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Evidence record

Why does anything help anything else?

Every sentence on the exploration belongs to at least one claim below. Each says what kind of statement it is, what it rests on, what the evidence does not establish, and how far it was checked. Nothing here is a score, and none of it is a verdict on a belief or a theory.

Last checked 24 September 2026.

  • Source checked: 42
  • A judgement, not a fact: 7
  • Partly checked: 1
  • Presented as open: 1

If something here is wrong, misquoted, out of date or unfair, write to support@unknownoceans.com and give the claim number, which does not change.

What the question takes for granted

A question in evolutionary biology with a well-developed theoretical answer. The conditions under which helping can evolve are stated in models; which of them explains a given case, and above all human cooperation with strangers, is argued.

  • Helping carries a cost that selection, left to itself, should remove

    Established

    In a well-mixed population with no mechanism at work, defectors do better than cooperators. That is the premise every mechanism on the page answers.

  • Human cooperation with strangers needs an explanation beyond kin and repeated dealings

    Contested

    Some researchers read one-off generosity as needing norms, punishment or group competition; others argue that selection for reciprocity produces it on its own.

  • Group selection and kin selection are different explanations

    Contested

    The page’s heading asks whether one is needed beyond the other. Most on both sides treat the two as equivalent descriptions; a minority argue they come apart in some models.

How the question is labelled

Claim: The cost that pays

Kind
Framing. Signposting. It asserts nothing a source could check.

Claim: Cooperation

Kind
Framing. Signposting. It asserts nothing a source could check.

The question

Claim: Natural selection rewards whatever leaves the most descendants

Kind
What a model says. What a theory or model predicts or describes, which is not the same as what has been observed.
Review
Source checked. The cited passage was read, and it says this.

The premise the rest of the page answers.

  • Supports

    The genetical evolution of social behaviour. Isection 1, Introduction, p. 1

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Theory · Model

    The source reads: Sacrifices involved in parental care are a possibility implicit in any model in which the definition of fitness is based, as it should be, on the number of adult offspring.

  • Context

    Five Rules for the Evolution of Cooperationp. 1560, opening paragraph

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Theory · Review of the field

    The source reads: based on a fierce competition between individuals and should therefore reward only selfish behavior.

What this does not establish

A compressed statement of classical selection, which is the premise the page goes on to qualify. Hamilton’s point is that the count has to include relatives.

Claim 3 · checked 24 September 2026 · AI-assisted audit

Claim: and yet cells cooperate, animals share food, and some insects spend their lives raising the offspring of others.

Kind
Observation. Something measured or seen, as the named source reports it.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Five Rules for the Evolution of Cooperationp. 1560, opening paragraph

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Theory · Review of the field

    The source reads: Genes cooperate in genomes. Chromosomes cooperate in eukaryotic cells. Cells cooperate in multicellular organisms. There are many examples of cooperation among animals.

  • Supports

    Food sharing in vampire bats: reciprocal help predicts donations more than relatedness or harassmentabstract

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Research in animals · Experiment

    The source reads: Common vampire bats often regurgitate food to roost-mates that fail to feed.

  • Supports

    The evolution of eusocialityfirst paragraph

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Research in animals · Review of the field

    The source reads: Eusociality, in which some individuals reduce their own lifetime reproductive potential to raise the offspring of others

What this does not establish

The food-sharing example is one species, vampire bats. Nowak, Tarnita and Wilson describe the worker castes as partially, not wholly, non-reproductive.

Later work looked for

Crossref, 2014 on, "vampire bat food sharing reciprocity": later work on the same colony (contact calls that attract past food-sharing partners, 2016) extends it; nothing that changes it.

Corrected

24 September 2026. Previously: “and some insects never reproduce at all.” Workers in social insect colonies are described in the sources as partially non-reproductive: Hamilton notes worker egg-laying in bees, wasps and ants, and Nowak, Tarnita and Wilson define eusociality by a reduction, not an end, of reproduction.

Claim 4 · checked 24 September 2026 · AI-assisted audit

Claim: Cooperation is not a puzzle without an answer.

Kind
This page’s reading. A judgement the page makes from the evidence. Others read it differently.
Review
A judgement, not a fact. Reviewed for whether it is fairly put and follows from the checked claims. No source can confirm it.

Follows from the five rules in Nowak’s review, each of which states when selection can favour cooperation. It does not say every case of cooperation is explained.

  • Context

    Five Rules for the Evolution of Cooperationabstract

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Theory · Review of the field

    The source reads: Here I discuss five mechanisms for the evolution of cooperation: kin selection, direct reciprocity, indirect reciprocity, network reciprocity, and group selection. For each mechanism, a simple rule is derived that specifies whether natural selection can lead to cooperation.

Claim 5 · checked 24 September 2026 · AI-assisted audit

Claim: Five mechanisms are understood well enough to be stated mathematically, each specifying the conditions under which helping pays.

Kind
What scholars argue. A report of what specialists argue, or where they disagree.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Five Rules for the Evolution of Cooperationabstract; Conclusion, p. 1563

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Theory · Review of the field

    The source reads: Here I discuss five mechanisms for the evolution of cooperation: kin selection, direct reciprocity, indirect reciprocity, network reciprocity, and group selection. For each mechanism, a simple rule is derived that specifies whether natural selection can lead to cooperation.

