We are driven to find chemical clues that can give us insight into how life began on our planet. Since biology is nothing more than chemistry and physics, it should not be surprising to think that the building blocks of life must have been produced through natural physical-chemical processes. In fact, analyses of carbonaceous meteorites that fall to Earth show the presence of the molecules of life, such as nucleobases and amino acids. If such molecules can be found in sterile meteorites, it seems logical to expect that the same molecules were on our planet before life emerged. But how can we ever know what molecules were there billions of years ago? In the absence of a historical record, we may never know the answers to such questions, but armed with the scientific method, there is much we can learn by experimenting and building in the laboratory.
We do not focus on how the building blocks were synthesized but on how the building blocks, once formed, could have assembled into life-like chemical systems. One way we do that is by exploring the complexes formed between iron ions and short, prebiotically plausible peptides. Iron is one of the most abundant metals on the Earth and in our bodies. For example, we observed that UV light from a laboratory model of the early sun was capable of facilitating the formation of all the major types of iron-sulfur clusters found in biology (Fig. 1). Such clusters are routinely exploited by biology to mediate metabolism, and we found that they form spontaneously from few ingredients in the presence of sunlight.
We are also fascinated by the properties of prebiotically plausible single-chain lipids. Such lipids spontaneously form cell-sized compartments. In other words, before there was life, the compartments that house life were likely already present on our planet. We investigate these lipid systems to understand which compositions would have been robust enough to survive the conditions of the early Earth (Fig. 2) and were additionally capable of supporting cell-like activity, including growth, division, and a type of protometabolism.