Assembly Theory and the Complexity of Life

Future Humans Fellows Lee Cronin and Sara Walker proposed that Assembly Theory, by uniting fundamental elements of physics and biology, can explain how objects come into existence in the universe—including those we call alive and even intelligent.

Associate Director of Future Humans, Claire Isabel Webb, interviewed Cronin and Walker on their path-breaking work. Assembly Theory, because it traces the emergence of life through its material history in deep, planetary time, is poised to unlock our own primordial beginnings.

In a paper published in the journal Nature, Cronin and Walker, along with their co-authors, argue that any object we can observe embeds its own history, and that life is a result of sufficiently complex interactions over time. Assembly Theory, then, does not define life by the usual measures, say, an organism’s ability to metabolize energy or respond to its environment. Rather, the theory proposes that the existence of objects we observe and interact with—from a peptide to a shark’s tooth to the entire planetary whole—can be explained by their formation histories. How some objects have assembled, through billions of years of selection and evolution, are complex enough to be considered alive—and even human.