Mosquitoes’ preference for human blood may have originated nearly 1.8 million years ago, coinciding with the emergence of Homo erectus in Southeast Asia, according to a study published Thursday in the journal Scientific Reports.
Researchers analyzed the DNA of 40 mosquitoes from 11 species within the Anopheles leucosphyrus group, finding that the inclination to feed on humans – known as “anthropophily” – likely developed between 2.9 and 1.6 million years ago. This timeframe aligns with the period when Homo erectus is believed to have arrived in the region, suggesting a link between the hominin’s presence and the mosquitoes’ dietary shift.
The study, led by Upasana Shyamsunder Singh of Vanderbilt University, focused on mosquito species found in Southeast Asia. Some species within the Anopheles leucosphyrus group strongly prefer human blood, even as others primarily feed on non-human primates like monkeys, gibbons, and orangutans. The genetic analysis allowed the team to reconstruct the insects’ evolutionary history by examining mutation rates in their genes.
“We were not expecting this group to have originated so long ago,” said Catherine Walton, an evolutionary biologist at the University of Manchester in England, as reported by SciTechDaily. “The most parsimonious explanation is that it was in response to these early hominins arriving.”
Before the arrival of Homo erectus, the mosquitoes exclusively fed on the blood of non-human primates in the rainforest canopy, a behavior that dates back more than 3.6 million years. The researchers believe the abundance of Homo erectus was a key factor in driving the evolutionary change, potentially due to the hominin’s unique odor.
The study pinpointed Sundaland – a now-submerged landmass encompassing the Malay Peninsula, Borneo, Sumatra, and Java – as the likely location where this adaptation first occurred. While only around 100 of the roughly 3,600 known mosquito species currently target humans, the research highlights the ancient origins of this problematic relationship.
The findings, too reported by Scientific American and Phys.org, suggest that the Anopheles leucosphyrus group was the first to adapt to feeding on humans, with other mosquito species acquiring this preference more recently, within the last 10,000 years.
