The cephalic index is a classic anthropometric measure used in physical anthropology, archaeology, and human biology to categorize head shapes. It compares the width of the skull to its length, producing a numerical value that was historically used to classify populations.

🌍 Definition

• Cephalic Index (CI):
  [ CI = \frac{\text{Maximum Skull Breadth}}{\text{Maximum Skull Length}} \times 100 ]
• Values:
  • Dolichocephalic (long-headed): CI < 75
  • Mesocephalic (medium-headed): CI 75–80
  • Brachycephalic (short-headed): CI > 80

🔑 Anthropological & Archaeological Contexts

• 19th–20th Century Anthropology:
  • Widely used to classify human populations by cranial morphology.
  • Linked (often problematically) to racial typologies and theories of human difference.
• Archaeology:
  • Applied to skeletal remains to infer population movements, ancestry, and cultural contacts.
• Modern Use:
  • Still used in forensic anthropology and bioarchaeology for descriptive purposes.
  • In medicine, applied to craniofacial studies (e.g., diagnosing craniosynostosis, assessing head shape in pediatrics).

📚 Importance in Anthropology

• Historical Significance: Shows how early anthropologists attempted to quantify human variation.
• Critical Lens: Modern anthropology critiques its misuse in racial science, emphasizing that cranial shape is influenced by environment, genetics, and plasticity.
• Comparative Value: Useful in bioarchaeology for population-level comparisons, but not for rigid racial classification.

In short: The cephalic index is a ratio of skull breadth to length, historically used to classify head shapes and populations, but now applied cautiously in anthropology, archaeology, and medicine.