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Adaptability is a distinguishing feature of the human species: We thrive as hunter-gatherers, farmers, and urbanites. What properties of our brains make us highly adaptable? Here we review neuroscience studies of sensory loss, language acquisition, and cultural skills (reading, mathematics, programming). The evidence supports a flexible specialization account. On the one hand, adaptation is enabled by evolutionarily prepared flexible learning systems, both domain-specific social learning systems (e.g., language) and domain-general systems (frontoparietal reasoning). On the other hand, the functional flexibility of our neural wetware enables us to acquire cognitive capacities not selected for by evolution. Heightened plasticity during a protracted period of development enhances cognitive flexibility. Early in life, local cortical circuits are capable of acquiring a wide range of cognitive capacities. Exuberant cross-network connectivity makes it possible to combine old neural parts in new ways, enabling cognitive flexibility such as language acquisition across modalities (spoken, signed, braille) and cultural skills (math, programming). Together, these features of the human brain make it uniquely adaptable.
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Plasticity, innateness, and the path to language in the primate brain: Comparing macaque, chimpanzee and human circuitry for visuomotor integration
Many researchers consider language to be definitionally unique to humans. However, increasing evidence suggests that language emerged via a series of adaptations to neural systems supporting earlier capacities for visuomotor integration and manual action. This paper reviews comparative neuroscience evidence for the evolutionary progression of these adaptations. An outstanding question is how to mechanistically explain the emergence of new capacities from pre-existing circuitry. One possibility is that human brains may have undergone selection for greater plasticity, reducing the extent to which brain organization is hard-wired and increasing the extent to which it is shaped by socially transmitted, learned behaviors. Mutations that made these new abilities easier or faster to learn would have undergone positive selection, and over time, the neural changes once associated with individual neural plasticity would tend to become heritable, innate, and fixed. Clearly, though, language is not entirely “innate;” it does not emerge without the requisite environmental input and experience. Thus, a mechanistic explanation for the evolution of language must address the inherent trade-off between the evolutionary pressure for underlying neural systems to be flexible and sensitive to environmental input vs. the tendency over time for continually adaptive behaviors to become reliably expressed in an early-emerging, canalized, less flexible manner.
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- Award ID(s):
- 1941626
- PAR ID:
- 10109985
- Date Published:
- Journal Name:
- Interaction Studies
- Volume:
- 19
- Issue:
- 1-2
- ISSN:
- 1572-0373
- Page Range / eLocation ID:
- 54 to 69
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Gene expression can be highly plastic in response to environmental variation. However, we know little about how expression plasticity is shaped by natural selection and evolves in wild and domesticated species. We used genotypic selection analysis to characterize selection on drought-induced plasticity of over 7,500 leaf transcripts of 118 rice accessions (genotypes) from different environmental conditions grown in a field experiment. Gene expression plasticity was neutral for most gradually plastic transcripts, but transcripts with discrete patterns of expression showed stronger selection on expression plasticity. Whether plasticity was adaptive and co-gradient or maladaptive and counter-gradient varied among varietal groups. No transcripts that experienced selection for plasticity across environments showed selection against plasticity within environments, indicating a lack of evidence for costs of adaptive plasticity that may constrain its evolution. Selection on expression plasticity was influenced by degree of plasticity, transcript length and gene body methylation. We observed positive selection on plasticity of co-expression modules containing transcripts involved in photosynthesis, translation and responsiveness to abiotic stress. Taken together, these results indicate that patterns of selection on expression plasticity were context-dependent and likely associated with environmental conditions of varietal groups, but that the evolution of adaptive plasticity would likely not be constrained by opposing patterns of selection on plasticity within compared to across environments. These results offer a genome-wide view of patterns of selection and ecological constraints on gene expression plasticity and provide insights into the interplay between plastic and evolutionary responses to drought at the molecular level.more » « less
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1075/is.17039.hec
