A large group of Neanderthal children were frisking in the paleodunes of Normandy around 80,000 years ago. No fewer than 257 footprints from the Neanderthals living there have been found by latter-day archaeologists in Le Rozel, a coastal area in northwest France — and most of the prints were small, evidently made by young ones. Possibly the kids scampered about so much they skewed the evidence, as young mammals do, or the Neanderthals in that area of France really had a lot of children.

The Le Rozel discovery is by far the largest of hominin fossil footprints, which are extremely rare. Fossil footprints of anything, human or otherwise, are only preserved when made in impressionable soil such as sediment or sand, and only when the prints get very rapidly buried. The lighter the animal, the unlikelier this is to happen: A brontosaurus would leave a more significant imprint than a shrew.

Apropos, Haaretz reported last week on a unique half-billion-year-old-track made by a proto-arthropod found dead in its tracks. The spoor of our human ancestors isn’t quite that rare, but only 40 sites with their fossil footprints are known worldwide — though they have been found from Africa to Asia to Europe, and even in Canada and South America. Our prehistoric ancestors did get about.

At Le Rozel, technically some of the footprints were isolated and some in trackways, meaning one footprint after another. Of the lot, 88 were complete footprints, and ranged in length from 11.4 to 28.7 centimeters (4.5 to 11.3 inches).

Given the rise of theories that Homo sapiens began to leave Africa at least 200,000 years ago, if not more, how can we be sure the French footprints were made by Neanderthals?

Neanderthals went there

Open gallery view One of the Neandertal footprints discovered at Le Rozel. Truth is, its shape doesn't look like ours. Credit: Image courtesy of Dominique Cliquet

No remains of the individuals themselves were found at the site. The researchers, Jérémy Duveau of the Museum of National History in Paris with colleagues, relied on three other forms of evidence to identify the species that make the tracks. The first and foremost signal was the shape of the foot.

The team compared the prints with ours and those of other hominins, including the tracks left by (apparently) australopithecines at Laetoli, Tanzania, about 3.6 million years ago.

The footprints in France show the beings had a less gracile foot compared with our delicate tootsies. They also featured a less pronounced plantar vault — meaning they had flat feet. This fits with what we know about Neanderthal foot structure compared with ours.

The Neanderthal foot was, however, more modern than the australopithecines’, as demonstrated by the prints discovered at Laetoli, which, by the way, were made in wet volcanic ash. They show the australopithecines who made the tracks were bipedal and had human-type big toes, not the opposable big toes like apes do. (Separate research finds that multiple types of australopithecines existed at the same time, and at least one apparently retained the apelike opposable big toe.)

The second piece of evidence is that no hominin species other than Neanderthals are known to have been living in the area of Le Rozel at the time.

Open gallery view Skeleton of an infant Neanderthal, found in Roc de Marsal, France, from 75,000 years ago Credit: Ryan Somma

As the complexities of human evolution come to light, especially in the last decade, that argument could change. But right now that’s the case. It’s the same reason art found from 64,000 years ago in a cave in Spain has been attributed to Neanderthals, not to early humans or some other species.

The third avenue of evidence is the stone tools, which are typical of Neanderthals of the time.

Given all this, the team decided the footprints in Le Rozel had been made by Neanderthals. Moreover, they could reach hypotheses about their living arrangements.

It takes a small village

Neanderthals, like us, were pack animals. Or as the paper puts it, they lived in social groups. Like the numbers postulated for modern human hunter-gatherers over 10,000 years ago, the groups would have been small, researchers believe: between 10 to 30 individuals, on average.

Open gallery view Reconstruction of Neanderthal man and child Credit: AFP

However, the data suggesting these group numbers has been critiqued for having other potential interpretations. For instance, data on sleeping space in a cave complex wouldn’t necessarily attest to how many slept there at a given time.

This study of footprints is more likely to represent a frozen moment in time. In Le Rozel, that frozen moment 80,000 years ago suggests the group consisted of at least four Neanderthals, but more likely up to 13.

Open gallery view Reconstruction of juvenile Neanderthal Credit: Hiarash

The long and short of the statistical analyses of the footprints is that the Neanderthals who made them ranged from nearly 74 centimeters in height (2 feet, 5 inches tall) — in other words, a toddler, to 185 centimeters (6 feet, 1 inch) — not a toddler.

They add that the average height within this Neanderthal group was 175 centimeters, i.e., 5 feet, 7 inches. The male Homo sapiens these days averages about 5 feet, 9 inches.

According to the size estimates and various other considerations, more than half the occupants were shorter than 130 centimeters tall. In fact, the researchers suggest that 80 to 90 percent of the individuals were minors, and that the smallest, with a footprint of 11.4 centimeters, was probably about 2 years old.

Based on sexual dimorphism in the human animal, the scientists suggest the longest footprints were made by men. But there’s really no telling.

There could be quite a margin of error regarding the numbers in the Neanderthal community. Kids scamper about like bipedal kittens, so one child would likely leave more marks in the sand than its parent. On the one hand, since they are so light they barely leave a print, children's spoor could be underrepresented in the fossil footprint record. On the other, because they run around more than adults, they’d leave an overrepresentation of prints. Ultimately, the researchers feel their conclusion that children made up most of the group is reasonable.

The only other site that they feel provides reliable information on Neanderthal group size is El Sidrón, a vast cave system in northern Spain. There, researchers reached other conclusions, finding a family (based on mitochondrial genetic analysis) with a larger proportion of adults: seven of them, plus three adolescents, two children and one infant. They lived in the cave about 48,000 years ago.

El Sidrón was also one of the several sources of the theory that Neanderthals indulged in cannibalism, because the 13 individuals found there had apparently been slaughtered and eaten. Their bones bear no signs of animal scavenging, but do bear cut marks by stone tools. Some researchers even suspect that cannibalism contributed to the extinction of the Neanderthal, because the practice can spread Creutzfeldt-Jakob (aka kuru), the human equivalent of mad cow disease. It is worth knowing that the Neanderthals could alternatively have developed the disease from eating the brains of ungulate prey.