The progenitors of contemporary malaria-transmitting mosquitoes belonging to the Anopheles leucosphyrus (Leucosphyrus) group may have transitioned to sanguivorous engagement with humans approximately 1.8 million years ago, a period aligning with the ingress of Homo erectus into Southeast Asia.
The advent of Homo erectus across Southeast Asia approximately 1.8 million years ago instigated the evolutionary trajectory of significant vectors for human malaria.
Among the vast catalog of 3,500 identified mosquito species, a predilection for hematophagy from human hosts is an infrequent characteristic. Nevertheless, this specific feeding inclination serves as a principal determinant of a mosquito’s capacity to disseminate pathogenic agents.
“Diseases transmitted by mosquitoes impose a considerable global health burden,” remarked the study’s principal investigator, Upasana Shyamsunder Singh, alongside her esteemed colleagues.
“The inclination exhibited by mosquitoes of a particular genus to engage in hematophagy from humans (termed anthropophily) constitutes the paramount factor governing their potential to transmit disease-causing pathogens.”
“While mosquitoes can exhibit opportunistic host selection, with numerous species displaying variable degrees of host specificity, comprehending the evolutionary genesis of anthropophily and the specific circumstances that precipitated its development can furnish invaluable insights for mitigating the ramifications of emergent diseases caused by mosquito-borne pathogens.”
In pursuit of their research objectives, the investigators meticulously sequenced genomic data from 38 mosquito specimens representing 11 distinct species within the Leucosphyrus group. These specimens were procured from Southeast Asia between the years 1992 and 2020.
Subsequently, these genetic sequences were integrated with computational models and estimations of DNA mutation rates to meticulously reconstruct the phylogenetic lineage of these species.
It is posited that the evolutionary development of a preference for human blood meals occurred on a singular occasion within the Leucosphyrus lineage, spanning a time frame between 2.9 and 1.6 million years ago, within a geographical expanse known as Sundaland. This region encompasses the Malay Peninsula, Borneo, Sumatra, and Java.
Prior to this evolutionary shift, the ancestral populations of Leucosphyrus mosquitoes subsisted on the blood of non-human primates.
This temporal window closely aligns with the earliest proposed timeline for the appearance of the hominin species Homo erectus in this geographical locale, estimated at approximately 1.8 million years ago. Furthermore, it predates the arrival of anatomically modern humans, which is dated between 76,000 and 63,000 years ago.
This finding also precedes previous estimations concerning the evolution of a human-feeding preference in the mosquito lineage that ultimately gave rise to the prominent African malaria vectors, Anopheles gambiae and Anopheles coluzzii, which occurred between 509,000 and 61,000 years ago.
Previous scientific inquiries have indicated that alterations in mosquito feeding proclivities necessitate multiple genetic modifications within genes that encode olfactory receptors crucial for detecting body odor.
The research team posits that the evolutionary adaptation of a preference for human body odor among the Leucosphyrus species might have been contingent upon the substantial numerical presence of Homo erectus in Sundaland around 1.8 million years ago.
“Our discoveries suggest that anthropophily within the Leucosphyrus group emerged in Sundaland during the Early Pleistocene epoch as a direct consequence of the arrival of early hominins. These hominins must have not only been present in this region by this epoch but also in sufficient numbers to precipitate an adaptation towards human host preference,” the authors elucidated.
“This assertion corroborates the hypothesis that early hominins inhabited and were abundant in Sundaland 1.8 million years ago, preceding their extensive migration to Java via land bridges.”
“Fossil evidence from the Middle Pleistocene era, specifically concerning Homo erectus, points to their enduring presence on the exposed Sundaland landmass, likely in proximity to extensive riverine systems.”
“Considering the highly fragmented nature of the fossil record in tropical Southeast Asia, our research contributes a significant piece of evidence to the broader enigma surrounding the colonization of insular Southeast Asia by hominins.”
The team’s conclusions have been formally published in the esteemed journal Scientific Reports today.
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U.S. Singh et al. 2026. Early hominin arrival in Southeast Asia triggered the evolution of major human malaria vectors. Sci Rep 16, 6973; doi: 10.1038/s41598-026-35456-y
