What Happens When Deep Earth Life Stays Dormant for Thousands of Years

Underneath the Earth’s crust, where pressure is immense and energy supply is scarce, life finds ways to flourish in forms that are completely foreign to traditional notions. Microbes embedded in the depths of the rock can hibernate for thousands or even millions of years due to their capability to enter a sort of suspended metabolism, according to a study in Nature Reviews Microbiology.

The survival of these microorganisms depends on drastically lowering their energy requirement and functioning exclusively based on their vital biological processes, in contrast to surface-dwelling creatures that depend on sunlight and quick cycles of nutrients. They are able to harness energy through chemical reactions occurring in rocks, thus surviving in the environment considered lifeless by humans.


Survival is possible through extreme adaptation

These organisms’ capacity to survive long periods of dormancy has been tied to very sophisticated survival mechanisms. In studies reported in Science and the Proceedings of the National Academy of Sciences, certain microbes have been found to mend damaged cells very slowly, enabling them to exist through geologic ages. The rate of metabolism of these organisms is so low that they take years to accomplish actions that might be completed within minutes by other organisms living on the surface. Slow metabolism means that fewer energy sources are needed for survival, thereby increasing the possibility of survival in environments where food is scarce. It is also believed that the microbes are able to resume activities under changed conditions. This ability to alternate between dormancy and activity suggests a unique type of resilience compared to other living things.

The limits of life are are changing

The existence of deep subsurface life has applications not just for our planet but also beyond it. Astrobiological research, which includes publications from the Astrobiology Journal, indicates that deep subsurface life may also exist on planets with extreme environments, like Mars and Europa. Learning more about the way life exists in our planet's deep biosphere helps researchers understand the minimal requirements for life. The study of deep subsurface life changes our concept of habitable zones by making us reconsider what counts as suitable living conditions. It shows us that when something seems inactive, it may actually be the most effective method of survival, which demonstrates that life finds ways to exist well beyond our scope of perception.