The announcement landed on the twenty-sixth of November 2025, in the pages of Nature, and it dismantled a title that had stood for fifty-one years. Eight bones from a right foot, found thirty-five kilometers from where Lucy’s remains had been discovered, were formally assigned to a different species. A species with a big toe that jutted out to the side like a thumb. For half a century, scientists had believed that Lucy’s kind walked alone.

They had been wrong. It is summer in Prague. Behind the glass of a museum display lie the broken brown bones of the most famous ancestor on Earth, the one often called the mother of us all. Weeks after the hall had gone dark, the crown shattered.

Who had been walking beside her? The answer had changed three times. And the final evidence had been hidden inside Lucy herself. That foot had walked upright on two legs across the same ancient landscape where Lucy’s species walked, yet it had not walked the way they did.

In Lucy’s kind, the big toe lines up with the other toes, as it does in yours, a rigid lever for pushing off the ground. The big toe of this foot stuck out to the side, built for gripping branches, which meant its owner most likely pushed off with the second toe instead. One of the scientists who first studied it called the discovery horrifying, describing its owner as moving with a somewhat unsteady gait on the ground, walking upright with a thumb on your foot. So what kind of creature spent half its life in the trees and half on the ground at a moment when Lucy’s kind was supposed to rule the walking world?

And why did this foot wait sixteen years to receive a name? Keep that image of the foot for later. There is also a scanner, thirty-five thousand slices, and inside Lucy’s right arm a bone broken into four pieces that a team believes reveals exactly how she died. Those bones had just finished a celebratory tour.

On the fifteenth of August 2025, Lucy arrived in Prague under heavy security, on loan from the Ethiopian National Museum. Traveling beside her was a three-year-old child of her own species, nicknamed Selam, a fossil never before exhibited abroad. For sixty days the crowds flowed past the glass in the Czech National Museum. The Czech prime minister opened the exhibition with a military brass band.

The museum’s director called the two fossils among the most valuable exhibits in the world of paleoanthropology. The man who had pulled Lucy from the ground half a century earlier flew in for the opening. It was the first time she had ever been shown in Europe. On the twenty-third of October the doors closed and she returned home.

Thirty-four days later came the Nature paper that took apart the title she had carried since the day she was found. That title was born in a dry gully. On the twenty-fourth of November 1974, in the Hadar region of Ethiopia’s Afar territory, Donald Johanson spotted the end of a forearm bone in a gully that other researchers had already examined at least twice. Hundreds of fragments followed, roughly two out of every five bones of one body.

That night, a Beatles song gave her a name. Thirty-five years later and thirty-five kilometers to the north, the challenge to that name emerged from the dirt. In February 2009, at a place the locals call Burtele, graduate student Stephanie Melillo was walking along a slope when she stopped. In her hand was half a small bone, the one that reaches the fourth toe.

She carried it to the team leader, Yohannes Haile-Selassie. His response was, go back. The other half has to be there. She did.

And it was. The entire team got down on their hands and knees and crawled up the slope, combing the gravel with their fingertips. When they stood up, they were holding eight pieces from the front half of a right foot, roughly three and a half million years old. In March 2012, the team announced the discovery in Nature, and the bones said something no one had expected.

Put the foot inside the outline of a gorilla foot and the big toe fits right in place, angled away from the rest like a thumb. Put it next to a foot from Lucy’s kind, where the big toe runs straight along its neighbors, and nothing matches. The project’s co-leader admitted they had never seen bones like these before. That grasping toe could swing from side to side, but the top of its joint lacked the expansion a true walker needs to push off the ground.

That toe design belonged to Ardipithecus, a human relative who lived 4. 4 million years ago. Haile-Selassie later said that finding a grasping toe in Ardipithecus had been a great surprise, completely unexpected so late in history, and finding it again a million years later at Burtele was even more astonishing. The same kind of foot was still roaming Lucy’s world.

Yet the team could not say what it was. A species needs a skull, a jaw, teeth. The foot had none of these. A few teeth had turned up nearby, but no one could prove they had come from the same layer of earth.

The foot was an orphan. And orphans attract stories. The most tempting story was ghostly: this was a remnant, a leftover branch of Ardipithecus design that should have gone extinct long before, still clinging to trees while Lucy’s kind strode across open ground. The second explanation was nearly its opposite.

