The term "modern humans" describes us and ancestors anatomically like ourselves, members of the sub-species Homo sapiens sapiens. We have inherited the physical characteristics and cultural capacities that we modern humans take for granted. These include the capability to speak and comprehend symbolically based language, the capacity to monitor and adjust behavior according to a framework of shared norms and values, the ability to imagine things that have never been observed, and the ability to externalized physical skills in the form of tools. As the anthropologist Leslie White once put it, "in understanding cultural differences among modern humans, biology can be considered a constant."