Intelligent Design Icon Intelligent Design
Life Sciences Icon Life Sciences

Recognizing Life Is Different from Natural Processes, Science Balances on the Edge of ID

Evolution News


Scientific materialists must live in a state of cognitive dissonance. They believe everything is “natural” (within nature), but they don’t hesitate to look for decidedly “un”-natural things about life. Consider this from New Scientist about how to detect alien life:

Now Lee Cronin, a chemist at the University of Glasgow, UK, argues that complexity could be a biosignature that doesn’t depend on any assumptions about the life forms that produce it. “Biology has one signature: the ability to produce complex things that could not arise in the natural environment,” Cronin says. [Emphasis added.]

We saw Lee Cronin last June arguing for a “radical rethink” of origin-of-life scenarios. Here, he’s thinking about generic life that could be found in space. Alien life might not be made of “amino acids, unequal proportions of mirror-image molecules, and unusual ratios of carbon isotopes, all of which are signatures of life here on Earth.” It could be totally different. Consequently, it could be missed by Earth-centric detection strategies.


There is one thing that would distinguish life from non-life, Cronin reasons: its complex organization. Here, the article by Bob Holmes engages in a delicate balancing act, coming dangerously close to intelligent design:

Obviously, an aircraft or a mobile phone could not assemble spontaneously, so their existence points to a living — and even intelligent — being that built them. But simpler things like proteins, DNA molecules or steroid hormones are also highly unlikely to occur without being assembled by a living organism, Cronin says.

Now that is dancing on the edge! We presume Cronin and Holmes are being careful not to topple over into the ID camp, but their ideas are closer than the usual materialist/reductionist talk of spontaneous emergence that makes life out to be a natural byproduct of matter. There’s even a faint echo of Thomas Nagel’s appeal to common sense in Mind and Cosmos where he intuits a limit to what can credibly be called natural:

And the coming into existence of the genetic code — an arbitrary mapping of nucleotide sequences into amino acids, together with mechanisms that can read the code and carry out its instructions — seems particularly resistant to being revealed as probable given physical law alone.

Cronin proposes a method for measuring complexity that doesn’t depend on life as we know it. He counts the number of unique steps required to get a molecule. Some molecules require so few steps that they can be explained by natural causes. But for a molecule of sufficient complexity, at some point in the sequence of events in its formation, probability would demand a “life inference” if not an inference to intelligence:

Any structure requiring more than about 15 steps is so complex it must be biological in origin, he said this week at the Astrobiology Science Conference in Mesa, Arizona.

Let’s pause to consider what this means. For something to be “biological in origin,” it cannot have emerged by natural law alone. It would be “un”-natural enough to warrant the inference that life or intelligence caused it to come into being.

One might argue that purely physical things can have unique signatures as well. For instance, planetary scientists find signatures of volcanism on the surfaces of Mercury, Io, and even Pluto and Ceres (ice volcanism). What’s the difference, then, between looking for a biosignature in one scientific context and a heat signature in another context? Clearly, it must be the degree of complexity. Heat is common everywhere just by normal thermodynamics. But some complex phenomena are never observed to emerge through natural law alone.

With volcanoes, laws of heat and buoyancy are sufficient to figure out how material makes its way up through a crust. If a volcano had to take a sequence of 15 unique steps, however, then we might be justified in looking into non-natural causes at work. That’s not likely, since well-known laws of physics can account for eruptions, and we witness volcanoes all the time. We never witness unguided chemical reactions going through 15 or more unique independent steps to arrive at a complex molecule, much less to produce a coding system with transcription, translation, and reproduction. That’s why the “complexity” Cronin tries to measure must equate to specified complexity.


The distinction between natural and intelligent causes becomes especially clear in SETI. In another piece in New Scientist, Geraint Lewis from the University of Sydney discusses not just bio-signatures but mind-signatures. Frustrated by the silence of traditional SETI, and realizing that the Fermi paradox (the “Where is everybody?” question posed by Enrico Fermi) has never been answered, he suggests a different search strategy closer to home: finding the remains of extinct civilizations in our own celestial backyard.

This apparent absence of evidence is known as the Fermi paradox. It has led to considerable head-scratching for more than half a century. Now, U.S. astronomer Jason Wright has a new twist on it, rephrasing Fermi’s question to: “Where was everybody?” In particular, one answer could be our own solar system. He wonders if “prior indigenous technological species” arose here, and what trace might they have left behind?

David Klinghoffer commented on Wright’s idea here last week. ID advocates should feel right at home with this strategy. It’s like archaeology. We know it’s possible in many cases to separate natural causes from intelligent causes when examining artifacts (see “Intelligent Design in Action: Archaeology”). It’s not even necessary to know anything about the builders to infer that an intelligent cause probably brought a structure into existence (see here for an example). Extending the same reasoning, we can expand the search space to other nearby worlds.

If they existed here, or on the other planets and moons, what signs should we look for and where? In the crushing environment of Venus, and the churning plate tectonics of Earth, buildings and monuments would be eroded and destroyed on such long timescales. But on slow-changing Mars, our moon, and possibly the frozen satellites of outer solar system planets, the tunnels and cities of ancient lost civilisations could survive buried under the soil and ice.

Lewis implies that the inference to intelligence is not only intuitive but robust. Tunnels, cities, and habitable structures are decidedly “un”-natural because, applying the same reasoning used by Cronin, too many unique steps would be required for their origin. Lewis is even willing to lower the bar for design detection:

Other signatures would be more durable still, with the slow decay of nuclear power sources apparent for billions of years, with distinct mixtures of elements and radioactivity.

We saw a similar type of reasoning used by experts in “nuclear forensics” a while back. Scientists can determine, through intuition supported by probability calculations, that certain things don’t “just happen” naturally.

Lewis admits that his thoughts about extinct civilizations are “pure speculation” at this point. But he implies that in principle one can distinguish natural causes from intelligent causes. That’s all intelligent design tries to do. He says, “When we finally start digging into the dirt of other worlds, we might uncover definitive signs that someone else has been there before.” This, too, dances right up to the perilous edge of ID.


ID is the science of determining “definitive signs” that “someone” (a mind) has been at work; a mind with the intelligence, intention, and ability to take natural materials and organize them into complex structures unreachable by unguided natural processes. For SETI, the inference to intelligent causation is intuitive and direct. For astrobiology, the inference is indirect, but logically similar: a biosignature points to a non-natural chain of events that had a goal and a purpose (life).

These scientists may not call it intelligent design, but ID is alive and well in their work. The challenge is to help them recognize it.

Image: © juanjo —

Evolution News

Evolution News & Science Today (EN) provides original reporting and analysis about evolution, neuroscience, bioethics, intelligent design and other science-related issues, including breaking news about scientific research. It also covers the impact of science on culture and conflicts over free speech and academic freedom in science. Finally, it fact-checks and critiques media coverage of scientific issues.



astrobiologyDavid KlinghofferGeraint Lewisintelligent designLee CroninMarsSETIThomas NagelUniversity of GlasgowUniversity of SydneyVenus