Have you ever gone on a hike and crossed a sandy stretch turned into mud due to recent rains? A forsaken Neanderthal group crossed a dune long ago, leaving their imprint —and a peek into their personality, as one individual with tiny feet was joking around, given the erratic footprints left for posterity.

When I read one article about the finding, I couldn’t help but reflect on my fascination with Neanderthals since I was probably that remote kid’s age. Not long ago, I self-published a fiction book about the quest of a Neanderthal group to reach a new world of pastures and plenty beyond a dangerous mountain pass, which somebody in Zenda Libros kindly reviewed.

In that book, I had to confront the stereotypes we’ve built about our close relatives, from their brutish behavior or lack of intelligence to the mystery of their extinction; consequently, which is something I intended, I had to go through books, articles, and scientific articles to learn about our close relatives. And yes, as in any complex human story, some moments can leave imprints for future researchers, like the footsteps recently discovered on the bare rock.

A group of people passing through

A little over a year ago, a group of Spanish paleontologists returned to the Asperillo cliff, on the seashore of the Doñana Natural Area in the Southwestern province of Huelva, to confirm the discovery of hominid footprints along with the footprints of animals.

Geological studies of the area led them to believe the footprints were from the Upper Pleistocene, left by a group of Neanderthals 106,000 years ago when the area was covered in dunes like the ones in most of today’s Doñana. But in late November 2022, the researchers sampled the surface where the footprints were found: it was much older.

The party had walked the area about 295,800 years ago, in the Middle Pleistocene. At the time, the sea level was 60 meters below the current level, and the coast was 20 to 25 kilometers further ahead. Eduardo Mayoral, a paleontologist from the University of Huelva, described the scene:

“We have found some areas where several small footprints appeared grouped in a chaotic arrangement.”

They also concluded that the 87 footprints belonged to 36 individuals: 11 children, and 25 adults. Among the adults, 5 were female, 14 were male, and a total of 6 were of undetermined sex due to a lack of evidence.

They were humans like us, an extinct species that, much like the modern humans that would take over their territory, were hunter-gatherers who moved regularly to acquire resources between Southern Spain and the Atlantic regions of Europe eastward to Central Asia, made sophisticated stone tools, built cave hearths, made adhesive with bark tar, weaved, sailed, knew medicinal plants, and used precise cooking techniques.

Cooking Neanderthal recipes

Modern humans may have even taken some inspiration from the Neanderthals’ accumulated knowledge and skills, as some paleontologists have proposed. A team of archaeologists claims that Neanderthals were the first to produce a specialized bone tool still used in human culture today. Does “first to produce” mean “teaching”? Remote cultural appropriation may have occurred in prehistory between different human species, or similar innovations could have arisen separately.

Ceren Kabukcu, a research associate in archeology at the University of Liverpool, wrote recently about how ancient humans prepared food by analyzing charred food remains dating back 70,000 years, a time when modern humans and Neanderthals coexisted in Western Eurasia:

“Our new study showed both Neanderthals and Homo sapiens had complex diets involving several steps of preparation, and took effort with seasoning and using plants with bitter and sharp flavors.”

We knew that culinary complexity was blooming much before the Neolithic, as hunter-gatherer leftovers found in Jordan in 2018, and dating to 14,400 years ago, attest. But could Neanderthals have taught us a thing or two about how to cook our food?

Mustard and pistachio in the wild

The newly found food remains include, for example, the use of wild mustard and terebinth (wild pistachio) mixed into foods, as found in Neanderthal tartar from 70,000 years ago:

“We discovered wild grass seeds mixed with pulses in the charred remains from the Neanderthal layers. Previous studies at Shanidar found traces of grass seeds in the tartar of Neanderthal teeth.

“At both sites, we often found ground or pounded pulse seeds such as bitter vetch (Vicia ervilia), grass pea (Lathyrus spp), and wild pea (Pisum spp). The people who lived in these caves added the seeds to a mixture that was heated up with water during grinding, pounding, or mashing of soaked seeds.”

Studies of the same footprints near Doñana had already depicted the character of some of the activities that —luckily for us— led to the ancient remains imprinted in rock: some of them are remains of “a youngster jumping irregularly as though dancing.”

Like in modern humans, our distant cousins dealt with the bitter taste of their healthy mixtures by soaking, heating, and de-hulling (removing the seed coat) the collected wild ingredients to decrease their toxin concentration and reduce their bitterness. Wild mustard, “with its distinctive sharp taste,” could be a seasoning brought to us by our distant cousins.

