Emergence of proto-organisms from bistable stochastic differentiation and adhesion

TL;DR

This study demonstrates that populations of cells with stochastic differentiation and differential adhesion can spontaneously form complex multicellular structures resembling proto-organisms in nutrient-limited environments.

Contribution

It introduces a model showing how simple cellular behaviors can lead to complex multicellular organization before genetic control evolved.

Findings

Complex multicellular patterns emerge under nutrient limitation.

Proto-organisms with internal structure can develop from simple cell populations.

The morphospace of possible structures is highly diverse.

Abstract

The rise of multicellularity in the early evolution of life represents a major challenge for evolutionary biology. Guidance for finding answers has emerged from disparate fields, from phylogenetics to modelling and synthetic biology, but little is known about the potential origins of multicellular aggregates before genetic programs took full control of developmental processes. Such aggregates should involve spatial organisation of differentiated cells and the modification of flows and concentrations of metabolites within well defined boundaries. Here we show that, in an environment where limited nutrients and toxic metabolites are introduced, a population of cells capable of stochastic differentiation and differential adhesion can develop into multicellular aggregates with a complex internal structure. The morphospace of possible patterns is shown to be very rich, including proto-organisms that display a high degree of organisational complexity, far beyond simple heterogeneous populations of cells. Our findings reveal that there is a potentially enormous richness of organismal complexity between simple mixed cooperators and embodied living organisms.