Tracing Ancient Migrations: a Look into the First Peopling of the Americas using mtDNA.

Authors: Samantha Rocke, Michel Shamoon-Pour, Emma Rodriguez, Naima Hussain

SUNY Campus: Binghamton University

Presentation Type: Poster

Location: UU 108

Presentation #: 85

Timeslot: Session D 3:00-4:00 PM

Abstract: During the Last Glacial Maximum, expansive glaciers lowered water levels, revealing a shelf of land connecting Eastern Asia to Alaska, called Beringia. This is the main route theorized to have been taken by the founding population of the Americas, but how long they were isolated there, when they entered the Americas, and what route they took to travel south is contested. Archaeological discoveries significantly shaped early scientific assumptions made about migration into the Americas, most notably through the Clovis-first hypothesis. However, this timeline was challenged once recent archeological and genetic evidence emerged supporting a pre-Clovis peopling. Phylogenetic analysis can be used to estimate coalescence times of maternally inherited mtDNA haplogroups and therefore give insight into these foundational questions. In this study, we analyzed over 1000 sequences of complete mitogenomes in Pan-American haplogroup B2 and its parent haplogroup B4b found mostly in Eastern Asia. The sequences were aligned then uploaded into BEAST for Bayesian analysis, allowing us to estimate times of most recent common ancestors (TMRCAs) using two molecular clock rates. We produced phylogenetic trees, Bayesian Skyline Plots, and a network which all support a pre-Clovis coastal migration followed by population growth and rapid expansion southward, with populations in southern Argentina and Chile by approximately 15 kya. Bridging this gap in knowledge is essential for gaining a better understanding of Native American history and the factors shaping haplogroup diversity across North and South America today.