For millions of years, the mighty baobabs have stood sentinel on three different landmasses, asking each other an existential question: Who came first?

The giant trees, with bulging trunks and pips, are easily distinguishable. The baobabs they can live for more than 1,000 years, according to CNN, acting as the keystone species in dry forest environments in Madagascar, a region of continental Africa and northwestern Australia. Known as the ‘mother of the forest’ and ‘the tree of life’, almost every part of the tree can be used by humans and animals, meaning they are of immense value to any ecosystem they inhabit.

Their reputation is overshadowed by the mystery surrounding their origins. Until now, science has had to make do with multiple conflicting hypotheses. The prevailing theory was that they came from mainland Africa. That appears not to be the case, according to a study published last month in the journal Nature. A team of international academics has successfully sequenced the genomes of each of the eight baobab species, examining their relationship to each other, and concluded that they originated in Madagascar.

The news comes at a time when trees are facing a steep decline on the island, home to six baobab species, with one of them likely to disappear by 2080, according to the study, unless major interventions are made.

Biologists have struggled to determine the tree’s origins, as no fossils of ancient baobabs or their ancestors have been discovered, explained Dr. Wang Jun-Nan, one of the study’s authors, a researcher at the Wuhan Botanical Garden in Hubei, China. The genetic data recovered from baobabs in previous studies was limited, he continued. But with the first complete genome sequence of any species, “we can tell a good story about their evolutionary history,” he argued.

This story begins with the rise of baobabs in Madagascar about 21 million years ago, before the genus (scientific name Adansonia) began to diversify and two species arrived in Africa and Australia about 12 million years ago. This happened long after the breakup of the Gondwana “supercontinent”, so the baobab is likely to have spread through seeds carried in the ocean on floating debris caused by flash floods, according to the researchers.

The study, a collaboration between the Wuhan Botanic Gardens in China, the Royal Botanic Gardens in the UK, the University of Antananarivo in Madagascar and Queen Mary University of London, was also able to trace gene flow between species of eight types of baobabs for the first time. These data, which showed low genetic diversity between two species and inbreeding of one species with another, offer insights into competition between baobabs today, Dr Wan said, and could help protect the trees of tomorrow.

“We hope that in the future, the people of Madagascar can take care of baobabs by considering them as different species, not as a whole,” he added.

Only one species of baobab is not on the IUCN Red List of Threatened Species: A. digitata, which inhabits mainland Africa. Three species in Madagascar are threatened with extinction, and the study recommended that the IUCN reclassify one, A. suarezensis, from “endangered” to “critically endangered.” Climate modeling has shown that the species could become extinct within 50 years without major intervention.

This prediction is “reasonable” and “underlines the urgent need for action”, according to Dr Seheno Andriantsaralaza, a tropical ecologist working in Madagascar.

Dr Andriantsaralaza, who was not involved in the research, supported the call to update the IUCN status of some Madagascar baobabs. Although he described the study as “fantastic and meaningful”, yielding “valuable” insights from genetic data, he warned that it represented “only one piece of the puzzle in understanding the evolutionary history and dispersal mechanisms of these iconic giant trees”.

“Madagascar’s baobab forests belong to local communities who rely on natural resources to feed their families,” he added. “It should be part of the solution, not the problem.”

Dr. Wan said he hopes the research and media attention will lead to further conservation efforts for the island’s baobabs.

The study concluded that the range of baobab species has been declining on the island for millennia, with human-induced climate change and ongoing deforestation exacerbating the shrinking and fragmentation of baobab populations in recent decades.