According updates on molecular genetics, the development of human schistosomes in Asia with subsequent migration to the African continent is considered to be the most probable course of events. Generally, there are 2 hypotheses of the genus Schistoma. A hypothesis of Gondvana origin was based on snail host phylogeny and paleonthology and considered first schistosomes to originate on this continent to and appear in Asia from the Indian subcontinent platform 70-150 million years ago and in South America before Gondvana's split 60-120 million years ago. The recent data of molecular genetics show a high similarity between ITS2 sequences of S.bovis and S.intercalatum, with slightly lesser one between S.bovis and S.matthei. The similar pattern with slightly fewer differences can be seen in variability of cytochrome C subunit 1. Webster et al. 2006 noted a generally high similarity among species of the African group of schistosomes and considered it to originate from interspecies hybridization inside this group. Such hydridization occurring in both nature and a laboratory can make uncertain the determination of schistosome species based on a certain single gene marker.