Ice Age landscapes were not quiet. Forests shook when mastodons moved through them. These elephantlike animals dominated swamps and woodlands across North America for thousands of years.

Their remains have fascinated scientists for centuries, but their evolutionary story always seemed unfinished. Were there one or several species? How far did they travel?

A new study now answers some of those questions. By extracting DNA from fossilized tusks, teeth, and bones, researchers have shown that mastodons were far more diverse than expected.

They also reveal that these animals migrated long distances whenever climates shifted. The story that emerges is not of a static giant but of a restless survivor, adapting again and again to a changing world.

DNA shows mastodon diversity

The findings, published in Science Advances, come from an international team led by McMaster University and Harvard.

They examined fossils dating back hundreds of thousands of years. Many held DNA so damaged and fragmented that past generations of scientists would have dismissed it as useless.

Today’s technology makes even the smallest genetic traces readable. From these tiny fragments, researchers built mitochondrial genomes.

They studied five specimens from Nova Scotia, including one that may be half a million years old, a rare Pacific mastodon from Oregon, and a partial genome from northern Ontario. Each sample added a new piece to the puzzle of mastodon history.

DNA confirms Pacific mastodon species

For decades, scientists grouped mastodons under one species, Mammut americanum. Later, some argued that the Pacific mastodon deserved its own category. The debate never settled because evidence was too thin.

This new analysis tips the balance. The Pacific mastodon forms its own genetic branch – one that is both ancient and deeply established.

Its range stretched much farther than anyone thought, from the Pacific Northwest possibly down to Mexico, and north into Alberta. That broad territory suggests a story of expansion rather than isolation.

Alberta shaped mastodon migrations

Alberta turns out to be more than just another fossil site. It was a meeting ground. The evidence shows that Pacific and American mastodon species overlapped there. They may have even mixed.

“The data shifts our view of the region today known as Alberta and the North more generally,” said senior author Hendrik Poinar of McMaster University.

“From a marginal roaming ground to a repeatedly occupied migratory corridor and significant landscape for mastodons with possible interbreeding.”

Alberta, once thought of as a fringe territory, now looks like a hub of Ice Age movement and contact.

Mastodons migrated east in waves

The specimens from Nova Scotia and northern Ontario revealed something equally striking. DNA showed two distinct genetic groups that lived in the same places but at different times.

Mastodons did not just move east once; they came in several waves. These arrivals lined up with warming cycles. When glaciers melted, mastodons spread northward.

When the cold returned, they retreated or disappeared locally. The East Coast record shows a constant rhythm of expansion and collapse, repeating at least three times.

Mexican fossil hints at new species

Mexico produced another surprise. One specimen carried DNA that didn’t fit with either the American or the Pacific branch.

It may represent a deeper branch of the Pacific mastodon. Or it could be something even more intriguing: a third species entirely.

This lineage shows how much remains hidden in mastodon history. The Ice Age was a time of mixing, migration, and unexpected diversity – and mastodons were no exception.

Mammoths grazed, mastodons browsed

Mastodons often get lumped with mammoths, but their lives were different. Mammoths grazed the grasslands and tundra.

Mastodons lived in wetlands and forests. They ate shrubs and branches, not grasses.

Both were massive, both carried tusks, but their roles in the ecosystem did not overlap. That distinction helps explain how two giants could thrive at the same time, side by side, in overlapping regions.

DNA leaves mysteries unsolved

“This study represents several firsts which includes our work on the Pacific mastodon. It also poses many new questions,” said lead author Emil Karpinski, now at Harvard Medical School.

“For example, how did these distant species of mastodon interact in Alberta? Did they compete for resources, or did they interbreed as our lab has previously shown for mammoths?”

The answers to these questions will need more fossils and more DNA. But the possibilities make clear that mastodons were not uniform. They were dynamic, sometimes competing, sometimes mixing, always adapting.

Mastodons offer climate lessons

This study builds on earlier work from 2020 by the same team. Together, the findings give us a richer picture of mastodon life. They also carry lessons for today.

Mastodons expanded north when climates warmed and retreated south when the cold returned. Their movements mirror the kinds of changes modern species face in a warming Arctic.

Understanding how mastodons responded to past climate change helps predict what may happen now. The giants may be gone, but their history still has something to teach us.

Mastodons were not passive victims of climate. They were travelers, survivors, and sometimes innovators in their own way.

Their legacy is not just bones in the ground but a vivid reminder that even the largest creatures depend on adaptation for survival.

The study is published in the journal Science Advances.

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