On the Role of Clothing in Human Expansion Out of Africa
Thermoregulatory Evolution, Paleoclimate, & Clothing
The human body is remarkably fragile. It is able to function at full physical and cognitive capacity only within an extremely narrow, and easily disrupted, range of temperatures and environmental conditions. Yet, despite this, humans have succeeded in inhabiting an incredibly diverse range of climates, from tropical rainforests to Arctic tundra. This expansion—far beyond the warm, dry African savannahs where our species evolved—was made possible through the innovative use of natural resources, one of the most important of which was the use of hides to clothe the body. In this way, clothing served as the crucial barrier between delicate body and hostile environment, allowing humans to push beyond their biological means of survival. This post is going to explore the mechanisms behind this including thermoregulatory adaptations, the climatic conditions of prehistoric Europe, and how clothing helped us navigate the space where they intersected.
Core body temperature is approximately 37°C (98.6°F). Maintaining this balance is essential, in large part, because the central nervous system, including the brain, is highly sensitive to disruptions in homeostasis. As a result, the optimal functionality of our bodies and minds depends on remaining within the limited environmental range necessary to preserving this balance. Even modest changes, like sun exposure, wind or precipitation, can dramatically alter how we experience temperature and, in turn, have effects on cognition, motor coordination, and decision-making abilities.
Understanding this constraint helps explain the environmental pressures that shaped early human evolution. Because much of this evolution took place in Africa, initial challenges to thermal stability would have been predominantly driven by heat stress. Natural selection would therefore have favoured traits that more effectively cooled and supported a body capable of physical activity on the savannah, encouraging long-distance movements associated with hunting and foraging.
These pressures appear to have become more amplified with the emergence of early Homo species, when increasing brain size, and the associated energetic costs that came with it, put greater demands on the body’s ability to manage heat during activity. In this context, the evolutionary trajectory of Homo erectus is often associated with a suite of adaptations that improved thermoregulatory efficiency – body hair was reduced1, the number of eccrine sweat glands increased, and limbs became elongated.
The reduction of body hair was one of the most consequential changes in human evolution. It not only improved cooling efficiency, but also exposed the skin to new environmental pressures. For example, as body hair was being shed, eccrine sweat glands were becoming increasingly important. Unlike apocrine sweat glands, which are concentrated in the armpits and groin, and respond primarily to emotional stress, eccrine sweat glands are located all over the body and specialise in evaporative cooling. These changes allowed the skin to become a key vector for actively managing thermoregulation.
But this was not the only change that was taking place. Elongated limbs further increased the body’s overall surface area, creating more opportunities for heat dissipation. At the same time, greater skin exposure intensified selective pressures on skin pigmentation, favoring darker skin as protection against sun damage. Consequently, because skin pigmentation is genetically visible, researchers looking at ancient DNA are able to use it as an indirect proxy for body hair loss. On this basis, it is estimated that this transformation took place by at least 1.2 million years ago.
This is all to say that humans have undergone a long evolutionary history of adaptation to hot environments, while our biological adaptations to cold are comparatively modest. Physiological responses include shivering, through which rapid muscle contractions generate heat, as well as some heat production through brown adipose tissue, though its role is still being studied. An additional response is vasoconstriction, which conserves heat by limiting blood flow to extremities, but these mechanisms are relatively short term solutions.
The most serious dangers of cold exposure are frostbite and hypothermia, but the body begins responding to cold long before either appears. Heat-conserving responses can begin in temperatures as high as 27°C (80°F), become more pronounced below 20°C (68°F) and are exacerbated by wet or windy conditions. Thus, seasonal weather can become a very distinct danger, as survival is less dependent on innate physiology and must instead rely on the successful use of technologies like shelter, fire, and clothing. It was these behavioural adaptations that would have been indispensable to humans moving out of Africa, northward into Europe.
If you were taught about human dispersal out of Africa in school, it was likely presented as a relatively straightforward movement of people into Europe. However, the process was far from this linear. During the Early Pleistocene, European landscapes were shaped by frequent climatic oscillations between cool glacial and warmer interglacial periods, creating an environment inhospitable to humans over the long term. Therefore, settlement was more likely episodic, with humans favoring the transitional times between glacial and interglacial, when the climate was mild and open landscapes supported grazing animals. When glacial conditions returned or interglacials gave way to dense woodland, humans likely retreated southward. It has been suggested that this cycle may have occurred up to 42 times before humans mastered the correct technological adaptations which allowed for survival in colder conditions.
However, archaeological traces of these technologies remain sparse. One of the earliest strong cases for habitual use of fire comes from Wonderwerk Cave in South Africa, dating to roughly 1 million years ago. Yet convincing evidence for regular fire use in Europe doesn’t appear until roughly 400,000 years ago at sites such as Beeches Pit in England and Schöningen in Germany – despite the presence of many earlier hominin occupations. Likewise, definitive evidence for built shelters in these early periods remains sparse and frequently contested. While this uneven record does not necessarily imply that fire and shelter were absent, it might suggest that were not consistently reliable or available. This, in turn, invites closer consideration of the role of clothing – often overlooked – as a more dependable strategy within these patterns of movement.
