New study sheds light on how earliest forms of life evolved on Earth
A new study led by ANU has shed light on how the earliest forms of life evolved on Earth about four billion years ago.
In a major advance on previous work, the study found a compound commonly used in hair bleach, hydrogen peroxide, made the eventual emergence of life possible.
Lead researcher Associate Professor Rowena Ball from ANU said hydrogen peroxide was the vital ingredient in rock pores around underwater heat vents that set in train a sequence of chemical reactions that led to the first forms of life.
"The origin of life is one of the hardest problems in all of science, but it is also one of the most important," said Dr Ball from the Mathematical Sciences Institute and Research School of Chemistry at ANU.
The research team made a model using hydrogen peroxide and porous rock that simulated the dynamic, messy environment that hosted the origin of life.
"Hydrogen peroxide played multiple roles in the emergence of living systems, and this study investigated how it ensured the randomly fluctuating temperatures and pH levels necessary to energise the production of a chemical world that made life on Earth possible," Dr Ball said.
"Our simulations reveal the importance of long rock pores or lengthy, interconnected porous structures in enabling the creation of long, large molecules."
The research advances upon previous studies by modelling the flow of reactive species through porous rock rather than through a single pore.
Dr Ball said the high temperature fluctuations must not rise too high or occur too often.
"The system needs to spend enough time at higher temperatures to carry out essential synthetic reactions, but not so much that the reactants are totally consumed or destroyed. We call this the 'Goldilocks' distribution," she said.
"This effectively gives us the 'fundamental equation of life'. It says that for life to begin and persist, the habitat must exhibit a specific range of temperature fluctuations."
This result provides new and valuable guidelines in the search for extraterrestrial life.
Hydrogen peroxide also promoted the evolution of enzymes called catalases that prevented a second 'origin of life' event.
"The ubiquitous presence of life, and hence catalases, in all habitable environments prevent hydrogen peroxide from accumulating sufficiently anywhere to drive a second origin event," Dr Ball said.
"Evolution can be thought of as burning a succession of small bridges. But the first cellular life destroyed probably one of the most important bridges, the one that spanned the living and non-living molecular worlds.
"Any chance of rebuilding that bridge was permanently rubbed out by the persistence of catalases throughout subsequent evolution."
The study is published in the international journal Royal Society Open Science.
More information: Rowena Ball et al. Toy trains, loaded dice and the origin of life: dimerization on mineral surfaces under periodic drive with Gaussian inputs, Royal Society Open Science (2017). DOI: 10.1098/rsos.170141
Provided by: Australian National University