Volume 7 Issue 4
Looking for the Last Universal Common Ancestor (LUCA)
Minna Koskela and Arto Annila
1Department of Biosciences, Viikinkaari 1, FI-00014 University of Helsinki, Finland
2Institute of Biotechnology, Viikinkaari 1, FI-00014 University of Helsinki, Finland
3Department of Physics, Gustaf Hällströmin katu 2, FI-00014 University of Helsinki, Finland
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Abstract
Genomic sequences across diverse species seem to align towards a common ancestry, eventually implying that eons ago some universal antecedent organism would have lived on the face of Earth. However, when evolution is understood not only as a biological process but as a general thermodynamic process, it becomes apparent that the quest for the last universal common ancestor is unattainable. Ambiguities in alignments are unavoidable because the driving forces and paths of evolution cannot be separated from each other. Thus tracking down life’s origin is by its nature a non-computable task. The thermodynamic tenet clarifies that evolution is a path-dependent process of least-time consumption of free energy. The natural process is without a demarcation line between animate and inanimate.
Keywords:evolution; geodesic; intractability; sequence alignment; the principle of least action; universal ancestor