New research led by anthropologist and paleobiologist Nina Jablonski and evolutionary biologist Tina Lasisi, published in the journal Proceedings of the National Academy of Sciences, shows that the human scalp played a crucial role in the evolution of our species. Long, curly hair would have protected early Homo erectus from the heat of the African savanna, thus promoting brain development.
The study also highlights the genetic mechanisms that allow human hair follicles to remain active for years, paving the way for new therapies against baldness.
The theoretical foundation of the research is based on the relationship between human evolution and thermoregulation. The authors show that humans are unique among mammals not only in the selective distribution of hair, but also in the great variability in hair texture, which has facilitated adaptation to different climates.
As Jablonski explains, humans shed body fur about two million years ago to improve heat dissipation during prolonged activities in warm environments through sweating and upright posture. However, the skull cap, directly exposed to sunlight, needed additional protection to safeguard the brain, which is particularly sensitive to heat.
The experimental study, conducted using thermal dummies and also published in the FASEB Journal, used wigs with hair of various textures (straight, wavy, curly) to measure heat flux under controlled conditions of temperature, humidity and solar radiation.
The results show that hair significantly reduces solar heat absorption compared to a shaved head. In particular, curly hair was found to be the most effective in limiting heating and reducing the amount of sweat required to maintain thermal equilibrium.
Jablonski, also known for her studies on skin and pigmentation, emphasizes that hair not only has a biological function, but also represents a powerful tool for social and aesthetic communication.
“Once the body became hairless and the head retained hair, people began to use it to express who they are, what group they belong to and even their social status,” the anthropologist explains.
Many indigenous and traditional cultures attach deep meanings to hairstyles: braids in African cultures, long hair among Native Americans, shaving rituals in some religions.
In many ancient civilizations-such as in Egypt, Greece, and India-hair length, color, and style were closely linked to social rank, caste, or religious roles.
