Neuroplasticity enables bio‑cultural feedback

The scientific reports article “Neuroplasticity enables bio‑cultural feedback in Paleolithic stone‑tool making” elaborates on the idea described in articles like

  1. Experimental evidence for the co-evolution of hominin tool-making teaching and language
    Hominin reliance on Oldowan stone tools—which appear from 2.5 mya and are believed to have been socially transmitted—has been hypothesized to have led to the evolution of teaching and language. An experiment investigating the efficacy of transmission of Oldowan tool-making skills along chains of adult human participants using five different transmission mechanisms shows across six measures: transmission improves with teaching, and particularly with language, but not with imitation or emulation.
    Our results support the hypothesis that hominin reliance on stone tool-making generated selection for teaching and language, and imply that
    (i) low-fidelity social transmission, such as imitation/emulation, may have contributed to the ~700,000 year stasis of the Oldowan technocomplex, and
    (ii) teaching or proto-language may have been pre-requisites for the appearance of Acheulean technology. This supports a gradual evolution of language, with simple symbolic communication preceding behavioural modernity by hundreds of thousands of years.
  2. “The extended evolutionary synthesis: its structure, assumptions and predictions” ( Kevin N. Laland
    The conceptual framework of evolutionary biology emerged with the Modern Synthesis in the early twentieth century and has since expanded into a highly successful research program to explore the processes of diversification and adaptation.
    Nonetheless, the ability of that framework satisfactorily to accommodate the rapid advances in developmental biology, genomics and ecology has been questioned. Some of these arguments, focusing on literatures (evo-devo, developmental plasticity, inclusive inheritance and niche construction) whose implications for evolution can be interpreted in two ways—one that preserves the internal structure of contemporary evolutionary theory and one that points towards an alternative conceptual framework. The latter, which we label the ‘extended evolutionary synthesis’ (EES), retains the fundaments of evolutionary theory, but differs in its emphasis on the role of constructive processes in development and evolution, and reciprocal portrayals of causation. In the EES, developmental processes, operating through developmental bias, inclusive inheritance and niche construction, share responsibility for the direction and rate of evolution, the origin of character variation and organism–environment complementarity. We spell out the structure, core assumptions and novel predictions of the EES, and show how it can be deployed to stimulate and advance research in those fields that study or use evolutionary biology.
  3. Coevolution of cultural intelligence, extended life history, sociality, and brain size in primates” (Sally E. Street, Ana F. Navarrete, Simon M. Reader, and Kevin N. Laland)
    Explanations for primate brain expansion and the evolution of human cognition and culture remain contentious despite extensive research. While multiple comparative analyses have investigated variation in brain size across primate species, very few have addressed why primates vary in how much they use social learning.
    The enhanced reliance on socially transmitted behavior observed in some primates has coevolved with enlarged brains, complex sociality, and extended lifespans. Across primate species, a measure of social learning proclivity increases with absolute and relative brain volume, longevity (specifically reproductive lifespan), and social group size, correcting for research effort. Also confirmed is the relationships of absolute and relative brain volume with longevity (both juvenile period and reproductive lifespan) and social group size, although longevity is generally the stronger predictor.
    Relationships between social learning, brain volume, and longevity remain when controlling for maternal investment and are therefore not simply explained as a by-product of the generally slower life history expected for larger brained species. Suggested is that both brain expansion and high reliance on culturally transmitted behavior coevolved with sociality and extended lifespan in primates.
    This coevolution is consistent with the hypothesis that the evolution of large brains, sociality, and long lifespans has promoted reliance on culture, with reliance on culture in turn driving further increases in brain volume, cognitive abilities, and lifespans in some primate lineages.
(a) A diagram of the stone knapping process. The hammerstone strikes the core with the goal of producing a flake. The platform edge and angle are important to the success of knapping. (bf) The five learning conditions.
(g) The structure of the experiment. For each condition, six chains were carried out (four short and two long); one of two trained experimenters started each chain (equally within each condition).
From: Experimental evidence for the co-evolution of hominin tool-making teaching and language

