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Twisted Evidence for Early Life

Anyone working on a home improvement project knows how important it is to have “the right tool for the right job.” This maxim also applies to science. Scientists need the right scientific tools if they ever hope to advance our understanding of the natural world. Perhaps no group of scientists has a greater need for the right tool than those exploring life’s origin and early history. Thankfully, help is on the way. Recent work by researchers from Germany and Switzerland describes a new tool that may help origin-of-life researchers finally identify fossils of the first life-forms.1

Earth’s oldest rock formations, located in western Greenland, date to 3.8 billion years in age. These rocks contain geochemical signatures that suggest life was present very early in the planet’s history—as soon as life support was even remotely possible.2 (For more details, check out the article, “When Did Life First Appear on Earth?”). Controversy accompanies the implications of these findings. Some researchers believe that these geochemical signatures may not reflect biological activity of first life. Instead, they argue, these features are due to abiotic processes that masquerade as biosignatures. To put it another way, geochemical markers aren’t necessarily the right tools to detect and characterize earliest life unambiguously.

If researchers could recover fossils of the first life-forms from the oldest rocks, it would go a long way toward demonstrating that life existed on Earth 3.8 billion years ago. Unfortunately, the rock formations of western Greenland have experienced extensive metamorphosis. High temperatures and pressures accompany these geological changes. These extreme conditions would have destroyed any fossils existing in the rocks.

Yet the researchers from Germany and Switzerland may have found a way, in principle, to detect fossils in these rock formations. Certain bacteria (microaerophilic Fe(II)-oxidizing bacteria) produce twisted stalk-like structures in the presence of high iron levels and low oxygen concentrations. The twisted stalks are formed from microbial secretions that then interact with iron minerals. These interactions stabilize the stalks. The researchers found these twisted structures in microbial mats recovered from a silver mine located in the Black Forest of Germany. When they subjected the microbial mats to high temperatures and pressures in the lab, the twisted stalks remained intact.

This exciting result suggests that it might be possible to recover twisted stalk fossils in the rock formations of Greenland. Twisted stalk structures have been observed in materials taken from rock formations that date to about 1.9 billion years in age. Early Earth’s oceans would have been loaded with iron in the form of Fe(II) and would have had low levels of oxygen. If microbes existed that could oxidize Fe(II), they would have likely produced twisted stalk structures. And if they did, then these structures have survived even if the rocks experienced extensive metamorphosis.

Unequivocal demonstration of life on Earth at 3.8 billion years ago would powerfully affirm RTB’s origin-of-life creation model. Our model predicts that life appeared soon after the planet’s formation. Meanwhile, an early appearance is unanticipated from an evolutionary perspective.

Will researchers be able to use this new tool to detect fossil evidence for life at 3.8 billion years ago? It is not clear yet—but the possibility puts RTB in a position to perform a definitive test of our creation model for life’s origin.

  1. Aude Picard et al., “Experimental Diagenesis of Organo-Mineral Structures Formed by Microaerophilic Fe(II)-Oxidizing Bacteria,” Nature Communications 6 (February 18, 2015): id. 6277.
  2. Researchers believe that the first life-forms on Earth resembled contemporary bacteria and archaea.