We have analysed mitochondrial DNA (mtDNA) from 111 hair samples (samples that were originally collected from Aboriginal Australians during Board of Anthropological Research expeditions to Cherbourg, QLD (23 samples), Point Pearce, SA (41 samples) and Koonibba, SA (47 samples). DNA was extracted from a portion of the hair (about 1/3 of what was in the envelope kept at the South Australian Museum) and used this to determine the mitochondrial “haplotype” (sequence) for each sampled individual. Several community visits are planned for 2017 to obtain concent for additional hair samples to continue the research.
Building an Aboriginal Australian family tree
- The DNA sequences tell us how closely people are related, with identical sequences showing members of the same family. In the case of mitochondrial DNA, we inherit our lineage from our female ancestors. When two people have a recent common female ancestor (e.g. the same mother or grandmother) then they will have identical mtDNA. Alternatively, if there is a longer time back to a common female ancestor (say, >5 generations) for two people, then they will tend to have differences in the mtDNA – the longer the time that has passed since that common ancestor, the more changes there will be.
- We use the differences in the mtDNA to build a tree that relates all people together, with those with more similar mtDNA sequences being closer together on the tree. We can do this for all people to tell us how we are related to one another, but in this project we concentrate on the relationships between Aboriginal Australians.
Typing the mtDNA to the landscape
- Once we have determined the mtDNA sequence for each individual, we look at where these are located on the Australian landscape. This tells us if people that are closely related tend to live in the same areas, or are more broadly dispersed around Australia.
- If closely related people are found to come from the same areas, then this tells us that families have stayed in one area for long periods of time, and in the past women have tended not to move into other areas of Australia and have children with members of the local populations.
- Alternatively, if closely related people are more broadly dispersed across Australia, this tells us that in the past Aboriginal Australian women have moved around the landscape and that relationships between people from different populations were more common.
- To determine the geographical location of the mtDNA, we use the genealogical records (i.e. family trees showing relationships over multiple generations) collected by Tindale and colleagues during the expeditions where the hair was collected.
- This genealogical information allows us to trace the mitochondrial sequence back on the landscape to the oldest known female ancestor of whoever donated the hair sample. This is important because we can see back to a time prior to the disruption of Aboriginal communities following European colonisation, providing a good idea of the original distribution of families and groups across Australia.
- Overall, the genetic patterns show that there are five major groups of mtDNA sequences in Australia – which are termed M, O, P, R and S, following the one letter ordering system used globally. These major groups are called ‘haplogroups’ to signify that they contain a large number of related mitochondrial haplotypes.
- The M, O, P, R and S haplogroups were formed shortly before or just after Aboriginal people originally colonised Australia, and record information about how and when people initially spread across Australia.
- While we have a good picture of M, O, P and S, we only have 3 samples of the R haplogroup so far so can’t say much about that group yet. As we obtain more individual haplotypes we can generate an increasingly detailed reconstruction of Aboriginal Australian population history.
- We see some striking geographic patterns when looking at the distribution of the haplogroups around Australia. The most obvious pattern is the absence of haplogroups O and R from eastern Australia, whereas the other haplotypes (M, P and S) are almost entirely located around eastern Australia. This suggests that the original population entering the very north of Australia then moved around each coast separately, with one group travelling around the West Coast (O and maybe R), while the other group (M, P and S haplogroups) moved around the East Coast. Members of these groups appear to have continued their migrations around the coasts until meeting up again in South Australia.
- Within each of the haplogroups, the most closely related individuals tend to be found further south than more distantly related individuals. This suggests the earliest splits within each group occurred in the north, and is another sign that these groups colonised Australia from the north and gradually made their way south.
- A key pattern is that closely related people tend to be found in the same area, so that related mtDNA lineages tend to cluster within relatively small areas of Australia. Taken together, these features all support an extremely long association between Aboriginal people and Country. The basic patterns that we see, which reflect Aboriginal life prior to European interference, indicate that little population movement has taken place since the original colonisation of Australia around 50 thousand years ago. This is truly remarkable given the massive climatic and environmental changes seen in Australia over the past 50 thousand years, and underlines the very deep cultural connection between Aboriginal people and their Country.
