Model may explain origin of life

Posted by Emma Woollacott

It's always been a bit of a mystery as to how life began on a molecular level. Theories tend to involve a network of molecules that have the ability to work together to jumpstart and speed up their own replication.

But it's not easy to imagine just how such a molecular network could have formed spontaneously - from scratch - from the chemical environment of early Earth.

"Some say it's equivalent to a tornado blowing through a junkyard and assembling the random pieces of metal and plastic into a Boeing 747," says Wim Hordijk, a visiting scientist at the National Evolutionary Synthesis Center.

He and colleague Mike Steel of the University of Canterbury in New Zealand have already used a mathematical model of simple chemical reactions to show that such networks might form more easily than many researchers thought. Indeed, biochemists have recently created such networks in the lab.

And, now, they've analyzed the structure of the networks in their mathematical models and found a plausible mechanism by which they could have evolved to produce the building blocks of life we know today, such as cell membranes or nucleic acids.

"It turns out that if you look at the structure of the networks of molecules [in our models], very often they're composed of smaller subsets of molecules with the same self-perpetuating capabilities," says Hordijk.

By combining, splitting, and recombining to form new types of networks from their own sub-units, the models indicate that these subsets of molecules could give rise to increasingly large and complex networks of chemical reactions - and thus, presumably, life.

"These results could have major consequences for how we think life may have originated from pure chemistry," says Hordijk.