Contrasting views of development.
(a) Programed development. Traditionally, development has been conceptualized as programed, unfolding according to rules and instructions specified within the genome. DNA is ascribed a special causal significance, and all other parts of the developing organism serve as ‘substrate’, or ‘interpretative machinery’ for the expression of genetic information. Evolutionarily relevant phenotypic novelty results solely from genetic mutations, which alter components of the genetic program. Under this perspective, organisms are built from the genome outwards and upwards, with each generation receiving the instruction on how to build a phenotype through the transmission of DNA.
(b) Constructive development. By contrast, in the EES, genes and genomes represent one of many resources that contribute to the developing phenotype. Causation flows both upwards from lower levels of biological organization, such as DNA, and from higher levels downwards, such as through tissue- and environment-specific gene regulation. Exploratory and selective processes are important sources of novel and evolutionarily significant phenotypic variation. Rather than containing a ‘program’, the genome represents a component of the developmental system, shaped by evolution to sense and respond to relevant signals and to provide materials upon which cells can draw.
From The extended evolutionary synthesis: its structure, assumptions and predictions
The structure of the EES.
The EES includes as evolutionary causes processes that generate novel variants, bias selection, modify the frequency of heritable variation (including, but not restricted to, genes) and contribute to inheritance. A variety of developmental processes (e.g. epigenetic effects, regulation of gene expression, construction of internal and external developmental environments) contribute to the origin of novel phenotypic variation, which may be viable and adaptive (i.e. ‘facilitated variation’). In addition to accepted evolutionary processes that directly change gene frequencies, the EES recognizes processes that bias the outcome of natural selection, specifically developmental bias and niche construction. All processes that generate phenotypic variation, including developmental plasticity and some forms of inclusive inheritance, are potential sources of bias. A broadened conception of inheritance encompasses genetic, epigenetic and ecological (including cultural) inheritance. Arrows represent causal influences. Processes shown in red are those emphasized by the EES, but not a more traditional perspective. 
Mutation pressure refers to the population-level consequences of repeated mutation, here depicted as dashed because mutation is also represented in ‘processes that generate novel variation’. 
In the EES, this category of processes will often need to be broadened to encompass processes that modify the frequencies of other heritable resources.  §Developmental bias and niche construction can also affect other evolutionary processes, such as mutation, drift and gene flow.
From The extended evolutionary synthesis: its structure, assumptions and predictions

The comparative neuroscience and neuroarchaeological evidence indicate that functional systems supporting stone tool making have undergone substantial change over human evolution, and that these changes may be relevant to a much wider range of distinctively human capacities, from social cognition to language. Specific evolutionary mechanisms underlying this pattern could include natural selection on genetic variation in technological aptitude as well as more extended interactions between plasticity, development, and non-genetic inheritance that are increasingly recognized in human evolution.

The neural traits underlying individual variation in stone- tool making aptitude, and neuroplasticity during stone-tool making skill acquisition are both crucial to understanding the evolution of toolmaking abilities because inter-individual variation is the foundation on which natural selection acts, and intra-individual variation (i.e., acquired plasticity) is theorized to facilitate adaptive change.

If individuals’ efficacy or efficiency at learning new skills is influenced by the prior skills they have learned, and this effect is mediated by plastic neuroanatomical accommodation, this creates a situation in which plasticity-led neural adaptations for one behavior could be readily co-opted (“exapted”) to facilitate the discovery and social transmission of additional, related skills.
Such a dynamic would provide one specific mechanism for the autocatalytic feedback between brain and cultural evolution suggested by formal models and phylogenetic comparative analyses. In other words, at times and places where more and more object-manipulatory, tool use, and tool making skills were socially learned and culturally transmitted within and between groups, the addition of further learned skills may have become easier and easier. 

it suggests that “skill begets skill”, i.e., that acquisition of one technical skill should facilitate acquisition of other skills.

Second language learning facilitates third language learning, and there is also evidence of skill transfer between music and speech, and even between simple tool use and language.
Suggest is that a similar process of facilitation could apply to technical skills, specifically including tool making abilities pivotal to the evolution of our species. If true, this idea could represent a behaviorally driven, feed-forward neuroanatomical mechanism contributing to increases in culturally transmitted technological skills and brain size over time.

(A) Summary diagram of the results of this study.
(B) Schematic of hypothetical bio-cultural feedback loop by which “skill begets skill” – acquisition of new technological skills exerts plastic effects on brain anatomy, which enhance technological learning abilities, thereby facilitating further cultural evolution of those skills and promoting further skill learning.
From: Neuroplasticity enables bio-cultural feedback in Paleolithic stone-tool making

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