Opposable Thumbs Make You Easier to Fool (Sometimes)
But would having non-opposable thumbs protect from other types of deception as well?
After all, as is currently being demonstrated, Lincoln was right when he observed: You can fool some of the Primates some of the time, and all of the Primates some of the time...
Only Monkeys With Opposable Thumbs Are Fooled By This Famous Magic Trick
Monkey magic reveals how our hands shape the way we think.
Scientists performed the famous magic trick known as the French drop for three species of monkeys and found one saw right through it. Crucially, the difference was not in the animals eyes, but in their hands. Those with opposable thumbs like our own were taken in by the performance, sharing our expectations of how the actions would play out, while those that lack thumbs didnt see the point...
...A skilled operator can make human eyes follow the second hand in the expectation the coin will be there. However,
a key part of the deception is hiding the thumb of the second hand in such a way that the audience thinks it is holding the coin. Garcia-Pelegrin wondered if this would work on less thumb-dependent animals.
https://www.iflscience.com/only-monkeys-with-opposable-thumbs-are-fooled-by-this-famous-magic-trick-68294
There's a YT video discussing this fascinating behaviour: