You might think that Neanderthals were very different from us modern-day humans. It’s true that lots about them is strange to us – from their biology to behaviors. That doesn’t mean we have nothing in common, and one study from 2020 shows a rather unexpected similarity. Yep, you might be surprised when you find out just what we share.
Quite a lot of things we know about Neanderthals come from DNA research. This has given us insight into how they looked and the likely structure of their society. There are still questions, though. Why, for instance, did Neanderthals go extinct while humans thrived? Well, mysteries like this have led scientists to try and explore just what makes us different to Neanderthals.
One of the enduring questions facing those who study human evolution is just how much of a resemblance can be found between ancient Homo sapiens and their Neanderthal cousins. A particularly difficult area of investigation is the early life of the latter – including their metabolism and how they grow. Does it have any similarity to human development?
The study we mentioned earlier was headed by Dr. Alessia Nava of both the Skeletal Biology Research Centre at the U.K.’s University of Kent and the Department of Maxillo-Facial Sciences in Rome’s Sapienza University. Other researchers came from different Italian and German institutions, so it was an international team. The work, meanwhile, was published in the Proceedings of the National Academy of Sciences.
Their focus was a little corner of northeastern Italy, where archeologists had uncovered several fossilized teeth. The most recent of these was 50,000 years old, while the oldest is from 70,000 years ago. They were Neanderthal teeth and the chemicals and isotopes they contained could provide fascinating answers to how these ancient people lived.
There were apparently three Neanderthal teeth in total. And they were compared to another ancient tooth that belonged to a human of the early Upper Paleolithic period. This meant analyzing their respective growth rates and chemical composition. And as the Neanderthal dentures were milk teeth, they could provide particular insight into the childhoods of their owners.
Scientists trying to date trees apparently do so by analyzing rings in the trunks. These show the pattern of growth and can teach us about the climate of the time. Experts looking to date teeth can actually use a similar technique, according to the study. With the help of a microscope, they can view tiny growth lines that help tell them how old the teeth are and the speed at which they grew.
The other main part of the tooth investigation involved isotope analysis. This is a common technique in archeology when researchers want to know what ancient people ate, where they lived and what kinds of interactions they had with other communities. In this case, the isotope of particular interest was strontium.
Strontium is an element found in water, rock and soil across the planet. Though the amount present can vary depending on a variety of geological processes. Humans consume strontium as part of their regular diet and it infuses their teeth and bones. This means the levels present in humans reflect the environment where they resided and can be used to tell what they were eating.
Through the analysis of the Neanderthal teeth, the researchers were able to learn a lot about where and how they lived. This information can now be added to the growing understanding of our ancient cousins and their relationship with early humans. It also joins a long list of other data that shows just how similar we are to them.
We already know quite a bit about other similarities between humans and Neanderthals. That’s partly because many people in the modern world have genetic traces from our Neanderthal ancestors. Up to 4 percent of the DNA in non-Africans comes from unions between humans and Neanderthals in prehistoric times, according to the US National Library of Medicine.
It all starts with a common ancestor shared by humans and Neanderthals around half a million years in the past. The two species became separated by geography as humans began developing in Africa, while Neanderthals evolved across Europe and Asia. Humans eventually traveled to the Eurasian continent and that’s where they were reunited.
When the two species began to breed together around 50,000 years ago it meant their DNA became mixed. And that’s why so many modern humans have Neanderthal ancestors. Genetic analysis has linked this DNA to everything from modern health conditions such as depression to protections from other diseases, The Verge notes.
It certainly makes sense that the humans who first arrived in Eurasia would have wanted to get to know the natives. Neanderthals were already adapted to colder weather than that familiar to the African-born humans. It would have been advantageous to pick up some Neanderthal traits as soon as possible, and breeding was one way to achieve that.
Modern researchers have sequenced DNA from Neanderthal bones and cross-referenced it with the traits and even diseases present in modern human populations. One place where they found similarities was in the skin. The genes for keratin – which is found in human skin, nails and hair – often sit next to Neanderthal genes.
Though tougher skin may not have been the biggest advantage we received from our Neanderthal ancestors, even if they helped us out 50,000 years ago. They’re genes that can cause us to develop skin conditions when we spend too much time in the sun. Dry, scaly skin known as actinic keratosis may be part of our Neanderthal inheritance.
Another unfortunate effect of our Neanderthal DNA is how it can cause blood to coagulate. For our ancient ancestors, this was a form of protection against strange diseases when they moved to a new continent. Yet for modern humans, it means an increased risk of having a stroke.
Perhaps strangest of all is the connection between Neanderthal DNA and nicotine addiction. According to a 2016 study published in Science, Neanderthal DNA can make you more likely to be a smoker. But how could this be, given that tobacco plants weren’t even growing in Europe and Asia back then? Well, it may be something to do with addictive behavior in general, but it’s also a sign of how complicated these DNA relationships can be.
One sequenced genome was from the so-called Vindija 33.19 bone fragment, which was found in a Croatian cave. It was over 50,000 years old and belonged to a Neanderthal woman whose genes were very similar to remains that were over 100,000 years old and found in Siberia. Max Planck Institute’s Kay Pruefer – who authored the study which appeared in Science in 2016 – talked to The Verge about its significance a year later. She said, “They are really so closely related that you cannot find any two people on this planet that are this close.”
Researchers then traced down appearances by the Vindija genome in modern human genes. And they found an extraordinary array of connections to arthritis, cholesterol levels, vitamin D levels, body fat, eating disorders, schizophrenia and reactions to antipsychotic drugs. Vanderbilt University evolutionary genomicist John Capra told The Verge that the gene’s “overall influence on any given person’s risk is really quite low.” But it’s astonishing to think it has any influence at all, right?
