The Neanderthals (scientific name: Homo neanderthalensis) are a species of extinct human relative (technically ‘hominin’) that occupied Europe, West and Central Asia from around 400,000 to a little less than 40,000 years ago.
Science has known about them for more than 180 years now and they were the first extinct hominin to be discovered. sapiensH. sapiens, pushing our understanding of human origins beyond a Biblical timeline for the Earth.
Scientists studying human evolution are fascinated by them for a multitude of reasons; with more written about them than any other extinct species. For example, 2014 has already seen dozens of scientific articles published about them and we’re not even halfway through the year!
The Neanderthals are also deeply embedded in Western culture as the archetypal “caveman” and have historically been given a bad wrap. In the English language, we even use the term “Neanderthal” in a derogatory way to describe an ignorant or unenlightened person.
So, why the fascination with them?
A little bit of history
The first Neanderthal fossil was found at Engis Cave in Belgium by Philippe-Charles Schmerling in 1829. Schmerling found fragments from the skull of a Neanderthal child. Slightly earlier, in 1823, a fossil had been found at Paviland Caves in Wales, but we now know it to be a member of Homo sapiens.
Quite remarkably, these two European caves provided the earliest evidence for humans living beyond the timeline inferred from the Bible. Paviland is now thought to be around 30,000 years old, while Engis is still of uncertain age, but older than Paviland Cave.
The first skull of an adult Neandertal was found at Forbes‘ Quarry in Gibraltar in 1848. But, it wasn’t announced to the scientific community until 1865. The most important of prehistoric human remains from this time were, however, those recovered from the Neander Valley in Germany in 1856 at a site called Feldhofer.
The Feldhofer Cave skeleton came to light during quarrying, much of it destroyed before being rescued by a local teacher. The top part of the braincase survived and was examined by the anthropologist Hermann Schaafhausen. He drew attention to its “savage” and “brutal appearance” implying great antiquity.
When his work was eventually translated into English, the amateur archaeologist George Busk emphasised several ape-like characteristics, such as its pronounced eyebrow ridges.
The famous anatomist, founder of human evolutionary science and “Darwin’s bulldog”, Thomas Henry Huxley, published the first detailed study of the Feldhofer fossil in 1863. While acknowledging it to be the most ape-like of fossils found so far, he felt that on account of its large brain, it would have fallen within the wide range of variation for living humans
At the time, the human brain was considered the cardinal feature that distinguishes us from all other organisms, including our Stone Age ancestors.
At least one worker felt the Feldhofer Neandertal was distinct enough from humankind to belong to a different species, and in 1863, William King dubbed it Homo neanderthalensis.
Soon after, more Neandertal remains were recovered, yet their place in human evolutionary history was far from settled, with scepticism from several scientific quarters. Only with the discovery of several further Neandertal remains at Spy in Belgium in 1886 were the sceptics were beginning to be silenced.
Another important figure from the early 20th Century time was the French anthropologist Marcellin Boule. He believed that the Neanderthals had played no role in the evolution of contemporary humans, but were instead a very primitive evolutionary side-branch or dead end.
Boule did all he could to portray the Neanderthals as brutish, stupid and very different to humans. It is fundamentally because of his work that we see them in popular culture as an unsophisticated cave dweller, the archetypal dumb “caveman”.
For the remaining 20th Century up until today, the precise place of the Neanderthals in evolutionary history has been hotly debated. Importantly, anthropologists have argued about whether they played a role in our evolution – as direct ancestors – or were simply close (?kissing) cousins.
When and why did they disappear?
Current evidence suggests that the Neanderthals disappeared around 40,000 years ago, perhaps slightly more recently. This is about the same time that H. sapiens settled Europe after our ancestors migrated out of Africa maybe 60,000 years ago.
We don’t yet know why they disappeared, just that it is broadly coincident with modern humans settling Europe. Yet, they seem to have overlapped for several thousand years or more in West Asia (Middle East) and probably even interbreed with H. sapiens in this region.
The sequencing of DNA from several Neanderthals and comparisons with the DNA of living people from Asia and Europe has provided a pretty convincing case that we interbred.
I’ve written several articles about this topic for The Conversation and in my blog if you wish to read more about the topic (see links below), but recent evidence suggests that while we interbred, it was likely to have been mating between different species. This is surprisingly common in nature.
Even if we interbred with them, which seems reasonable, they were not our ancestors as such.
The ancestors of Europeans seemed to have hung around Asia for 10,000 years or more before they migrated into Europe. Why? Was it because of the climate? Or, because of competition with Neanderthals? Were the Neanderthals already in decline before modern humans settled Europe, providing impetus for the colonisation of the region by our species?