  • Qualifies

    Five Rules for the Evolution of CooperationConclusion, p. 1563

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Theory · Review of the field

    The source reads: I have not discussed all potential mechanisms for the evolution of cooperation.

What this does not establish

Five is the number in one influential review. Nowak says he has not discussed every possible mechanism, and names green-beard recognition and voluntary participation as others.

Claim 6 · checked 24 September 2026 · AI-assisted audit

Claim: What remains argued is which of them explains human behaviour, and whether group selection explains anything kin selection does not.

Kind
What scholars argue. A report of what specialists argue, or where they disagree.
Review
Source checked. The cited passage was read, and it says this.

Corrected

24 September 2026. Previously: “What remains argued is which of them explains human behaviour.” The page’s own last section reports a second open dispute, over group selection, which the summary left out.

Claim 7 · checked 24 September 2026 · AI-assisted audit

Claim: A worker ant raises young that are not her own.

Kind
Observation. Something measured or seen, as the named source reports it.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    The evolution of eusocialitysecond paragraph

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Research in animals · Review of the field

    The source reads: where adult members are divided into reproductive and (partially) nonreproductive castes and the latter care for the young

  • Supports

    The evolution of eusocialitythird paragraph

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Research in animals · Review of the field

    The source reads: Modern students of collateral altruism have followed Darwin in continuing to focus on ants, honeybees, and other eusocial insects

  • Qualifies

    The genetical evolution of social behaviour. IIsection on colonies of social insects, p. 29

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Research in animals · Argument

    The source reads: Laying by workers is known to occur in each of the main social groups, bees, wasps and ants.

What this does not establish

Workers in many species lay some eggs of their own, usually males. The claim is that their working life goes to young that are not theirs, not that they never reproduce.

Later work looked for

Crossref, 2015 on, "worker reproduction ants eusocial": work on how queens and brood regulate worker reproduction, which assumes the division of labour; nothing that changes it.

Corrected

24 September 2026. Previously: “A sterile worker bee has no offspring.” Worker bees are not strictly sterile: Hamilton records worker egg-laying in bees, wasps and ants, and Nowak, Tarnita and Wilson call the worker castes partially non-reproductive.

Claim 8 · checked 24 September 2026 · AI-assisted audit

Claim: A vampire bat regurgitates blood for an unrelated roostmate.

Kind
Observation. Something measured or seen, as the named source reports it.
Review
Source checked. The cited passage was read, and it says this.

What this does not establish

Twenty captive bats over two years. “Unrelated” means an estimated relatedness below 0.05. Some sharing is between relatives too.

Later work looked for

Crossref, 2014 on, "vampire bat food sharing reciprocity": later papers on food-sharing partners in the same species; nothing that changes it.

Claim 9 · checked 24 September 2026 · AI-assisted audit

Claim: A cell in your skin is kept from dividing freely, though skin is constantly renewed.

Kind
Observation. Something measured or seen, as the named source reports it.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Cancer across the tree of life: cooperation and cheating in multicellularitysection 2(a), proliferation inhibition

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Research in animals · Review of the field

    The source reads: With the exception of specialized stem cells and their immediate descendants as well as a few highly regenerative tissues such as the liver, the capacity of proliferation is strictly suppressed, even in high-turnover tissues such as mammalian skin or intestine.

What this does not establish

Stem cells in the skin do divide; it is proliferation in general that is held in check.

Later work looked for

Crossref, 2016 on, "cancer cheating multicellularity cooperation": later reviews and a 2019 book on cheating cells keep the same account; nothing that changes it.

Corrected

24 September 2026. Previously: “A cell in your liver forgoes reproduction entirely.” The liver is the review’s own example of a highly regenerative tissue whose cells do divide. Aktipis and others give skin as a tissue where proliferation is strictly suppressed even though it turns over quickly.

Claim 10 · checked 24 September 2026 · AI-assisted audit

Claim: Each is a cost paid to benefit something else, and each has an explanation that does not require selection to have stopped working.

Kind
This page’s reading. A judgement the page makes from the evidence. Others read it differently.
Review
A judgement, not a fact. Reviewed for whether it is fairly put and follows from the checked claims. No source can confirm it.

The page’s reading of the three examples: kin selection, reciprocity and the suppression of cheating inside a body are all accounts that work through selection.

  • Context

    Five Rules for the Evolution of Cooperationabstract

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Theory · Review of the field

    The source reads: Here I discuss five mechanisms for the evolution of cooperation: kin selection, direct reciprocity, indirect reciprocity, network reciprocity, and group selection. For each mechanism, a simple rule is derived that specifies whether natural selection can lead to cooperation.

Other readings

For the social insects, Nowak, Tarnita and Wilson argue that the explanation is not kin selection but population structure; either way it runs through selection.

Claim 11 · checked 24 September 2026 · AI-assisted audit

When helping pays

Claim: When helping pays

Kind
Framing. Signposting. It asserts nothing a source could check.

Five conditions under which helping pays

Claim: Five conditions under which helping pays

Kind
What scholars argue. A report of what specialists argue, or where they disagree.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Five Rules for the Evolution of CooperationConclusion, p. 1563

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Theory · Review of the field

    The source reads: Each rule can be expressed as the benefit-to-cost ratio of the altruistic act being greater than some critical value.