There are also cosmetic similarities between Neanderthals and humans because of the genes that control hair and skin color, according to a study published in the American Journal of Human Genetics. Contrary to some popular depictions, Neanderthals never actually had red hair, but they may have ranged from blonde to dark just like us. But what we don’t know is how humans continued to thrive even as Neanderthals became extinct.
It may be something to do with that unexpected similarity between the Vindija Neanderthal and the Siberian remains. It suggests that there wasn’t much genetic diversity in Neanderthal populations, which in turn would have made them more susceptible to disease and deformity. Yet evidence suggests that early humans may have been a much more diverse species.
If humans lived in larger social groups and traveled more, then there would have been much more opportunity to swap genes along with goods and ideas. University of Adelaide research fellow Bastien Llamas explained to The Verge that they may even have had a similar social structure to those we have today. This includes small family groups that had frequent contact with outsiders.
Another theory claims that humans simply outnumbered Neanderthals by breeding much faster than them until they couldn’t compete. The latter group may also have been edged out when humans started domesticating dogs and using them for hunting – leaving limited food behind. It’s not certain though, which is another reason why scientists are so eager to study the links between the species even more.
Many of the traits shared by humans and Neanderthals are shown in DNA, but there may also be behavioral similarities that we can study when exploring ancient remains. This includes things like the structure of family groups. The most recent study focused on early life and how young Neanderthals may not have been so different from human babies.
Rather than just extracting DNA from the teeth, the scientists turned to different forms of research like the isotope analysis we mentioned earlier. This allowed them to discover new aspects of Neanderthal life that they compared with humans in the modern world. And what they found provides a fascinating insight into a subject that has generally been poorly understood.
Specifically, the experts found similarities between the milk teeth of Neanderthals and humans that indicate something important about their early diet. They studied the combination of isotopes, the rate at which the teeth appear to have grown and the histomorphometry – a microscopic study. And the results suggested that, like humans, Neanderthals switched from milk to solid food at around five to six months.
The introduction of solid food is a significant part of a young child’s life and it serves a very important purpose. According to the author of the 2020 report Dr. Alessia Nava, it occurs because the child needs a “more energetic food supply.” If Neanderthals were weaned at the same age as humans, it suggests they had similar energy requirements, body types and lifestyles to us.
Interestingly, the weaning process is a common topic of study even among modern humans. Questions about how long it should take, cultural differences in approaches and the effect it has on babies generally are frequently asked. And it all centers on what is the best way to ensure the child has their nutritional needs met.
When babies are born, they have very specific dietary requirements that can usually be met entirely by breast milk. It has the ideal combination of vitamins and other nutrients that a child needs as well as offering some protection from infections, cot death and childhood leukemia. According to the U.K.’s NHS, it even has implications for long-term health – such as the likelihood of developing diabetes.
Breastfeeding can also have health benefits for the mother as well. These things are especially true in the first six months, though the process can continue past this point. It’s not always that easy though; there are lots of things that can make breastfeeding more difficult. And that’s when formula comes in.
Baby formula can be made from cows’ milk or other alternatives and is treated so it’s more suited to babies. Some of them come as liquids, while other types are a powder form that needs to be mixed with water. It doesn’t have all the advantages of breast milk, but the formula still offers a healthy diet before the baby can be weaned.
It’s at around six months that breast milk or the equivalent formula no longer meets all a baby’s needs, the NHS notes. That’s when solids can be introduced as “complementary feeding” in addition to breast milk. This doesn’t just mean the baby gets extra nutrients, but they also have to learn how to chew and swallow. Indeed, as any parent will tell you, it’s a big moment!
The NHS adds that a combination of breast milk and solid food should be used until the baby is at least a year old. Though the point where mothers stop breastfeeding completely is a matter of personal preference. Experts recommend gradually introducing a variety of different tastes and textures to a baby early on to discourage fussy eating.
The reason weaning occurs at around six months isn’t just a cultural norm. No, it actually has genuine physiological reasons relating to the energy required for human development, according to Nava. One of the 2020 study’s co-authors is University of Bologna researcher Dr. Federico Lugli, and he talked about the “high-energy demand of the growing human brain” in comparison to other primates.
Yet another of the study’s authors – Dr. Stefano Benazzi – explained in the report that human and Neanderthal babies may have had “similar energy demands.” And that suggests that they would have had similar rates of growth. Amazingly, just this one little detail about weaning has much wider implications regarding Neanderthal development.
So, we can now extrapolate that Neanderthal babies may have been a lot like human babies. They were probably a similar sort of size and grew in a similar way. It’s yet another piece of the puzzle, but it’s not all we learned from the research. It also suggests more about Neanderthal society and how and where they lived.
The levels of strontium in the Neanderthal teeth indicated they spent most of their lives within that one area of northeast Italy. There were lots of caves in the area where they could shelter and plenty of food to eat, so it makes sense as a home. They must have been careful in how they used their resources and may even have used the same thought processes modern humans do when deciding to settle down.
Neanderthals were living in that part of Italy up until 45,000 years ago. And they were doing so while living and growing, much as modern humans do. It tells us more about their existence, but not about their extinction. The report seemingly ruled out the weaning process as a contributing factor to that, but there’s still such a lot we need to learn.
This may not be the single conclusive piece of evidence that resolves all our questions about Neanderthals. But it still sheds a fascinating light on our ancient cousins. Every new thing we learn is an important step not just to understanding them, but filling in the gaps in our own history as a species. And it tells us more about what it means to be human.