Re‐evaluating the correlated evolution of human hands and feet using viability selection modeling
Bibliographic record
Abstract
Abstract Objectives Bipedalism and enhanced manipulative abilities are defining features of the hominin lineage, associated with derived foot and hand skeletal morphology, respectively. These unique morphologies are traditionally thought to have evolved independently, but previous work suggests that some aspects of hand and foot skeletal morphology coevolved, due to strong phenotypic correlations among serially homologous elements. Materials and Methods Here, I further tested this hypothesis using viability selection modeling, which simulates phenotypic evolution based on the likelihood of individual survival, determined using individuals' distance to a predetermined adaptive peak, in this case modern Homo . Using chimpanzees ( Pan ) as a proxy for hominin ancestral hand and foot morphology, I quantified morphological changes in the hand when only homologous foot elements were targets of selection, as well as the reverse scenario in which only hand morphology influences viability. Results Simulation results show that in both scenarios, one autopod evolves as correlated response to selection acting on the other. Importantly, however, simulation outcomes show that the adaptive evolution of the uniquely derived human foot can indirectly produce Homo‐ like manual proportions, but the reverse is not true: adaptive evolution of an African ape‐like hand is not sufficient to produce a Homo‐ like human foot. Discussion These simulations thus lend further empirical support to the hypothesis that human hands and feet coevolved, and indicate that selection acting on the foot may have produced derived hand morphology that facilitated the evolution of enhanced manipulative behaviors.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.002 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.002 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".