## 1. Identity
**Title:** The Extended Selfish Gene (orig. *The Selfish Gene*, 1976; 40th-anniversary ed. 2016 with chapters from *The Extended Phenotype*)
**Author:** Richard Dawkins
**Source summary:** polymatas.com/biblioteca/el-gen-egoista-extendido (Spanish, 25 pp.)
**Original URL:** https://polymatas.com/biblioteca/el-gen-egoista-extendido
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## 2. Core Contribution
Dawkins reformulates Darwinian natural selection as a gene-level process. The organism — any organism, from virus to human — is a *survival machine* built and steered by its genes. Natural selection acts on genes (replicators), not on individuals or groups. The 40th-anniversary edition appends two chapters from *The Extended Phenotype*, arguing that gene effects reach beyond the body of the organism that carries them.
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## 3. Method and Structure
Thirteen chapters structured as a logical sequence:
- **Chs. 1–4** — Lay foundations: why the gene is the unit of selection, what replicators are, how DNA replicates and recombines.
- **Chs. 5–10** — Show survival machines maximising gene propagation: aggression, parental investment, sex-ratio conflicts, kin altruism, reciprocal cooperation.
- **Ch. 11** — Introduces *memes* as cultural replicators analogous to genes.
- **Ch. 12** — Evolutionarily Stable Strategies (ESS) and the hawk-dove game from evolutionary game theory.
- **Ch. 13** — Summarises the Extended Phenotype thesis: gene effects can extend beyond the organism's body.
- **Appended chapters from *The Extended Phenotype*** — Deepens the replicator/vehicle distinction and parasite manipulation examples.
A large endnotes section corrects or extends claims from the 1976 text without altering the original prose.
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## 4. Key Results and Ideas
| Concept | Claim |
|---|---|
| Replicator | First self-copying molecules; ancestors of DNA; the true unit of selection |
| Selfish Gene | Genes that promote their own copying propagate; "selfish" is metaphorical, not intentional |
| Survival machine | Organisms as vehicles built by genes for gene propagation |
| Inclusive fitness | Altruism toward kin explicable by shared gene fraction (Hamilton's rule: *rb > c*) |
| ESS | A behavioural strategy that, once prevalent, resists invasion by alternatives |
| Meme | Cultural unit propagating by imitation; subject to selection-like pressures |
| Extended Phenotype | Gene effects (dams, nests, parasite behaviour manipulation) extend beyond the organism |
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## 5. Why It Matters
Reframes the entire question of animal (and human) behaviour — altruism, aggression, parental investment, cooperation — in a coherent gene-centred framework. Introduces the concept of memes, anticipating much of cultural-evolution theory. Offers a powerful rebuttal to group-selection thinking. Remains foundational reading in evolutionary biology more than four decades after first publication.
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## 6. Limitations Noted by Dawkins Himself
- The meme hypothesis is explicitly speculative; the dual inheritance / gene-culture coevolution framework has since become the dominant paradigm.
- The original text is preserved verbatim; corrections appear only in endnotes, so readers must cross-reference.
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## 7. Link to Original
https://polymatas.com/biblioteca/el-gen-egoista-extendido