How are there microorganisms on every surface imaginable on Earth? How did they get there in the first place?
In: Biology
Microbes are subject to, theoretically, the same evolutionary pressures that bigger animals are, so after generations of a microbe being exposed to a specific selection pressure (say, high heat) they will start to develop adaptations which enable them to survive via random mutation, and the ones which are unspecialized die off. That community will usually become better and better at surviving a given environment over time due to natural selection. A plethora of hyperspecialized microorganisms exist in a wide variety of environments, from undersea hydrothermal vents to sub-zero ocean water to acid mine drainage. Then there are microbes which exist only within our gut, only on our skin, etc. Basically, they exist in a wide variety of places because they are evolutionarily specialized to do so.
How they got there is a different question. A lot of scientists suggest that life first evolved near hydrothermal vents at the sea floor due to suitable chemical and thermal dynamics. (constant infux of thermal energy allowed for ‘chemical life’ to develop maybe in the form of complex enzymes which managed to begin replicating themselves, then biological life was a short jump from that when RNA got involved. Then DNA evolved.) Other people suggest maybe microbial life came here from outer space, maybe when a meteor with water on it crashed.
It’s been a while since my environmental microbiology class so je m’excuse if there are any errors, please correct me.
Attempted 5-year-old explanation:
Microbes evolve different body parts to help them survive in crazy environments, like places where it is very hot or where it is very cold or even in acid. Some people think that the first microbes were born at the bottom of the sea where there is very hot water being pumped from inside the earth. That hot water gave energy so that different chemicals could play with each other and turn into different things until it started turning into something ALMOST that was alive. Then that almost-alive thing developed into something that was the first microbe, which split to make other microbes until there was a lot of them.
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