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Tuesday, June 14, 2016

Ancient mtDNA sequences from the First Australians revisited

Ancient mtDNA sequences from the First Australians revisited 


The publication in 2001 by Adcock et al. [Adcock GJ, et al. (2001) 
Proc Natl Acad Sci USA 98(2):537–542] in PNAS reported the recovery of 
short mtDNA sequences from ancient Australians, including the 
42,000-y-old Mungo Man [Willandra Lakes Hominid (WLH3)]. This landmark 
study in human ancient DNA suggested that an early modern human 
mitochondrial lineage emerged in Asia and that the theory of modern 
human origins could no longer be considered solely through the lens of 
the “Out of Africa” model. To evaluate these claims, we used second 
generation DNA sequencing and capture methods as well as PCR-based and 
single-primer extension (SPEX) approaches to reexamine the same four 
Willandra Lakes and Kow Swamp 8 (KS8) remains studied in the work by 
Adcock et al. Two of the remains sampled contained no identifiable 
human DNA (WLH15 and WLH55), whereas the Mungo Man (WLH3) sample 
contained no Aboriginal Australian DNA. KS8 reveals human mitochondrial 
sequences that differ from the previously inferred sequence. Instead, 
we recover a total of five modern European contaminants from Mungo Man 
(WLH3). We show that the remaining sample (WLH4) contains ~1.4% human 
DNA, from which we assembled two complete mitochondrial genomes. One of 
these was a previously unidentified Aboriginal Australian haplotype 
belonging to haplogroup S2 that we sequenced to a high coverage. The 
other was a contaminating modern European mitochondrial haplotype. 
Although none of the sequences that we recovered matched those reported 
by Adcock et al., except a contaminant, these findings show the 
feasibility of obtaining important information from ancient Aboriginal 
Australian remains.


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