Clothing offers clear advantages over fire and shelter : it is portable and not dependent on specific environmental conditions or stationary locations. It is, however, only as effective as the materials from which it is made. To be an effective technology for entering the unpredictable conditions of Europe during the Palaeolithic, clothing would have to operate as the mediator between human thermoregulatory biology and the climate. This required a material with very specific properties. It had to be a strong insulator, even when wet, yet breathable. At the same time, it had to be resistant to wind, flexible enough to move with the body, and, most importantly, accessible.
Early humans were likely well familiar with plant fibres and used them for cordage, nets, mats, and possibly even early clothing. But as protective garments, these materials only offer very limited advantages in cold, wet or windy conditions. And wool, which performs far better than plant materials in this context, would not become available for several hundreds of thousands of years. So, though there is no direct material evidence of the use of hides during this time period, it is because of their material properties that they thought to have been widely used as garments.
Insulation is, essentially, the reduction of heat loss by trapping warm air close to the body. In this sense, clothing functions as a good insulator not because the material itself is thick or heavy, but because it can hold air well. This is the principle behind down, where the fluffy, branching structure of the small feathers creates a dense matrix that traps large volumes of air, and fishnet-style baselayers, which lift outer garments away from the skin and create pockets of air. In the case of hides, spaces between densely laid hairs capture and retains air. In some cases, such as caribou, the structure of the hairs themselves are porous, offering even more places where warm air can be held2.
Beyond insulation, a garment’s ability to manage moisture is equally critical. Wet clothing can increase the rate of heat loss from the body by up to 50%, significantly elevating the risk of danger in cold or variable weather conditions. Hides also perform well in this regard because they combine water resistance and breathability. In most mammals, the outer layer of guard hairs help prevent rain and snow from penetrating the more insulating under layers, preserving their loft and thermal efficiency. At the same time, the structure of the skin acts as a semi-permeable barrier, which allows water vapour produced by the body, most often in the form of sweat, to diffuse outward, rather then condensing on the inside of the garment which would lead to internal dampness and rapid heat loss. Just as importantly, this layered structure also disrupts wind penetration, which reduces cold air moving across the body and interfering with the insulating air.
For a hide to maintain its full insulating and protective properties, it must be taken from a recently dead animal, before microbial decay and structural degradation begin to compromise the structure of the skin and fur. Therefore, it follows that hides would have been utilised as an immediate by-product of hunted game. In doing this, humans not only made smart use of available resources that would otherwise go to waste but also effectively repurposed that which had already been evolutionarily engineered for life in specific climate systems — an approach that reflects a sophisticated form of textile intelligence.
While there is no direct material evidence for hides being used as clothing in this period, evolutionary thermoregulatory adaptions, the broader climatic context of Europe, and functional properties of the material make their use highly plausible. Moreover, other elements of the archaeological record, such as cut marks on bone, needles, and lithic tools may offer indirect support for the use of hides for garments, something I will discuss in more detail in Part 2.
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Bibliography:
Berna, F., Goldberg, P., Horwitz, L.K., Brink, J., Holt, S., Bamford, M., Chazan, M., 2012. Microstratigraphic evidence of in situ fire in the Acheulean strata of Wonderwerk Cave, Northern Cape province, South Africa. Proceedings of the National Academy of Sciences U.S.A. 109.
Castellani, J.W., Young, A.J., 2016. Human physiological responses to cold exposure: Acute responses and acclimatization to prolonged exposure. Autonomic Neuroscience 196, 63–74.
Gilligan, I., 2010. The Prehistoric Development of Clothing: Archaeological Implications of a Thermal Model. Journal of Archaeology Method and Theory. 17, 15–80.
Jablonski, N.G. 2004. The Evolution of Human Skin and Skin Color. Annual. Review of Anthropology. 33, 585–623.
Jöris, O. 2025. Human evolution and the origins of Stone Age clothing. A Stone Age history of clothing. Universität Heidelberg. Heidelberg.
Leroy, S.A.G., Arpe, K., Mikolajewicz, U., 2011. Vegetation context and climatic limits of the Early Pleistocene hominin dispersal in Europe. Quaternary Science Reviews 30, 1448–1463.
Rogers, A.R., Iltis, D., Wooding, S., 2004. Genetic Variation at the MC1R Locus and the Time since Loss of Human Body Hair. Current Anthropology 45, 105–108.
Roebroeks, W., Villa, P., 2011. On the earliest evidence for habitual use of fire in Europe. Proceedings of the National Academy of Sciences. U.S.A. 108, 5209–5214.
There are many theories as to why humans began to lose body hair, but thermoregulation is the most widely believed.
The genetic separation of human body lice from head lice gives a good indication of the origin of clothing.
https://www.sciencedirect.com/science/article/pii/S0960982203005074