Scientists have a new explanation for how life could have evolved on earth

Vladi333/Shutterstock

Evolution is full of chicken-and-egg scenarios, but one of the trickiest to solve is whether life existed before there was nucleic acid.

Researchers have now provided evidence of primitive biochemistry occurring without phosphate – an essential component of the nucleic acid building blocks of our genetic chemistry – adding fuel to the argument that before there was life, there was metabolism.

Scientists from MIT and Boston University have identified a number of alternative metabolic pathways that have no need of phosphate – and the findings could fill a gap in our understanding of how complex organic chemistry evolved into life on Earth.

Life as we define it today is largely based on imperfectly replicating chemistry – something that requires both a template that can be copied and the means to capture enough energy to physically rearrange simple carbon-based chemicals into more complex forms.

The question is which came first: a chemical code that could evolve in complexity, or complex pathways that could use energy to turn simple chemicals into complex organic compounds.

In the so-called RNA-world hypothesis, strings of free-floating ribonucleic acid (RNA) facilitated processes we might describe as precursors to life, with the polymer taking on the roles of both an early kind of information template and chemical machinery.

One problem with this concept is that RNA can't do its thing without an energy source, which would require a sequence of chemical reactions we could think of as an early form of metabolismo.

This research was published in Cell