In 2019, a team of archaeologists climbed a steep, rocky hill in central Germany and dug into the collapsed entrance of the unicorn cave, so named because people searched it for unicorn bones in the Middle Ages. Today it is famous for its animal fossils.

Over the course of about a month, they excavated an area of ​​only 16 square feet and pulled dozens of ancient mammal bones out of the brown dirt. Most were inconspicuous, either the remains of bears that had once hibernated the cave or the butchered castaways of cadavers hunted by Neanderthals tens of thousands of years ago.

But one specimen, a two-inch long footbone of a giant deer, stood aside. It was carved in a distinct chevron pattern with six thick rectangular notches.

When Thomas Terberger, the head of the project, saw these crop marks for the first time, he knew that they couldn’t have come about by chance. “We found it was deeper – it was something that was intentionally engraved on the bone surface,” said Dr. Terberger, archaeologist at the Lower Saxony State Office for Cultural Heritage in Hanover.

The bone was likely cooked before it was carved, and it took about an hour and a half to make, said Dr. Terberger. When the bone is upright, the chevron pattern faces the sky.

Although Neanderthals were known to live in and around the cave, Dr. Terberger initially that the carving must have come from an early Homo sapiens. After all, such Neanderthal cultural artifacts are extremely rare and often controversial. Radiocarbon dating, however, showed the foot was 51,000 years old – meaning it was made several thousand years before the first early modern humans appeared in the area.

The carving, as the scientists published in Nature Ecology & Evolution this week, is almost certainly from Neanderthals. As Silvia Bello, a researcher at the Natural History Museum in London who was not involved in the discovery, wrote in the same issue of the magazine, the find is “one of the most complex artistic expressions known to date by Neanderthals.”

Since the first large Neanderthal fossil was found in another German cave in 1856, our hominin cousins ​​have been considered fat, stupid animals. Although recent discoveries have shown that Neanderthals used elaborate tools, buried their dead, and naturally mated with Homo sapiens, “we’re still kind of a bit trapped in our image of the 19th-century Neanderthals,” said Dr. Terberger.

The new carving is one of only a few examples of Neanderthal art, such as body ornaments, rock engravings and notched animal bones. Many scholars have expressed doubts as to whether some of these Neanderthal works of art were actually tools and whether they derived their creative leanings from interacting with early ancestors of our species.

The carving was made on the foot of a giant deer, a majestic animal that was rare in the area and may have symbolic meaning for the people who killed it, said Dr. Terberger.

But is this bone carving with its chevron patterns really art? Dr. Terberger prefers to call it a complex decoration, perhaps a forerunner of art. “But they don’t make such a decoration complex just for fun,” he said.

“The size suggests that you can hold it in your hand, look at it, and stimulate your imagination,” he said. “Everyone can decide for himself what he sees in it.”