What this does not establish

The five of one review. They are conditions in models, not measurements of any population.

Claim 13 · checked 24 September 2026 · AI-assisted audit

Claim: A 2006 review set out five mechanisms and the inequality each one requires.

Kind
What scholars argue. A report of what specialists argue, or where they disagree.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Five Rules for the Evolution of Cooperationabstract; Table 1

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Theory · Review of the field

    The source reads: Here I discuss five mechanisms for the evolution of cooperation: kin selection, direct reciprocity, indirect reciprocity, network reciprocity, and group selection. For each mechanism, a simple rule is derived that specifies whether natural selection can lead to cooperation.

Corrected

24 September 2026. Previously: “A 2006 review set out the mechanisms and the inequality each one requires.” Nowak says he did not discuss every potential mechanism; "the mechanisms" implied these five were all of them.

Claim 14 · checked 24 September 2026 · AI-assisted audit

Claim: Each describes a different circumstance, and more than one can operate at once:

Kind
This page’s reading. A judgement the page makes from the evidence. Others read it differently.
Review
A judgement, not a fact. Reviewed for whether it is fairly put and follows from the checked claims. No source can confirm it.

Each of Nowak’s mechanisms is defined by a setting (relatives, repeated meetings, reputation, a network, groups). The bat study that follows is an instance of two acting together.

  • Context

    Five Rules for the Evolution of CooperationFig. 3 caption

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Theory · Review of the field

    The source reads: Kin selection operates when the donor and the recipient of an altruistic act are genetic relatives. Direct reciprocity requires repeated encounters between the same two individuals. Indirect reciprocity is based on reputation

  • Context

    Five Rules for the Evolution of CooperationConclusion, p. 1563

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Theory · Review of the field

    The source reads: All evolutionary models of punishment so far are based on underlying mechanisms such as indirect reciprocity

Corrected

24 September 2026. Previously: “They are not competing theories: they are different circumstances, and more than one can operate at once.” "Not competing theories" sat badly with the page’s own later section on the dispute between group and kin selection, and no source said it. The claim that more than one can operate at once now carries an example from a study that measured both.

Claim 15 · checked 24 September 2026 · AI-assisted audit

Claim: vampire bats share food with relatives, but what a bat has been given predicts what it gives better than relatedness does.

Kind
Experimental result. What an experiment or trial found, under its own conditions. A result in animals, cells or a simulation is not a result in people.
Review
Source checked. The cited passage was read, and it says this.

What this does not establish

Twenty captive bats, fasted and observed under controlled conditions. In the best model relatedness on its own was not a significant predictor; it mattered through its interaction with food received, and related pairs reciprocated more symmetrically.

Later work looked for

Crossref, 2014 on, "vampire bat food sharing reciprocity": later work by the same group on food-sharing partners; nothing that reverses the result.

Claim 16 · checked 24 September 2026 · AI-assisted audit

Claim: What they share is that cooperation is never free.

Kind
What a model says. What a theory or model predicts or describes, which is not the same as what has been observed.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Five Rules for the Evolution of Cooperationp. 1560

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Theory · Review of the field

    The source reads: A cooperator is someone who pays a cost, c, for another individual to receive a benefit, b.

What this does not establish

True in the framework: a cooperator is defined as one who pays a cost. It is a premise of the models.

Claim 17 · checked 24 September 2026 · AI-assisted audit

Claim: Each specifies what has to be true about relatedness, repetition, reputation, space or group structure for the cost to be repaid.

Kind
What a model says. What a theory or model predicts or describes, which is not the same as what has been observed.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Five Rules for the Evolution of CooperationFig. 3 caption

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Theory · Review of the field

    The source reads: Kin selection operates when the donor and the recipient of an altruistic act are genetic relatives. Direct reciprocity requires repeated encounters between the same two individuals. Indirect reciprocity is based on reputation

  • Supports

    Five Rules for the Evolution of CooperationTable 1 caption

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Theory · Review of the field

    The source reads: All conditions can be expressed as the benefit-to-cost ratio exceeding a critical value.

What this does not establish

Conditions derived in models, several of them under simplifying assumptions.

Claim 18 · checked 24 September 2026 · AI-assisted audit

Claim: The five, and what each requires

Kind
Framing. Signposting. It asserts nothing a source could check.

Claim: Kin selection

Kind
Framing. Signposting. It asserts nothing a source could check.

Claim: Help relatives.

Kind
What a model says. What a theory or model predicts or describes, which is not the same as what has been observed.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Five Rules for the Evolution of CooperationKin Selection, p. 1560

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Theory · Review of the field

    The source reads: natural selection can favor cooperation if the donor and the recipient of an altruistic act are genetic relatives

What this does not establish

A summary of the mechanism, not advice.

Claim 21 · checked 24 September 2026 · AI-assisted audit

Claim: Pays when the benefit to the recipient, weighted by how closely related they are, exceeds the cost to the helper.

