By all accounts Homo neanderthalensis should’ve driven Homo sapiens extinct. They had larger brains, stronger muscles and thicker bones. Yet we are the only species of Homo alive in the world today, creating one of the most puzzling aspects of recent human evolution. How did we beat the neanderthals?
Answering this question is made even more difficult by the fact that every time scientists believe they have found something which separates humans from neanderthals, it is promptly discovered neanderthals had that trait too.
In the past the fact we used fire (showing we were more intelligent), ate plants (showing we were more adaptable) and had personal ornamentation (showing our culture was more developed) – but neanderthals didn’t – has been used as evidence we were superior. Yet it turns out neanderthals used fire, ate plants and had personal ornamentation too.
Neanderthals: a pain in the arse from beyond the grave.
Recent research, however, seems to have discovered a difference between Homo sapiens and Homo neanderthalensis which might explain why we out-competed them: our brains are a different shape to theirs.
On the bottom of our cranial cavity are depressions, technically called fossa (that’s your science word of the day), in which the brain sits rather snugly. Thus the shape of the brain is related to the shape of these fossae, which in turn means we can infer the shape of bits of the brain from the shape of the fossae these bits rest in.
And that is precisely what the scientists did. They compared the fossae of humans and neanderthals – specifically those fossae in which the frontal lobes, olfactory bulbs and temporal lobes sit – in an effort to determine if our brains are differently shaped to theirs.
The analysis revealed that Homo sapiens‘ olfactory bulbs were larger than those of neanderthals, who also had more oval shaped bulbs. Our frontal lobes are also wider, as are our temporal lobes which are also longer. Neanderthal temporal lobes did have an increase in width, but not as much as modern humans.
Left: Neanderthal skull; Right: Human skull. Science fact: The skull isn't actually blue
So, what does this all mean? Well,the olfactory bulbs are responsible for our sense of smell and how their size and shape influences this sense has been extensively studied. That research suggests that our bulbs would result in a better sense of smell than a neanderthal’s bulbs.
As well as giving us the advantages associated with an improved ability to sniff, a better sense of smell is also correlated with a better immune system and a better memory.
Now, that’s not to say that a better sense of smell gives one better memory but that the association of memories with odours makes those memories stronger. Nor does a larger olfactory bulb give us a better immune system. Instead, a larger olfactory bulb is typically associated with an increase in size of the other bits of the brain associated with immune response.
The other changes to the brain are less well studied, but at least now the data is there for future reference should someone identify the implications of having a wider frontal lobe etc.
There is some current use for that information, however, since they also ran this analysis on older members of Homo. This allows the frontal and temporal lobe changes to be placed in an evolutionary context. Such a placement suggests that whilst neanderthals had a larger brain, structurally it was more primitive. This might help explain why we out-competed them.
He looks confused because there's a monkey brain in his head.
At this point I would normally go on to discuss the strengths and weaknesses of the paper, but this one appears fairly strong. The analysis is rigorous, the data used to infer we had a better sense of smell and its implications is strong and where they don’t have the data to make such inferences they don’t guess, they just say ‘there’s insufficient data.’
One shortcoming is that they didn’t use very many neanderthals in the study, which could mean the results are simply an artefact of individual variation: we didn’t have larger olfactory bulbs, the scientists just found some neanderthals with freakishly small bulbs by accident.
So some further up research may be required, but all in all its a fairly rigorous study and I fully expect its conclusions to be borne out by any replication.
As such, it seems fairly safe to conclude we did have differently shaped brains to neanderthals and this was likely a factor in allowing us to outcompete them. There were likely other factors too, but at least one piece of the puzzle is in place.
| Henry, A.G., Brooks, A.S. & Piperno, D.R., 2011. Microfossils in calculus demonstrate consumption of plants and cooked foods in Neanderthal diets (Shanidar III, Iraq; Spy I and II, Belgium). Proceedings of the National Academy of Sciences, 108(2), pp.486 -491. |
| Bastir M, Rosas A, Gunz P, Peña-Melian A, Manzi G, Harvati K, Kruszynski R, Stringer C, & Hublin JJ (2011). Evolution of the base of the brain in highly encephalized human species. Nature communications, 2 PMID: 22158443 |
| Rightmire, G.P., 2004. Brain size and encephalization in early to Mid‐Pleistocene Homo. American Journal of Physical Anthropology, 124(2), pp.109-123. |
| Zilhão, J. et al., 2010. Symbolic use of marine shells and mineral pigments by Iberian Neandertals. Proceedings of the National Academy of Sciences, 107(3), pp.1023 -1028. |
EvoAnth 
Fascinating!
Interesting.
Something new I learnt today.
I never understood why anthropologists associates brain size with intelligence. Whales have huge brains, and they’re not that smart.
I understand it has to do with the ratio of body size to brain size, but I don’t see why it seems like the way the circuitry is wired would be way more important.
Take a CPU, for example. A physically larger CPU isn’t necessarily able to process instructions faster.
You are correct that when people talk about brain size they typically mean brain size relative to body size, rather than as an absolute term.
However, when such measurements are compared with intelligence, the term is normally being only used as a placeholder. Making a direct comparison between brainsize and intelligence can’t really be done since the IQ of our smaller brained ancestors doesn’t really preserve.
