The sub-field is also defined as, "the study of relationships between a population of humans and their biophysical environment".
ðə sˈʌbfˈiːld ɪz ˈɔːlsoʊ dᵻfˈaɪnd æz, "ðə stˈʌdi ʌv ɹᵻlˈeɪʃənʃˌɪps bᵻtwˌiːn ɐ pˌɑːpjʊlˈeɪʃən ʌv hjˈuːmənz ænd ðɛɹ bˌaɪoʊfˈɪzɪkəl ɛnvˈaɪɹənmənt".