Dual Inheritance Theory - Criticisms

Criticisms

A number of criticisms of DIT have been put forward. From some points of view, use of the term ‘dual inheritance’ to refer to both what is transmitted genetically and what is transmitted culturally is technically misleading. Many opponents cite horizontal transmission of ideas to be so "different" from the typical vertical transmission (reproduction) in genetic evolution that it is not evolution. However, 1)even genetic evolution uses non-vertical transmission through the environmental alteration of the genome during life by acquired circumstance: epigenetics, and 2) genetic evolution is also affected by direct horizontal transmission between separate species of plants and strains of bacteria: horizontal gene transfer. Other critics argue that there can be no "dual" inheritance without cultural inheritance being "sequestered" by the biotic genome. Evidence for this process is scarce and controversial. Why this is a demand of critics, however, can be considered unclear as it refutes none of the central claims laid down by proponents of DIT.

More serious criticisms of DIT arise from the choice of Darwinian selection as an explanatory framework for culture. Some argue, cultural evolution does not possess the algorithmic structure of a process that can be modeled in a Darwinian framework as characterized by John von Neumann and used by John Holland to design the genetic algorithm. Forcing culture into a Darwinian framework gives a distorted picture of the process for several reasons. First, some argue Darwinian selection only works as an explanatory framework when variation is randomly generated. To the extent that transmission biases are operative in culture, they mitigate the effect of Darwinian change, i.e. change in the distribution of variants over generations of exposure to selective pressures. Second, since acquired change can accumulate orders of magnitude faster than inherited change, if it is not getting regularly discarded each generation, it quickly overwhelms the population-level mechanism of change identified by Darwin; it ‘swamps the phylogenetic signal’. However, DIT proponents might reply that, 1) biotic evolution does not function only on randomly generated phenotypes either, since the phenotypes present in a population are the combined result of random and selective effects during the last generation; and 2)that transmission bias would quite often also reinforce "Darwinian change" since it is widely evidenced that Culture has adaptive value in increasing human fitness.

Another discord in opinion stems from DIT opponents' assertion that there exists some "creative force" that is applied to each idea as it is received and before it is passed on, and that this agency is so powerful that it can be stronger than the selective system of other individuals assessing what to teach and whether your idea has merit. But if this criticism was valid then it would be comparatively much easier to argue an unpopular or incorrect concepts than it actually is. In addition, nothing about DIT runs counter to the idea that an internally selective process (some would call creativity) also determines the fitness of ideas received and sent. In fact this decision making is a large part of the territory embraced by DIT proponents but is poorly understood due to limitations in neurobiology (for more information see Neural Darwinism).

Related criticisms of the effort to frame culture in Darwinian terms have been leveled by Richard Lewontin, Niles Eldredge, and Stuart Kauffman.