I have long had interests in the origin of life and starting in about 2016 decided to get involved. Through some good fortune (and excellent collaborators), this side project has now become my primary research area.
I take the view that life began as autocatalytic ensembles of chemicals that, in the presence of a constant flux of food and energy, could collectively propagate (grow) and evolve adaptively. This model suggests that cells arose late, possibly via selection for dispersal among discontinuous mineral surfaces, and allows that a nucleic acid-based genetic system might also have originated long after adaptive evolution kicked-in. More concretely, this hypothesis implies that we might be able to induce the formation of new life-like chemical ensembles in the laboratory and detect them via their capacity to evolve adaptively. We have begun such experiments in the Wisconsin Institute for Discovery.
The conceptual framework was laid out in a few early publications: One on selection prior to cell formation, one on the late origins of genetic information encoding, one on how these insights can be combined to suggest a fruitful experimental approach, and one on developing a broader theoretical framework for conceptualizing these changes. More recently we have formalized the theory, thanks to the hard work of post-doc Zhen Peng, graduate student (Physics), Praful Gagrani, and several undergraduates, past and present. We have generated two additional theoretical publications, with several in the works. Key insights of this theoretical work are the recognition that chemical reaction networks with multiple autocatalytic cycles are analogous to biological ecosystems, including in having food webs, and can show complex dynamics resembling ecological succession. We have also determined that the supposed distinction between succession and Darwinian evolution is not sharp. This supports the idea that the first evolver was a chemical ecosystem feeding on a flux of food and energy from the environment that underwent adaptive evolution long before acquiring any genetic system. Our modeling is shedding light on how this adaptive evolution works in different spatial setting and also elucidating the steps by which genetic polymers would tend to emerge (in environments conducive to group selection). Work is continuing in collaboration with Eric Smith (Santa Fe Institute, Georgia Tech. and ELSI) and Emily Dolson (Michigan State).
I had the good fortune of leading a large multi-institution NSF/NASA Ideas Lab grant: A Chemical Ecosystem Selection Paradigm for the Origin of Life, or CESPOoL. With this funding, and prior support from an NSF EAGER award, we have developed an experimental methodology call Chemical Ecosystem Selection. This simple method provides a way to detect the spontaneous emergence of ecological or evolutionary dynamics in chemical systems maintained out of equilibrium by a flux of food and energy from the environment.
Origin of life publications
Peng, Z., Linderoth, J., Baum, D. A. (preprint). The hierarchical organization of autocatalytic reaction networks and its relevance to origins of life.
Vincent, L., Colón-Santos, S., Henderson J. Cleaves II, Baum, D. A.*, Maurer, S. E. * [co-corresponding author] 2021. The Prebiotic Kitchen: A Guide to Composing Prebiotic Soup Recipes to Test Origins of Life Hypotheses. Life 11(11): 1221.
Peng, Z., Plum, A., Gagrani, P., and Baum, D. A. 2020. An ecological framework for the analysis of prebiotic chemical reaction networks. J. Theoretical Biology 507:1-15.
Vincent, L., Berg, M., Krismer, M., Saghafi, S., Cosby, J., Sankari, T., Vetsigian, K., Cleaves, H. J. III, and Baum, D. A. 2019. Chemical Ecosystem Selection on Mineral Surfaces Reveals long-term dynamics consistent with the spontaneous emergence of mutual catalysis. Life. 9(4), doi:10.3390/life9040080
Mizuuchi, R., Blokhuis, A., Vincent, L., Nghe, P., Lehman, N., and Baum, D. A. 2019. Mineral surfaces select for longer RNA molecules. Chemical Communications 10.1039/C8CC10319D
Baum, D. A. 2018. The origin and early evolution of life in chemical complexity space. Journal of Theoretical Biology. 456: 295-304.
Baum, D. A. and Lehman, N. 2017. Life’s late digital revolution and why it matters for the study of the origins of life. Life 7(3), 34: doi: 10.3390/life7030034
Baum, D. A. and K. Vetsigian. 2016. An experimental framework for generating evolvable chemical systems in the laboratory. Origins of Life and Evolution of Biospheres, 47:481–497.
Baum, D. A. 2015. Selection and the origin of cells. Bioscience 65: 678-684.