Passionate argument and reasoned judgment, he warned, were being driven to the margins by scales of one to four stars, by opposed thumbs and sound bites.
Terrestrial monkeys, such as the baboon, do not have reduced thumbs and can carry out precise movements with fingers and opposing thumb.
You can squeeze the bejeebers out of the gun if you wish, using the natural pincer made up of your index finger and opposing thumb.
They also split their fingers so that, counting the space between the opposing thumbs, there were five spaces for each hand.
In primates, the combination of opposing thumbs, short fingernails (rather than claws) and long, inward-closing fingers is a relict of the ancestral practice of gripping branches, and has, in part, allowed some species to develop brachiation (swinging by the arms from tree limb to tree limb) as a significant means of locomotion.
Subjects sat with their arms supported (flexed at the elbow, forearm semi‐pronated) and opposed their thumb to the other fingers against resistance of a semi-compliant object.
Now that we have the sensation of the left thumb and hand sewn together, we now want to make sure that we have a short left thumb opposed to a long left thumb.
For example in a power grasp, one virtual finger might be the thumb and the other might be the palm while a precision pinch might oppose the thumb to a virtual finger comprising one or more of the other fingers.
Subjects naturally grasp the small objects between the thumb and either (or both) the index and the middle fingers and the large objects opposing the thumb with all the other fingers.
Other muscles named for this function include the adductor pollicis, which draws in and opposes the thumb, and the adductor hallucis, which acts on the great toe.