Studies show a diet of abundant meat in Neanderthals and early humans. However, early modern humans already enjoyed a more diverse diet, with a higher proportion of plants, which could have given our ancestors a survival edge during harsh weather periods.

If young Claude Lévi-Strauss could have traveled in time

We keep debating about the intelligence and symbolic behavior of Neanderthals, their “culture,” possibly including human-like language. There is evidence of Paleolithic art, ornaments from bird claws, feathers, and shells, as well as collections of objects, as well as instruments to make music. Life in their small, sparse groups may not have been that different from that of the human hunter-gatherers they interbred with several times in many moments in prehistory, as our genetic record shows.

We may even imagine one ethnologist like Claude Lévi-Strauss, father of structuralism, traveling in time and meeting a group of Neanderthals to conclude (like in his famous 1955 book Tristes Tropiques) that, in the human experience, it all comes down to the way in which any human finds relatedness, making sense of oneself and the world.

In the absence of time travel or sufficient archeological evidence, we have to make do with scientific speculation about the few Neanderthal remains and what their total or partial DNA sequencing tells about their groups and life, including diet, health, and family ties with other close remains, a potential peek into social structures and family ties.

The rise of sea levels and erosion may prevent paleontologists from finding more evidence about the day-to-day life of Neanderthals, but a few coastal zones with steep cliffs were spared of the sea rise and, in some cases, have led to discoveries such as Neanderthal remains in several caves along the Gibraltar rock.

A cave with a view

Gibraltar’s Gorham’s Cave opens to the sea from a vantage point that makes it ideal as a shelter. Behind the cave’s opening, several chambers that stay warm in winter and cool in summer, the perfect hideout for late Neanderthals, their population becoming so small and sparse that it could have reached a point of no return.

To some of these last populations, contact with nearby modern humans or total isolation from other human groups (forcing small groups to extreme inbreeding and eventual fading) may have been more probable than meeting their same kin. Male fossils recovered from a cluster of Siberian caves give a valuable glimpse into Neanderthal family groups.

The Siberian remains confirm a low genetic diversity —much lower than that recorded in remote and isolated human groups—. About 49,000 years ago, a Neanderthal family settled in a cave in Siberia’s Altai Mountains, a vantage point perched over a river valley with plenty of game and plants to survive.

The cave has yielded DNA remains of several individuals, including a father and daughter and 12 of their relatives. The genetic evidence shows that the group’s males remained in their families as adults. In contrast, their nuclear DNA related more to later Neanderthals in Spain than to earlier remains found at the nearby Denisova cave. The genetic similarities among men are stark, suggesting they lived in a population stuck in inbreeding, where only a few hundred men in more and more isolated groups had children. If we were to extrapolate the evidence to a currently isolated human group, researchers explain, this group would be endangered.

In contrast, the group’s female heritage (mitochondrial DNA) was more diverse than males, implying that more fertile women contributed to the gene pool than fertile males. This might also mean that women didn’t stay within their families. Laurits Skov of the Max Planck Institute for Evolutionary Anthropology believes Neanderthals lived in small groups of 30 to 110 breeding adults, and young females left their families of origin to live with the families of their mates.

Lack of diversity in our closest cousins meant higher odds for the remaining population to have offspring affected by recessive traits or homozygosity. A few millennia after the analyzed patrilocal Neanderthal family sheltered near a Siberian valley with pastures and roaming animals, their whole population went extinct.

The opportunity for mass DNA testing

If you were to develop an impairing or potentially lethal disorder or suffer from a genetic condition that can influence your descendants’ health, would you consider doing everything that’s in your hands to reduce the risk for you and yours?

It’s less of a rhetorical question than it seems, considering that genetic testing for health, ancestry, and discovery of our particularities continues to be a minority despite the affordability and lack of risk of commercial genetic tests done with mailed saliva samples.

Genetic testing can have an emotional impact, and any information stored on arguably secure databases dimmed scrupulous with privacy protections, is at a higher risk than 0; also, the information provided, if useful information on our genetic propensities and ancestry, is very limited: saliva tests usually don’t determine symptoms or maladies but a person’s “carrier status,” our odds to develop them due to the detection of certain analyzed.

If genetic testing provides limited information about an inherited condition, it can help anybody pursue available testing based on blood samples: saliva-derived DNA contains less amplifiable DNA, and error margins get higher. Commercial samples analyze only commonly identifiable markers that signal the potential to develop health conditions.

Unfortunately, the capabilities of online genetic reports to inform us whether we carry specific variants— that may not affect us but could affect our children’s health— are limited to a few dozen conditions. 23andMe, for example, analyzes 45 variants and eludes rare diseases, leaving people suffering or carrying them without a potential aid that could help them build their case for medical institutions to invest in their study and treatment.

