In my recent blog posting entitled “What Is the Most Intriguing Scientific Question?” I described the interesting fact that about half of the people (in that rather random poll) ranked the emergence of life, or life’s abundance in the universe, as their top question. Indeed, I am convinced that the process through which inanimate molecules transform into living organisms—literally the transition from chemistry to biology—intrigues us all. One of the ways in which biologists are attempting to decipher this mystery is through endeavors aimed at creating synthetic life. Geneticist and Nobel Laureate, Jack Szostak (Figure 1) is one of the leaders in this fascinating field, so I decided to ask him for a brief update on where things are standing. I started with the million-dollar question:
Livio: I know that it is difficult to make predictions, especially about the future… but how long do you think it will take for you to create synthetic life?
Szostak did not hesitate one bit.
Szostak: I feel like we are getting closer, perhaps five years, maybe less if everything goes well. Of course, there could be problems we have not anticipated, which could take more time to solve.
Wow! I thought to myself. This is truly exciting. So I felt that I could press on.
Livio: What is currently the main obstacle?
Szostak: The main obstacle is finding a pathway for the replication of RNA (or some other genetic polymer) that works independently of modern protein enzymes. We are primarily working on a simple chemical path for RNA replication, but we are also pursuing ribozyme-catalyzed RNA replication. Several parts of this problem, which seemed like huge barriers just a few years ago, have turned out to either not be problems at all, or to have fairly simple solutions. If we can solve the remaining problems, we should be able to observe the replication of short RNAs inside membrane vesicles, which also replicate. This would look like a very simple cell that could grow and divide, and most importantly, would have the potential to evolve into more complex structures, which is what we really want to see.
This really made sense. Today’s RNA utilizes complex protein enzymes for replication, but the production of those kinds of modern proteins requires the information-rich nuclei acids, creating a classical chicken-and-egg problem for the early life. A simple, purely chemical path for RNA replication would solve this problem. Basically, Szostak’s group is “fabricating” simple sequences that can all replicate themselves—things that can grow, divide, and exhibit Darwinian evolution. Szostak and his colleagues had realized early on that a primitive cell has to have two parts. First it needs a membrane, something that would separate it from its environment and identify it as a cell. Second, it needs the genetic material for replication, useful functions, and inheritance. They have essentially solved the first part and they are working on the second.
I was, of course, also interested in the astrobiological angle, so my last question was predictable.
Livio: If through astronomy or space exploration we find extraterrestrial life, how important would that be, from the purely scientific perspective of origin-of-life studies?
Szostak replied immediately.
Szostak: It would be extremely important. At the moment, with only one example of life emerging from chemistry, we have no idea whether the process is easy (and common), or very difficult (and hence rare). A second independent example would say right away that the emergence of life cannot be that difficult. That would inspire our lab studies with greater confidence; and conversely, if we are able to show a simple pathway from chemistry to life in the lab, that should inspire greater confidence in the search for life on other planets.
I couldn’t agree more! In a future blog posting I will describe the current paths that astronomers are taking to discover extraterrestrial life.