Without oxygen, Earth’s early microbes relied on arsenic to sustain life

microbe
Credit: CC0 Public Domain

Much of life on planet Earth today relies on oxygen to exist, but before oxygen was present on our blue planet, lifeforms likely used arsenic instead. These findings are detailed in research published today in Communications Earth and Environment.


A key component of the oxygen cycle is where plants and some types of bacteria essentially take sunlight, water, and CO2, and convert them to carbohydrates and oxygen, which are then cycled and used by other organisms that breathe oxygen. This oxygen serves as a vehicle for electrons, gaining and donating electrons as it powers through the metabolic processes. However, for half of the time life has existed on Earth, there was no oxygen present, and for the first 1.5 billion years, we really don’t how these systems worked, says lead author of the study and UConn Professor of Marine Sciences and Geosciences Pieter

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