Kind
What a model says. What a theory or model predicts or describes, which is not the same as what has been observed.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Five Rules for the Evolution of Cooperationequation 1, p. 1560

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Theory · Review of the field

    The source reads: Hamilton’s rule states that the coefficient of relatedness, r, must exceed the cost-to-benefit ratio of the altruistic act

What this does not establish

Nowak finds this condition for all three of his measures of evolutionary success.

Claim 22 · checked 24 September 2026 · AI-assisted audit

Claim: Direct reciprocity

Kind
Framing. Signposting. It asserts nothing a source could check.

Claim: Help those who may help you back.

Kind
What a model says. What a theory or model predicts or describes, which is not the same as what has been observed.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Five Rules for the Evolution of CooperationDirect Reciprocity, p. 1560

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Theory · Review of the field

    The source reads: Assume that there are repeated encounters between the same two individuals.

What this does not establish

A summary of the mechanism, not advice.

Claim 24 · checked 24 September 2026 · AI-assisted audit

Claim: Pays when the chance of meeting again exceeds the cost to benefit ratio.

Kind
What a model says. What a theory or model predicts or describes, which is not the same as what has been observed.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Five Rules for the Evolution of Cooperationequation 2, p. 1561

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Theory · Review of the field

    The source reads: Direct reciprocity can lead to the evolution of cooperation only if the probability, w, of another encounter between the same two individuals exceeds the cost-to-benefit ratio of the altruistic act

  • Qualifies

    Five Rules for the Evolution of CooperationComparative Analysis, p. 1563

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Theory · Review of the field

    The source reads: Slightly more stringent conditions must hold for cooperation to be RD or AD.

What this does not establish

This is the condition for cooperation to be stable once common, with tit-for-tat as the strategy. Nowak notes slightly stricter conditions for the other two measures of success.

Claim 25 · checked 24 September 2026 · AI-assisted audit

Claim: Indirect reciprocity

Kind
Framing. Signposting. It asserts nothing a source could check.

Claim: Help those with a reputation for helping.

Kind
What a model says. What a theory or model predicts or describes, which is not the same as what has been observed.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Five Rules for the Evolution of CooperationIndirect Reciprocity, p. 1561

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Theory · Review of the field

    The source reads: Natural selection favors strategies that base the decision to help on the reputation of the recipient.

What this does not establish

A summary of the mechanism, not advice.

Claim 27 · checked 24 September 2026 · AI-assisted audit

Claim: Pays when the chance that your behaviour is known exceeds the cost to benefit ratio.

Kind
What a model says. What a theory or model predicts or describes, which is not the same as what has been observed.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Five Rules for the Evolution of Cooperationequation 3, p. 1561

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Theory · Review of the field

    The source reads: Indirect reciprocity can only promote cooperation if the probability, q, of knowing someone’s reputation exceeds the cost-to-benefit ratio of the altruistic act

What this does not establish

As with direct reciprocity, this is the stability condition; slightly stricter ones hold for Nowak’s other two measures.

Claim 28 · checked 24 September 2026 · AI-assisted audit

Claim: Network reciprocity

Kind
Framing. Signposting. It asserts nothing a source could check.

Claim: Help your neighbours.

Kind
What a model says. What a theory or model predicts or describes, which is not the same as what has been observed.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Five Rules for the Evolution of CooperationNetwork Reciprocity, p. 1561

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Theory · Review of the field

    The source reads: A cooperator pays a cost, c, for each neighbor to receive a benefit, b.

What this does not establish

A summary of the mechanism, not advice.

Claim 30 · checked 24 September 2026 · AI-assisted audit

Claim: Pays when the benefit to cost ratio exceeds the average number of neighbours each individual has, so clusters of cooperators can hold.

Kind
What a model says. What a theory or model predicts or describes, which is not the same as what has been observed.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Five Rules for the Evolution of Cooperationequation 4, p. 1561

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Theory · Review of the field

    The source reads: The benefit-to-cost ratio must exceed the average number of neighbors, k, per individual

  • Supports

    Five Rules for the Evolution of CooperationNetwork Reciprocity, p. 1561

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Theory · Review of the field

    The source reads: cooperators can prevail by forming network clusters, where they help each other

What this does not establish

A result for games on graphs, which Nowak notes are hard to analyse exactly.

Claim 31 · checked 24 September 2026 · AI-assisted audit

Claim: Group selection

Kind
Framing. Signposting. It asserts nothing a source could check.

Claim: Groups of cooperators outcompete groups of defectors.

Kind
What a model says. What a theory or model predicts or describes, which is not the same as what has been observed.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Five Rules for the Evolution of CooperationGroup Selection, p. 1561

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Theory · Review of the field

    The source reads: pure cooperator groups grow faster than pure defector groups

What this does not establish

In Nowak’s model, within any mixed group defectors still do better.

Claim 33 · checked 24 September 2026 · AI-assisted audit

Claim: Pays when the benefit to cost ratio exceeds one plus the maximum group size divided by the number of groups, in a model that assumes weak selection and rare splitting.

Kind
What a model says. What a theory or model predicts or describes, which is not the same as what has been observed.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Five Rules for the Evolution of Cooperationequation 5, p. 1562

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Theory · Review of the field

    The source reads: In the mathematically convenient limit of weak selection and rare group splitting, we obtain a simple result (51): If n is the maximum group size and m is the number of groups, then group selection allows evolution of cooperation, provided that b/c > 1 + (n/m)

What this does not establish

A result in one model under a convenient limit.

