Early Life Remains Complex

By Fazale R. Rana

(First published in FACTS for FAITH Issue 7, 2001)

Recent discoveries continue to indicate that life appeared suddenly and early in Earth’s history. While substantiation for a rapid and early origin of life is fragmentary, the scientific community, by and large, views the evidence as convincing. Chemical residues of biological activity dated at greater than 3.8 billion years and fossilized bacteria recovered from rocks dated at around 3.5 billion years present primary indicators for early life.¹ The incomplete nature of the evidence, the great antiquity of the rocks, and the geological processes operating on life’s remains obscure understanding of the first life on Earth, leaving many questions unanswered.

However, recent discoveries begin to address some of these questions. These new discoveries not only provide important additional support for an early origin of life, but also yield insight into the type of bacterial communities and metabolic processes at work.

The first of these new discoveries, made by an international team of scientists, uncovered fossilized bacterial remains in rocks from South Africa dated between 3.3 and 3.5 billion years in age.² Spherical, “sausage-shaped,” and filamentous bacterial fossils in thin sections of the rock samples indicate the presence of a complex microbial ecology made up of different types of microorganisms. Additionally, the chemical make up of the bulk carbon isolated from the rock indicates that it resulted from biological processes-quite likely photosynthesis.

Researchers from Indiana University and Kanagawa University (Japan) sought to gain an understanding of early photosynthesis by employing a different approach from that of the scientists studying ancient rocks from South Africa. Working from an evolutionary perspective, these investigators compared genes from the various groups of photosynthetic bacteria that play a role in making a key molecule needed for photosynthesis.³ These scientists hoped to uncover the evolutionary origin and development of photosynthesis. Due to similarities and differences among the genes, they concluded that if evolution brought about photosynthesis, anoxygenic photosynthesis (that which occurs in the absence of oxygen) must have emerged before oxygenic (that which occurs in the presence of oxygen).

Researchers from Princeton University and the Russian Academy of Sciences, employing a chemical approach, reached a similar conclusion.⁴ Namely, to fit an evolutionary model, anoxygenic photosynthesis must have emerged prior to oxygenic. Remarkably, the biosynthetic routes needed to make the key molecular component of anoxygenic photosynthesis are more complex than the pathways that produce the corresponding component required for the oxygenic form.

These findings create problems for the evolutionary paradigm when examined in the context of the geological record. Fossil deposits clearly indicate the presence of a diverse collection of microbes capable of oxygenic photosynthesis on Earth 3.5 billion years ago.⁵ This means, from an evolutionary perspective, more complex anoxygenic photosynthesis must have been in operation well before 3.5 billion years ago. According to these results, evolutionary models for the origin of life must now account for the rapid and early appearance of photosynthesis.

The rapid and early appearance of life on Earth represents, perhaps, the most remarkable discovery in origin-of-life research. Yet this scenario does not fit within the various evolutionary portrayals of life’s origin. By emerging strictly through natural processes, life’s appearance on Earth should have taken place over a relatively long period. In contrast, the rapid and early beginning of life on Earth signifies the hallmark characteristics expected of life with a supernatural origin.

References:

Manfred Schidlowski, “A 3,800-Million Year Isotopic Record of Life from Carbon in Sedimentary Rocks,” Nature 333 (1988), 313-18; Manfred Schidlowski, “Carbon Isotopes as Biogeochemical Recorders of Life Over 3.8 Ga of Earth History: Evolution of a Concept,” Precambrian Research 106 (2001): 117-34; S. J. Mojzsis et al., “Evidence for Life on Earth before 3,800 Million Years Ago,” Nature 384 (1996), 55-59; J. William Schopf, “Microfossils of the Early Archean Apex Chert: New Evidence of the Antiquity of Life,” Science 260 (1993), 640-46.
Frances Westall et al., “Early Archean Fossil Bacteria and Biofilms in Hydrothermally Influenced Sediments from the Barberton Greenstone Belt, South Africa,” Precambrian Research 106 (2001): 93-116.
Jin Xiong et al., “Molecular Evidence for the Early Evolution of Photosynthesis,” Science 289 (2000), 1724-30.
G. C. Dismukes et al., “The Origin of Atmospheric Oxygen on Earth: The Innovation of Oxygenic Photosynthesis,” Proceedings of the National Academy of Sciences, USA 98 (2001): 2170-75.
Schopf, 640-46.