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Neuroplasticity enables bio-cultural feedback in Paleolithic stone-tool making - PubMed

  • ️Sun Jan 01 2023

Neuroplasticity enables bio-cultural feedback in Paleolithic stone-tool making

Erin Elisabeth Hecht et al. Sci Rep. 2023.

Abstract

Stone-tool making is an ancient human skill thought to have played a key role in the bio-cultural co-evolutionary feedback that produced modern brains, culture, and cognition. To test the proposed evolutionary mechanisms underpinning this hypothesis we studied stone-tool making skill learning in modern participants and examined interactions between individual neurostructural differences, plastic accommodation, and culturally transmitted behavior. We found that prior experience with other culturally transmitted craft skills increased both initial stone tool-making performance and subsequent neuroplastic training effects in a frontoparietal white matter pathway associated with action control. These effects were mediated by the effect of experience on pre-training variation in a frontotemporal pathway supporting action semantic representation. Our results show that the acquisition of one technical skill can produce structural brain changes conducive to the discovery and acquisition of additional skills, providing empirical evidence for bio-cultural feedback loops long hypothesized to link learning and adaptive change.

© 2023. The Author(s).

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Conflict of interest statement

The authors declare no competing interests.

Figures

Figure 1
Figure 1

Participant artifacts and training. (A) Sample handaxes produced by participants for skill assessments at Scans 1, 2, and 3. (B) A practice session. Photo copyright Gregory Miller (gregorymillerpictures.com). (C) Learning curve in the whole trained group. (D) Learning curve separated by prior gross motor craft experience.

Figure 2
Figure 2

Baseline FA in ventrolateral prefrontal cortex is predictive of pre-training toolmaking performance. (A) Voxels showing a significant positive correlation between FA and toolmaking score at scan 1 are illustrated in orange. In 2D slices, the white matter skeleton is shown in green. (B) Probabilistic tractography from voxels showing a significant positive relationship between baseline FA and pre-training toolmaking scores. This is a composite image representing above-threshold connectivity in at least 67% of the participants. (C) Relationship between FA and toolmaking scores at scan 1 for the voxels indicated in (A). (D) Within these voxels, individuals with > 10 years of gross motor craft experience had significantly higher FA than subjects without this prior experience (t(15) = 2.3684, p = .002). This relationship did not hold for prior experience with fine motor crafts (t(15) = 0.465, p = .649). (E) Individuals with > 10 years of gross motor craft experience also had significantly higher toolmaking scores before training began (t(15) = 2.947; p = .010). Again, this relationship was not significant for fine motor craft experience (t(15) = 0.382; p = .708). (F) A causal mediation analysis showed that the effect of prior gross motor experience on pre-training toolmaking scores occurred almost entirely via the effect of prior experience on baseline FA.

Figure 3
Figure 3

Neuroplastic change in the experimental group as compared to the control group. (A) Voxels illustrated in orange show a significantly more positive slope from scan 1 to scan 3 in the experimental group as compared to the control group in F2x (i.e., the estimated proportion of the diffusion signal that can be accounted for by the second fiber orientation after alignment of diffusion vectors across subjects). In 2D slices, the white matter skeleton is shown in green. (B) Probabilistic tractography from voxels showing neuroplastic change in (A). This is a composite image representing above-threshold connectivity in at least 67% of the participants. (C) Mean F2x value (i.e., the estimated proportion of the diffusion signal that can be accounted for by the second fiber orientation after alignment of diffusion vectors across subjects) at scans 1, 2, and 3 in the control and toolmaking groups. (D) F2x increased more rapidly in toolmaking participants with > 10 years of prior experience in gross motor crafts as compared to toolmaking participants without this prior experience, although no pairwise comparisons reached significance. (E) A similar pattern was visible in participants with > 10 years of prior experience with fine motor crafts.

Figure 4
Figure 4

(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.

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