Autocatalytic cycles are of intense interest to the prebiotic chemistry and biosignature characterization communities. Both of these communities contribute to our search for life in the universe.
Prebiotic Chemistry
When there is at least one autocatalytic relationship between different chemical compounds in a system, it can generate extremely complex, ‘life-like’ patterns. The Belousov-Zhabotinsky (BZ) reaction is the most well known example, in part because the reaction patterns can be see with your eyes without the use of expensive analytical equipment:
One of the major problems in prebiotic chemistry, though, is that there are no clear indications of which autocatalytic relationships in life preceded the others when life emerged. Some argue that metabolism preceded genetics, since it seems to be a physical necessity that free energy be made available and be channelized to make genetic compounds. Others argue that genetics preceded metabolism, since it also seems to be a physical necessity that information about a system be replicated and processed to afford Darwinian evolution. Still others argue that compartmentalization preceded either genetics or metabolism, since it also seems to be a physical necessity to avoid the deleterious effects of diffusion and dilution of all chemical components.
In any case, though, autocatalysis (the ability to sustain and replicate some particular chemical compound or class of compounds) is fundamentally found at the base of each of these arguments.
Biosignature Characterization
Closely related to the points made above regarding how life initially started, there are parallel efforts to characterize the specific indicators of living systems that could be used to assess whether life is present or absent on another planet. These are known as biosignatures: chemical or physical signals that biological systems existed in the past or still exist today. It is important to assess biosignatures because planets that are found outside of our solar system are beyond our ability to visit. We can observe them with telescopes, we might even measure the composition of the gases in their atmospheres or the properties of their oceans by studying the light that bounces off of them, but we will not be able to physically visit these places and directly interact with their surfaces.
As seen in the video above, non-living chemical systems with autocatalytic relationships can generate patterns that look extremely life-like. Autocatalytic chemical systems are therefore capable of making ‘false-positive’ indications of life. It is therefore extremely important to have a complete inventory of likely autocatalytic cycles that can generate complex patterns that might be mistaken for indications of life on distant exoplanets. If astronomers and planetary geologists observe complex patterns or chemical compounds that are far from equilibrium, this inventory can first be checked to see if there are any non-biological ways of generating the same patterns.
Encyclopedia Autocatalytica 