isotope and Ancient DNA research
IAP team members are studying isotopes and DNA from the bones of muskox and caribou found on archaeological sites across Banks Island. Their work will help us understand past human-animal-environment interactions and how these species are likely to respond to present-day climate change.
What are isotopes?
All matter is made up of atoms, but not all atoms are the same. Inside the nucleus of every atom are protons and neutrons, and atoms of the same chemical element sometimes have a different number of neutrons in their nuclei. This gives these atoms, called isotopes or isotopologues, a different atomic mass. Isotopologues of a chemical element with more neutrons are atomically “heavier” than those with fewer neutrons.
Why do archaeologists study isotopes?
Studying isotopes can help archaeologists in different ways. Unstable, or radioactive isotopes, can be used to date materials recovered from archaeological sites. Radiocarbon dating is perhaps the most obvious example of isotopic dating in archaeology. Stable isotopes are important as well. The ratios of different stable isotopes of a chemical element can also help archaeologists understand the diet and migration of animals and people, and where materials originated.
Isotopic Research and the Ikaahuk Archaeology Project
IAP team member Jordon Munizzi’s PhD research used carbon, nitrogen, and oxygen stable isotope analysis to understand changes in the diets of muskox and caribou on Banks Island over the last 4000 years. His work suggests that sedges and yellow lichen were important foods for both species in the past, while arctic willow was not. It also indicates that both species tend to rely on similar foods during milder periods of climate, while they prefer different foods in cooler or unstable periods.
What is DNA?
DNA, deoxyribonucleic acid, is a molecule in the cells of every organism that controls their growth and function. Sequences of DNA that code for different structures (mostly proteins) are called genes. Haplotypes are groups of genes inherited from a single parent. Similar haplotypes form a haplogroup and individuals in a haplogroup all share a common ancestor.
Why do Archaeologists Study DNA?
Looking at the DNA of individuals within a population can tell us how closely related they are. Individuals from the same haplogroup are more closely related to one another than those from different haplogroups. Changes in the importance of different haplogroups over time can tell us about population size and movements in the past.
Ancient DNA Research and the Ikaahuk Archaeology Project
IAP team member Antonia Rodrigues studied the DNA from muskox bones found on Banks Island archaeological sites to understand changes in the muskox population on the island over time. Her work shows overlap in muskox haplogroups from the earliest human occupation of the island until about 1300 AD. The appearance of a completely new haplogroup around 1450 AD suggests the muskox population on the island died out completely or moved elsewhere sometime around 1300 AD and was then replaced by a new group of muskoxen from a separate population. Archaeological sites in the interior of Banks Island that date from about 1450 AD to the present contain large numbers of muskox bones, suggesting that people hunted large numbers of muskoxen from this new population.