Perhaps it was simply an unusual individual of Lucy’s own species, an odd foot in a diverse family. And there was a third possibility hanging over the entire region. Far to the south in Kenya, a flat-faced skull had been excavated in 1999, about three and a half million years old, already given its own name, and some researchers suspected it had lived at the same time as Lucy’s kind. But a skull in Kenya and a foot in Ethiopia do not prove anyone had neighbors.

For that, you need two species in the same place, at the same time, in the same layers of rock. Burtele held half of that equation. The other half was lying on the surface. On the fourth of March 2011, at one of the Burtele sites, an upper jaw with teeth settled on top of the silty clay that wind and rain had uncovered.

That day and the next, two lower jaws appeared, one in the same spot, broken in two pieces, and the other at a place called Waytaleyta, about two kilometers to the east. The teeth had thick enamel. The lower jaws were more massive than those of Lucy’s kind. In May 2015, the team gave a name to an entirely new species: Australopithecus deyiremeda.

In the local Afar language, deyiremeda means close relative. Everyone expected the obvious next sentence. The foot belonged to this species. It never came.

The team refused to assign the foot to their new species. Some jaws had been found very close to it, but proximity does not mean the same layer. So they kept going back. Year after year, for another decade, the team returned to the same hills, about 520 kilometers northeast of Ethiopia’s capital, in a region most maps barely mark.

The project’s geologist did the unglamorous work that settles such a case, tracing how each band of rock connected to the next, until she could show which fossils lay in the same slice of time as the foot. Finds accumulated. Twenty-five teeth from the Burtele area, fragments of a pelvis, pieces of a skull, and a small jaw still containing twelve teeth that clearly belonged to a child. All of it came from the same section of earth as the foot, in layers dated to between about 3.

47 million and 3. 33 million years ago. The teeth and jaws matched the species named in 2015 in form. The rocks tied them to the foot.

For the first time, the orphaned foot had a family standing on the same ground. On the twenty-sixth of November 2025, they said it out loud. The Burtele foot belonged to Australopithecus deyiremeda. Haile-Selassie told journalists the team had no doubt at all that the foot belonged to the same species as the teeth and jaws, and he called it the most definitive evidence yet of several related species coexisting at the same time in our evolutionary history.

Here lies the painful part. Lucy was never alone. For half a century her species had been seen as the only human relative roaming this part of Africa between roughly 3. 8 million and 3 million years ago.

Fred Spoor, the paleontologist at London’s Natural History Museum who wrote the accompanying commentary in Nature, described how her species had been seen as the ancestral lineage from which everything else descended, as if she were the mother of us all. He now warned that it might lose that iconic status. Woranso-Mille, the extension of the Afar desert that includes Burtele, became the only place on Earth offering direct evidence of two related human relatives sharing the same landscape at the same time. It sits thirty-five kilometers from Hadar.

That is less than a marathon. A determined walker could cover it in a day. Lucy herself stood about three feet seven inches tall and weighed roughly sixty-four pounds, the size of a six-year-old child, with a brain her discoverer said was the size of a grapefruit. Her Ethiopian name, Dinkinesh, means you are marvelous.

Her species lasted for nearly a million years, and this neighbor had been there long before she was born. So how did two species of wandering creatures share one valley? The answer was locked in their teeth. Naomi Levin, a geochemist at the University of Michigan, took eight of those twenty-five teeth and drilled into them.

Her tool was a dental drill, the kind your dentist uses, with a head less than a millimeter wide. Up close it looks delicate. A small spinning head, a little pale powder rising from the ancient enamel. That powder carries a chemical signature of the plants the creature had eaten while the tooth was forming.

Trees and shrubs leave one signature; tropical grasses and sedges leave another. Levin expected it would be hard to spot the difference between the two species. Instead, she was startled by how clear the signal was. The neighbor’s tooth readings were low and barely changed from tooth to tooth, as if every individual ate from the same limited menu.

It had eaten leaves, fruit, and nuts from trees, shrubs, and herbs, a list nearly identical to that of Ardipithecus and other species from a million years earlier. Lucy’s kind ate from the forests too, but they also raided the grasslands. They are the oldest known human relatives ever to use grass-based foods. One species foraged only in the forest; the other foraged everywhere.

That may be precisely why they could live so close without one starving out the other. And it flips the story of who was more advanced on its head. The species with the grasping toe ate exactly like its early ancestors. Lucy’s kind was the experiment.

