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Towards Universal Biology: Constraints From Early and Continuing Evolutionary Dynamics of Life on Earth

“How does life begin and evolve?” This simple question, a fundamental topic within astrobiology, remains still today an enigma. The University of Illinois team is exploring how molecules come to life by investigating fundamental principles of biology from a multidisciplinary perspective – encompassing microbiology, geobiology, computational chemistry, genomics and even physics.

It is now known that life descended from a common ancestor billions of years ago. The University of Illinois team attempts to see even further back in time, uncovering features of the first billion years of life that have until now been inaccessible to us. This can be accomplished by analyzing the behavior of judiciously chosen modern microbial systems and communities; by using detailed analyses of fully-sequenced genomes to explore for the first time cellular processes of the Archaea; and by focusing on specific organisms whose lifestyle and characteristics are exemplars for key evolutionary transitions. These experimental projects will be combined with theoretical work that extends the scope of evolutionary theory — currently very focused on genes — to a period in time when genes as we know them had yet to emerge. The goal of this team is to understand the major evolutionary transitions that occur in living matter, constrain the diversity of life, and govern the way in which energy and information are utilized by life.

A series of four innovative and extremely cross-disciplinary research themes have been established by this team that define their research program, all of which map directly into the goals and objectives of the NASA Astrobiology Roadmap. These Themes are:

1. Develop a mathematical understanding of the general physical principles underlying the emergence of life and the open-ended growth of complexity. Life in this context means evolvable systems that spontaneously create ever-increasing levels of hierarchical organization with multiple levels of feedback. This team seeks to understand whether the phenomenon of life is a generic one, inexorably the outcome of the laws of physics, and what governs its complexity and diversity.
2. Constrain the nature of life before the Last Universal Common Ancestor (LUCA). The term “Last Universal Common Ancestor” implies that there were earlier organisms and modern life by chance descended from one of them. However, prior work by this team suggests that on generic and universal grounds, the modern era of vertical descent was preceded by a communal state for which there was no notion of “tree of life”. They now wish to explore the properties of this state — the progenote — using detailed and sophisticated analyses of core translational machinery, building in some sense the genomic analogue of the Hubble telescope to see further back in time than has been possible by simple comparative genomics.
3. Explore how life made the transition from a communal progenote state to the present era of vertically-dominated evolution. To do this, this team is initiating an unprecedentedly detailed study of the Archaeal domain and its transition to the Eukaryote lineage. The significance of this research is that an understanding will be obtained of why there are only three Domains of life, and not many more. The team expects that their conclusions will be of general applicability to all life that balances the requirements of energy utilization, information processing, replication and evolvability.
4. Determine what factors govern the rate of evolution, and how organisms interact with their environment. How do cells observe their environment and regulate their response to stress? How do cells regulate their ability to evolve? The University of Illinois team will answer these questions through detailed experimentation with microbial systems.