Ancient mitochondrial DNA from Alaska babies

Quickies

Two new ancient Native American mtDNA sequences from what is now Alaska and back in the day, some 11,500 years ago, was linked to Asia forming the Beringia isthmus.

Justin C. Tackney et al., Two contemporaneous mitogenomes from terminal Pleistocene burials in eastern Beringia. PNAS 2015. Pay per view (free in 6 months) → LINK [doi: 10.1073/pnas.1511903112]

Abstract

Pleistocene residential sites with multiple contemporaneous human burials are extremely rare in the Americas. We report mitochondrial genomic variation in the first multiple mitochondrial genomes from a single prehistoric population: two infant burials (USR1 and USR2) from a common interment at the Upward Sun River Site in central Alaska dating to ∼11,500 cal B.P. Using a targeted capture method and next-generation sequencing, we determined that the USR1 infant possessed variants that define mitochondrial lineage C1b, whereas the USR2 genome falls at the root of lineage B2, allowing us to refine younger coalescence age estimates for these two clades. C1b and B2 are rare to absent in modern populations of northern North America. Documentation of these lineages at this location in the Late Pleistocene provides evidence for the extent of mitochondrial diversity in early Beringian populations, which supports the expectations of the Beringian Standstill Model.

A very good article in Spanish is available at Paleoantropología Hoy, which mentions that the only modern population to have both matrilineages are the Hualapai, who live in the state of Arizona (USA). 

Other populations carrying the C1b lineage are the Pima (Arizona), Delta Yuman (California), Ignacianos (Bolivia), extinct Tainos from Puerto Rico and the Norris Farm remains from pre-contact Illinois, as well as a few unspecificied "other tribes". 

B2 is more common, being found in some 37 populations, including Yakama, Wishram, Northern Paiute-Shoshone, Navajo, Zuni, Jemez (all these from North America), Quechua and Aymara (Peru, Bolivia). It was also common among the old Fremont and Anasazi populations of SW USA. 

He also mentions that the archaeological data for the remains was described by Potter et al. 2014. The two babies are post-natal and pre-natal deaths respectively and were carefully buried with ochre paint on their bodies, arrow points (bow and arrows originally, I presume) and organic remains (food). Then a hearth was built over the tomb, which had absolutely normal use, including disposing of food remains (although it can be speculated that they were additional food offerings), except for another baby that was apparently cremated at it in later times. The deaths of the two babies took place in summer, judging from the animal remains of the burial context.