Possible handshapes are constrained by a variety of mechanic and neural factors.
Evolutionary forces have led to some handshapes being easier or more natural for humans to produce than others. These tendencies can be summarized as follows: • The selected (extended) finger is either the thumb or the index finger • Neighboring fingers are coupled • All fingers have the same shape A 2022 study of handshapes found that 85.6% of handshapes in 33 sign languages conform to these biological tendencies. Additionally, 35 handshapes were found to be represented in 89.2% of the 33 languages examined. Handshapes that did not conform to these tendencies were common in
fingerspelling. This may be due to fingerspelling being a result of culture and explicit learning rather than arising naturally. ==In American Sign Language==