A Tentative Role for FOXP2 in the Evolution of Dual Processing Modes and Generative Abilities

A Tentative Role for FOXP2 in the Evolution of Dual Processing Modes and Generative Abilities Courtney Chrusch (courtney_chrusch@hotmail.com) and Liane Gabora (liane.gabora@ubc.ca) Department of Psychology, University of British Columbia Arts Building, 333 University Way, Kelowna BC, V1V 1V7, CANADA Abstract It has been suggested that the origins of cognitive modernity in the Middle/Upper Paleolithic following the appearance of anatomically modern humans was due to the onset of dual processing or contextual focus (CF), the ability to shift between different modes of thought: an explicit mode conducive to logical problem solving, and an implicit mode conducive to free-association and breaking out of a rut. Mathematical and computational models of CF supported this hypothesis, showing that CF is conducive to making creative connections by placing concepts in new contexts. This paper proposes that CF was made possible by mutation of the FOXP2 gene in the Paleolithic. FOXP2, once thought to be the “language gene”, turned out not to be uniquely associated with language. In its modern form FOXP2 enabled fine-tuning of the neurological mechanisms underlying the capacity to shift between processing modes by varying the size of the activated region of memory. Keywords: Associative thought; Contextual focus; Creativity; Divergent thought; Dual process; FOXP2; Human evolution; Language evolution; Paleolithic; Neural basis of language Introduction The realization that FOXP2 was not the “language gene” generated much-needed sober discussion about the simplicity of single-gene explanations of complex traits. However, if one finds a relatively simple explanation that is consistent with a wealth of data from multiple disciplines, it is parsimonious to start with that and see if it needs to be modified or elaborated. We suggest that while FOXP2 is not the ‘language gene’ it may have a broad but well-defined impact on cognition. This paper synthesizes genetic, neurological, cognitive, and anthropological research into an integrated account of the cognitive changes underlying behavioral modernity, including language, came about. Specifically, we propose that it enabled the onset of contextual focus—the ability to shift between explicit / analytic and implicit / associative modes of thought—which paved the way for not just language, but a range of cognitive abilities considered by anthropologists to be diagnostic of behavioral modernity. First we place the discussion in its historical context by reviewing both the studies that implicated the FOXP2 gene in the evolutionary origins of language, and the evidence that caused this connection to come into question. Second, we review anthropological and archaeological evidence that the coming into prominence of creative and cognitive abilities (including but not limited to those that involve language) coincides with the evolutionary origins of FOXP2. Third, we review literature on dual processing theories and generative abilities. Finally, we synthesize these literatures in a new explanation of the role of FOXP2 in language specifically and cognitive development more generally. The Search for a Genetic Basis for Language FOXP2 is a transcription gene on chromosome 7 (Reimers- Kipping et al., 2011). It regulates the activity of other genes that play a role in the development and function of the brain (Fisher & Ridley, 2013; Kovas & Plomin, 2006). It is associated with proper functioning of the motor cortex, the striatum, and the cerebellum, which controls fine motor skills (Liegeois, Morgan, Connelly, & Vargha-Khadem, 2011). It was proposed that the FOXP2 gene plays an important role in language acquisition when a mutation in this gene was associated with language impairment in a British Family known as the KE Family (Lai, Fisher, Hurst, Vargha-Khadem, & Monaco, 2001). Approximately half the members of this family, across several generations, exhibited verbal dyspraxia and severe difficulty in controlling the orofacial muscles required for speech articulation (Lalmansingh, Karmakar, Jin, & Nagaich, 2012). The family was diagnosed with Specific Language Impairment: a significant deficit in language development that exists despite adequate educational opportunity and normal nonverbal intelligence (Lai et al., 2001; Morgan, 2013). Those affected by SLI show deficits to the articulation of speech sounds, verbal expression, comprehension of speech, and have trouble controlling the movement and sequencing of orofacial muscles resulting in deficits in fluent speech. Transcript sequencing showed that a mutation of FOXP2 widespread in the KE family results in language deficiencies (Lai et al., 2001). FOXP2 thus became prematurely referred to as the “language gene” (Bickerton, 2007). However, from the start there was question concerning its involvement in language because as a transcription gene it only has an indirect effect on neural structure or behavior (Bickerton, 2007; Reimers-Kipping et al., 2011). Moreover, although FOXP2 is involved in motor control and learning, there ae indications that it has a role in other abilities that do not involve language (Kurt, Fisher, & Ehret, 2012). Indeed, the KE Family demonstrated minor non-verbal disabilities such as lack of cognitive fluidity, and below-average IQ (Lai et al., 2001). It was concluded that the neurological basis of deficits associated with FOXP2 lie in the structural and functional abnormalities of cortico-striatal and cortico- cerebellar circuitries of the brain, which are important for learning, memory, and motor control, not language exclusively.