Molecular and morphological congruence in hominoid trans-species polymorphisms

Molecular and morphological data increasingly have confirmed that Homo sapiens is more closely related to the African apes than to the Asian orangutan. At the same time, this evolutionary relationship has been questioned persistently from the standpoint of cladistic analyses of morphological characteristics, such as the incisive foramen; some proponents of cladistic approaches to phylogeny propose instead that Homo sapiens is closer to the orangutan. This contrast can be resolved, and various kinds of evidence brought into consistency, by (1) demonstrating that particular morphological traits, including the incisive foramen, are variable across taxa, not taxon-specific; and (2) utilizing the principle of polyclinal variation to describe the preservation of widespread, shared genetic diversity among mammalian populations, particularly those of hominoid primates.