Polyelectrolyte theory of the gene

The polyelectrolyte theory of the gene proposes that for a linear genetic biopolymer dissolved in water, such as DNA, to undergo Darwinian evolution anywhere in the universe, it must be a polyelectrolyte, a polymer containing repeating ionic charges. These charges maintain the uniform physical properties needed for Darwinian evolution, regardless of the information encoded in the genetic biopolymer. DNA is such a molecule. Regardless of its nucleic acid sequence, the negative charges on its backbone dominate the physical interactions of the molecule to such a degree that it maintains uniform physical properties such as its aqueous solubility and double-helix structure.

The polyelectrolyte theory of the gene was proposed by Steven A. Benner and Daniel Hutter in 2002 and has largely remained a theoretical framework astrobiologists have used to think about how life may be detected beyond Earth. This idea was later linked by Benner to Erwin Schrödinger's view of the gene as an "aperiodic crystal" to make a robust, universally generalized concept of a genetic biopolymer—a biopolymer acting as a unit of inheritance in Darwinian evolution.

Benner and others who built on his work have proposed methods for how to concentrate and identify genetic biopolymers on other planets and moons within the solar system using electrophoresis, which uses an electric field to concentrate charged compounds.

Although few have tested the polyelectrolyte theory of the gene, in 2019, lab experiments challenged the universality of this idea. This work was able to create non-electrolyte polymers capable of limited Darwinian evolution, but only up to a length of 72 nucleotides.