The Arrival of Homo erectus in Southeast Asia Suspected of Changing Mosquito "Diet"

The arrival of Homo erectus in Southeast Asia approximately 1.8 million years ago did not merely reshape the evolutionary map of ancient humans. A new study indicates that this pivotal event likely also transformed the dietary preferences of mosquitoes—shifting them from primarily feeding on non-human primates to preferring human blood.

The research focuses on the Anopheles leucosphyrus (Leucosphyrus) mosquito group, now recognised as a major malaria vector in Southeast Asia. Researchers hypothesise that the ancestral mosquitoes of this species began transitioning to human blood during the period between 2.9 and 1.6 million years ago—a timeframe that coincides with Homo erectus’s arrival in the region known as Sundaland.

“Mosquito-borne diseases impose a significant burden on human health,” stated Upasana Shyamsunder Singh, lead author of the study, alongside the research team. They further explained, “The tendency of certain mosquito species to feed on human blood (anthropophily) is a principal factor influencing their potential to transmit disease-causing pathogens.”

In essence, the greater a mosquito’s preference for human blood, the higher the risk of disease transmission, such as malaria.

Using genetic data, computer modelling, and DNA mutation rate estimates, the research team reconstructed the evolutionary history of this mosquito group. The findings reveal that the preference for human blood likely evolved only once within the Leucosphyrus group, specifically in the Sundaland region—an area now encompassing the Malay Peninsula, Kalimantan, Sumatra, and Java.

Prior to this period, the ancestral Leucosphyrus mosquitoes are believed to have predominantly fed on non-human primate blood.

This discovery predates previous estimates regarding the evolution of human blood preference in African mosquito lineages, such as Anopheles gambiae and Anopheles coluzzii, which were thought to have occurred between 509,000 and 61,000 years ago.

This indicates that close interaction between ancient humans and malaria-transmitting mosquitoes in Southeast Asia may have commenced substantially earlier than previously believed.

Consequently, researchers conjecture that for this adaptation to occur, Homo erectus must have already been present in considerable numbers in Sundaland.