For decades, scientists have debated where bats first evolved, with Africa, Asia and North America among the proposed origins of the only mammals capable of powered flight. A study published in Nature offers new evidence for a different answer: Europe. According to the research, an international team analysed genomes from 103 bat species and combined genetic evidence with a dataset containing 44 fossil bats. The results suggest that bats most likely originated in Europe during the late Paleocene. University announcements about the research have described the origin as approximately 65 million years ago, but that figure should not be paired with the late Paleocene date unless the paper’s root-age estimate confirms it. The work was carried out through the Bat1K consortium, a global initiative to generate high-quality reference genomes for living bat species. The researchers also reconstructed how early bat lineages spread into other regions, offering a revised picture of the evolutionary history of one of the most distinctive groups of mammals.
Bat origins in Europe: how 103 genomes and 44 fossils reveal where bats originated
The scale of the dataset is central to the study. The researchers analysed genomes from 103 bat species, including 42 newly generated chromosome-level assemblies, representing all 21 currently recognised bat families. They combined this genomic evidence with a morphological dataset containing 44 pre-Quaternary fossil taxa. The paper, titled Reference genomes and fossils revise bat family phylogeny and biogeography, integrates genetic information with anatomical evidence from living and extinct bats to reconstruct their evolutionary relationships and geographical history.The researchers used these combined datasets to address long-standing disagreements about how bat families are related and where their ancestors lived. Earlier studies proposed different origins for bats using different approaches. Some analyses favoured North America by combining fossil and molecular evidence, others pointed to Africa through early biogeographical models, while studies relying on living species alone supported an Asian origin. These differences reflect, in part, the limitations of individual methods and the scarcity of fossils that can clarify the earliest stages of bat evolution. By incorporating fossils into their evolutionary and biogeographical models, the team estimated that the ancestral bat lineage originated in Europe during the late Palaeocene. The analysis assigned a 99.2% posterior probability to Europe as the origin of bats under the study’s model. This is strong support within the analysis, rather than proof that every aspect of bat origins has been settled. The researchers inferred that descendants of this European ancestor most probably dispersed to Africa. From the Europe–Africa region, separate lineages subsequently expanded into the Americas, Asia and Australia as modern bat groups diversified. The study therefore suggests a more complex history of dispersal than a single migration route across continents.
Bat1K consortium study in Nature: a revised bat family tree
Reconstructing the bat family tree presented a substantial challenge. Different regions of a genome can preserve conflicting signals about evolutionary relationships, and the history of bat lineages is more complicated than a straightforward branching pattern. The researchers used large-scale genomic comparisons and additional analyses to investigate these conflicting signals and revise relationships among bat families. The resulting phylogeny resolves several contested relationships among major bat groups. It also places the family Myzopodidae, which includes bats native to Madagascar, as the earliest branch within the superfamily Vespertilionoidea. These results help explain why earlier genomic studies reached different conclusions about parts of the bat family tree.The research forms part of Bat1K, an international effort to generate chromosome-level reference genomes for all living bat species. The 103-species dataset includes 42 new assemblies produced for this study, with representatives from every currently recognised bat family. Such reference genomes allow researchers to compare DNA across species and investigate the genetic changes associated with the evolution of distinctive bat characteristics. Beyond this study, bats are known to perform important ecological roles, although these vary by species. Many consume insects, while fruit-eating and nectar-feeding species can contribute to seed dispersal and pollination. Some bats are exceptionally long-lived relative to their body size, and research has identified unusual features of bat immunity. The new phylogeny provides a framework for investigating how these characteristics evolved across different lineages; it does not, by itself, establish the biological mechanisms behind them.
Flight, echolocation and what ancient bat fossils reveal
The study also examines the evolutionary history of powered flight and laryngeal echolocation. Bats are the only mammals capable of powered flight, while many species use echolocation, producing sounds and interpreting returning echoes to navigate and locate prey. The researchers’ biogeographical analysis indicates that bats, and therefore powered flight, most likely originated in Europe during the late Palaeocene.Fossil evidence also helped the team investigate when echolocation appeared. The researchers placed the fossil bat Vielasia within the oldest “Eochiroptera” clade in their analysis, although this placement had a posterior probability of 68%, which the authors characterised as medium support. The result is consistent with laryngeal echolocation having evolved before the diversification of crown-group bats, but the uncertainty in the fossil’s placement should be kept in mind. Because this conclusion depends on the fossil’s placement within the reconstructed evolutionary tree, it should be understood as an inference from the combined evidence.The researchers reconstructed an ancestral bat karyotype, identifying 26 ancestral bat chromosomes. This provides a framework for investigating how chromosome organisation changed during bat evolution. These data can help scientists investigate the genetic history of bat adaptations, including those associated with flight and immunity. The resource may also support future research into longevity and disease, although any implications for human health would require further investigation.
