The surface metabolism theory posits that adaptive evolution initiated when autocatalytic chemical systems became spatially localized on mineral surfaces. We searched for such surface-limited metabolisms (SLiMes) using a chemical ecosystem selection paradigm. This involves creating a prebiotic microcosm containing mineral grains and a “soup,” rich in food and potential sources of chemical energy, and then serially transferring a subset of the grains to a new microcosm containing fresh soup and new grains. This repeated dilution should enrich for chemical systems that can self-propagate more rapidly than the rate of serial dilution, and such enrichment should be detectable based on changes in microcosm chemistry over the course of multiple transfers. We deployed chemical ecosystem selection on several different soups and minerals and identified a combination that appears to be conducive to the enrichment of a SLiMe. In these conditions, chemical changes were observed over the first 12–18 transfers, most notably a loss of both orthophosphate and organics (as detected by optical density) from the solution. This loss from the solution correlated with the appearance of fractal structures on the surface of the grains. The putative SLiMes show clear evidence of self-propagation ability and manifest basic ecological dynamics. Ongoing work is evaluating the systems’ evolutionary capacity.

Active matter sometimes exhibits life-like complex spatiotemporal patterns. Here we report on complex oscillatory behaviors of droplets floating on an aqueous surfactant solution. Even if the droplets consist of only simple chemicals, the behaviors they exhibit are unexpectedly complicated. They are likely induced by the interaction among droplets, which is mediated through the surface tension field as well as Marangoni flow field created by the droplets themselves.

Synthetic biology lies on the interface between natural and artificial life. It consists of the assembly of natural biological components into artificially configured biological systems. A main focus of synthetic biology has been the engineering of new gene circuits that can produce artificial cellular functions. I propose to scale up this approach to include, beyond single cells and gene circuits, also entire multi-cellular organisms and the brain circuits that regulate their behavior. Such synthetic biology in the brain will offer new ways for understanding how brain connectivity relates to brain function, and could ultimately lead to futuristic technologies such as neuronally-programmed organic robots or biologically-based brain repair. As a first step towards this ambitious goal I have developed a technique for genetically inserting new synaptic connections into the nervous system of the nematode worm C. elegans , enabling the manipulation of information flow in the nervous system and the reprogramming of whole animal behavior in this organism. This approach may be expanded and adapted to other genetic models, and opens the way to possible new forms of artificial life. Such technology, if practiced responsibly, could offer considerable benefits to science, industry and medicine.

One of the salient features of living systems is presence of autocatalytic chemical reaction networks. Here we present a stochastic model of an inorganic autocatalyst, which is derived directly from empirical results. Using the model, we can explore the emergence of autocatalysis and its consequences on the larger, hierarchical, chemical network. This model provides a useful tool to study the emergence and organization of autocatalytic chemical networks and the effect autocatalysis has on the global system dynamics.

Liquid droplets possess some life-like behaviors and have been the subject of artificial life studies. Life-like behaviors such as fission, fusion and movement can be artificially recreated exploiting highly simplified chemical systems. Recently we showed that droplet-based chemotactic systems can be interfaced with biological systems (1). We developed a chemotactic droplet able to move light cargos such as hydrogel alginate capsules embedded with living cells as a transporter. We transported efficiently and in a sterile way a few types of bacteria and yeast, and we are now modifying our protocols to transport efficiently human cell lines. We recently discovered that some eukaryotic cell lines release surfactants when placed in our artificial transport system, thereby reinforcing the interface between the artificial and living systems. This is an example of not only how the interface between artificial life and biological life could be designed but how the one system can augment the other. In this case the living system produces the surfactants that the droplet needs for cargo transport and the artificial system provides the transport for the otherwise sessile mammalian cells.