When pondering the probability of life existing on other planets it’s important to consider extremophiles.
What are Extremophiles?
Good question to be answered. The ‘ophiles’ part can trigger a negative reaction right off the bat, for obvious reasons. But what we’re talking about are living organisms that can exist in the most extreme circumstances imaginable on planet Earth.
It’s counter intuitive to imagine life not only existing, but thriving, inside a roiling hot volcano, in the depths of outer space, or so deep in the ocean where water pressure would crush the life from us almost instantly. It’s a tribute to evolution by natural selection that there are microbial organisms that have managed this feat, and gives us good cause to believe life could evolve on planets previously thought uninhabitable by standards previously understood prior to the discovery and examination of these extremophiles.
Biology is the study of life, and evolution by natural selection the study of the diversification of species. I point out the obvious because there are many people who confuse this field of study with abiogenesis, which is the process by which a living organism arises naturally from non-
Charles Darwin believed that the most probable place for life to have originated was in a warm tidal pool, a place where amino acids could mix with organic chemical compounds in water with access to a heat source. Thermophiles may give us some insight into just how durable life can thrive in temperatures that would cook us alive.
A thermophile is an organism — a type of extremophile — that thrives at relatively high temperatures, between 45 and 122 °C (113 and 252 °F). Many thermophiles are archaea. Thermophilic eubacteria are suggested to have been among the earliest bacteria. [ Wikipedia ]
The adaptability of these organisms comes down to their enzymes that have evolved to operate at high temperatures that would otherwise kill most other forms of bacteria. One possibility to extrapolate from this is that the first living organisms to thrive on Earth were located near vents at the bottom of the sea floor where volcanic activity operates, serving as a natural heat source generated from the core of our planet.
Tardigrades are a type of extremophile that can survive in outer space. In 2007 tardigrades were taken into low Earth orbit and exposed to the vacuum of space for ten days. Upon their return to Earth over 68% of the subjects protected from high-energy UV radiation survived and many of these produced viable embryos. How is this possible?
Desiccation is extreme dryness or extreme drying of the extremophile. This isn’t such a good thing because all living things on earth depend on water but the extremophile anhydrobiosis can do without moisture. Anhydrobiosis goes into a state of suspended animation where there is little transfer of water in the cell and no metabolic activity. The organism therefore looks dead when it has dried up but with the application of moisture it comes back to life. This happens in bacteria, yeast, fungi and in plants and animals where water is sporadic. [ weirdwarp.com ]
Implications for Life on Other Planets
The Goldilocks Zone is a popular phrase to describe the habitable zone a planet can orbit its Star. In the case of our solar system, our planet seems perfectly situated within this habitable zone, where it so not so close to the Sun as to be too hot, and not so far as to be too cold.
Without our ever growing understanding of the conditions in which life can thrive, largely derived from the study of extremophiles, many types of which have gone unexplored in this article, we are able to expand the potential goldilocks zones when searching not only distant planets in far away solar systems throughout the Milky Way Galaxy for signs of life, but on planets and their moons right here in our own humble solar system.
Taking this into consideration along with the fact there are on average about 100 billion stars in a galaxy, and about 100 billion galaxies in our observable Universe, and that life as we know it is comprised almost entirely of the most abundant elements in the Universe, the chances seem quite excellent that there is not only life on other planets, but that our Universe may be absolutely teeming with it.
Check out the video to learn more about tardigrades, because it’s worth it.