Life's beginning just keeps getting less and less simple.

 Study Finds Life’s Origin “Required a Surprisingly Short Interval of Geologic Time”

Casey Luskin

An article at ScienceAlert reports, “Gobsmacking Study Finds Life on Earth Emerged 4.2 Billion Years Ago.” They write, “By studying the genomes of organisms that are alive today, scientists have determined that the last universal common ancestor (LUCA), the first organism that spawned all the life that exists today on Earth, emerged as early as 4.2 billion years ago.” The article then offers an intriguing point about the rapidity with which life appeared on Earth:

Earth, for context, is around 4.5 billion years old. That means life first emerged when the planet was still practically a newborn.

The technical paper in Nature Ecology and Evolution notes that they used not fossil evidence to arrive at such an early date of life on Earth, but molecular clock techniques. The claim that life existed on Earth at 4.2 billion years ago (also noted as “4.2 Ga”) is consistent with some geological evidence (see below), but life at such an early stage is certainly not expected. Some will surely claim that it’s impossible because the heavy bombardment period which frequently saw the Earth sterilized by impacts had not yet concluded. Here’s some of the best early fossil evidence of life on Earth (Ma means “millions of years” ago):

Potential filamentous microfossils from Canada: >3750 – 4280 Ma (Papineau et al., 2022)

Microfossils from Canada: >3770 Ma (Dodd et al., 2017)

δ13C — Excess light carbon: 3.7 Ga. (Rosing, 1999, Ohtomo et al., 2014)

Stromatolites from Greenland: ~3700 Ma (Nutman et al., 2016)

Stromatolites from Western Australia: 3480 Ma (Van Kranendonk et al. 2008, Walter et al., 1980)

As you can see, most of the early fossil evidence of life on Earth is significantly younger than 4.2 Ga, but the possibility of life at 4.2 Ga is allowed by one study. Despite this potential consistency with some fossil evidence, there are multiple reasons to be skeptical of the article’s methods. 

Genetic and Phenotypic Traits

First, it infers the genetic and phenotypic traits of LUCA by assuming that biological similarity always results from common ancestry — and never from common design. This dubious logic is seen in the opening statement from the technical paper which reads, “The common ancestry of all extant cellular life is evidenced by the universal genetic code, machinery for protein synthesis, shared chirality of the almost-universal set of 20 amino acids and use of ATP as a common energy currency.” It’s true that all life uses those components (although the genetic code is not exactly universal), but this does not provide special evidence for common ancestry because the commonality of these similar features could be explained by common design due to their functional utility. After all, the optimization of the genetic code to minimize the effects of mutations upon amino acid sequences has been cited as potential evidence for intelligent design — showing that there could be good reasons for a designer to re-use the standard genetic code across many organisms.

Second, there are fundamental components of life that show great differences across different types of organisms. For example, the mechanisms of DNA replication and cell division in prokaryotes and eukaryotes are highly distinct. Ribosomes in prokaryotes and eukaryotes have fundamental differences, as one paper explains: “Structures of the bacterial ribosome have provided a framework for understanding universal mechanisms of protein synthesis. However, the eukaryotic ribosome is much larger than it is in bacteria, and its activity is fundamentally different in many key ways.” Many other examples could be given.

Third, the paper uses molecular clock methods to date the timing of LUCA, and molecular clock techniques are problematic for many reasons: they’re highly assumption-dependent and notoriously variant, unreliable, and controversial.

Intriguing Implications

All that said, it’s certainly not impossible that life was already present on Earth at 4.2 Ga. And if it were true it would have intriguing implications. As the study concludes:

The result is a picture of a cellular organism that was prokaryote grade rather than progenotic and that probably existed as a component of an ecosystem, using the WLP for acetogenic growth and carbon fixation. … How evolution proceeded from the origin of life to early communities at the time of LUCA remains an open question, but the inferred age of LUCA (~4.2 Ga) compared with the origin of the Earth and Moon suggests that the process required a surprisingly short interval of geologic time.

This suggests that not only did the origin of life occur very soon after the Earth formed but life diversified into a prokaryotic cellular form very soon as well.

The notion that life appeared on Earth shortly after it became habitable is not new. In the past, experts have said just that. For example:

Stephen Jay Gould: “[W]e are left with very little time between the development of suitable conditions for life on the earth’s surface and the origin of life.” (“An Early Start,” Natural History 87 (February, 1978))

Cyril Ponnamperuma: “[W]e are now thinking, in geochemical terms, of instant life…” (Quoted in Fred Hoyle and Chandra Wickramasinghe, Evolution from Space (New York, NY: Simon & Schuster, 1981))

Widespread Life in the Universe?

I don’t think Gould or Ponnamperuma would have anticipated life as early as 4.2 Ga. If such a timeframe is correct, however, it is extraordinary indeed. The ScienceAlert article also gets this point, stating, “This implies that it takes relatively little time for a full ecosystem to emerge … It also demonstrates just how quickly an ecosystem was established on early Earth. This suggests that life may be flourishing on Earth-like biospheres elsewhere in the Universe.” The last point — their punchline about astrobiology and the existence of life elsewhere — of course assumes that life on Earth originated naturally in the first place. It also seems to further assume that, under the right conditions, life originates easily. If it has sprung up early and easily on multiple other planets, according to this naturalist way of thinking, shouldn’t it have sprung up multiple times on Earth, too? And yet universal common ancestry denies that this is so. To all appearances, that’s a conundrum for the naturalist.

But a single origin of terrestrial life has not been established by this study. The most that has been demonstrated is that life appeared early in Earth’s history. Given the difficulties surrounding a natural origin of life, a better inference might be to take this evidence of life’s rapid appearance as evidence that it did NOT arise naturally and required intelligent design.