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REVIEW 2 major objections 1 minor 35 references

External Entropy Production and Human Evolution toward Multi-body Life

T0 review · 2 major / 1 minor · reviewed 2026-06-26 · grok-4.3

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Pith's one-line read Human evolution added external entropy production through cooperating groups controlling fire, creating multi-body life.

desk verdict The paper's claim about external entropy production in human evolution depends on an untested link between brain size growth and awareness for fire control. read the letter →

arxiv 2606.19066 v1 pith:KYAKAG5J submitted 2026-06-17 physics.bio-ph nlin.AOphysics.soc-ph

Yasuji Sawada , Kenji Toma This is my paper · ORCID
classification physics.bio-phnlin.AOphysics.soc-ph
keywords externalentropyproductionhumanevolutionmulti-bodylifebrainsizecooperationfirecontrolthermodynamicsof
verification ladder T0 review T1 audit T2 compute T3 formal

The pith

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The reading

The paper proposes that late-stage human evolution introduced external entropy production outside the body, in addition to internal entropy production within multi-cellular life. This external production is driven by tool use and fire control, which required increased cooperation and awareness linked to rapid brain size growth around 2.5 million years ago. Coupled equations model the growth of brain size and group size, estimating that external entropy production per human increases over about 20 million years from a critical time. This results in the coexistence of traditional internal entropy production and new external entropy production in multi-body life. The authors discuss resulting psychological issues and suggest the framework aids understanding global warming.

What carries the argument

Coupled equations for brain growth rate including awareness and group size growth rate, linking awareness to cooperation for fire control and thus to external entropy production.

What would settle it

Archaeological evidence showing that the timing of brain size increase does not coincide with the start of tool use and fire control, or that group sizes do not increase in the manner predicted by the coupled equations.

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Extended reading notes

Core claim

Ancient human beings started external entropy production in addition to internal entropy production. The mechanism is theoretically investigated using coupled equations for the growth rate of brain including awareness and for growth rate of size of the interacting human beings. The external entropy production per one human being which is directly related to the group size of cooperating human beings is estimated to increase as about 20 million years in the beginning from the critical time. This evolution created coexistence of internal entropy production of traditional multi-cellular life and new external entropy production of multi-body life.

Load-bearing premise

The rapid growth of brain size around 2.5 million years ago is directly caused by growth in awareness that enabled cooperation for controlling fire.

Editorial extensions

If this is right

  • External entropy production becomes a distinct evolutionary development in humans.
  • Multi-body life emerges as a new form coexisting with multi-cellular life.
  • Psychological problems arise from the coexistence of two entropy production mechanisms.
  • Thermodynamic evolution theory can inform technologies and countermeasures for global warming.

Reading between the lines

Editorial extensions of the paper, not claims the author makes directly.

  • The model suggests that larger modern human groups continue to amplify external entropy production.
  • Similar dynamics might explain cooperation in other social species or emerging collective systems.
  • Future work could test if the predicted time scale matches extended archaeological records of group sizes.
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Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit.

Referee Report

2 major / 1 minor

Summary. The paper claims that humans began 'external entropy production' (tied to group cooperation in tool use and fire control) in addition to internal entropy production, starting around 2.5 Ma when brain size increased rapidly. It models this via coupled equations for brain/awareness growth and interacting group size, estimating that external entropy production per human increases over ~20 million years from the critical time. This is said to produce coexistence of traditional multi-cellular internal entropy production with new 'multi-body life' external production, with discussion of psychological issues, technology, and global warming origins.

Significance. If the central derivation holds, the work attempts to extend the maximum entropy production principle to human social evolution by introducing external entropy production linked to group size, potentially offering a thermodynamic lens on cooperation and modern environmental challenges. No machine-checked proofs, reproducible code, or falsifiable predictions are provided.

major comments (2)
  1. [coupled equations analysis] The section analyzing the coupled equations: the ~20 Myr timescale for the rise in external entropy production per human is obtained from the solution of the growth-rate equations, but the growth rates are calibrated to the same archaeological timelines used as input, so the reported timescale is not an independent prediction.
  2. [model assumptions] The model assumptions paragraph linking brain-size data: the rapid brain-size increase at 2.5 Ma is mapped directly onto growth of an 'awareness' variable that enables multi-human fire control, without any independent verification, sensitivity analysis, or comparison to alternative causal accounts (diet, tool complexity, social structure); this mapping is load-bearing for connecting the data to the external-entropy-production claim and the multi-body-life conclusion.
minor comments (1)
  1. [coupled equations] The notation used for the coupled differential equations is not defined explicitly (variables for awareness, group size, and entropy-production terms), making it difficult to reproduce the integration that yields the 20 Myr estimate.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for the constructive and detailed comments on our manuscript. We address each major comment point by point below, providing honest responses and indicating planned revisions where appropriate.

read point-by-point responses

  1. Referee: The section analyzing the coupled equations: the ~20 Myr timescale for the rise in external entropy production per human is obtained from the solution of the growth-rate equations, but the growth rates are calibrated to the same archaeological timelines used as input, so the reported timescale is not an independent prediction.

