Phylogenetic Evidence for the Early Origin of the Homeostatic Influence of the Biota on Planetary-Scale Geophysical Processes

• Published in: Qeios
• Main Authors: Leggett, Mark, Ball, David A.
• Format: Journal Article
• Language: English
• Published: 01.09.2023
• ISSN: 2632-3834; 2632-3834
• DOI: 10.32388/52ZE92.2

This paper uses empirical evidence to address the subject of when and how Gaia arose. To set the scene for this, the paper first proposes two core necessary attributes for Gaia: each individual having control systems and joint action of groups of such individuals producing results that are more beneficial to the group than would have arisen from the isolated action of each individual. We make the case that the predominantly recognised “planetary” nature of Gaia is a contingent rather than necessary attribute. The paper next identifies representative examples in contemporary organisms of each of the two core attributes of Gaia in operation. For each of these examples, genes making up part of the genetic specification of the example were identified. We then sought these same genes in the earliest examples of life that have been genetically characterised in empirical terms - the Last Universal Common Ancestor (LUCA) and the Last Bacterial Common Ancestor (LBCA). These arose respectively between 4 and 3.5 billion years ago. Examining both the pools of known modern genes and demonstrated LUCA and/or LBCA genes, sufficient relevant modern genes were also found in LBCA and/or LUCA to provide empirical evidence that the core attributes of Gaia were present in LBCA and/or LUCA. Hence, we claim that the first Gaia likewise arose between 3.5 to 4 billion years ago. The paper also provides case studies showing similar results at increasing scales of organismal aggregation over the intervening period to the present.