Pursueing the logic of life

Ricard Solé, an ICREA group leader at GRIB and external Professor at the Institute of Santa Fe (US), aims to understand what the common laws of organization of both natural and artificial complex systems are. This 45-year-old Catalan scientist received the Premi Ciutat de Barcelona in 2003 for his studies on the complexity of language. Now, his team is part of PACE, an interdisciplinary group of European researchers trying to build a very simple artificial cell that is able to self-replicate and evolve under controlled conditions.


How would you define life?
The consensus is that life is a system far from equilibrium with the capacity of auto replicating and evolving. It needs a compartment that isolates it (the membrane), an information system to adapt to new conditions (for example DNA) and a minimal metabolism. These are the three basic processes, and several studies suggest that life defined as such is the only possible solution to get an auto replicating system.

So if we were to find life in other planets it would have these same characteristics?
We believe so. But at a practical level, it is interesting to create a model that does not evolve, that always does that for which it has been designed. So, we have also created models without information, unable to evolve.

Why creating an artificial protocell?
To begin with, being able to answer the big question that human beings have been wondering for centuries: is it possible to cross the border from inert matter to life? And there are also potential medical and technological applications, such as cells that can capture CO2 or create biofuel, or cells that can substitute liposomes for medical treatments.

It certainly has great potential, but it carries ethical and security implications…
The cells we are trying to create are very simple and totally artificial: none of the three elements they contain exist in the wild. We use artificial genetic material called PNA (peptide DNA), as well as special lipids for the membrane. And the only metabolic reaction they do is not found in nature. It consists in capturing the light and breaking a precursor molecule into two pieces: one will be part of the membrane, and one of the information system. Therefore, these cells could not live outside of a very controlled environment and do not represent any danger. Other groups, however, start with a living organism and eliminate the non-essential elements until they get to the minimal genome. These modified organisms come from living matter and therefore they would have more opportunities to survive in the wild… In any case, in PACE we have annual meetings about ethics to talk about these issues.

How old is this field?
It’s been years that people are working on it, but until recently it was nearly alchemy. In the last 4 years several groups have started working on this seriously. Now the theoretical models are complete and, experimentally, we have managed to combine all possible pairs of the three basic elements. I think the missing step to integrate the whole machinery can be done in 3 or 5 years.