    Authors: We agree with the referee's observation. The growth rates in the coupled equations are calibrated directly to the archaeological timelines, so the ~20 Myr timescale is a derived outcome of the model rather than an independent prediction. The model is intended to demonstrate internal consistency between the proposed thermodynamic mechanism and the observed data. We will revise the relevant section to explicitly clarify this point and reframe the timescale as a model-derived estimate illustrating evolutionary dynamics. revision: yes

  2. Referee: The model assumptions paragraph linking brain-size data: the rapid brain-size increase at 2.5 Ma is mapped directly onto growth of an 'awareness' variable that enables multi-human fire control, without any independent verification, sensitivity analysis, or comparison to alternative causal accounts (diet, tool complexity, social structure); this mapping is load-bearing for connecting the data to the external-entropy-production claim and the multi-body-life conclusion.

    Authors: The referee correctly notes that the mapping from brain-size increase to the awareness variable rests primarily on temporal coincidence with tool use and fire control, without independent verification, sensitivity analysis, or explicit comparison to alternatives such as dietary or social factors. This assumption is indeed central. While the manuscript presents it as a reasonable hypothesis based on the record, we acknowledge the limitation. We will add discussion of the assumption's foundational role, note alternative causal accounts, and highlight the need for future validation, without altering the model itself. revision: partial

Circularity Check

0 steps flagged · score 0.0 of 10

No significant circularity; derivation relies on external archaeological input and model analysis without reduction to fitted inputs by construction.

full rationale

The paper takes the 2.5 Ma brain-size jump from archaeological data as an external starting point, states an assumption linking it to awareness, sets up coupled equations for brain and group-size growth, and reports an estimated 20 Myr timescale as the outcome of analyzing those equations. No quoted equations or text show that the 20 Myr result is mathematically identical to the input data or parameters by construction, nor is there a self-citation chain that bears the central load. The mapping assumption is presented as natural rather than derived, placing any weakness under correctness rather than circularity. The derivation chain therefore remains self-contained against the stated inputs.

Assumptions & free parameters 1 free parameters · 1 assumptions · 2 invented entities

The central claim depends on the maximum entropy production principle from prior literature and introduces new parameters and entities without external validation in the abstract.

free parameters (1)
  • coupled equation growth rates
    Parameters in the equations for brain and group size growth are adjusted to match the observed 2.5 million year onset and the 20 million year increase estimate.
assumptions (1)
  • domain assumption Maximum entropy production principle applies to the evolution of life including external mechanisms
    Cited as the basis for both internal and the new external entropy production.
invented entities (2)
  • external entropy production
    purpose: Describes dissipation of energy outside the individual body through tools and fire
    New concept introduced to explain human-specific evolution beyond multi-cellular life.
  • multi-body life
    purpose: Conceptualizes groups of cooperating humans as a higher level of life organization
    Invented term for the coexistence of internal and external entropy production mechanisms.

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Cite this review

Pith. "Pith review of External Entropy Production and Human Evolution toward Multi-body Life." pith.science (2026). https://pith.science/paper/KYAKAG5J

@misc{pith2026260619066,
  author       = {Pith},
  title        = {Pith review of: External Entropy Production and Human Evolution toward Multi-body Life},
  year         = {2026},
  howpublished = {\url{https://pith.science/paper/KYAKAG5J}},
  note         = {Machine review of arXiv:2606.19066}
}
read the original abstract

Ancient human beings started "external entropy production" in a late stage of evolution, in addition to the internal entropy production by which energy was dissipated within the body of life, as previously described consistently with the birth of life by maximum entropy production principle. In this paper, the mechanism for development of external entropy production, which is strongly related with use of tools and controlling fire, is theoretically investigated. Archaeological data show that the brain size of ancient human beings started rapid increase around 2.5 million years ago when the usage of tools and control of fire started. It may be natural to assume that the rapid growth of brain size is related to the growth of awareness which helped cooperation with the other human beings for control of fire. Coupled equations for the growth rate of brain including awareness and for growth rate of size of the interacting human beings are analyzed. The external entropy production per one human being which is directly related to the group size of cooperating human beings is estimated to increase as about 20 million years in the beginning from the critical time. This evolution created coexistence of internal entropy production of traditional multi-cellular life and new external entropy production of multi-body life. A psychological problem due to the coexistence of two kinds of entropy production mechanism in human being and concept of technologies based on the present thermodynamic evolution theory are discussed. It is suggested that the evolutionary understanding of the origin of global warming based on the external entropy production may be important to create an useful countermeasure.

Figures

Figures reproduced from arXiv: 2606.19066 by the authors.

Figure 1
Figure 1. Archaeological data of brain size from chimpanzee to ancient human beings versus time. The green crosses correspond to the different types of homo with chimpanzee. The vertical dashed lines indicate the rough periods when the use of tools and control of fire started. The red point at Tc = −2.5 million years, Nc = 480 cc is assumed as the critical point for the transition to a phase of new life with in a society and … view at source ↗
Figure 2
Figure 2. Interaction of internal and external worlds through awareness for N > Nc. The two worlds interacts through the boundary world representing awareness of human beings shown by the gray ring. The yellow arrows represent interaction of the external world and the brain through the awareness, described by Equation (3). The blue arrows represent action of the brain upon the external world through the awareness, described b… view at source ↗

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Reference graph

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