Brain Function of Homo Neanderthalensis

Scientists have the fossilized skulls the Neanderthals left behind to decipher information about the brain and its function, which isn’t extremely helpful. Anthropologists now know that they used tools, made art, and may have talked. Still, nobody fully knows how their brains worked, or how their thinking was different from modern day humans. Fresh analysis of fossil data suggests that their brain structure was rather different. Although the brains of our ancestors and Neanderthals were about the same size, Neanderthals had larger brain areas related to vision and body control. Homo Neanderthalensis seem to have adopted an alternative strategy that involved enhanced vision coupled with retention of the physical robusticity of H. heidelbergensis, but not superior social cognition. Results imply that larger areas of the Neanderthal brain, compared to the modern human brain, were given over to vision and movement and this left less room for the higher level thinking required to form large social groups. For example, if the Neanderthals had less brain area devoted to social cognition, it might explain why they traveled shorter distances, had fewer symbolic artifacts and lived in smaller communities.

“Neanderthals had smaller social networks than modern humans because Neanderthals had smaller areas in their brains to deal with social complexity,” says investigator Eiluned Pierce.

Smaller social groups is an aspect of Neanderthal explaining why Neanderthals went extinct whereas modern humans survived hence many theories surrounding this observation. Smaller social groups might have made Neanderthals less able to cope with the difficulties of their harsh Eurasian environments, because they would have had fewer friends to help them out in times of need (Fenlon, 2013).

Once the differences in body and visual system size are taken into account, researchers are able to compare how much of the brain was left over for other cognitive functions. Research by the Oxford scientists shows that modern humans living at higher latitudes evolved bigger vision areas in the brain to cope with the low light levels. This latest study builds on that research, suggesting that Neanderthals probably had larger eyes than contemporary humans because they evolved in Europe, whereas contemporary humans had only recently emerged from lower latitude Africa. Because this study is based on a hypothesis it is important to note certain regions are specialized to process certain types of sensory inputs and are active during certain tasks. But they’re all part of distributed functional networks, and we’re nowhere near understanding how those networks lead to this or that behavior. Scientists must always be careful about how to interpret any particular finding. In this case, the study shows a contrast between the visual systems of Neanderthals and our ancestors. That could underlie a difference in their social processing, or it could very well not (University of Oxford, 2015).

Who are Homo sapiens?

The name Homo sapiens, selected for ourselves means ‘wise human’. Homo is the Latin word for ‘human’ or ‘man’ and sapiens is derived from a Latin word that means ‘wise’ or ‘astute’. Homo sapiens is the name given to our species if we are considered a subspecies of a larger group. This name is used by those that describe the specimen from Herto, Ethiopia as Homo sapiens idàltuor by those who believed that modern humans and the Neanderthals were members of the same species. (The Neanderthals were called Homo sapiens neanderthalensis in this scheme). Homo sapiens evolved in Africa from Homo heidelbergensis. They co-existed for a long time in Europe and the Middle East with the Neanderthals, and possibly with Homo erectus in Asia and Homo floresiensis in Indonesia, but are now the only surviving human species. African fossils provide the best evidence for the evolutionary transition from Homo heidelbergensis to archaic Homo sapiens and then to early modern Homo sapiens. There is some difficulty in placing many of the transitional specimens into a particular species, because they have a mixture of intermediate features which are especially apparent in the sizes and shapes of the forehead, brow ridge and face. Some suggest the name Homo helmei for these intermediate specimens that represent populations on the brink of becoming modern. Late surviving populations of archaic Homo sapiens and Homo heidelbergensis lived alongside early modern Homo sapiens before disappearing from the fossil record by about 100,000 years ago (Australian Museum, 2015).

The earliest Homo sapiens had bodies with short, slender trunks and long limbs. These body proportions are an adaptation for surviving in tropical regions due to the greater proportion of skin surface available for cooling the body. More stocky builds gradually evolved when populations spread to cooler regions, as an adaptation that helped the body retain heat. Modern humans now have an average height of about 160 centimetres in females and 175 centimetres in males.

Cranial/ Brain Size of Homo Sapiens

Homo sapiens living today have an average brain size of about 1350 cubic centimetres which makes up 2.2% of our body weight making the brains of this species absolutely smaller than those of Homo neanderthalensis. However, due to its gracile postcranial skeleton, the brain of Homo sapiens is larger relative to body size than that of Homo neanderthalensis. Early Homo sapiens, however, had slightly larger brains at nearly 1500 cubic centimetres. The skulls of modern Homo sapiens have a short base and a high braincase. Unlike other species of Homo, the skull is broadest at the top and the sides of the skull are nearly vertical. The fuller braincase also results in almost no post-orbital constriction or narrowing behind the eye sockets. The back of the skull is rounded and indicates a reduction in neck muscles. The face of Homo sapiens is reasonably small with a projecting nose bone. They also have a limited brow ridge and the forehead is tall with orbits that are square rather than round. The skull of Homo sapiensgenerally lacks evidence of being strongly built (e.g., it lacks the large brow ridges and bony prominences seen in Homo neanderthalensis and Homo heidelbergensis) (Australian Museum, 2015) (Figure 3).

As early humans faced new environmental challenges and evolved bigger bodies, they evolved larger and more complex brains. Large, complex brains can process and store a lot of information. That was a big advantage to early humans in their social interactions and encounters with unfamiliar habitats. These unique features of Homo sapiens including changes in the skull and postcranial skeleton suggest changes in brain size and architecture and an adaptation to tropical environments. Over the course of human evolution, brain size tripled. The modern human brain is the largest and most complex of any living primate.

These anatomical changes are linked to cognitive and behavioral changes that are equally unique among hominin species. In particular, the archaeological evidence of behaviors thought to be unique to Homo sapiens, which appear first in Africa around 170,000 years ago, highlight the importance of symbolism, complex cognitive behaviors, and a broad subsistence strategy.

Even within the last 100,000 years, the long-term trends towards smaller molars and decreased robustness can be discerned. The face, jaw and teeth of Mesolithic humans (about 10,000 years ago) are about 10% more robust than ours. Upper Paleolithic humans (about 30,000 years ago) are about 20 to 30% more robust than the modern condition in Europe and Asia. These are considered modern humans, although they are sometimes termed "primitive". Interestingly, some modern humans (aboriginal Australians) have tooth sizes more typical of archaic sapiens. The smallest tooth sizes are found in those areas where food-processing techniques have been used for the longest time. This is a probable example of natural selection which has occurred within the last 10,000 years (Brace 1983).