Instead, we can only look at the products of this intelligence – tools, personal ornamentation, fire etc. However, these products can’t really be correlated with intelligence since it might be that an exceptionally smart individual had to produce “dumb” tools for some reason.
Although that might sound like an esoteric issue, it’s actually a rampant problem underlined by the fact that the first “primitive” stone tools continue to be used alongside spears millions of years later.
As such, there is a push for using the “concepts” expressed in stone tools, rather than tools themselves because whilst a type of tool might be present or absent, concepts are less variable and so a better overall indicator.
However, most research into this is focusing on the past 200,000 years, after anatomically modern humans arise. As such, if they do determine there has been an increase in intelligence it can’t be explained by an increase in brain size since we’re talking about people whose brain size remained fairly stable. So they’d have to explain it with “rewiring” if a biological explanation is necessary.
So does that all mean? Well, evolutionary anthropologists – in my experience – tend to shy away from talking about intelligence because there’s no real way of quantifying it in the fossil record.
And they do acknowledge rewiring is important as this paper, the “concept” research and a few other things suggest.
Juju2112, your comment got me thinking. CPU is deprecated recently because it’s meaning became ambiguous. If by it you meant processor core, then yes, larger cores aren’t necessarily faster; but it usually refers not to a single core, but to a processor consisting of several, in which case bigger is better.
Thinking about it, my mind jumped to why algorithms are important. I considered writing about it in more distant future, but this awesome post and your comment gave me an idea. So I’ll probably write about it soon and I’ll include a link to here.
All cetaceans are extremely intelligent. I don’t know where you got this idea that they are “not that smart.”
Yes they are, but not smarter..
Prove it. How do you measure “intelligence?” If you’re measure is by human parameters, how do you justify analyzing non-human intelligence by human criteria?
Also, the assertion was that cetaceans were “not that smart.” Not that they just weren’t quite as smart as humans. Yet all evidence I’ve seen suggests quite the contrary: they have language, they live in familial groups, they express complex social behaviors and problem solving abilities, etc. If we found whales on an alien planet we’d likely be spending billions trying to communicate with them as “extraterrestrial intelligence.” But instead we are used to them as fellow earthlings and so take them for granted.
juju2112 also made the gross fallacy of comparing brains to CPUs, as if the two are equivocal without question or explanation.
Well…walruses have human sized brains so maybe they are equally smart as us? Or dolphins are dumber than Blue whales? Or dumber than elephants? Crows are extremely smart and yet they have smaller brains than a walnut. Horses have bigger brains than chimps, but chimps far outsmart horses.Do you get my point? Brain size is not important that much….Encephalization Quotent and brain anatomy are far more important.Humans have EQ of 7, dolphins have EQ of 5 and chimps – 3. Its seems accurate and do not try to correct me with shrews and humming birds because a recent research shows that humming birds and shrews have EQ slightly lower than 1.80.People sometimes confuse EQ with the simpler brain-to-body mass ratio.Humans, chimps and dolphins have higher neuron number, density and better connection between neurons (and also more spindle cells) than whales and elephants.
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So the larger size of relative portions of our brains allowed us to compute certain things better (ie. smell -though I’ve read elsewhere they had 40X the nasal sensors. and would wonder if it were more a difference , ie. dog-eye motion vs. human eye colored patterns. ). So what parts did they have bigger than us. what would be an hypothesis of what they might excel us in doing? C.lupus has much larger brain and can problem solve much better than C. fam. , but C.fam. can read humans much better. If I were to meet a Neanderthal , besides being built like a pro-wresler, what might I be in delight of him being able to do?
Well neanderthals had a larger visual cortex than us so they could better see in Europe’s low light levels. On the other hand, an increased visual cortex left less room in their head for other bits of the brain which would indicate they are less able to keep track of social relationships (brain size minus visual cortex being correlated with group size).
So you could show off to a neanderthal with all your facebook friends whilst he could impress you by spotting things in the distance.
There were likely other differences but we’ve yet to hammer them down. Increased visual cortex size, for example, has been associated with more mathematical ability. Maybe neanderthals were also better at sums, although this work is a bit more iffy.
For more information on these issues, the “in brief” page at the top of this blog contains links to most of the posts I’ve written, maybe something you see there sparks your interest. In particular I’d recommend
https://evoanth.wordpress.com/2011/12/25/explaining-our-big-brains/
https://evoanth.wordpress.com/2012/01/29/neanderthals-had-differently-organised-brains/
The former elaborates on the link between group size and brain size whilst the latter talks about neanderthal’s visual cortices.
I hope this has been helpful.
Yes, thank you.
Really though, don’t you think you’re assuming a little much?
Neanderthals may just have had a more basic sense of the world around them and didn’t think to think about the deep scientific mysteries like we do.
Look at the bird. The bird can fly. If this bird does not fly again, there is something wrong.
It could have just been inductive instead of deductive reasoning that made the difference. What is is, and if it is not how it is before, something is wrong or has changed. Is this a problem?
Next issue.
Look at this video. (No seriously look, and take me seriously)
Identifying the extent of Neanderthal cognitive abilities is difficult, the best we can do is to try and infer potential differences based on physical/cultural differences between us but even then there can be a large margin of error. That’s why this paper didn’t delve into the specifics of any cognitive differences: it would be almost impossible to work out.