--- name: dunbars-number description: > Activate when: team headcount is approaching or crossing 150 (or 50, or 500); someone says "coordination is getting harder," "we lost the startup feel," or "we don't know who does what anymore"; deciding whether to split a team, open a new office, or add a management layer. Do NOT activate when: group is well below 50 and problems are clearly interpersonal; core issue is incentive misalignment rather than group size (use principal-agent instead). --- # Dunbar's Number ## Overview **Dunbar's number** (~150) is the cognitive limit on stable social groups the human neocortex can sustain, with nested layers at ~5, ~15, ~50, then outer bands at ~500 and ~1,500. Derived by Robin Dunbar (1992) from primate neocortex ratios. Key implication: **below ~150, informal trust coordinates behavior; above ~150, formal hierarchy becomes architecturally mandatory** — not a cultural choice. Composes with [`network-effects`](../network-effects/SKILL.md) (different coordination mechanisms below vs. above 150), [`principal-agent`](../principal-agent/SKILL.md) (exceeding 150 multiplies agency problems informal trust can no longer cover), [`founder-mindset`](../founder-mindset/SKILL.md) (founder relationship bandwidth peaks at ~150 — first breakpoint demanding shift from doing to delegating structure). ## When to Use - Headcount approaching or crossing 150 (or 50, or 500) - "Coordination getting harder" complaints with no obvious structural cause - Deciding to split a team, open a new office, or create a sub-unit - Designing org structure for a scaling startup; evaluating acquisition integration plans - Diagnosing why informal culture "felt different" after a headcount milestone - AI-native startup hiring fast on abundant AI-era capital / AI-adoption demand — "we scaled from 20 to 150 in a year and coordination is breaking" **Not when:** group well below 50 and problems are interpersonal; constraint is incentive misalignment (use [`principal-agent`](../principal-agent/SKILL.md)); challenge is growing a network beyond 150 (use [`network-effects`](../network-effects/SKILL.md)). ## Coaching Novices (Adaptive Front Door) - **Engine mode:** user has a concrete org design or headcount question → run The Process directly. - **Coach mode:** user is unfamiliar → guide step by step. In Coach mode, respond one step at a time. Each [WAIT] is a hard stop — output only that step's question, then stop. 1. One-liner: once a group exceeds ~150 people, informal trust cannot coordinate it — formal structure is architecturally required by the human neocortex. 2. Check fit: what is the current headcount? Which Dunbar layer, which breakpoint is approaching? 3. Elicit the structure: what coordination mechanisms exist? Where are they breaking down? > **[WAIT — do not advance until user responds]** 4. Run The Process one step at a time with their input. > **[WAIT — do not advance until user responds]** 5. Close: group layer + breakpoint diagnosis + structural prescription (split / formalize / layer) named. > **[WAIT — do not advance until user responds]** ## The Process **Step 1 — Identify layer:** headcount → Dunbar layer (5/15/50/150/500/1,500) → distance to next breakpoint. **Step 2 — Audit coordination:** how does the group coordinate? (informal trust / formal process / hierarchy) — where are breakdowns? **Step 3 — Diagnose mismatch:** does coordination mechanism match group size? (below 50: direct knowledge ok; 50–150: structured trust ok; above 150: formal hierarchy required) **Step 4 — Prescribe structure:** A) Split — sub-units each below 150 with explicit interfaces; B) Formalize — replace relationship-based coordination with documented processes; C) Layer — add management tier. **Step 5 — Set thresholds:** current ceiling / trigger for next structural review / Gore parking-lot rule (headcount cap per unit). **Step 6 — Validate culture claims:** "Lost startup feel" — Dunbar exceeded or culture drift? "Need better communication" — is structure the actual solution? ### Output template ``` Dunbar Org Analysis: Current layer: [X] | Distance to next breakpoint: [N] Coordination mechanism: [informal/formal] | Breakdown points: [list] Root cause: [architectural / interpersonal / incentive] Prescription: [split / formalize / layer] | Sub-unit targets: [≤150] | Trigger: [headcount] ``` *→ Method in Action: [Dunbar 1992 + W.L. Gore & Associates](examples/dunbar-1992-wl-gore-associates.md)* *→ 2026 lens: [Scaling an AI-native startup team (2023–2026)](examples/ai-native-startup-scaling-2023-2026.md) — how AI capital compresses the timeline to the ~50 and ~150 breakpoints* ## Pack: Dunbar Number Across Domains | Domain | Layer | Key implication | |---|---|---| | Founding team (1–15) | Sympathy group | No process needed; direct knowledge | | Seed-stage (15–50) | Affinity group | Informal still works; minimize overhead | | Series A (50–80) | Approaching ceiling | Begin formalizing roles + reporting | | Series B / Pre-150 (80–149) | Just below limit | Build management layer before hitting 150 | | 150-person threshold | Dunbar crossed | Mandatory: documented processes + explicit hierarchy | | 150–500 / 500+ | Acquaintance / multiple groups | VP layer + OKRs; federated units each below 150 | | Remote teams | ~50–70 (compressed) | Video/async reduces relationship maintenance efficiency | *→ Primary sources: [references/sources.md](references/sources.md)* ## Common Rationalizations **[D] = designed upfront | [O] = observed in real use. [O] entries are more valuable.** | Fake move | Reality | |---|---| | [D] "We just need better communication tools" | Above 150, the problem is neocortical capacity. Slack does not fix Dunbar. | | [D] "We can maintain flat culture as we grow" | Flat culture works below 50. Above 150, informal coordination structurally fails. | | [D] "We'll hire great people who don't need management" | Quality of people doesn't change cognitive limits. | | [D] "Communication problems are a people issue" | At ~150, communication problems are architectural. HR interventions treat the symptom. | | [D] "The founders just need to be more visible" | Founder visibility works below 150. Above it, all-hands don't substitute for structure. | | [D] "We lost our startup feel — must have been wrong hires" | The startup feel was a Dunbar-layer property of a sub-50 group. Hires are not the issue. | | [D] "More team-building will restore cohesion" | Works within the 150-layer. Across groups above 150, it produces temporary warmth, no structural repair. | | *→ Add [O] entries here after each real use — paste the actual failure pattern* | *What went wrong and why* | ## Red Flags - Headcount crossed 150 without any structural change or management layer addition - Founder still coordinating a 200-person company via personal relationships - "Communication problems" diagnosed as interpersonal without checking if Dunbar limit was crossed - Org chart flat beyond 50 with no explicit coordination mechanism - Acquisition integration plan assumes two informal cultures can merge without formal structure ## Verification - [ ] Headcount mapped to Dunbar layer explicitly; distance to next breakpoint calculated - [ ] Coordination mechanisms audited against group size requirements - [ ] Root cause identified: architectural vs. interpersonal vs. incentive - [ ] Structural prescription chosen (split / formalize / layer); sub-unit targets set below 150 - [ ] Growth trigger for next structural review defined - [ ] "Culture problem" vs. "architecture problem" distinction made explicitly --- *Part of **deciqAI Knowledge Skills** — 225 open-source thinking skills that make rigor executable for AI agents. The same skills power every deciqAI agent, which runs them autonomously to operate your company. **See it run → https://www.deciqai.com/s/dunbars-number** · Built by deciqAI · github.com/deciqAI · Contributions welcome.*