How Bats Evolved Wings: Scientists Uncover the Genetic ‘Switches’ Behind Flight

Bats are the only mammals capable of true powered flight, yet their wings are built from the same basic five-digit limb structure found in all mammals. A new study in Nature Ecology & Evolution sheds light on how these common genes can create such extraordinary adaptations.

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The Mystery of the Chiropatagium

In most mammals, the skin between fingers disappears before birth through programmed cell death (apoptosis). Bats, however, retain this skin to form the chiropatagium—the wing membrane crucial for flight. Scientists long hypothesized that bats evolved wings by suppressing this cell death, but the new research tells a more nuanced story.

Using single-cell RNA sequencing and other genomic tools, researchers analyzed over 180,000 embryonic limb cells from bats (Carollia perspicillata) and mice. Surprisingly, the same cell types appeared in both species, with apoptosis still occurring in bat fingers. The chiropatagium, it turns out, forms thanks to a specialized population of fibroblasts—connective tissue cells—repurposed from areas normally closer to the shoulder in mice.

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Regulatory Genes Make the Difference

These fibroblasts showed high activity of two transcription factors, MEIS2 and TBX3, genes usually switched off before finger formation in other mammals. In bats, these genes are reactivated in the developing digits, guiding the fibroblasts to persist between fingers while surrounding tissue still undergoes apoptosis. This evolutionary co-option allows bats to use existing genetic programs to build new structures without inventing new cell types.

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Testing the Wing Blueprint in Mice

To confirm the role of these genes, researchers engineered transgenic mice to express bat versions of MEIS2 and TBX3 in the distal limb and interdigital tissue. The results were striking: mouse embryos developed webbed digits and thickened connective tissue resembling early bat wings. 3D imaging revealed physical changes, including partially fused digits and expanded tissue—the hallmarks of chiropatagium formation.

Dr. Christian Feregrino, a lead author, explained, “With just these two transcription factors, we could partially recapitulate the bat’s wing-building program. Flight itself requires changes in bones, muscles, and skin, but this shows how powerful regulatory shifts can be.”

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Broader Implications

Beyond understanding bat evolution, the findings may illuminate human developmental disorders such as syndactyly, where fingers remain fused. They also provide insight into how evolution repurposes existing genes to create new structures, a principle that may apply to bird wings, fish fins, and whale flippers.

“The study demonstrates how minor tweaks to shared genetic programs can generate major anatomical innovations,” said Magdalena Schindler, co-lead author. “Single-cell tools are opening a window into the creative ways evolution rewires old genes.”

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