[4][2] The pisiform is the only carpal bone with insertions and attachments for the abductor digiti minimi and the flexor carpi ulnaris.

[2] It is suggested that due to the pisiform's surprisingly large range of movement along its articulation surface with the triquetral bone (about 1 cm of movement is allowed), contraction of the flexor carpi ulnaris is necessary for the pisiform to remain stable enough for the abductor digiti minimi to function effectively.

Others suggest that the pisiform's link with Hoxa11 and Hoxd11 could tie its developmental history to that of the forearm, whose length is determined by Hox gene expression.

[2] Within the context of this hypothesis, because modern forearm proportions are not seen until Homo erectus at 1.5 million years ago, it is possible that pisiform reduction would have also occurred around this time.

[2] Alternatively, the same group suggests that the reduction could be a reflection of independent selection associated with the production and use of stone tools,[2] but changes in pisiform morphology have yet to be studied in relation to their effect on wrist function.

[9] In mammals and non-human primates, the pisiform is an enlarged and elongated bone that articulates with the distal ulna.