But not everyone accepts the new name. A paleoanthropologist at the Spanish National Research Center for Human Evolution looked at the same teeth and saw something else. In her view, they blend features of an older species with features of Lucy’s kind, exactly what you would expect from a lineage slowly changing over time. For her, deyiremeda is just a transitional stage.

She also notes that the Burtele foot is incomplete and that feet within Lucy’s own species vary in shape. That skepticism does not return the foot to Lucy’s kind. Fred Spoor, reading the same evidence, finds assigning the foot to deyiremeda reasonable. That skepticism opens the door to something stranger.

If she is right, this neighbor might not be a distant relative at all, but a remnant of the very lineage from which Lucy’s kind arose, perhaps still wandering the neighboring hills. Even Haile-Selassie says there is not enough conclusive evidence to say which one, deyiremeda or Lucy’s kind, is our true ancestor. For fifty-one years that answer had seemed clear. Now no one can give it.

The next piece of evidence was not another foot bone. It was the jaw of a child. What the scanner found inside it turned this neighbor from a scientific classification into someone’s child. It began with a single bone fragment, then more pieces emerged from the same earth until the team could hold the lower jaw of a young deyiremeda.

From the outside it looks like a small broken jaw with baby teeth. The inside is what stops you. They examined it with a high-resolution CT scanner that sees inside fossil bones in thin slices and rebuilt it on screen. Rotate that digital model slowly and every baby tooth is in place, a complete set.

Beneath them, deep in the bone, the permanent teeth wait. The molars are still forming. Crowns buried in the jaw point toward a surface they will never reach. Based on the growth stage of those teeth, the team estimated the child died at about four and a half years old.

Imagine that small life around them: a forest of trees and shrubs, leaves and fruit, a grasping toe on a low branch, a lurching gait across the ground between trunks. Something ended all of it before a single permanent tooth had emerged. The team’s dental development specialist saw something more in the scan. The front teeth and the back chewing molars were growing out of sync, the same gap you see in living apes and in the children of Lucy’s own species.

Two kinds of children growing up the same way, thirty-five kilometers apart. One never finished growing. And if two kinds of human relatives walked differently, they should have left different footprints. Someone had seen those footprints and then walked away.

In 1976, at Laetoli in northern Tanzania, the most famous fossil-hunting team in Africa found a short trail of strange prints at a site called A. They partially excavated the prints and initially assigned them to a human relative. Two years later, near site G, they found the trail that made Laetoli world-famous. Dating to 3.

66 million years ago, it had been left by Lucy’s kind and was considered the oldest indisputable evidence of fully upright walking in our lineage. Every camera turned toward it. In the 1980s, an analysis suggested the site A prints might belong to a small bear walking on its hind legs. After that, interest faded so completely that the site itself was lost.

Some of the oldest evidence of a second creature walking the earth had been classified as a bear, then forgotten. Decades later, a Dartmouth graduate student studying how bears walk on two legs came across a reference to those forgotten prints and could not ignore them. In 2019, her team returned to Laetoli inside the Ngorongoro Conservation Area, just south of Olduvai Gorge, located site A, excavated it, and cleaned it. They photographed every print using laser scanning and photogrammetry.

Hundreds of overlapping images were merged into a single three-dimensional surface. On screen, the contour map shows five footprints in a row, each a shallow depression with a wide heel and the impression of a large big toe with a smaller second toe beside it. Then they did something unusual. They partnered with a black bear rescue center in New Hampshire and compared the prints to those of bears, chimpanzees, and humans.

The bears failed the test. A bear standing upright usually clings to a tree and rarely manages four or more steps. Site A has five. Stranger still, each foot crossed in front of the body’s midline, a cross-step like someone placing one foot over the other on a narrow ledge.

Bears lack the hip and knee anatomy to balance while doing that. Picture the plain as it was: fresh volcanic ash covering everything, soft underfoot, a small upright shape crossing it, foot swinging over foot, pressing into a surface no one had read correctly for decades. Five footprints nearly forgotten for four decades. In December 2021, the results were published in Nature.

The site A prints looked more like a human relative than a bear, and their narrow steps confirmed what the first excavators had guessed: a small creature walking on two legs with cross-steps. But their foot proportions, gait, and three-dimensional shape were clearly different from the trail left by Lucy’s kind at site G. The conclusion: at least two types of human relatives with different feet and different ways of walking lived at Laetoli at the same time. Their prints were pressed into the same layer of ancient clay.

