Bats originated in Europe, rewriting mammals’ family tree, study reveals

In the northern forests of the Congo-Brazzaville, as the sun slips away, a distinctive honking fills the dusky sky. Every evening, thousands of hammer-headed fruit bats depart their daytime roosts in search of mates, calling out through large, box-shaped snouts that give the flying mammals the appearance of a winged moose. Here, along the Congo River, scientists have been collecting DNA swabs and tissue samples from the bats for years, working deep into the night in spacesuit-like protective gear.

Those hard-won samples are now among the thousands of specimens gathered from bats across the world that have helped to reshape what we know about the bat family tree.

In a landmark study published today in the journal Nature, a team of more than 130 international researchers combed through ancient bat fossils and genomic data from living species to establish that bats likely originated in Europe about 65m years ago – not in Africa, Asia or North America, as had previously been thought.

Rather, it seems that the earliest descendants of modern bats dispersed from Europe into Africa, then expanded onwards to Asia, the Americas and Australia. The findings also reveal that echolocation, like flight, also evolved near the dawn of bat evolution.

“Bats, on a scale of amazing to amazing, they’re super amazing,” said Sarah Olson, one of the study’s authors and director of health research at the nonprofit Wildlife Conservation Society. “It’s fun to have part of that puzzle piece in the block, and then we can keep finding and adding other puzzle pieces to it now.”

The work is part of a larger global effort known as Bat1K, launched in 2017, which seeks to sequence the genomes of all the living 1,500 bat species – the second most diverse mammal species in the world, and accounting for one-fifth of all mammals. Genomes are an organism’s complete set of genetic constructions, containing all the DNA needed to build, grow and live.

The Nature study ultimately drew on 103 bat genomes from 21 bat families, alongside 44 fossil bats – mostly their teeth – unearthed across the globe.

Olson said their findings lay the groundwork for better understanding bat physiology and, critically, how the mammals have evolved to be so resistant to disease. Bats are often identified as reservoirs of fatal zoonotic viruses, including Ebola, Nipah and Marburg – but the bats don’t get sick themselves.

“How are they living with these viruses that, when they get into us, they cause so much damage?” Olson said. “What we have now is a kind-of code book of life.”

A 2025 study based on the Bat1K genomic work found that early bat ancestors seemed to have excessive immune gene adaptations. “We showed for the first time that these adaptations associated with viral tolerance and disease resistance probably evolved at the same time that all bats evolved,” said the evolutionary biologist Ariadna Morales, who worked on both studies.

Bats are also unique among mammals in that they live exceptionally long for their size, showing few signs of ageing or cancers. Now, scientists say they will be able to investigate the genes driving those traits. What they learn could be a gamechanger for research into human ageing, immunity and disease resistance.

“With the genetic information that we can find in bats, it could be used to develop therapeutics associated with zoonotic disease. And they could also be models to develop treatments for cancer,” Morales said.

Olson added that the research can also strengthen our understanding of “what makes a healthy bat a healthy bat, and what are bats going to be susceptible to?”

About half of the known bat species have unknown or decreasing populations, with 18% of species considered threatened by the International Union for the Conservation of Nature.

Bats are at risk from the climate crisis, habitat loss, and bat persecution and harvesting, said study co-author Liliana Dávalos, a conservation biologist at Stony Brook University in New York. At the same time, bats play an important role in ecosystems, helping to pollinate plants, spread seeds, and keeping insect numbers – particularly mosquitoes, another spreader of disease – in check.

“Unlike most small mammals, all but one bat species have very small litters of one or two pups, so when individuals drop dead from scorching temperatures, or get killed through persecution or harvesting, populations cannot quickly recover their numbers,” Dávalos said.

And while bats have shown resilience to Ebola and Marburg, in Canada and the United States bats have perished by the millions from a fungal pathogen called white nose syndrome, which grows on the skin of hibernating bats.

“This research can help us go back and look at what makes the myotis bat species more susceptible to these fungal diseases,” Olson said. “There may be some interesting findings that other researchers can take from this study … to go back and piece together what’s happening with white nose syndrome.”