Climate change, infectious disease, and the spread of microblades across the Qinling-Huaihe line

Abstract

Aoki et al. (2023) proposed that the sharp difference in microblade distribution between the north and south of the Qinling-Huaihe (H-Q) line before the early Holocene could have been due to a higher frequency of pathogens in the south. Greater susceptibility to pathogen-induced disease among northerners could have effectively prevented migration across the H-Q line. Here, we explore the possibility that migration between the north and south could have been stalled by a vector-borne disease whose vector distribution was climate dependent. The original wave equation approach is extended to include climate variation in the forms of (i) a period of linear warming; (ii) a period of linear cooling; and (iii) a period of temperature oscillations. Simulations of this extended model are carried out using published estimates of the climate record for the Northern Hemisphere since the Upper Paleolithic. This analysis suggests possible time intervals during which microblades could have reached the south.