Corrected

24 September 2026. Previously: “exceeds one plus the group size divided by the number of groups” Nowak’s n is the maximum group size.

Claim 34 · checked 24 September 2026 · AI-assisted audit

The inequality that started it

Claim: The inequality that started it

Kind
Framing. Signposting. It asserts nothing a source could check.

Claim: J. B. S. Haldane anticipated the first of the five, and W. D. Hamilton wrote it down in 1964 as an inequality

Kind
Historical claim. A statement about the past that historical evidence can test.
Review
Source checked. The cited passage was read, and it says this.

Hamilton’s own statement is in terms of a benefit-to-loss ratio for each degree of relationship; the compact form r > c/b is the later standard way of writing it.

  • Supports

    Five Rules for the Evolution of CooperationKin Selection, p. 1560

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Texts · Review of the field

    The source reads: he anticipated what became later known as Hamilton’s rule ... Hamilton’s rule states that the coefficient of relatedness, r, must exceed the cost-to-benefit ratio of the altruistic act: r > c/b

  • Supports

    The evolution of eusocialitysection "The rise and fall of inclusive fitness theory"

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Texts · Review of the field

    The source reads: The idea was first stated by J. B. S. Haldane in 1955

  • Supports

    The genetical evolution of social behaviour. Isection 3, p. 16

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Theory · Model

    The source reads: the benefit to a sib must average at least twice the loss to the individual, the benefit to a half-sib must be at least four times the loss, to a cousin eight times

Corrected

24 September 2026. Previously: “The first of the five was written down in 1964 by William Hamilton, as an inequality” Both Nowak and Nowak, Tarnita and Wilson credit Haldane with the idea first. No cited source gives Hamilton’s first name; the sources give W. D. Hamilton.

Claim 36 · checked 24 September 2026 · AI-assisted audit

Claim: help a relative when the benefit to them, multiplied by how closely related you are, exceeds the cost to you.

Kind
What a model says. What a theory or model predicts or describes, which is not the same as what has been observed.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    The genetical evolution of social behaviour. Isection 3, p. 16

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Theory · Model

    The source reads: the benefit to a sib must average at least twice the loss to the individual, the benefit to a half-sib must be at least four times the loss, to a cousin eight times

  • Supports

    Five Rules for the Evolution of Cooperationequation 1, p. 1560

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Theory · Review of the field

    The source reads: Hamilton’s rule states that the coefficient of relatedness, r, must exceed the cost-to-benefit ratio of the altruistic act

What this does not establish

A condition for a gene for helping to spread, in a model. It is not a claim that animals calculate it.

Claim 37 · checked 24 September 2026 · AI-assisted audit

Claim: It reframed the unit of accounting.

Kind
This page’s reading. A judgement the page makes from the evidence. Others read it differently.
Review
A judgement, not a fact. Reviewed for whether it is fairly put and follows from the checked claims. No source can confirm it.

Hamilton’s inclusive fitness counts a gene’s effects on relatives as well as on its bearer’s own offspring; the page calls that a change in what is counted.

Claim 38 · checked 24 September 2026 · AI-assisted audit

Claim: A gene that causes its bearer to help relatives is helping individuals likely to carry copies of it, so behaviour that looks costly to an individual can be profitable to the gene producing it.

Kind
What a model says. What a theory or model predicts or describes, which is not the same as what has been observed.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    The genetical evolution of social behaviour. Isection 1, Introduction, p. 1

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Theory · Model

    The source reads: A gene causing its possessor to give parental care will then leave more replica genes in the next generation ... on a set of relatives each of which has a half chance of carrying the gene in question.

What this does not establish

Hamilton makes the point first for parental care and then extends it to other relatives. "Profitable to the gene" is a way of describing selection, not a claim that genes have aims.

Corrected

24 September 2026. Previously: “is helping copies of itself” Hamilton’s point is probabilistic: a relative has a chance, set by the degree of relationship, of carrying the gene.

Claim 39 · checked 24 September 2026 · AI-assisted audit

Claim: A second paper the same year turned the idea on the worker castes of the social insects.

Kind
Historical claim. A statement about the past that historical evidence can test.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    The genetical evolution of social behaviour. IIabstract

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Texts · Primary text

    The source reads: is outlined concerning social evolution in the Hymenoptera; but the evidence that at present exists is found somewhat contrary on certain points.

  • Supports

    The genetical evolution of social behaviour. IIp. 28, "Colonies of social insects"

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Theory · Argument

    The source reads: family relationships in Hymenoptera are potentially very favourable to the evolution of reproductive altruism.

Corrected

24 September 2026. Previously: “turned the idea on the sterile castes of the social insects” Hamilton himself records egg-laying by workers; the castes are not strictly sterile.

Claim 40 · checked 24 September 2026 · AI-assisted audit

Claim: Because of how sex is determined in the Hymenoptera, a female whose mother mated only once is more closely related to her sisters than she would be to her own daughters, so raising the queen’s brood can pay better than laying.

