We might be the only species of human alive today, but just a few hundred thousand years ago there were a handful of different species living across the world. The Neanderthals were one of these species, and having evolved from the same ancestor as us, they’re our closest cousins.
How closely related are we to Neanderthals?
It was long thought that we (Homo sapiens) evolved from Neanderthals (Homo neanderthalensis) and that these stocky ‘almost-humans’ were a transitional phase between chimpanzees and modern humans. This ‘March of Progress’-style image is often how our evolutionary history is depicted, but it couldn’t be further from the truth.
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Instead, modern humans and Neanderthals are sister species that evolved from the same common ancestor, diverging from one another roughly half-a-million years ago. As a species, Neanderthals emerged earlier than modern humans, roughly 400,000 years ago compared to 300,000 years ago, but it wasn’t until 130,000 years ago that ‘classic Neanderthals’ really appeared.
It’s unclear exactly who gave rise to modern humans and Neanderthals. It’s suggested we descend from an African population of Homo heidelbergensis, or perhaps another archaic species known as Homo antecessor, or ‘pioneer man’. It has even been theorised that the common ancestor of modern humans and Neanderthals may be a so-far-undiscovered species.
Regardless of who this common ancestor was, genetic studies show that Neanderthals are our closest relatives and share up to 99.7% of our DNA. These similarities run so deep that some suggest Neanderthals may actually represent a subspecies of Homo sapiens and should be renamed Homo sapiens neanderthalensis.
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Could Neanderthals speak?
The linguistic ability of Neanderthals has long been debated. From their discovery in the mid 19th century until quite recently, they were often portrayed as dim-witted ‘cavemen’, their communicative abilities thought to be limited to grunts and simple gestures.
It’s clear from the wealth of archaeological artefacts left by Neanderthals alone that this was simply not the case. The discovery of clothes, jewellery, weapons, and sophisticated homes crafted by Neanderthals paint a picture of people who could not only communicate, but collaborate and even create art.
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As well as archaeological artefacts, researchers also point to similarities in their vocal anatomy with modern humans and their known cognitive abilities. Neanderthals had larger brains, on average, than modern humans and while this doesn’t mean they were necessarily smarter, it does suggest they were a highly intelligent species - just like us.
In order to find out just how well Neanderthals could speak, a team of researchers from the University of Iowa examined their genetic code for genomic regions known as ‘human ancestor quickly evolving regions’, or HAQERS. These aren’t genes, rather sequences that affect how and when certain genes are expressed, and they’ve been shown to have a large effect on human language development.
What these researchers found as part of a study published in April, 2026, surprised them. Neanderthals not only had HAQERS, but they were even more prominent than those found in humans today. This doesn’t confirm Neanderthals hadlanguage, but it does suggest that the genetic hardware was there for it to develop.
If that was the case, and Neanderthals were capable of language, surely they could have found ways to communicate with the humans they bumped into - right?
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Could humans and Neanderthals communicate?
It’s clear, based on the genetic evidence, that humans and Neanderthals regularly ‘bumped’ into one another - in more ways than one…
In 2010, researchers successfully sequenced the Neanderthal genome and discovered that modern humans of non-African descent carry roughly 2% Neanderthal DNA in their genomes. Some populations carry even more: the proportion in East Asian populations can be as high as 4%!
This genetic evidence proves that humans and Neanderthals interbred quite regularly, and suggests some may have even lived together in mixed groups. The individuals living in these mixed groups, nurturing and raising hybrid offspring, must have been able to communicate to some degree.
While this may seem a little far-fetched, it’s backed up by fossil and archaeological evidence. In 1931, archaeologists discovered the 140,000-year-old remains of a child in Skhūl Cave on Israel’s Mount Carmel. This is widely recognised as the oldest known deliberate human burial.
Later CT scans revealed the skull base and inner ear of the Skhūl 1 child are anatomically modern, while the jaw is Neanderthal, suggesting it was an early Homo sapiens-Neanderthal hybrid.
Another jaw bone found in a cave in southwestern Romania also displays a mosaic of Homo sapiens and Neanderthal features. This 40,000-year-old bone was subjected to genetic sequencing in 2015 and was found to have a surprisingly high amount of Neanderthal DNA, suggesting the individual had a Neanderthal ancestor between four to six generations back.
In February, 2026, a genetic study on three female Neanderthal specimens found that female Homo sapiens and male Neanderthals mated more often than male Homo sapiens and female Neanderthals did. According to the authors of this study, these prehistoric sexual preferences helped to shape the modern human genome.
This wealth of genetic and archaeological evidence certainly suggests Homo sapiens and Neanderthals could communicate, but whether or not they could understand one another is a different question.
Did a difference in understanding ultimately lead to Neanderthals’ demise?
We’re fascinated with human-animal communication and, as a species, have successfully communicated with dozens of different animals, from other great apes such as chimpanzees and gorillas, to birds such as crows and parrots.
However, to what degree these animals truly understand us is questionable. They may recognise expressions of aggression, hostility, appeasement, approachability, submission, and fear - and we may recognise theirs in return - but whether they grasp our intentions and the meaning behind these interactions remains unclear.
These kinds of philosophical questions are impossible to answer, particularly in the case of us and our long-extinct cousins. Until we invent time travel and visit a mixed community of Homo sapiens and Neanderthals, we’ll never know to what degree they understood each other.
In recent years it has been suggested that a difference in Neanderthals’ understanding of each other may have ultimately led to their demise. Using a combination of modelling, archaeological evidence, and ethnographic data, a study published in April, 2026, discovered that a key factor in the extinction of Neanderthals may have been social connectivity - or the lack thereof.
The researchers involved with this recent study found Homo sapiens formed stronger, more flexible social networks that helped them survive periods of climatic instability. Neanderthals likely had similar connections, but researchers found they were more fragile and regionally limited, which made them less resilient as conditions got more and more unpredictable.
Neanderthals faced extinction 40,000 years ago and those that weren’t assimilated into groups of Homo sapiens faded into the annals of history, their genes lost. Those that did assimilate, however, passed on their genes, contributing to the gene pool that eventually spawned modern humans.
It’s not difficult to imagine that these assimilated Neanderthals not only learnt how to communicate with their neighbours, but understand them too.
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Top image: VICTOR HABBICK VISIONS/SCIENCE PHOTO LIBRARY / Getty Images
