The largest combined bat genome and fossil study ever conducted has rewritten the evolutionary history of one of Earth's most remarkable animal groups. The findings, published this week in the journal Nature, show that bats first appeared in Europe about 65 million years ago, in the immediate aftermath of the asteroid impact that wiped out the dinosaurs. This challenges long-held assumptions that bats originated in North America, Asia, or Africa.
Bats are critical players in global ecosystems. They pollinate plants, disperse seeds, and consume enormous numbers of insects. As one of only three lineages of flying vertebrates in Earth's history, they now account for more than a fifth of the world's mammal species. Yet their evolutionary story has remained surprisingly murky, until now.
What did the largest bat genome study reveal?
Researchers assembled the most extensive collection of high-quality bat genomes to date, covering 103 species representing all 21 recognised bat families. They combined this genetic data with an analysis of 44 fossil bats to construct a detailed family tree and pinpoint when and where bats first emerged.
The evidence points to Europe as the cradle of bat evolution, roughly a million years after the asteroid strike 66 million years ago that enabled mammals to become the dominant land animals. Relatively soon after their European debut, bats reached Africa, making those two continents the early hubs of bat diversification, according to evolutionary biologist Liliana Davalos of the State University of New York at Stony Brook, one of the study's leaders.
Did flight and echolocation evolve together?
The study also concluded that echolocation, the biological sonar system many bats use to navigate and hunt in darkness, evolved near the very dawn of bat evolution, alongside powered flight.
“I think being able to do both, fly and echolocate, opens up the most amazing opportunities to move into new niches. Hunting at night when there's less competition and fewer predators, for example. Flight got them into the air. Echolocation let them own the night,” said Sonja Vernes, a professor of biology at the University of St Andrews in Scotland and a co-leader of the study.
“Echolocation allowed bats to become nocturnal, essentially, and not compete with birds or be preyed on by diurnal birds,” added Emma Teeling, a zoology professor at University College Dublin and another study leader.
Whether flight or echolocation came first remains an open question. The oldest known bat fossils, dating to roughly 52 million years ago, already show both capabilities. “We need to find the oldest 'pre-bats,' or transition fossils, and see if they had anatomical characteristics indicative of flight or echolocation,” Teeling said.
Why did bats take to the skies after the dinosaurs?
Bats are the only mammals to have achieved powered flight, joining the flying reptiles called pterosaurs and birds as the only vertebrates to do so. While birds survived the asteroid, pterosaurs did not. Their extinction may have opened ecological niches that a new lineage of flying vertebrates could fill.
Bat wings are built differently from those of birds and pterosaurs. They are modified forelimbs with greatly elongated fingers supporting a large skin membrane, a design unique among vertebrates.
What did the ancestors of bats look like?
The appearance of the earliest bats remains a mystery. “We don't know for sure but I reckon they looked like tree shrews starting to grow long fingers. This is just a guess as all of the oldest fossils look like modern bats,” Teeling said.
What can bat genetics teach us about human health?
Beyond evolutionary history, the study lays important groundwork for medical research. Many bat species show remarkable resistance to disease and live exceptionally long lives relative to their size. Understanding the genetic basis of these traits could have significant implications for human health.
“This work could eventually inform human research into ageing, immunity and disease resistance,” Teeling said.
What are the most remarkable bats alive today?
Modern bats display an extraordinary range of shapes, sizes, and lifestyles. The largest is the giant golden-crowned flying fox of the Philippines, with a wingspan of 1.7 metres. The smallest is the bumblebee bat of Thailand and Myanmar, with a wingspan of about 13 centimetres.
Many bats are insectivores, while others consume fruit, nectar, fish, and in the infamous case of vampire bats, blood. The diversity includes horseshoe bats, leaf-nosed bats, mouse-tailed bats, trident bats, ghost-faced bats, mustached bats, sucker-footed bats, hammer-headed bats, and wrinkle-faced bats.
“Bats constantly surprise us. They're one of evolution's greatest experiments,” Vernes said.
Frequently asked questions about bat evolution
When did bats first appear on Earth?
According to the new study, bats first appeared in Europe about 65 million years ago, roughly one million years after the asteroid impact that killed the dinosaurs.
Where did bats originate?
The study indicates bats originated in Europe, not in North America, Asia, or Africa as previously hypothesised. They spread to Africa relatively soon after, making both continents early centres of bat evolution.
Did bats evolve flight or echolocation first?
It is still unclear. The oldest bat fossils show both capabilities, so scientists need to find transitional fossils to determine which evolved first.
Why are bats important to ecosystems?
Bats pollinate plants, disperse seeds, and eat vast quantities of insects. They represent more than a fifth of all mammal species and are one of only three vertebrate lineages to have evolved powered flight.