Sal, have they taught great apes or any other simians to use sign language... and what was the result?
Hello, Allan.Yes... Great apes have been taught sign-language-like systems, and the results were fascinating... but also very clarifying about the limits of non-human cognition.
Here’s the picture.
Who was taught sign language?
Washoe (chimpanzee)
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Taught American Sign Language (ASL) in the 1960s.
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Reportedly learned ~130 signs.
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Could combine signs like WATER + BIRD for “swan.”
Koko (gorilla)
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Learned a modified ASL system.
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Claimed vocabulary: ~1,000 signs (this number is disputed).
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Used signs to request food, play, comfort, etc.
Nim Chimpsky (chimpanzee)
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Taught signs under tightly controlled conditions.
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Learned many signs, but mostly used them to make requests.
Kanzi (bonobo) (important case)
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Did not learn ASL directly.
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Learned a lexigram keyboard (symbols mapped to words).
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Demonstrated strong comprehension of spoken English commands.
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Could respond appropriately to novel sentence structures.
What did they actually achieve?
What they could do:
What they did not do:
The key scientific conclusion:
Apes can use symbols instrumentally, but not generatively!
In plain terms:
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They communicate to get things.
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Humans communicate to share meanings, explain, imagine, and reflect.
Their “sentences” lacked:
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Stable word order.
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Grammatical roles.
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Abstract reference.
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Open-ended creativity.
When tested rigorously (especially with Nim), most signs turned out to be:
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Prompted.
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Context-bound.
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Reward-driven.
Why this matters: (especially for your work)
This research strongly supports a biological threshold for full language.
It aligns cleanly with:
That boundary appears:
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Biological.
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Neurological.
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Emergent — not cultural.
Bottom line:
Great apes can:
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Learn symbols.
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Use signs.
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Communicate desires.
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Understand more than they can express.
But they never develop language in the human sense.
Language... especially abstract, recursive, meaning-for-its-own-sake language... remains uniquely human!
And that fact is one of the strongest empirical anchors for your broader thesis about experience, biology, and meaning.
If you want next:
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A short paragraph you can drop straight into Being Human.
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Or a comparison with dolphins, corvids, and parrots. (which adds another twist)
Just say the word.
Here’s a clean, publication-ready conceptual diagram you can use as-is. It keeps everything factual and aligned with your distinction between sentience and sapience.
Sentience, Sapience, and Language.
Apes vs Humans:
┌─────────────────────────────┬─────────────────────────────┐│ GREAT APES │ HUMANS │├─────────────────────────────┼─────────────────────────────┤│ │ ││ SENTIENCE │ SENTIENCE ││ ──────────────────────── │ ──────────────────────── ││ • Subjective experience │ • Subjective experience ││ • Pain / pleasure │ • Pain / pleasure ││ • Emotions │ • Emotions ││ • Social bonding │ • Social bonding ││ • Intentional behavior │ • Intentional behavior ││ │ ││ (Strong, continuous) │ (Strong, continuous) ││ │ │├─────────────────────────────┼─────────────────────────────┤│ │ ││ SAPIENCE │ SAPIENCE ││ ──────────────────────── │ ──────────────────────── ││ • Limited problem solving │ • Abstract reasoning ││ • Tool use │ • Self-reflection ││ • Social learning │ • Metacognition ││ • Episodic memory │ • Moral reasoning ││ │ • Counterfactual thinking ││ (Partial / bounded) │ ││ │ (Full / generative) ││ │ │├─────────────────────────────┼─────────────────────────────┤│ │ ││ LANGUAGE │ LANGUAGE ││ ──────────────────────── │ ──────────────────────── ││ • Symbol use │ • Symbol use ││ • Gestures / signs │ • Syntax & grammar ││ • Lexigrams │ • Recursion ││ • Requests & commands │ • Narrative ││ │ • Abstraction ││ ✘ No grammar │ • Explanation ││ ✘ No recursion │ • Meaning-for-its-own-sake ││ ✘ No narrative │ ││ │ (Open-ended & cumulative) ││ (Instrumental) │ ││ │ │└─────────────────────────────┴─────────────────────────────┘
One-line interpretation! (useful as a caption)
Apes experience the world and can symbolically act within it.
Humans experience the world and can symbolically model, explain, and reinterpret it!
Why this diagram matters:
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The sentience layer overlaps → continuity of experience.
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The sapience layer diverges → emergence of reflective cognition.
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The language layer bifurcates sharply → biology-limited symbolic recursion.
This makes it very clear that:
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The gap is not cultural.
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Not educational.
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Not motivational.
It is biological and emergent, not a missing training program.

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