The human opposable thumb: with reason neurologist Frank R. Wilson called it ‘the Twenty-Four-Karat thumb’. Because thumb studies in primates have revealed that only humans have ‘perfect opposable thumbs’. But there is more, because new evidence indicates that the opposable thumb has a direct correlation with self-awareness in the primate family!
Scientists say that there are two things that have given rise to man’s dominance as a species: one is the opposable thumb, the other is self-awareness. Interestingly, scientists also developed a test to assess ‘self-recognition’ (which is in psychology known as a first milestone in the development of self-awareness in young children) via the so-called ‘mirror test’.
The video below shows how this ‘mirror test’ has also been used to assess the capability for self-recognition in primates. And the table below displays a strong correlation between self-recognition and the opposable thumb in the primate family tree (+ a the bottom a picture is presented summarizing the hand characteristics seen in the listed primate species).