Was the Origin of Life an Instantaneous Event?
Evidence that life arose on Earth within a geologic instant poses an outstanding problem for naturalistic explanations for the origin of life—and research attempts to broaden the window of time for life’s emergence have only resulted in a much stronger case for life arising instantaneously.
Evolutionary biologist Niles Eldredge observes, “In the very oldest rocks that stand a chance of showing signs of life, we find those signs.”1 Indeed, multiple isotope signatures establish that life was present as soon as Earth’s surface cooled sufficiently from the Late Heavy Bombardment.2
Recognizing the challenge an instantaneous origin poses to naturalistic interpretations of life history, many non-theistic scientists have searched for indications of a much wider time window. In particular, they questioned the early dates for the isotope signatures for Earth’s first life found in graphitic granite.3
One challenge posited that the zircon minerals used to determine the date for the graphitic granite could have originated from unknown older rocks that were infused into the granite.4 Others disputed the early date for life’s origin based on the argument that graphitic granite may not be sediment that could contain organic matter. However, more research defends the early date for life’s emergence. Below I highlight six arguments in favor of an early date.
Defending the Early Date from Graphitic Granite
1. Re-dating the zircons. The team that had used the zircons5 to publish a date of 3.86 ± 0.01 billion years for Earth’s first life refuted criticism by re-dating their best sample at 3.825 ± 0.006 billion years ago.6 They also showed that the mineral contents of the suspect zircons are consistent with what would be expected if they had crystallized from their host rocks.7 Also, though it is true that the formations in which the graphitic granite is found do not clearly resemble organic-rich sediments—such as normal-banded iron formations—they do look very much like metamorphosed marine sediments.8
2. Independent confirmation. A second team used ion microprobe measurements to provide independent confirmation that the graphitic granite contains isotope signatures of life.9 This team’s samples indicate life was present on Earth at least 3.830 billion years ago.10 They conclude, “It seems likely that the record of life on Earth is as old as the oldest sedimentary rocks now known.”11
3. Uranium-to-thorium ratios. A third team found the carbon isotope signature of planktonic organisms in metamorphosed shale that was dated to be older than 3.70 billion years.12 In the same shale they measured a high uranium-to-thorium ratio. These data demonstrate that organic debris produced a local reducing environment, which precipitated uranium that oxidized ocean water then transported to the shale sediment. So much oxidized water implies that oxygenic photosynthetic life was abundant previous to 3.70 billion years. Even the simplest oxygenic photosynthetic bacteria contain over 1,800 gene products. Thus, uranium-thorium ratios establish that even complex unicellular life was already prevalent well before 3.70 billion years ago.
4. Confirming the source of the graphitic granite. In 2014, researchers addressed the challenge of whether or not the graphitic granite is indigenous to the early rocks or was precipitated from younger metamorphic or igneous fluids.13 First, they affirmed the carbon isotope signature for life with transmission microscope observations, showing that the granite occurs as nanoscale polygonal and tube-like grains—typical of biotic graphite and in sharp contrast to abiotic graphite, which appears as flakes.
Next, the team used Raman spectroscopy on their samples to establish that the granite formed from marine sediments containing the carbon isotope signature of life from the time of deposition. Thus, the graphitic granite really is indigenous to the early dated rocks.
5. Photosynthetic energy source. Eventhe very presence of so much granite 3.83 billion years ago could qualify as a signature for life. Photosynthesis harvests solar energy and channels that solar energy into geochemical cycles. These cycles, if they operate at high levels, produce granite. Presently, photosynthesis contributes about three times more energy to these cycles than heat flow from Earth’s interior. Thus, photosynthetic life may explain the unique presence of granite on Earth.14
6. Black shale abundance. A team led by geophysicist Norman Sleep demonstrated that black shale was prevalent in rocks dated at about 3.85 billion years old. They point out that so much black shale shows that iron- and sulfur-based anoxygenic photosynthetic life must have been well established at that time.15
Attempted challenges to evidence that life originated within a geologic instant has produced a much stronger case for an instantaneous beginning, a result that bodes well for the biblical view that God brought life into existence.
- Niles Eldredge, The Triumph of Evolution and the Failure of Creationism (New York: W. H. Freeman, 2000), 35–36.
- Fazale Rana and Hugh Ross, Origins of Life (Colorado Springs: NavPress, 2004), 63–92.
- Martin J. Whitehouse, Balz S. Kamber, and Stephen Moorbath, “Age Significance of U-Th-Pb Zircon Data from Early Archaean Rocks of West Greenland—A Reassessment Based on Combined Ion-Microprobe and Imaging Studies,” Chemical Geology 160 (August 10, 1999): 201–24; Christopher M. Fedo and Martin J. Whitehouse, “Metasomatic Origin of Quartz-Pyroxene Rock, Akilia, Greenland, and Implications for Earth’s Earliest Life,” Science 296 (May 24, 2002): 1448–52; Aivo Lepland et al., “Questioning the Evidence for Earth’s Earliest Life—Akilia Revisited,” Geology 33 (January 2005): 77; Martin J. Whitehouse, John S. Myers, and Christopher M. Fedo, “The Akilia Controversy: Field, Structural and Geochronological Evidence Questions Interpretations of >3.8 Ga Life in SW Greenland,” Journal of the Geological Society 166 (March 2009): 335–48.
- Whitehouse, Kamber, and Moorbath, “Age significance of U–Th–Pb Zircon Data”: 201–24.
- S. J. Mojzsis et al., “Evidence for Life on Earth before 3,800 Million Years Ago,” Nature 384 (November 7, 1996): 55–59; Heinrich D. Holland, “Evidence for Life on Earth More than 3850 Million Years Ago,” Science 275 (January 3, 1997): 38–39.
- Craig E. Manning, Stephen J. Mojzsis, and T. Mark Harrison, “Geology, Age and Origin of Supracrustal Rocks at Akilia, West Greenland,” American Journal of Science 306 (May 2006): 303–66.
- Ibid.; John M. Eiler, “The Oldest Fossil or Just Another Rock?” Science 317 (August 24, 2007): 1046–47.
- Kevin D. McKeegan, Anatoliy B. Kudryavtsev, and J. William Schopf, “Raman and Ion Microscopic Imagery of Graphitic Inclusions in Apatite from Older than 3830 Ma Akilia Supracrustal Rocks, West Greenland,” Geology 35 (July 2007): 591–94.
- Ibid.; Allen P. Nutman and Clark R. L. Friend, “Raman and Ion Microscopic Imagery of Graphitic Inclusions: COMMENT,” Geology 36 (2008): doi: 10.1130/G24384C.1; McKeegan, Kudryavtsev, and Schopf, “Raman and Ion Microscopic Imagery of Graphitic Inclusions: COMMENT and REPLY,” Geology 36 (2008): doi: 10.1130/G24987Y.1.
- McKeegan, Kudryavtsev, and Schopf, “Raman and Ion Microscopic Imagery of Graphitic Inclusions”: 593.
- Minik T. Rosing and Robert Frei, “U-Rich Archaean Sea-Floor Sediments from Greenland—Indications of >3700 Ma Oxygenic Photosynthesis,” Earth and Planetary Science Letters 217 (January 2004): 237–44.
- Yoko Ohtomo et al., “Evidence for Biogenic Graphite in Early Archaean Isua Metasedimentary Rocks,” Nature Geoscience 7 (January 2014): 25–28.
- Minik T. Rosing et al., “The Rise of Continents—An Essay on the Geologic Consequences of Photosynthesis,” Palaeogeography, Palaeoclimatology, Palaeoecology 232 (March 22, 2006): 99–113.
- N. H. Sleep, E. Pope, and D. Bird, “Two-Way Feedback Between Biology and Deep Earth Processes,” presented at the American Geophysical Union 2012 Fall Meeting, abstract #P14A-07.