Some scientists remain unconvinced that footprints alone can prove a separate species. But Stephanie Melillo, the same researcher who once picked up that first toe bone at Burtele, told journalists the site was unique. Now the map lights up. A foot with a thumb in Ethiopia.

Five footprints with cross-steps in Tanzania. A flat-faced skull in Kenya. And from Chad, far to the west, another species some researchers believe lived alongside Lucy’s kind. Haile-Selassie put it plainly: there were many ways to walk on two legs, not just one until later.

And he went further, telling journalists that coexistence is deeply rooted in our ancestors. Lucy’s gait was one experiment among many taking place side by side across a continent. Lucy’s own body had carried the evidence for years. Between 2007 and 2013, she toured museums across the United States, the only other time she had been exhibited outside Ethiopia.

In 2008, after a showing at the Houston Museum of Natural Science, she spent ten days at the University of Texas at Austin. A team led by John Kappelman put her through a high-resolution CT scanner. Every piece, because, as he explained, this might never happen again. The machine produced 35,000 slices, a digital copy of the most famous skeleton on Earth.

Kappelman planned to use the scans to settle an old argument about how much time her species spent in the trees. He was deep in that work when he saw it. One slice through her right humerus, near the shoulder, showed the bone broken in a strange pattern. Clean, sharp fractures with fragments and small splinters still in place, as if the bone had been crushed against itself.

He consulted an orthopedic surgeon from Austin. Then his team printed a three-dimensional copy of the bone and showed it to nine orthopedic specialists. All nine agreed. It was a four-part fracture of the humerus, a type of compressive break associated with a hard fall from height.

The breaks did not stop at the arm. The team agreed many of her cracks occurred after death. But one subset looked different. Bones driven into bones, high-energy impacts at many of her joints.

Lucy was a young adult, yet the scans showed fractures on her right ankle, left knee, pelvis, and first rib. None showed any sign of healing. In some, one side of the bone had cracked while the other held together, exactly as a green branch splits rather than breaking clean. Living bone breaks that way.

Some of the damage ran from her ankles all the way up to her jaw. Other researchers, using the same scans, found robust arm bones, the arms of someone who climbed a lot. Then there was the place where she was found, beside a stream in relatively flat terrain with no cliffs or ledges, and no predator’s feast either. From the beginning, the only sign of carnivores on her skeleton was a single small tooth mark on her pelvis.

So what could knock a small upright-walking creature flat to the ground with enough force to break an ankle, knee, hip, and arm all at once? Here is how Kappelman’s team thinks it happened. With no cliffs or cars in her world, they argued, the only thing tall enough was a tree. Lucy is up in a tall tree near the water.

Something gives way. She falls from a great height, feet hitting the ground first. The force of impact travels through her right ankle, left knee, and into her pelvis. Her body pitches forward and twists.

On instinct she throws her arms out to protect herself, her right arm strikes the ground and shatters into four pieces. The team concluded the injuries were so severe she probably died very quickly after the fall. Kappelman told journalists he did not believe she suffered. He later said understanding how she died was the moment she stopped being just a box of bones to him.

Not everyone accepts this scene. Johanson, the man who found her, calls the tree-fall story merely a hypothesis, arguing that the immense weight of sediment accumulated over the ages can also break buried bones. But if Kappelman’s team is right, the most famous member of the species known for leaving the trees died falling out of one. And a short distance north, in the same earth, a species with a toe built for gripping branches had lived beside her kind for generations.

In Prague, the display cases honored her as the mother of us all. Today she is back at the Ethiopian National Museum in Addis Ababa, where she is not even on permanent display in her homeland, her broken right arm resting in darkness. Thirty-five kilometers from her valley lies a foot of eight bones arranged toe by toe, the big toe angled like a thumb, pointing another way. Lucy’s species is known from nearly four hundred specimens in Hadar alone.

Her neighbor is known from a foot, a child’s jaw, and a few dozen teeth. Between them and us lies a gap in the fossil record stretching from 3. 2 to 2. 8 million years ago, the period in which our own genus is believed to have emerged.

And somewhere in those four hundred thousand missing years, one of those walkers became us. When the first fossil finally comes out of that gap, which foot will it match?