People and the dispersal of baobabs around the Indian Ocean

April 2, 2015

The baobab, that iconic, majestic, and grotesquely massive roots-in-the-sky tree, teaches us something surprising about “nature”.  It demonstrates that what appears to be “natural” has been – for millennia and millennia – also fundamentally “social”, for people have been important dispersal agents of these trees.  Researchers like Chris Duvall and Jean-Michel Leong Pock Tsy have shown this for the African baobabs.[1,2]  Our recently completed research project, led by Priya Rangan, demonstrates this in multiple ways around the Indian Ocean.  Baobabs are such useful and remarkable trees [3], it is hardly difficult to imagine people not picking up the hard but pleasantly light and fuzzy fruit pods and walking with them.

A young baobab near an Aboriginal rock art site

A young baobab near an Aboriginal rock art site (photo: CKull)

One part of our project looked at the single species of baobabs found in Australia: Adansonia gregorii, called boab. It grows in the Kimberley region in the northwestern part of the continent.  In a study just published in PLoS ONE [4], we combine evidence from baobab genetics [5] and Australian Aboriginal languages to show that humans have been the primary agents of baobab dispersal.  In particular, we reveal their crucial role in dispersing baobabs inland from now-submerged areas of northwest Australia during the dramatic sea-level rises at the end of the last glaciation.  (See also this article in The Conversation as well as  Priya’s blog about the study)

A further question is how the baobabs arrived in Australia in the first place.  Oceanic dispersal via seed pods floating in currents, several million years ago, remains the most plausible explanation, as our collaborator David Baum has shown [6].  Yet, another one of our baobab collaborators (and veritable Renaissance man) Jack Pettigrew advances an interesting speculative argument about a possible human role in transporting the baobabs, building on evidence from rock art in the Kimberley and in Read the rest of this entry »