"In principle, there's now nothing to stop intelligent moral agents "fixing" the [conditionally-activated level of] subjective physical distress undergone by members of entire free-living species by choosing and propagating benign alleles of SCN9A or its homologs via gene drives, i.e. engineering via CRISPR-mediated gene-editing not a currently utopian "no pain" biosphere ... but a “low pain” biosphere."