- IMPORTANTLY, because we have only analysed mtDNA data to date, these patterns reflect to history of female ancestors of Aboriginal Australians and remain to be tested for male ancestors. It is possible that they could be different for males, for instance if females tended to stay in Country, whereas males were more mobile and moved between populations.
- Below we briefly summarise the findings for the different haplotype groups. Please note that the precise naming of haplotypes may be modified over time as we discover new genetic types. For example, S1 has become S1a, S1b etc. We will provide a list of these changes so it is possible to trace the history of each sequence through the project.
Details of the Haplogroups
- The O haplogroup can be split into a two major sub-groups, O1 and O2. Both groups appear to be part of a single migration that passed along the Western side of Australia, with the most recent groups being concentrated along the western coast of South Australia. O1 contains some of the more distantly related O lineages, and is found mostly in northern and central Australia. However there are few of this group (5 samples) and they all come from previous genetic studies using modern Aboriginal people, and as a result the reported geographic locations may not accurately reflect the ancestral patterns. O2 (includes O2a, O2b, O2c etc) appears to be found almost exclusively in South Australia, with most members concentrated around the western coast and surrounding inland regions of South Australia, with all but one individual lying east of Fowler’s Bay and west of Yorke Peninsula. Nearly all of the O2 individuals share a fairly recent common ancestor, suggesting that this group grew very rapidly from a single family starting about 8 thousand years ago (or about 400 great-grandmothers back!).
- The S haplogroup is also split into two major subgroups (S1/S6 and S2-S5), and has the most complicated internal relationships of all the major haplogroups. S lineages are largely eastern and Riverine in their distribution, and probably arose as part of the initial eastern migration route around Australia.
- The first subgroup consists of S1 and S6. Subgroup S1 is split into smaller groups (S1a and S1c) that are found around the Riverine and southern coast regions stretching between Melbourne and Ceduna, with another group (S1b) on the east coast near Brisbane. These patterns may reflect some more recent movement of people between the north-east and south coast within the last 30 thousand years.
The other subgroup comprises S2, S3, S4 and S5. Subgroups S3, S4 and S5 are all older northern lineages that come from previous genetic studies. Subgroup S2 also comprises several northern lineages from other studies (most of S2b), with a handful of lineages ranging from central Queensland down to the Yorke Peninsula on the southern coast. The latter pattern may reflect historical movements along the river corridors that run through these regions (i.e. along the Murray Darling River).
- The P haplogroup can also be split into two major subgroups (P4/P6 and other P’s) that appear to have arisen very early in the colonisation of the Australian and New Guinea landmass (which was joined together at the time). We know this because each of the two Aboriginal Australian P subgroups are more closely related to people now living in New Guinea, than they are to each other. This suggests a mixed population of these genetic types entered northern Australia, with some members of each group headed into New Guinea, which other members headed south into Australia. The Australian P lineages show an eastern coast-Riverine-southern coast pattern that reflects the eastern migration route.
- One P subgroup comprises P4 (also known as P11) and P6, with P6 being older northern lineages from previous genetic studies. The P4 lineages show patterns similar to S2 – there is a large group based along the southern coast (between Fowler’s Bay and Adelaide), with a smaller number of individuals arranged along the Riverine area between central southern Queensland and Victoria. The other P subgroup comprises a range of lineages (P-new, P2, P5, P6, P7, P8 and P12). P5 is the largest lineage, and is located primarily along the eastern Queensland coast between Brisbane and Cairns. The other lineages are older, with many lying in the north of Australia (e.g. P-new near Cooktown).
- The M haplogroup contains a single major subgroup (M42) and a handful of older, more northern lineages (M14, M15, M16). Once, again we see a connection between Riverine areas and the north-eastern and southern coasts, implying this river corridor has been important for human dispersal in the distant past. The M42 subgroup is broken into three regional groups with one near Adelaide (M42d), another around the Brisbane area (M42c) and a final group being spread across the Riverine and southern Queensland (M42a).
- Finally, the R haplogroup comprises only 3 samples, which are located in the Nullarbor or Simpson Desert regions.