Human maladies, then and now

Some time ago, a relative of mine from the Catalan Pyrenees, a middle-aged woman in her early forties raising a teenage girl, began to feel muscular fatigue, brain fog, and other symptoms people relate with long Covid.

In her case, though, there were other risks: her father, as well as his immediate male relatives sharing the same paternal haplogroup (or direct lane of male ancestors), had suffered a rare degenerative disease that prevents those manifesting it from properly codifying the protein perilipin-4, a recessive metabolic disorder that impairs their victims’ mobility, causing total paralysis and death in middle-aged men, and impairment in women.

Like any other family issued from mountain valleys in areas that have suffered isolation and, as a result, higher rates of degenerative and rare diseases (among them valleys from the Alps or the Pyrenees), my cousin’s paternal side carry genetic variants associated with a rare condition that lacks basic research. Apparently, an Italian family from the Alps suffers the same hereditary disease, and there’s at least one study quoting their condition, but there’s little progress on it.

If vague, ancestry reports can offer a valuable glimpse of our remote origins, though such services are more meaningful in areas with a big immigrant influx during the last few generations. This variability was crystal clear for Kirsten and me when we received our ancestry reports. As a Spaniard, I could confirm that my ancestors had not traveled much and all settled in the Iberian Peninsula a long time ago, whereas Kirsten, an American citizen, experienced a more interesting result and an ancestry belonging to different areas of the European continent.

The Neanderthal in us

With all their limitations, any basic online genetic test will offer a fascinating door to our complexity and uniqueness, and, to a significant part of the world population of at least partial Eurasian descent, it also opens a door for paleogeneticists to vindicate their work: in a little over a decade, evidence has accumulated that most Europeans and Asians carry between 1% and 2% of their genetic code from Neanderthals and their related hominin cousins, Denisovans, respectively.

We both could attest we don’t have increased likelihood or carry the few variants that confirm personal and hereditary predispositions of maladies that, to us, had justified taking the test (among others, Alzheimer’s disease, Parkinson’s disease, or a few types of cancer), and we felt such information already justified the hassle of taking the genetic test.

That said, a little section in the report fascinated us more than expected: our neanderthal side. The information I stumbled upon within my report is rather vague and broadly inconsequential, but I felt its relevance:

“You inherited a small amount of DNA from your Neanderthal ancestors. Out of the 7,462 variants we tested, we found 233 variants in your DNA that trace back to the Neanderthals. All together, your Neanderthal ancestry accounts for less than ~2 percent of your DNA.”

The report goes on and matches one’s genetic traits with specific Neanderthal variants. In my case, I have two variants associated with having difficulty discarding rarely-used possessions; one variant associated with having a worse sense of direction; two variants associated with being less likely to have a fear of heights; and three variants associated with being a better sprinter than a distance runner. Especially as a kid, I can attest to this last trait.

Open conversation with our remote past

Also thanks to these hominini, I’m apparently less likely to prefer salty foods over sweet (not sure about this one, but hey, there’s one variant detected); I also have one variant associated with having more dandruff (really?); one variant suggests I’m less likely to sneeze with a full stomach (I didn’t know some people experienced this, it sounds pretty distressing); and one last variant attests that I’m prone to eat leafy greens less frequently (this is a call to arms).

Still, that’s a very reduced sample of variants, considering the report claims to have found “233 variants in your DNA that trace back to the Neanderthals” out of a total of 7,462 variants tested (Kirsten has 220 out of 7,462). Thank you anyway, Neanderthal ancestors. Judging from the rather obsessive quest for a personal definition that clarifies a sense of belonging, having a significant amount of DNA originated in Neanderthals when they interbred with modern humans before disappearing 28,000 years ago or so should be read by anyone as way more than a mere footnote.

Neanderthals have fascinated us long before finding out that they roamed the same landscapes for thousands of years and interbred with our ancestors, to begin vanishing around 40,000 years ago and completely disappearing ten millennia after from the remote areas and cul-de-sacs of Western Europe where they could have been prompted to reside as modern human populations settled in.

Neanderthals may have taught us some things, and some of us carry an important amount of genetic heritage from this and other vanished human species. It’s not a coincidence that the demise of Neanderthals coincides with modern humans moving into their territory in several migratory waves. New findings complexify our narrative about our distant cousins.

Our evolution as a species isn’t a one-off event but the outcome of a continuing cultural and genetic interaction between different human species in a remote past we carry with us. Maybe, instead of going extinct, the remaining, already dwindling Neanderthal assimilated into groups of modern humans by interbreeding. Some studies propose this theory.