HAR2 includes HACNS1 a gene enhancer "that may have contributed to the evolution of the uniquely opposable human thumb, and possibly also modifications in the ankle or foot that allow humans to walk on two legs".
The HAR2 gene, specifically its component HACNS1, is suggested to have contributed to the development of the human thumb's unique grasping ability and may also be involved in changes to the ankles and feet that allow for bipedal walking.