Questioning the India-Australia link and timeline

Darshi Arachige recently made me aware of a study of his authorship, which is broadly coincident with the criticisms I made to Pugach 2013:

Darshi Arachige, Do the Estimated Admixture Times Confirm the Proposed Holocene Gene Flow from India to Australia? Social Science Research Network 2013 → LINK

Abstract

This paper argues that the current estimates for the time of influx of Indian genes into some sections of Australian Aboriginal population during Holocene bear large uncertainties which make elimination of the probability of a more recent gene flow less likely. It also highlights that indications for the plausibility of a later gene flow exist and can also be placed in a likely archaeological perspective.

My own very brief synthesis of the criticisms (all very legitimate) is as follows:

• Excessive conclusions come from subjective interpretation the PC (eigenvector) analysis. 
• Too large, diverse dataset: Pugach et al. use an excessively broad dataset, what tends to hide important information unless you look at great depths, which they do not.
• Confidence intervals were hugely underestimated (a way too common academic malpractice).
• The arbitrarily wrong interpretation of the Holocene techno-cultural changes in Australia, which in no way are related to India but to SE Asia.
• Ignoring Kumar 2009, whose estimates for the South Asia - Australia gene flow is of 60-50 Ka BP. 

Intriguingly however, Arachige mentions the Aboriginal legends about the Bajini, which he considers as possible Dravidian migrants, with all cautions. 

Conclusion

In the preceding discussion, it was shown that the possibility of a Holocene gene flow between Indian people and Australian Aboriginal people is real. However, the external evidence quoted to support the thesis of such genomic fusion around four thousand years ago is inadequate and does not enjoy the support of many experts in the field. Given the errors associated with the estimated times of a localised admixture between these populations, it is not impossible to find a more recent time for an encounter between South Indian migrants to South East Asia and Aboriginal people from northern parts of Australia. Such an encounter is far more plausible from the archaeological evidence available in the neighbouring islands. Even though it is not possible to link the Baijini gypsies with the Dravidians due to flimsiness of the available information about the former, it is a possibility worth pursuing.