Editing Pisiform bone (section)

== Development ==
Compared with other non-human primates, [[human]]s have a short pisiform bone. This dramatic size difference is suggested to be the outcome of a lost growth plate in hominins some time between ''[[Australopithecus afarensis]]'', who has been shown to have an elongated and ape-like pisiform, and ''[[Neanderthal|Homo neanderthalensis]]'', who is suggested to have a pisiform resembling the modern human condition.

It is suggested that the first signs of human pisiform ossification, observed between the ages of 7 and 12, corresponds to the period of secondary pisiform ossification in apes. This can point to a couple different changes in development: either this growth plate loss in humans is also accompanied by a developmental shift in the timing of pisiform formation, or it is the primary center that fails to form in humans and as a result our pisiform is homologous to the [[epiphysis]] of other mammalian pisiforms.<ref name=":0" />

Studies looking at the effect of [[Hox gene]] knockouts on the formation of the pisiform in mice have suggested that the modification of Hoxa11 or Hoxd11 genes, or the downstream targets they affect, could have acted as the mechanism for the reduction we see in the human pisiform condition.<ref name=":0" />