Evolution field guide

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Consensus and debate · quick reference

One synthesis, extended?

Scientists largely agree on the observations. They disagree about whether familiar evolutionary tools already handle them well, or whether textbooks and theory should be reorganized around them.

Short version: natural selection was not replaced. The evidence and causal picture expanded; how much that expansion changes the theory’s architecture remains debated.

Four bins prevent false revolutions

DURABLE COREPopulation accountingMutation, inheritance, selection, drift, and gene flow change variant frequencies; recombination reshuffles inherited combinations.
MAJOR EXPANSIONNew access and emphasisGenomics, development, plasticity, niche feedback, symbiosis, culture, and multilevel processes are experimentally tractable and central in many cases.
LIVE DEBATEExplanatory architectureDo biased variation and reciprocal causation deserve status alongside traditional evolutionary forces? How common are plasticity-first pathways?
NOT CONSENSUSReplacement headlinesGenes no longer matter; epigenetics restores broad Lamarckism; organisms direct useful mutation; one universal holobiont replaces the organism.

Best book-club formulation: evolutionary theory has expanded substantially since 1995; no single agreed replacement has displaced the Modern Synthesis. EES proponents and critics often agree on observations while differing over causal emphasis, novelty, and what a “synthesis” must include.

Putting it together: outbreak reasoning

A hospital bacterial population contains rare resistant cells before treatment. Antibiotic kills susceptible cells. A resistance plasmid also enters later from another strain. The ward population crashes to 30 cells, then rebounds.

Which causal map is complete?

Your reusable five-question diagnostic

  1. What varies? Sequence, regulation, phenotype, symbiont, learned behavior, or environment?
  2. How is it transmitted? DNA, developmental state, parent, social learning, ecological persistence, or not at all?
  3. Where does reproduction differ? Genes, cells, organisms, groups, or lineages?
  4. What else changes frequency? Drift, gene flow, mutation bias, recombination, demographic history?
  5. What evidence separates the story from alternatives? Replicates, fitness measures, pedigrees, time-series genomes, developmental experiments, or phylogenetic models?

Book-club takeaway

What is the most defensible 2025 update to Dennett?

Enter the debate through paired sources

Book-club prompt: Which parts of Dennett’s “algorithm” remain durable, and which parts of the surrounding causal picture now deserve more emphasis? Use one concrete example from genomes, development, ecology, or cooperation.

The paired papers below are useful when the group wants to inspect the disagreement rather than settle for a headline.

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