Latest ideas about our cousins
Over the last month since my last blog, some interesting papers about the Neanderthals have been published. I’ll outline the findings of two of them that received quite a bit of media attention to give you a taste of some the current research on them and how our ideas about them are changing.
More on DNA diversity
In the first one, authored by Sergi Castellano and a large team of geneticists and published in PNAS, the DNA of two Neanderthals – one from Spain dated ~49,000 years old and one from Croatia aged about 44,000 thousand years – was studied to try to understand how much diversity there was in the species.
The team studied more than 17,000 genes that produce proteins, or play a role in the physiology of the body.
We know that in our species, genetic diversity is quite low, especially compared to our living cousins, the chimpanzees, even though there are 7 billion of us. This is because we all descend from a very small Stone Age population living in Africa around 200,000 years ago.
Also, genetic diversity can be an indicator of recent evolutionary history and, when it is especially low, a species is vulnerable to extinction. This could have been an issue for the Neanderthals.
It seems that the Neanderthals had much less genetic variation (diversity) than living humans and probably lived in very small and isolated groups.
Other important findings of this research relate to the particular genes that have changed between Neanderthals and us after we shared a common ancestor 500,000 years ago or more.
Castellano and co-workers found that after the split, Neanderthal DNA shows an abundance of gene changes related to metabolism, the cardiovascular system, hair distribution, and physical features affecting the genitals, palate, face, limb extremities, joints, fingers and toes, thorax, and other parts of the skull. There is also evidence for even later changes to genes involved in the curvature of the spine.
In modern humans, they found a large number of changes in genes associated with skin and hair pigmentation (colour) and also some behavioral traits. In the latter group, they identified genes that are clinically associated with disorders like psychomotor retardation, autism and Tourette syndrome including some involved in “hyperactivity” and “aggressive behavior.”
It is difficult to know precisely how these genes would have affected the behavior of our Ice Age ancestors. Human behavior is controlled by much more than just our DNA, the authors concluded that even if these genes changes affected behaviour,
“…the way in which they occurred is unknown. For example, if they affected activity or aggression levels, it is unclear whether they increased or decreased such traits.”
More on the Neanderthal Demise
The second and final research article I’ll discuss was published by Paola Villa and Wil Roebroeks in PLoS One. It set out to test whether the archaeological evidence for Neanderthals indicates that they were behaviourally less sophisticated than Ice Age modern humans: yet another study in a long history of such investigations beginning with Boule.
A common view is that (quoting Villa and Roebroeks),
“the disappearance of the archaic populations, including Neandertals, is routinely explained in terms of the ‘’superiority’’ of modern humans, who had developed in Africa the ability to evolve complex cultural traditions and had become equipped with cognitive capacities which allowed them to expand globally and replace all other hominins.”
They undertook a detailed review of the archaeological evidence for Neanderthals comparing it with similar evidence for modern humans who lived about the same time. In particular, they examined issues such as:
- Language and symbolism,
- Hunting methods and diet,
- Organised use of space,
- Capacity for innovation,
- Size of social networks, and
- Hafting Procedures, Heat Treatment and Cognition (i.e. tool making as evidence for complex thinking).
They end their review concluding,
“…as we tried to show here, the Neandertal archaeological record was not different enough to explain their demise in terms of inferiority in archaeologically visible domains. Thus, if Neandertals were not technologically and cognitively ‘‘disadvantaged’’, how can we explain that they did not survive?”
Well, actually, they don’t in the end have an answer as such. They conclude that there was unlikely to have been a single cause and that it certainly wasn’t the result of more sophisticated behaviour by migrating modern humans.
As I noted above, the DNA evidence suggests they could have been vulnerable to extinction on account of their low genetic diversity and living in small and isolated groups.
To be frank, I’m pretty skeptical that we can really get at the cognitive (thinking) capacities of any hominin by looking just at archaeological evidence. There is so much missing (e.g. wooden tools) and we don’t really understand the reasons why certain types of tools were made or how they were used or why they took a particular form over another.
Neuropsychologists experimenting with living people have difficulty enough understanding how the brain functions and why people do the things they do, even when they have the luxury of being able to study their brains with sophisticated techniques like magnetic resonance imaging and asking people questions in surveys.
We don’t have fossilised brains and have no chance of really understanding why particular choose were made or cultural traditions developed. Moreover, we know that many other animals are capable of very complex behaviours as well but this doesn’t mean that their brains function the same way as our does.
Different species have brains that function differently, and clearly also have distinct behavioural repertoires. How can it be any other way?
I find stone tools to offer a crude window into past behaviour and motivations and think that we need to be a lot more careful in claiming thinking capacities from was is ultimately very limited evidence.
First published in May 2014.
Posted in: Meet the cousins