Kind
Hypothesis. A proposed explanation, not an established one.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    The genetical evolution of social behaviour. IIp. 28, "A hypothesis concerning the social tendencies of the Hymenoptera"

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Theory · Argument

    The source reads: their system of sex-determination gives their population genetics a peculiar pattern ... family relationships in Hymenoptera are potentially very favourable to the evolution of reproductive altruism. If a female is fertilized by only one male all the sperm she receives is genetically identical.

  • Supports

    The genetical evolution of social behaviour. IIpp. 28–29

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Theory · Argument

    The source reads: Our principle tells us that even if this new adult had a nest ready constructed and vacant for her use she would prefer ... returning to her mother’s and provisioning a cell for the rearing of an extra sister to provisioning a cell for a daughter of her own.

  • Supports

    The evolution of eusocialitysection "The rise and fall of inclusive fitness theory"

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Theory · Review of the field

    The source reads: As a result, sisters are more closely related to one another (R = 3/4) than daughters are to their mothers (R = 1/2). Haplodiploidy happens to be the method of sex determination in the Hymenoptera

What this does not establish

Hamilton’s hypothesis, which he qualified at once, and which later work has not kept (claim 43 and claim 44). The queen’s brood also includes brothers, to whom a worker is less closely related.

Corrected

24 September 2026. Previously: “a female is more closely related to her sisters” Hamilton’s asymmetry holds only if the mother was fertilised by one male; with multiple mating it does not.

Claim 41 · checked 24 September 2026 · AI-assisted audit

Claim: Hamilton put that forward as a hypothesis and said the evidence then available was somewhat contrary to it on certain points.

Kind
Historical claim. A statement about the past that historical evidence can test.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    The genetical evolution of social behaviour. IIabstract

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Texts · Primary text

    The source reads: is outlined concerning social evolution in the Hymenoptera; but the evidence that at present exists is found somewhat contrary on certain points.

Corrected

24 September 2026. Previously: “said the evidence then available ran contrary to it on several points” Brought to Hamilton’s own wording, which is more guarded.

Claim 42 · checked 24 September 2026 · AI-assisted audit

Claim: It has not held up.

Kind
What scholars argue. A report of what specialists argue, or where they disagree.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    The evolution of eusocialitysection "The rise and fall of inclusive fitness theory"

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Research in animals · Review of the field

    The source reads: As a result the haplodiploid hypothesis was in time abandoned by researchers on social insects

  • Supports

    Inclusive fitness theory and eusocialityfifth paragraph

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Research in animals · Argument

    The source reads: It was already known that haplodiploidy itself may have only a relatively minor bearing on the origin of eusociality

What this does not establish

What was set aside is haplodiploidy as the explanation, not kin selection; the two papers disagree sharply about kin selection.

Other readings

A 2011 model by Fromhage and Kokko (abstract seen in the currency search, not cited on the page) argues that haplodiploidy and single mating act together.

Corrected

24 September 2026. Previously: “” The passage presented Hamilton’s hypothesis without saying what became of it. Both sides of the 2010 to 2011 exchange treat haplodiploidy alone as a minor factor at most.

Claim 43 · checked 24 September 2026 · AI-assisted audit

Claim: In an exchange in Nature in 2010 and 2011, critics of kin selection theory and 137 of its defenders agreed on one point: haplodiploidy by itself probably has only a minor bearing on how worker castes arose.

Kind
What scholars argue. A report of what specialists argue, or where they disagree.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    The evolution of eusocialitysection "The rise and fall of inclusive fitness theory"

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Research in animals · Review of the field

    The source reads: By the 1990s, however, the haplodiploid hypothesis began to fail.

  • Supports

    Inclusive fitness theory and eusocialityfifth paragraph

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Research in animals · Argument

    The source reads: It was already known that haplodiploidy itself may have only a relatively minor bearing on the origin of eusociality

  • Supports

    Inclusive fitness theory and eusocialityfirst paragraph

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Texts · Argument

    The source reads: argue that inclusive fitness theory has been of little value in explaining the natural world

What this does not establish

"Probably" stands for the reply’s "may have"; the critics call the hypothesis abandoned.

Later work looked for

Crossref, 2011 on, "haplodiploidy eusociality monogamy": a 2026 Current Biology paper is titled "Haplodiploidy alone does not predict the evolution of eusociality" (record only); Fromhage and Kokko 2011 argue for synergy with monogamy. Consistent with the page.

Claim 44 · checked 24 September 2026 · AI-assisted audit

Claim: The defenders point instead to monogamy: worker castes, they write, evolved only in monogamous lineages.

Kind
What scholars argue. A report of what specialists argue, or where they disagree.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Inclusive fitness theory and eusocialityfifth paragraph

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Research in animals · Argument

    The source reads: Inclusive fitness theory has explained why eusociality has evolved only in monogamous lineages

What this does not establish

The reply cites comparative studies for this; those were not read. Nowak, Tarnita and Wilson dispute that relatedness is what drives it.

Claim 45 · checked 24 September 2026 · AI-assisted audit

Claim: What the inequality did settle was the standing of the question. It stopped being an objection to natural selection and became a subject within it.

Kind
This page’s reading. A judgement the page makes from the evidence. Others read it differently.
Review
A judgement, not a fact. Reviewed for whether it is fairly put and follows from the checked claims. No source can confirm it.

