Extended Inheritance

Extended inheritance is the proposal, developed by Eva Jablonka, Marion Lamb, and others, that biological inheritance operates through multiple channels beyond the DNA sequence. The standard model recognizes one channel: genetic inheritance via nucleotide sequences transmitted through germ cells. Extended inheritance adds three further channels: epigenetic inheritance (DNA methylation patterns, histone modifications, and chromatin states that can persist across cell divisions and, in some cases, across generations); behavioral inheritance (learned behaviors transmitted socially, as in song learning in birds or tool use in primates); and symbolic inheritance (culturally transmitted information in humans and, arguably, other species). The claim is not that Lamarckism is correct — environmentally acquired characteristics do not systematically become genetically encoded. The claim is that the informational resources available to evolution are broader than the genome, and that niche construction, cultural transmission, and epigenetic variation create heritable variation that population genetics in its standard form does not model. Whether extended inheritance requires a revision of evolutionary theory or merely an extension of existing tools is an ongoing dispute in the extended evolutionary synthesis debate.