The First Dire Wolves in 10,000 Years Just Turned Two, and They’re Measuring Up to the Ice Age

Almost every family has a doorframe somewhere with pencil marks climbing up it — a birthday-by-birthday record of a child getting taller. Romulus and Remus have one too, except their marks were drawn more than 10,000 years ago. The first dire wolves to walk the Earth since the Ice Age just celebrated their second birthday, and Colossal Biosciences is marking the occasion with its most detailed look yet at the pack the world fell in love with: brothers Romulus and Remus, born October 1, 2024, and their little sister Khaleesi, named for the Game of Thrones queen, who arrived four months later.

The headline news is wonderfully simple. The wolves are thriving. Romulus now weighs 134 pounds and Remus 132, their growth plates closed and their bodies in ideal condition. Each has had two complete veterinary workups a year apart: physical exams, whole-body CT scans, ultrasounds, heart scans, and bloodwork. Giving Colossal a year-over-year health record no animal from an extinct lineage has ever had. And the trio lives as a genuine pack. Remus leads. Romulus and Khaleesi defer to him and consult with him, and the only real jostling happens at dinnertime. Together, they’ve caught rabbits and now chase deer across a wide, naturalistic enclosure, gorging after a big meal and fasting between them, just like wild canids do.

But this is much bigger than just two candles on a cake: those ancient pencil marks are real. The pack’s size and proportions match the body measurements scientists have taken from dire wolf fossils; a growth chart left behind by the Ice Age, hit mark for mark. For a project that has drawn as much skepticism as wonder, that’s evidence with weight. “To me, the most important thing is that our dire wolves are happy and healthy,” says Colossal CEO Ben Lamm. “Our dire wolf pack is tracking directly with the morphometrics documented in the ancient dire wolf fossil record, offering further confirmation of our de-extinction process.”

Then there’s Khaleesi, who turned out to have her own plot twist. Chromosomally, she’s XY, the genetic signature of a male. But the gene that normally switches on male development never flipped, and she grew into a completely normal female, an outcome documented before in cloned dogs, naturally bred dogs, and wild wolves alike. Her recently planned spay confirmed that her female anatomy is healthy. Lamm, for one, is delighted. “Colossal got an early ‘life finds a way’ moment,” he says, “which should make all the Ian Malcolm meme creators happy.”

Two years ago, Romulus and Remus were snow-white pups whose first howls traveled around the world. Today they’re full-grown predators with a leader, a pecking order, and a sister who rewrote the script. For the first time in 10,000 years, a dire wolf is growing into those old marks on the doorframe, and right on schedule.