Beneath Earth's surface lies a hidden kingdom of microscopic life, a realm of "intraterrestrials" that survive in some of the planet's harshest conditions. These organisms, which can live for hundreds of thousands, if not millions, of years in a dormant state, are the subject of intense scientific interest. In this article, we explore the idea of evolution among these intraterrestrials and what they might be waiting for to "wake up."
How do these microbes evolve to stop growing for thousands of years? Recent research suggests that microbes buried deep in oceanic seafloor sediments may be doing just that. These intraterrestrials, small microorganisms living inside Earth's crust, experience unique environmental conditions that shape their evolutionary journey. While they might not notice changes in seasons, they are attuned to longer geological rhythms, such as the opening and closing of oceanic basins through plate tectonics, the formation and subsidence of new island chains, and the slow formation of cracks in Earth's crust. These events, occurring over millions of years, could act as evolutionary cues for these organisms.
The concept of living for millions of years raises intriguing questions about adaptation and evolution. Can microbes be adapted to avoid cell division for thousands of years, and how does evolution work for organisms that seemingly never produce offspring? The author delves into these questions, exploring the possibility that these microbes are evolutionarily predisposed to endure long periods of dormancy, rather than just persisting due to a lack of special adaptations. This leads to a discussion of the evolutionary advantage of long-term dormancy, drawing parallels to short-term seasonal dormancy in organisms like Escherichia coli.
The article then delves into the idea that intraterrestrials might be waiting for geological events, such as volcanic eruptions or tectonic plate movements, to awaken them from their deep-sea slumber. These events, occurring on geological timescales, could provide new food sources and opportunities for growth. The author presents a thought experiment involving day-lifespan humans, where the concept of waiting for geological events becomes more understandable. This thought experiment highlights the potential evolutionary payoff for intraterrestrials, who might be adapted to events with even longer periods, such as glacial cycles or the slow movement of tectonic plates.
In conclusion, the article invites readers to contemplate the hidden life beneath Earth's surface and the evolutionary mysteries of intraterrestrials. It encourages further exploration and discussion, leaving readers with thought-provoking questions about the nature of life and evolution on our planet.
