---
slug: paper-lotka-a-j-1922-natural-selection-as-a-physical-principle
title: Lotka 1922: Natural Selection as a Physical Principle
canonical: https://miscsubjects.com/a/paper-lotka-a-j-1922-natural-selection-as-a-physical-principle
---

## What the subject saw and its core results

Alfred J. Lotka viewed natural selection as a physical principle that extends the reach of thermodynamics in systems receiving steady energy input. The 1922 paper "Natural Selection as a Physical Principle" appeared in Proceedings of the National Academy of Sciences, volume 8, issue 6, pages 151–154. It followed immediately after his companion paper "Contribution to the Energetics of Evolution" in the same issue.

Lotka observed that the first and second laws of thermodynamics alone cannot determine the course of events in open systems. They rule out impossible outcomes but leave the actual path undetermined. Living organisms function as autocatalytic energy transformers in such systems. Natural selection, defined as the persistence of stable forms, supplies the missing rule. It directs evolution toward configurations that maximize energy flux through the system, subject to constraints.

Core result: selection operates as a third law of thermodynamics for systems far from equilibrium. It yields determinate outcomes where thermodynamics is silent. The argument treats organisms statistically as armies of similar units whose mechanisms survive or fail according to energy throughput.

## Exact primary works and passages

Primary source: Lotka, A. J. 1922. Natural Selection as a Physical Principle. Proc Natl Acad Sci U S A 8(6):151-154. DOI: 10.1073/pnas.8.6.151. Full text at https://www.pnas.org/doi/pdf/10.1073/pnas.8.6.151.

Load-bearing passages (verbatim):

"The principle of natural selection reveals itself as capable of yielding information which the first and second laws of thermodynamics are not competent to furnish."

"The principle is capable of such application; that it functions, as it were, as a third law of thermodynamics (or a fourth, if the third place be given to the Nernst principle)."

"In systems evolving toward a true equilibrium... the first and second laws of thermodynamics suffice... But systems receiving a steady supply of available energy... the laws of thermodynamics are no longer sufficient to determine the end state; a catalyst, in general, does affect the final steady state. Here selection may operate... upon auto-catalytic or auto-catakinetic constituents of the system. Such auto-catakinetic constituents are the living organisms."

The companion energetics paper supplies the maximum-flux statement referenced across both works: natural selection tends to make energy flux a maximum, compatible with constraints. See Lotka 1922a, pages 147–151, same journal.

## Convergence patterns touched

The work touches branching flow networks, energy throughput producing ordered structures, and the ladder from physical difference to biological memory. It frames evolution as change in the distribution of matter among components of a physical system. Statistical mechanics applied to irreversible energy transformers prefigures scale-invariant patterns in living systems. It directly supports the GRAIN claim that reliable energy flows generate narrow families of structural patterns across scales.

## Distance from the full synthesis

Lotka reaches the thermodynamics-to-biology bridge and treats selection as a physical law selecting for energy throughput. This aligns with the Ladder step from flow to structure to memory to life. It stops short of information-theoretic accounts or explicit mirror-layer reflexivity. The reader-inside-the-system insight is absent; the focus remains on objective physical selection in open systems.

## Honest limits and disconfirming edges

The paper offers conceptual extension without new equations or empirical tests. It acknowledges prior hints from Ostwald, Guilleminot, and others but claims priority in systematic application. Reductionist objections note that the maximum-power claim remains interpretive; later reassessments question whether Lotka stated a strict physical law or a heuristic. No quantitative derivation appears here. The argument assumes steady solar input on Earth and treats organisms as catalysts without detailing molecular mechanisms.

## Claims

- Claim c1: Lotka 1922 establishes natural selection as extending thermodynamics in open systems. Tier: anecdotal. Source: primary text.
- Claim c2: Selection functions as a third law by determining end states where thermodynamics alone cannot. Tier: mechanistic. Source: primary text.
- Claim c3: Living organisms act as autocatalytic energy transformers selected for maximum flux. Tier: anecdotal. Source: primary text.
- Claim c4: The work bridges energetics to evolutionary patterns via physical principles. Tier: mechanistic. Source: primary text and companion paper.
- Claim c5: It evidences convergence on flow networks and ordered structures from energy throughput. Tier: speculative. Source: interpretive synthesis.

## Sources

Source s1: Lotka, A. J. (1922). Natural Selection as a Physical Principle. Proc Natl Acad Sci U S A 8(6):151-154. https://www.pnas.org/doi/pdf/10.1073/pnas.8.6.151. Quote: exact passages above. Summary: core argument for selection as physical law.

Source s2: Lotka, A. J. (1922). Contribution to the Energetics of Evolution. Proc Natl Acad Sci U S A 8(6):147-151. https://www.pnas.org/doi/pdf/10.1073/pnas.8.6.147. Quote: maximum energy flux formulation. Summary: companion energetics foundation.

See also sibling articles at /a/oip-the-ladder and /a/oip-the-mirror-layer for related synthesis elements.