Before Hamilton, the classical models admitted no helping beyond parental care; after him, helping had a condition within selection theory.

  • Context

    The genetical evolution of social behaviour. Isection 1, Introduction, p. 1

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Theory · Model

    The source reads: If natural selection followed the classical models exclusively, species would not show any behaviour more positively social than the coming together of the sexes and parental care.

Other readings

Nowak, Tarnita and Wilson accept that selection explains social behaviour but argue that inclusive fitness is not the best way to account for it.

Claim 46 · checked 24 September 2026 · AI-assisted audit

The major transitions are all cooperation problems

Claim: The major transitions are all cooperation problems

Kind
What scholars argue. A report of what specialists argue, or where they disagree.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Five Rules for the Evolution of Cooperationabstract

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Theory · Review of the field

    The source reads: Cooperation is needed for evolution to construct new levels of organization. Genomes, cells, multicellular organisms, social insects, and human society are all based on cooperation.

What this does not establish

Nowak’s framing in a review. "Major transitions" is a wider literature the page does not cite.

Claim 47 · checked 24 September 2026 · AI-assisted audit

Claim: Genes cooperating in a genome, cells cooperating in a body, individuals cooperating in a colony: each is a larger unit built from smaller ones that forgo some of their own reproduction to help one another.

Kind
What scholars argue. A report of what specialists argue, or where they disagree.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Five Rules for the Evolution of Cooperationabstract

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Theory · Review of the field

    The source reads: Genomes, cells, multicellular organisms, social insects, and human society are all based on cooperation. Cooperation means that selfish replicators forgo some of their reproductive potential to help one another.

  • Supports

    Five Rules for the Evolution of CooperationConclusion, p. 1563

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Theory · Review of the field

    The source reads: New levels of organization evolve when the competing units on the lower level begin to cooperate.

Corrected

24 September 2026. Previously: “each of these is a case where entities that could have reproduced independently stopped doing so.” Nowak’s definition is that cooperators forgo some of their reproductive potential; "stopped" overstated it, and not all of these units could reproduce independently.

Claim 48 · checked 24 September 2026 · AI-assisted audit

Claim: Cancer is what happens when that settlement breaks down in one of them

Kind
What scholars argue. A report of what specialists argue, or where they disagree.
Review
Source checked. The cited passage was read, and it says this.

What this does not establish

A framing of cancer in a review; it describes the breakdown, not every cause of it.

Claim 49 · checked 24 September 2026 · AI-assisted audit

Claim: which is a useful reminder that the cooperation inside a body is enforced rather than automatic.

Kind
What scholars argue. A report of what specialists argue, or where they disagree.
Review
Source checked. The cited passage was read, and it says this.

Claim 50 · checked 24 September 2026 · AI-assisted audit

Which of it explains us

Claim: Which of it explains us

Kind
Framing. Signposting. It asserts nothing a source could check.

Claim: Cancer is the settlement inside a body failing, which is a reminder that it is a settlement.

Kind
This page’s reading. A judgement the page makes from the evidence. Others read it differently.
Review
A judgement, not a fact. Reviewed for whether it is fairly put and follows from the checked claims. No source can confirm it.

Restates claim 49 and claim 50 as the page’s own reflection.

Claim 52 · checked 24 September 2026 · AI-assisted audit

Which mechanism explains people

Claim: Which mechanism explains people

Kind
Framing. Signposting. It asserts nothing a source could check.

Claim: Humans cooperate with strangers they will never meet again, in experiments where reputation is controlled away.

Kind
Experimental result. What an experiment or trial found, under its own conditions. A result in animals, cells or a simulation is not a result in people.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Altruistic punishment in humansMethods, p. 139

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Research in people · Experiment

    The source reads: no one ever met the same person more than once

  • Supports

    Altruistic punishment in humansMethods, p. 139

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Research in people · Experiment

    The source reads: which ensured that subjects could not develop any kind of reputation

  • Qualifies

    Altruistic punishment in humansabstract

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Research in people · Experiment

    The source reads: We show that cooperation flourishes if altruistic punishment is possible, and breaks down if it is ruled out.

What this does not establish

240 students in Zurich, in one laboratory. Cooperation held up when punishment was possible and decayed when it was not.

Later work looked for

Crossref, 2010 on, "altruistic punishment cooperation strangers": a 2016 Nature Communications study reports that concern for social image promotes cooperation more than altruistic punishment does (record only); it bears on why people cooperate, not on whether they do.

Claim 54 · checked 24 September 2026 · AI-assisted audit

Claim: On their face, kin selection and direct reciprocity do not cover that.

Kind
What scholars argue. A report of what specialists argue, or where they disagree.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Altruistic punishment in humansabstract

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Research in people · Experiment

    The source reads: These patterns of cooperation cannot be explained by the nepotistic motives associated with the evolutionary theory of kin selection and the selfish motives associated with signalling theory or the theory of reciprocal altruism.

  • Qualifies

    Markets, religion, community size, and the evolution of fairness and punishmentabstract

    Cited · Link answered, 19 October 2026 · Abstract only, 24 September 2026 · Research in people · Experiment

    The source reads: The evolutionary mechanisms associated with kinship and reciprocity, which underpin much of primate sociality, do not readily extend to large unrelated groups.

