Editing Natural selection (section)

===Origin of life===
{{Main|Abiogenesis}}

How life originated from inorganic matter remains an unresolved problem in biology. One prominent hypothesis is that life first appeared [[RNA world|in the form of short self-replicating RNA]] polymers.<ref>{{cite journal |last1=Eigen |first1=Manfred |author-link1=Manfred Eigen |last2= Gardiner |first2=William |last3=Schuster |author-link3= Peter Schuster |first3=Peter |last4= Winkler-Oswatitsch |first4=Ruthild |display-authors=3 |date= April 1981 |title= The Origin of Genetic Information |journal=[[Scientific American]] |volume= 244 |issue=4 |pages= 88–92, 96, ''et passim'' |doi=10.1038/scientificamerican0481-88|pmid=6164094|bibcode=1981SciAm.244d..88E }}</ref> On this view, life may have come into existence when [[RNA]] chains first experienced the basic conditions, as conceived by Charles Darwin, for natural selection to operate. These conditions are: heritability, [[Genetic variability|variation of type]], and competition for limited resources. The fitness of an early [[RNA world|RNA replicator]] would likely have been a function of adaptive capacities that were intrinsic (i.e., determined by the [[Nucleic acid sequence|nucleotide sequence]]) and the availability of resources.<ref name="Bernstein">{{cite journal |last1=Bernstein |first1=Harris |last2=Byerly |first2=Henry C. |last3=Hopf |first3=Frederick A. |last4=Michod |first4=Richard A. |last5=Vemulapalli |first5=G. Krishna |display-authors=3 |date=June 1983 |title=The Darwinian Dynamic |journal=The Quarterly Review of Biology |volume=58 |number=2 |pages=185–207 |doi=10.1086/413216 |jstor=2828805|s2cid=83956410 }}</ref><ref name="Michod">{{harvnb|Michod|1999}}</ref> The three primary adaptive capacities could logically have been: (1) the capacity to replicate with moderate fidelity (giving rise to both heritability and variation of type), (2) the capacity to avoid decay, and (3) the capacity to acquire and process resources.<ref name="Bernstein" /><ref name="Michod" /> These capacities would have been determined initially by the folded configurations (including those configurations with [[ribozyme]] activity) of the RNA replicators that, in turn, would have been encoded in their individual nucleotide sequences.<ref>{{cite journal |last=Orgel |first=Leslie E. |author-link=Leslie Orgel |year=1987 |title=Evolution of the Genetic Apparatus: A Review |journal=Cold Spring Harbor Symposia on Quantitative Biology |volume=52 |pages=9–16 |doi=10.1101/sqb.1987.052.01.004 |pmid=2456886}}</ref>