In the frozen soils of North America, fragments of a long-lost world have been waiting. Fossilized tusks, teeth, and bones of mastodons—giant relatives of today’s elephants—carry inside them a secret story. For centuries, these remains were silent witnesses to an age of glaciers and megafauna. But now, with the help of cutting-edge ancient DNA techniques, scientists are bringing their voices back.
A new study published in Science Advances by researchers from McMaster University and Harvard has unveiled surprising insights into the migration, diversity, and evolutionary history of mastodons. What emerges is a tale far richer than anyone expected: these Ice Age giants did not simply roam aimlessly across the continent. They migrated vast distances, responded dramatically to climate change, and carried within their genomes a diversity as complex as their landscapes.
The Power of Ancient DNA
Recovering DNA from fossils that are hundreds of thousands of years old is no easy task. Time erodes genetic material, leaving behind only fragile, fragmented traces. Yet, with refined techniques, scientists were able to reconstruct mitochondrial genomes—the genetic blueprints passed down through the maternal line—from mastodon remains scattered across North America.
The specimens came from both coasts and the continent’s interior: five from Nova Scotia and the eastern seaboard, a unique Pacific mastodon from Tualatin, Oregon, a partial genome from Northern Ontario, and even an ancient individual possibly dating back half a million years. By stitching together these fragments, researchers pieced together a genetic map that challenges long-standing ideas about mastodon evolution.
Rethinking Mastodon Species
For decades, mastodons were thought to belong to one species, Mammut americanum. Later, paleontologists proposed that at least two species existed: the American mastodon and the Pacific mastodon (M. pacificus). The debate has simmered ever since.
Now, DNA evidence shows that Pacific mastodons are not just a local offshoot but part of an ancient, well-established branch. Their range was far wider than scientists believed, stretching through the Pacific Northwest, possibly down into Mexico, and northward into Alberta. This finding hints that M. pacificus was not a rare, regional variant—it was a major player in Ice Age ecosystems.
Even more intriguing is the discovery of a mysterious Mexican mastodon lineage. Its genetic distinctiveness raises the possibility of a third mastodon species entirely, lurking in the evolutionary tree.
Alberta: A Meeting Ground of Giants
One of the most striking revelations comes from Alberta. Far from being a marginal habitat, Alberta appears to have been a key corridor where different mastodon groups converged. The genetic record suggests that Pacific and American mastodons overlapped here, expanding northward during warm periods and possibly interbreeding.
This raises fascinating questions: Did these populations compete for food in swampy forests and wetlands? Or did they mix, exchanging genes in ways that enriched their diversity? The answers may reshape how we understand Ice Age ecosystems and the adaptability of megafauna to shifting environments.
East Coast Surprises
The mastodons of the East Coast add another layer of complexity. The DNA reveals two previously unknown genetic clades—distinct groups that occupied the same regions at different times. This suggests that mastodons migrated eastward in repeated waves, each tied to cycles of warming and cooling.
As glaciers retreated, forests opened new pathways northward, inviting mastodons to expand into fresh territory. But when ice advanced again, populations were forced southward or extinguished entirely. These cycles of expansion and retreat created a dynamic pattern of movement, reminding us that Ice Age landscapes were far from static.
The Broader Picture of Mastodon Life
Mastodons were among the largest land animals of their time, rivaling mammoths in size. But unlike mammoths, which thrived on open tundra and grasslands, mastodons preferred wetter, forested environments. They browsed on shrubs, trees, and swamp vegetation, leaving behind fossilized dung that confirms their woodland diet.
From Beringia in the far north (modern Alaska and Yukon) down to Central Mexico, mastodons carved out a vast range. Yet within this expanse, their populations were anything but uniform. Diversity flourished, shaped by climate shifts, migrations, and possible interbreeding.
What the Study Means for Science
This new research does more than solve puzzles about an extinct species. It highlights how climate shaped migration, diversity, and survival in the past—and offers lessons for today. Just as mastodons were forced to move northward during warming periods, modern species are shifting their ranges in response to climate change. Understanding how ancient animals adapted—or failed to adapt—can help conservationists predict the future of today’s ecosystems.
The findings also remind us of how much remains hidden in the fossil record. Each tusk, each tooth, each scrap of bone holds the potential to rewrite history. The mastodon’s story is not just one of extinction, but of resilience, adaptation, and the constant push and pull between life and a changing planet.
A Story Still Unfolding
As lead author Emil Karpinski reflects, the discoveries raise new questions as much as they provide answers. How often did mastodons from different groups meet and interact? Did genetic mixing help them thrive, or did competition hasten their decline? And what role did shifting forests, wetlands, and glaciers play in shaping their fate?
For now, the mastodons remain enigmatic giants, their DNA a faint echo of a vanished world. But each new discovery brings us closer to seeing them not as static relics, but as vibrant, adaptable beings whose lives were bound up with the rhythms of ice, climate, and time itself.
Conclusion: Giants With Lessons for Today
The story of the mastodons is more than a prehistoric tale. It is a mirror for our own age, where species face the pressures of a changing climate and shrinking habitats. Just as the mastodons once moved in search of survival, today’s animals—from caribou to polar bears—are being pushed to adapt or perish.
By unlocking the mastodon’s DNA, scientists are not only restoring the lost history of these majestic creatures, but also reminding us of our shared responsibility: to learn from the past so that the giants of today—and the ecosystems they depend on—do not vanish into silence.
More information: Emil Karpinski et al, Repeated climate-driven dispersal and speciation in peripheral populations of Pleistocene mastodons, Science Advances (2025). DOI: 10.1126/sciadv.adw2240. www.science.org/doi/10.1126/sciadv.adw2240
