One‐Few‐Many
Play it: testingthetree.com/one-few-many · ~2 minutes · no background needed
An interactive argument about LUCA — the Last Universal Common Ancestor, the single point where every family tree of life is usually said to converge.
You don't read this one so much as walk through it. Three questions, and each answer locks in the next step of the logic. There's no way to dodge the conclusion your own answers lead to.
1. Was LUCA a single cell, or a population? Darwin's own phrase was "one primordial form." But nothing forces the ancestor of all life to have been literally one cell instead of a group of similar early organisms.
2. If it was a population, did that population share one common ancestor of its own? This is the question that does the real work. Say yes, and you've just pushed LUCA back one more step — the "single ancestor" reappears, just earlier than you thought. Say no, and you're now saying life started independently, more than once.
3. If there were multiple independent starts — how many? A slider lets you pick your number. Then Darwin (a small animated character who reacts to your choices) shows you what that number actually implies.
- Path A — LUCA stays. You've decided the population shared one ancestor. The "one common ancestor" idea survives, unchanged.
- Path B — LUCA reappears. You said no shared ancestor for the population, but that just relocates the single-ancestor point one step earlier — it doesn't remove it.
- Path C — Many. You said there wasn't one shared ancestor, and pushing it back doesn't fix that either. You're left with N independent origins of life, where N is whatever you chose.
None of the three endings is "the trap." They're all logically available — the game just makes you follow the one you picked all the way to where it actually leads, instead of stopping halfway.
Most people have a gut answer to "did all life come from one ancestor?" before they start. This game doesn't argue with that gut answer — it just asks you to define your terms precisely enough that the gut answer turns into a real, followable claim. A lot of the tension lives in Question 2, not Question 1.
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