This study integrated from the onset, anthropological, molecular and ecological research to test if Aboriginal-mediated dispersal can explain the distribution of a valuable but non-cultivated resource tree, the Black Bean (Castanospermum australe, Fabaceae). The Black Bean is a culturally important rainforest tree that produces toxic but highly nutritious water-dispersed seed.
Anthropological evidence for prehistoric Aboriginal-mediated dispersal includes: extensive use by Aboriginal people of the species; several verbal sources including Songlines (Dreaming tracks) describing the deliberate movement of this species by Aboriginal people; linguistic evidence (homogeneity across NSW, heterogeneity in the Wet Tropics).
This ethnographic data and first-hand corroboration by Aboriginal knowledge custodians was supported by genomic data. By using whole-chloroplast sequencing, we showed genomic homogeneity across in NSW but not in northern Queensland. This suggests recent and rapid dispersal across multiple NSW catchments from a single maternal lineage, as expected from a scenario of recent indigenous deliberate dispersal. Our data could also exclude the potential contribution of other dispersal mechanisms.
Evidence of prehistoric Australian Aboriginal people dispersing plants for their direct need and benefit challenges assumptions of “natural” plant distributions. Current debates on the role of human-assisted migration and other active management options could benefit from the acceptance that Aboriginal people deliberately dispersed species in the past. This is particularly relevant since current measures of restoration success are often based pre-European reference systems.
We are continuing our research on the Black Bean in collaboration with Macquarie University, aiming to continue combining cultural knowledge and genomic data to investigate continent-wide human-mediated dispersal pathways.
Some of the questions from our current research include:
- Have indigenous people dispersed Black Bean from Queensland to NSW (and maybe across a small number of Pacific Islands)?
- If so, what pathways and distribution mechanisms did they use?
- Were the seed sourced from a specific area, or randomly collected along the way?
Some of our relevant publications:
- Rossetto M, Ens EJ, Honingh T, Wilson PD, Yap JYS, Costello O, Round ER, Bowern G (2017) From Songlines to genomes: prehistoric assisted migration of a rain forest tree by Australian Aboriginal people. PLOS ONE 12(11): e0186663
- Rossetto M, Yap JYS, Kooyman R, Laffan S (2015) From ratites to rats: the size of fleshy fruits shapes species distributions and continental rainforest assembly. Proceedings of the Royal Society B 282:20151998.