Neanderthals (Homo neanderthalensis) and modern humans (Homo sapiens) are closely related hominins who shared the Eurasian landscape for thousands of years, but their faces evolved along markedly different paths. The comparison of their craniofacial morphology reveals anatomical differences reflecting unique developmental processes and adaptive pressures. These structural variations, from the brow ridge to the chin, provide the clearest visual distinction between our species and our closest extinct relatives.
The Supraorbital Torus and Forehead Shape
The upper face of the Neanderthal is characterized by the prominent, double-arched brow ridge, known as the supraorbital torus. This heavy bony structure is continuous across the top of the eye sockets, forming a pronounced overhang. The Neanderthal forehead is low and slopes backward, resulting in a long, low cranial vault shape.
In contrast, the modern human face features a relatively flat and vertical forehead, indicating a more globular braincase. The heavy brow ridge is significantly reduced or completely absent in Homo sapiens, often appearing only as two slight arches above the orbits. This reduction contributes to the overall gracile appearance of the modern human face compared to the robust Neanderthal structure.
The difference in forehead shape is tied to variations in cranial development and size. The transition to a vertical forehead in modern humans is linked to the expansion and reshaping of the frontal lobe of the brain.
Mid-Facial Projection and Nasal Structure
The Neanderthal mid-face is defined by mid-facial prognathism, where the central part of the face projects forward. This projection includes the nasal and maxillary regions, creating a face that appears pulled away from the sides of the skull. The cheekbones, or zygomatic arches, are often swept back relative to the upper jaw, emphasizing the forward thrust of the nose.
The nasal structure is substantially larger and wider than that of modern humans. The nasal aperture, or nose opening, is broad, suggesting a large internal nasal cavity. This configuration contrasts sharply with the modern human face, which is flatter, or orthognathic, and tucked more beneath the cranium.
The large Neanderthal nose is often linked to the “air conditioning” hypothesis, suggesting its size was an adaptation to the cold, dry climates of Ice Age Eurasia. A larger nasal passage, lined with mucosal tissue, would have been more effective at warming and humidifying frigid air before it reached the lungs. This capacity for high airflow may also have supported the high metabolic demands of their robust bodies and active lifestyle.
Mandibular Differences and the Chin
The lower face provides a clear point of distinction centered on the mandible, or lower jaw. The Neanderthal jaw is robust and lacks the defining bony projection found in Homo sapiens. The mandibular symphysis, the area forming the chin, slopes backward, meaning Neanderthals had no true bony chin prominence.
The Neanderthal jaw is also characterized by a retromolar gap, a space located behind the third molar. This gap results from the forward position of the entire mid-face and the length of the jawbone. The modern human mandible, by comparison, is more gracile and terminates in the unique feature of the mental eminence, or prominent, triangular bony chin.
The presence of a bony chin is considered a uniquely modern human trait, though its function remains debated. The modern human jaw typically lacks the retromolar space, as the face and dentition are tucked further back under the braincase. The Neanderthal jaw structure indicates greater robusticity, which some researchers link to handling greater stresses, potentially from using their front teeth as a tool.
Functional and Evolutionary Drivers of Facial Divergence
The differences in facial structure reflect different evolutionary trajectories influenced by environmental and functional pressures. The broad, projecting Neanderthal mid-face and robust jaw are often cited as adaptations to a mechanically demanding lifestyle. One hypothesis suggests the robust facial architecture helped dissipate stress from heavy bite forces, perhaps from habitually using their teeth to grip materials or process tough foods.
The development of the modern human face, which is smaller and less projecting, is linked to changes in cranial growth and development. In Homo sapiens, the face grows flatter because the upper jaw undergoes bone remodeling that removes tissue from the mid-face region. Neanderthals maintained a protruding face because their upper jaw continued to add bone tissue throughout development, a pattern seen in other ancient hominins.
The overall shift in Homo sapiens toward a smaller, more retracted face may be a byproduct of changes in the size and shape of the braincase. As the brain expanded and became more globular, the face retracted beneath it. This developmental change, combined with a reduction in the need for high bite force due to the use of fire and more complex tool technologies, favored a more gracile facial skeleton and the emergence of the bony chin.