanation for natural phenomenon), something abhorrent to atheistic naturalism.

This contradictory philosophy is discussed in a paper written by Roger White, a professor at MIT. In his paper, “Does Origins of Life Research Rest on a Mistake?,”⁴ he points out that OOL research is marked by two features:

1. The conviction that life did not arise largely by chance; and
2. The view that purposeful agency as the source of the origin of life is not a serious option and does not play any explicit role in theorizing.

White’s paper demonstrates how these two working assumptions cannot sensibly hang together. This incoherence, it would seem, also extends to astrobiology research.

But in spite of this philosophical issue, astrobiologists could possibly gain some confidence in the abundance of life in the universe by pointing to a history of repeated natural originations of life on Earth. Theoretical physicist Paul Davies and astrobiologist Charles Lineweaver studied the probabilities of life emerging multiple times on Earth. They report, “Our analysis confirms this expectation [multiple origins] by deriving moderate to high probabilities for multiple geneses using plausible assumptions about the rapidity of life’s emergence on the early Earth.”⁵ Furthermore, they also conclude that “the default assumption should be that one or more alternative biologies should be expected.”

To paraphrase Enrico Fermi: Where are they? Why are these “multiple geneses” not obviously evident? Lack of an alternative biology on Earth, arguably the most life-friendly planet imaginable, calls into question the most basic assumption of astrobiologists. By coincidence, Scharf’s post “Universal Common Grandma” reports on new research that shows the three great domains of life (bacteria, archaea, and eukarya) all share a universal ‘Grandma,’ or single origin. While this report does not prove definitively that there has been only one natural origin of life on Earth, it vividly demonstrates the lack of evidence for “alternative biologies.” 

Even if the emergence of life is assumed to be a continuous natural process from inert matter to life, and is in principle reproducible, that assumption provides little comfort to astrobiology when historical contingency is also included in the mix. It could be said that a non-teleological paradigm for the origin of life would inevitably lead back to the view that origins are “almost a miracle.” In contrast, astrobiologists, with their insistence that the existence of friendly environments makes the emergence of life typical, are implicitly invoking a purposeful non-Darwinian view.

Astrobiologists seem to be in a bind. Either they must accept that a purposeful, creative force played a role in the emergence of life or they must reduce their expectations of finding life on Earth-like planets. When secular scientists “assume” that life will be found on other planets, they are, by default, assuming design and purpose in the universe. They immerse themselves in a paradox by injecting into the emergence of life a kind of teleology, which is at odds with atheistic naturalism.

From RTB’s biblical creation model perspective, the paradox disappears and the uniqueness of life on Earth makes sense when you invoke an all-powerful, all-loving Creator.