ByUniversity of Alaska FairbanksAugust 13, 2021
An illustration of an adult male woolly mammoth navigates a mountain pass in Arctic Alaska, 17,100 years ago. The image is produced from an original, life-size painting by paleo artist James Havens, which is housed at the University of Alaska Museum of the North. Credit: Painting by paleo artist James Havens
An international research team has retraced the astonishing lifetime journey of an Arctic woolly mammoth, which covered enough of the Alaska landscape during its 28 years to almost circle the Earth twice.
Scientists gathered unprecedented details of its life through analysis of a 17,000-year-old fossil from the University of Alaska Museum of the North. By generating and studying isotopic data in the mammothâ€™s tusk, they were able to match its movements and diet with isotopic maps of the region.
Few details have been known about the lives and movements of woolly mammoths, and the study offers the first evidence that they traveled vast distances. An outline of the mammothâ€™s life is detailed in the new issue of the journal Science.
A view of a split mammoth tusk at the Alaska Stable Isotope Facility at the University of Alaska Fairbanks. Karen Spaleta, deputy director of the facility, prepares a piece of mammoth tusk for analysis in the background. Credit: Photo by JR Ancheta, University of Alaska Fairbanks
â€œItâ€™s not clear-cut if it was a seasonal migrator, but it covered some serious ground,â€ said University of Alaska Fairbanks researcher Matthew Wooller, senior and co-lead author of the paper. â€œIt visited many parts of Alaska at some point during its lifetime, which is pretty amazing when you think about how big that area is.â€
Researchers at the Alaska Stable Isotope Facility, where Wooller is director, split the 6-foot tusk lengthwise and generated about 400,000 microscopic data points using a laser and other techniques.
The detailed isotope analyses they made are possible because of the way that mammoth tusks grew. Mammoths steadily added new layers on a daily basis throughout their lives. When the tusk was split lengthwise for sampling, these growth bands looked like stacked ice cream cones, offering a chronological record of an entire mammothâ€™s life.
â€œFrom the moment theyâ€™re born until the day they die, theyâ€™ve got a diary and itâ€™s written in their tusks,â€ said Pat Druckenmiller, a paleontologist and director of the UA Museum of the North. â€œMother Nature doesnâ€™t usually offer up such convenient and life-long records of an individualâ€™s life.â€
Mat Wooller, director of the Alaska Stable Isotope Facility, kneels among a collection of some of the mammoth tusks at the University of Alaska Museum of the North. Credit: Photo by JR Ancheta, University of Alaska Fairbanks
Scientists knew that the mammoth died on Alaskaâ€™s North Slope above the Arctic Circle, where its remains were excavated by a team that included UAFâ€™s Dan Mann and Pam Groves, who are among the co-authors of the study.
Researchers pieced together the mammothâ€™s journey up to that point by analyzing isotopic signatures in its tusk from the elements strontium and oxygen, which were matched with maps predicting isotope variations across Alaska. Researchers created the maps by analyzing the teeth of hundreds of small rodents from across Alaska held in the museumâ€™s collections. The animals travel relatively small distances during their lifetimes and represent local isotope signals.
Using that local dataset, they mapped isotope variation across Alaska, providing a baseline to trace the mammoth movements. After taking geographic barriers into account and the average distance it traveled each week, researchers used a novel spatial modeling approach to chart the likely routes the animal took during its life.
DNA, or deoxyribonucleic acid, is a molecule composed of two long strands of nucleotides that coil around each other to form a double helix. It is the hereditary material in humans and almost all other organisms that carries genetic instructions for development, functioning, growth, and reproduction. Nearly every cell in a personâ€™s body has the same DNA. Most DNA is located in the cell nucleus (where it is called nuclear DNA), but a small amount of DNA can also be found in the mitochondria (where it is called mitochondrial DNA or mtDNA).
“>DNA preserved in the mammothâ€™s remains allowed the team to identify it as a male that was related to the last group of its species that lived in mainland Alaska. Those details provided more insight into the animalâ€™s life and behavior, said Beth Shapiro, who led the DNA component of the study.For example, an abrupt shift in its isotopic signature, ecology and movement at about age 15 probably coincided with the mammoth being kicked out of its herd, mirroring a pattern seen in some modern-day male elephants.
A close-up view shows a split mammoth tusk at the Alaska Stable Isotope Facility. Blue stain is used to reveal growth lines. Samples were taken along the tusk using lasers and other techniques, allowing isotope analysis that provided a record of the mammothâ€™s life. Credit: Photo by JR Ancheta, University of Alaska Fairbanks
â€œKnowing that he was male provided a better biological context in which we could interpret the isotopic data,â€ said Shapiro, a professor at the University of California Santa Cruz and investigator at the Howard Hughes Medical Institute.
Isotopes also offered a clue about what led to the animalâ€™s demise. Nitrogen isotopes spiked during the final winter of its life, a signal that can be a hallmark of starvation in mammals.
â€œItâ€™s just amazing what we were able to see and do with this data,â€ said co-lead author Clement Bataille, a researcher from the University of Ottawa who led the modeling effort in collaboration with Amy Willis at the University of Washington.
Discovering more about the lives of extinct species satisfies more than curiosity, said Wooller, a professor in the UAF College of Fisheries and Ocean and Institute of Northern Engineering. Those details could be surprisingly relevant today as many species adapt their movement patterns and ranges with the shifting climate.
â€œThe Arctic is seeing a lot of changes now, and we can use the past to see how the future may play out for species today and in the future,â€ Wooller said. â€œTrying to solve this detective story is an example of how our planet and ecosystems react in the face of environmental change.â€
Reference: â€œLifetime mobility of an Arctic woolly mammothâ€ by Matthew J. Wooller, Clement Bataille, Patrick Druckenmiller, Gregory M. Erickson, Pamela Groves, Norma Haubenstock, Timothy Howe, Johanna Irrgeher, Daniel Mann, Katherine Moon, Ben A. Potter, Thomas Prohaska, Jeffrey Rasic, Joshua Reuther, Beth Shapiro, Karen J. Spaleta and Amy D. Willis, 12 August 2021, Science.DOI: 10.1126/science.abg1134
Other institutions contributing to the study included Florida State University, MontanuniversitÃ¤t Leoben, Liaocheng University and the National Park Service.
ByUniversity of Alaska FairbanksAugust 13, 2021