Today's wild mustangs are native to North America, not heirs of Spanish conquistadors' mounts, according to a Locust Valley rescuer who says new DNA research should help save them from being slaughtered by the thousands in Mexico and Canada.

Manda Kalimian said a soon-to-be-published study reveals the horses did not go extinct — as long believed — but instead were alive as recently as 5,000 years ago. She hopes this finding will help reverse policies partly based on their misclassification as an invasive species that can be eradicated.

This study should speed fundamental reforms, she said, in what she and other critics regard as the Bureau of Land Management's deeply flawed way of managing the herds: rounding them up, penning them, adopting small numbers out — and then failing to ensure they are not soon sold for slaughter.

Kalimian's nonprofit helped pay for some initial DNA research done by the University of California Santa Cruz. It did not fund the new study done at McMaster University in Hamilton, Ontario, but will support a post-doctoral position for a researcher there.

Scientists previously deduced wild horses and other large mammals that migrated between Alaska and Russia on a Bering Strait land bridge all died off about 10,000 years ago — when the fossil record ends — from still not wholly understood reasons.

Yet DNA samples from Yukon sediments in research done by scientific advisors to CANA reveal horses and other species lived as recently as 5,000 years ago.

"We’ve found genetic evidence for the late persistence of mammoths, steppe bison, and horses surviving for thousands of years longer than fossils like bones and teeth would suggest," said Tyler Murchie, a postdoctoral fellow at McMaster University. He said his research is under review for publication in the journal Nature Communications.

"If horses did persist in the Yukon, until 5,000 or 6,000 years ago, it would seem to imply they are Native American horses," Murchie said.

Hendrik Poinar, a McMaster anthropology professor working with Murchie, said: "The real interesting question… is to flesh out between 1,000 and 5,000 years ago … who hung around and for how long."

He added: "Now, we have been humbled by the evidence."

Kalimian, a Long Island native and lifelong rider, has her own 16-acre farm, which she says is a "re-wilding" showcase, where native plants and insects all flourish — along with her mustangs — because fertilizers and pesticides are banned. She says wild horses will help preserve grasslands.

"The horse plays an integral role in our native systems, the natural order of things," she said. "I see that every day, here on my farm, in the way I manage my horses — so what I’ve done is, as I’ve worked to bring this solution forward, which of course could not be more necessary with this climate crisis and the pandemic we are in."

Fifty years ago, Congress enacted the "Wild Free-Roaming Horses and Burros Act," calling them "living symbols of the historic and pioneer spirit of the West." The U.S. in 2004 banned slaughtering horses for people to eat; slaughterhouses here shut a decade later after their meat inspections were ended.

But advocates say, farmers, miners, oil drillers, and protections for native species, crowd too many horses on too little public land — while private companies pay too little for the land they lease. The bureau, charged with their care, for decades has experimented with birth control, still seen as too costly or unworkable. Paying adopters $1,000 per horse backfired, they say, after it failed to stop them from being resold for slaughter outside the U.S.

Said Dr. Doug Antczak, a Cornell University professor of equine medicine: "They multiply at a high rate and many do not have happy lives."

The West's drought and almost unstoppable wildfires may only intensify land wars. Industry and trade groups note their products are essential and aren't always compatible with wild horses.

National Cattlemen's Beef Association Director of Natural Resources Kaitlynn Glover said by email: "The conflict is not between horses and cattle — the conflict is between overpopulated horse herds and everything else that wants to live on that range. Overpopulated horse herds create a monoculture, in which many don’t survive and nothing thrives."

Just last month, the U.S. Geological Service warned that unless herds of wild horses are reduced, populations of the greater sage-grouse, a native species, could drop 70% in those areas.

But Kalimian said mustangs should be honored as an ancient and integral part of the West — and one that can help fight climate change if given the grasslands to do so.

"This country was built on the back of a horse," she said. "Our horses need to step back in and lead the way in rebuilding the grassland — and all the community horses bring and build around them; we will be physically and mentally healthier."