  • Qualifies

    Evolution of direct reciprocity under uncertainty can explain human generosity in one-shot encountersabstract

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · A simulation · Model

    The source reads: such generosity is the necessary byproduct of selection on decision systems for regulating dyadic reciprocity under conditions of uncertainty

Other readings

Delton and colleagues argue, from simulations, that selection for direct reciprocity itself produces generosity toward strangers, because a one-off meeting is hard to tell from the start of a repeated one.

Corrected

24 September 2026. Previously: “Kin selection and direct reciprocity do not cover that by themselves.” One of the candidate accounts the page lists next is that direct reciprocity does cover it, through uncertainty about whether a meeting will repeat; the sentence now says what the objection is without ruling that out.

Claim 55 · checked 24 September 2026 · AI-assisted audit

Claim: Candidate accounts include a disposition to reciprocate that evolved where a one-off encounter was hard to tell from a repeated one, norms and institutions built up over human history along with the punishment that enforces them, and competition between groups.

Kind
Hypothesis. A proposed explanation, not an established one.
Review
Partly checked. Only part of the source could be read. What was not read is listed.

What this does not establish

Three proposals, each argued by particular researchers; the first rests on agent-based simulations, which its authors say are hard to map precisely onto real-world conditions. Henrich’s main text was not read; its abstract and supplement carry the second and third.

Corrected

24 September 2026. Previously: “Candidate accounts include an evolved disposition calibrated to ancestral conditions where anonymity was rare, cultural transmission of norms and the punishment that enforces them, and competition between groups.” The first account is now stated as its proponents state it, and carried by a readable source; the second follows Henrich and others’ wording.

Claim 56 · checked 24 September 2026 · AI-assisted audit

Claim: The argument among them is active.

Kind
What scholars argue. A report of what specialists argue, or where they disagree.
Review
Source checked. The cited passage was read, and it says this.

What this does not establish

The currency search found a 2020 review of cultural group selection and a 2016 Behavioral and Brain Sciences exchange over it; those were seen as records only.

Claim 57 · checked 24 September 2026 · AI-assisted audit

Claim: The experiments are also hard to read: participants know they are being watched, and Levitt and List argue that this exaggerates how prosocial they appear.

Kind
What scholars argue. A report of what specialists argue, or where they disagree.
Review
Source checked. The cited passage was read, and it says this.

Other readings

Henrich and colleagues report that double-blind procedures made no measurable difference in two of their non-Western populations, and suggest the large effect may be particular to Western students.

Corrected

24 September 2026. Previously: “The argument among them is active and the experiments are hard to interpret, because the participants know they are in an experiment.” The reason given for the difficulty is an argument made by particular economists, now attributed and cited.

Claim 58 · checked 24 September 2026 · AI-assisted audit

Whether group selection is needed

Claim: Whether group selection is needed

Kind
Framing. Signposting. It asserts nothing a source could check.

Claim: Whether selection acting on groups explains anything that kin selection does not is one of the long-running disputes in evolutionary biology

Kind
What scholars argue. A report of what specialists argue, or where they disagree.
Review
Source checked. The cited passage was read, and it says this.

Claim 60 · checked 24 September 2026 · AI-assisted audit

Claim: and it is partly a dispute about accounting rather than about biology.

Kind
This page’s reading. A judgement the page makes from the evidence. Others read it differently.
Review
A judgement, not a fact. Reviewed for whether it is fairly put and follows from the checked claims. No source can confirm it.

Follows from the equivalence most on both sides accept (claim 62): where two descriptions agree, choosing between them is bookkeeping.

Claim 61 · checked 24 September 2026 · AI-assisted audit

Claim: Both sides have generally accepted that the two descriptions are formally equivalent, so the same outcome can be told either way.

Kind
What scholars argue. A report of what specialists argue, or where they disagree.
Review
Source checked. The cited passage was read, and it says this.

Later work looked for

Crossref, 2012 on, "group selection kin selection equivalence inclusive fitness": van Veelen 2020 disputes the equivalence (now on the page); other results are books and chapters. Page updated.

Corrected

24 September 2026. Previously: “the same outcome can be described either way.” The equivalence was stated as settled. It is the majority position, which Marshall’s review defends, and it has a named dissent.

Claim 62 · checked 24 September 2026 · AI-assisted audit

Claim: Van Veelen argued in 2020 that this fails where the effect of cooperating depends on how many others cooperate.

Kind
What scholars argue. A report of what specialists argue, or where they disagree.
Review
Source checked. The cited passage was read, and it says this.

Other readings

Marshall’s 2011 review argues that the non-additive case was already identified and resolved in the literature.

Claim 63 · checked 24 September 2026 · AI-assisted audit

Claim: Where it is not merely bookkeeping is in the empirical question of whether the conditions for group selection are met often in nature, and that is not settled.

Kind
Open question. Something the page says is not known.
Review
Presented as open. The page says this is unresolved, and the review found that it is.

The page presents this as open. Nowak notes continuing controversy, and van Veelen leaves the weighing of the empirical evidence on cultural group selection to others.

Claim 64 · checked 24 September 2026 · AI-assisted audit

What was read