A nearly century-old dead date palm tree helped solve an ancestry mystery

What the island nation of Cape Verde cherishes as its own distinctive kind of date palm is getting an ancestry reveal.

The Cape Verde date palm (Phoenix atlantica), native to the island nation it’s nicknamed for, is one of three trees there that don’t grow in the wild anywhere else. The islands, scattered off western Africa’s big bulge, have six known species of native trees all together.

Now a new DNA and seed-shape analysis adds weight to the idea that the remote palms aren’t desert-island wildlings at all. Researchers analyzed DNA from various Cape Verde date palms including a precious bit of the original 1934 specimen that a roving French botanist used to define the species.

The isolated island palms arose from the most famous, economically important and definitely domesticated date species on the planet, the analysis finds. This commercial date palm species, Phoenix dactylifera, at some point gave rise to feral offshoots that sustain themselves on sandy, dry Cape Verde, researchers report February 11 in Plants, People, Planet.

The origin wouldn’t have to be dramatic. “One or a few date seeds escaped from their grove,” speculates evolutionary biologist Jerónimo Cid Vian, who works at both the Royal Botanic Gardens, Kew in England and Bangor University in Wales.

Knowing that there’s a close gone-wild cousin on Cape Verde could cheer breeders of the commercial species. With diseases spreading and the climate changing, researchers can explore the wild island cousin for some genetic aids for coping with many dangers to dates in the rest of the world.

Though should the Cape Verde date palm still be considered a separate species? Like much of real-world biology, the species question gets “more messy than what we are taught in school — and I love that,” Cid Vian says.

Classroom rules often make it sound simple: Lump as one species all creatures whose matings could yield fertile offspring. (Perhaps a bias of Homo sapiens who haven’t had Homo relatives around in eons for fertile flirting?) Real nature, however, is more of a blur of varied life that can be categorized into separate entities in various ways.

Cid Vian, however, is not saying yet what he would want done. The palm is endangered and also has “strong cultural and ecological significance” in Cape Verde, so taxonomists, conservation experts and island people need to talk. “We are working on doing just that,” he says.

After all, how would we Earthlings feel if recently arrived Martians termed kittens and cockroaches all as Under-bedus scuttlerus?