Evidence for the Existence and Early Origin of Genes Making Possible the Darwinian Evolution of Biogeochemical Homeostasis at a Planetary Scale
Authors: Leggett Mark , Ball David A. 
Published: July 2024

This paper uses empirical evidence to address the subject of when and how the processes for the homeostatic influence of the biota on planetary-scale biogeochemical processes first arose. To set the scene for the study, the paper first proposes three core necessary attributes for Gaia: (1) individual organisms possessing control systems using feedback loops to regulate their external environment (the _environmental regulation_ core attribute); (2) joint action of groups of such organisms leading to the achievement of larger scale environmental regulation (the_ joint action_ core attribute); and (3) such action occurring at a planetary scale. Doolittle (1981) and Dawkins (1982) stated, in essence, that it was impossible for them to imagine any evolutionary way by which Gaia could have arisen. The Doolittle and Dawkins positions were influential and interpreted by some as evidence that Gaia could not exist at all. New evidence against this interpretation is provided in this paper by reference to recent studies providing multiple lines of empirical evidence at planetary scale that Gaia exists. In the present paper these results are put to tests from the epistemic position of scientific realism, the dominant view held by scientists, philosophers, and the educated public about the relationship between scientific evidence and truth. This is the position that empirically successful theories are likely to be at least approximately true. The scientific realism tests applied to the recent studies providing multiple lines of empirical evidence at planetary scale that Gaia exists are empirical success, falsifiability, the no-miracles argument, abduction, and predictive success. This body of results passes the scientific realism tests applied, showing that the statement that Gaia exists is likely to be at least approximately true. If Gaia exists, it had to have evolved somehow. One way is that proposed by Doolittle (2014) and Boyle and Lenton (2022). This is that Gaia could evolve not by genes but by persistence, at clade level. This paper complements that work by seeking to determine whether Gaia could evolve on the precise ground stated by Dawkins and Doolittle in their objections – that is, by standard gene-based Darwinian natural selection. To do this, the paper identifies genes in modern organisms that relate to functionality that is analogous to that of each of two of the core attributes of modern Gaia. A number of these modern genes are also found from phylogenetics to be statistically significantly likely to be present in the Last Universal Common Ancestor or the Last Bacterial Common Ancestor 3.5 to 4 billion years ago. These results provide statistically significant evidence that functionality analogous to core attributes of Gaia was present in LBCA and/or LUCA. In other words, the potentiality for Gaia arose between 3.5 to 4 billion years ago. Doolittle (1981) and Dawkins (1982) as quoted at the outset wrote of the impossibility of imagining any evolutionary way in which Gaia could have arisen. In this paper we provided evidence (i) that Gaia likely exists, and (ii) that clade-based (Doolittle, 2014 and Boyle and Lenton, 2022) and now standard – that is, gene-based – Darwinian natural selection (this paper) provide a range of ways for Gaia to evolve. We submit that this evidence shows that, in contrast to when Doolittle (1981) and Dawkins (1982) wrote, it is now not impossible to imagine evolutionary ways in which Gaia could have arisen.