Arrival of Homo Erectus may have triggered Mosquitoes鈥� taste for human blood
The arrival of substantial numbers of early human ancestors (Homo erectus) in the Southeast Asian prehistoric landmass of Sundaland, approximately 1.8 million years ago, likely triggered an evolutionary shift in Leucosphyrus mosquitoes, according to a new study.
Researchers from The University of Manchester suggest that during the Early Pleistocene, the arrival and presence of these early hominins drove the mosquitoes to adapt to feeding on humans.
The study, published in , uncovers how and why certain mosquitoes developed this preference, and the environmental triggers which brought about its development.
The findings could provide critical insight into mitigating the impacts of novel diseases caused by mosquito-borne pathogens, which place a significant burden on global human health, and shed light on the colonisation of Southeast Asia by early humans.
, Senior Lecturer in Earth and Environmental Sciences at The University of Manchester, said 鈥淥ur findings suggest that early humans must not only have been present in Sundaland at this time, but there in substantial numbers, which is an important piece of evidence, beyond fossil records, to the broader puzzle of the colonization of hominins in insular Southeast Asia.
Our findings suggest that early humans must not only have been present in Sundaland at this time, but there in substantial numbers, which is an important piece of evidence, beyond fossil records, to the broader puzzle of the colonization of hominins in insular Southeast Asia.
The team focused on the Anopheles leucosphyrus group, made up of 20 different species of mosquitoes native to Southeast Asia. Some species are extremely anthropophilic (human targeting) and very efficient spreaders of human malaria parasites. Others feed mainly on monkeys, gibbons, and orangutans in forest canopies, spreading a form of malaria that would be harmless to humans, but can be deadly for these other primates.
In the study, the researchers sequenced 38 mosquitoes - supplemented with publicly available genome data of two others - from 11 species within the leucosphyrus group. The specimens were collected between 1992-2020 and involved sampling larvae from animal wallows hidden deep in the forest or in remote areas of Southeast Asia.
The study included species of all three subgroups (Leucosphyrus, Riparis and Hackeri), and represent all three blood-feeding behaviours - human, non-human primate, and mixed - providing a solid evolutionary framework mapping host preference within the Leucosphyrus group.
They found that the ancestors of the Leucosphyrus Group likely originated in the permanently humid conditions of Sundaland (Borneo, peninsular Malaysia, Sunda Shelf), during the early Pliocene, between 5.3 and 3.6 million years ago. These conditions favoured feeding in the canopy, so the mosquitoes most likely fed primarily on non-human primates.
However, the late Pliocene and into the Pleistocene, saw extensive environmental change, where the global climate became cooler and drier. The shift from permanent humidity to seasonal, open forest and expanding savannah, saw the arrival of a host of new mammals. This led to an adapted species of mosquitoes that could feed readily both in the canopy and on the ground.
The researchers suggest that this shift toward more flexible feeding behaviour may have been the bridge to human-feeding behaviour.
This paper was published in the journal Scientific Reports
Full title: Early hominin arrival in Southeast Asia triggered the evolution of major human malaria vectors
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