A bird did not literally come back from the dead on Aldabra. Something more subtle happened: after an earlier flightless population disappeared, flying rails colonized the island again, and their descendants independently lost the ability to fly.
The same island, two evolutionary episodes
Aldabra is an atoll in the Seychelles. During a major rise in sea level roughly 136,000 years ago, it was submerged, eliminating its terrestrial inhabitants. Earlier rails that had become flightless could not simply move away as conditions changed.
When land became available again, flying relatives could recolonize it. Fossils from before and after the inundation record features associated with flightlessness. Researchers Julian Hume and David Martill interpreted them as evidence that the transition happened independently on two occasions.
The University of Portsmouth’s research account describes the comparison of wing and leg bones; the 2019 paper sets out the fossil evidence.
The flying ancestor was the white-throated rail, a chicken-sized bird associated with Madagascar. The researchers’ explanation depends on flying relatives surviving beyond the flooded atoll and reaching it again; the first local flightless population did not survive underwater and later revive.
Julian Hume, the study’s lead author and an avian palaeontologist at the Natural History Museum, described the fossils in the 2019 research announcement:
“These unique fossils provide irrefutable evidence that a member of the rail family colonized the atoll, most likely from Madagascar, and became flightless independently on each occasion. Fossil evidence presented here is unique for rails, and epitomizes the ability of these birds to successfully colonize isolated islands and evolve flightlessness on multiple occasions.”
Co-author David Martill of the University of Portsmouth explained why Aldabra’s fossil sequence and ecological setting mattered:
“We know of no other example in rails, or of birds in general, that demonstrates this phenomenon so evidently. Only on Aldabra, which has the oldest palaeontological record of any oceanic island within the Indian Ocean region, is fossil evidence available that demonstrates the effects of changing sea levels on extinction and recolonization events. Conditions were such on Aldabra, the most important being the absence of terrestrial predators and competing mammals, that a rail was able to evolve flightlessness independently on each occasion.”
These quotations preserve the researchers’ interpretation at publication. The absence of terrestrial predators and competing mammals was the ecological explanation they emphasized for repeated loss of flight, not a claim that evolution follows an inevitable schedule.
What “iterative evolution” means
The term refers to the repeated evolution of similar features in related lineages at different times. It does not mean an extinct individual was revived, an old genome was reconstructed or time somehow ran backward.
Keeping the population and the ancestral lineage separate solves much of the confusion. One island population can disappear while flying relatives survive elsewhere and later reach the same place.
The comparison extends beyond birds. The 2019 feature linked work on ammonites, sea-turtle feeding forms, and sea-cow communities. Those examples concern repeated structures, ecological roles or community patterns; they should not be collapsed into the claim that an identical extinct species repeatedly comes back to life. The sea-cow study, for example, compares coexisting species with differing feeding-related anatomy across several fossil assemblages.
Why fossils are essential here
Looking only at living birds would show the present outcome. Fossils add earlier chapters, allowing researchers to compare anatomy on opposite sides of a major environmental event.
The bones do not record every generation or every movement between islands. Their value lies in the pattern they preserve and the geological context that places them in time.
This is also why the discovery should not be turned into reassurance that extinction can always be reversed. A repeated trait is not a replacement for a lost ecological community, and evolution offers no promise to recreate what disappears.
Movement makes very different stories possible
For another example of how birds’ histories are tied to place, meet Hokkaido’s white-faced long-tailed tits. To see migration on a very different scale, explore the monarch butterflies that travel to Mexico.
Aldabra’s rail is memorable because the story is both surprising and comprehensible. Flying ancestors reached an island twice; similar conditions were followed by a similar change. The wonder lies in that repeat, not in resurrection.
Earlier sources and credits: 2019 rail study · 2019 research announcement · The Mind Unleashed.
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