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Cephalic index

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Cephalic index

The cephalic index or cranial index is the ratio of the maximum width (bipareital diameter or BPD, side to side) of the head of an organism (human or animal) multiplied by 100 divided by its maximum length (occipitofrontal diameter or OFD, front to back). The index is also used to categorize animals, especially dogs and cats.


Early anthropology

The cephalic index was widely used by anthropologists in the early 20th century to categorize human populations, and by Carleton S. Coon in the 1960s. It is now mainly used to describe individuals' appearances and for estimating the age of fetuses for legal and obstetrical reasons.

The cephalic index was defined by Swedish professor of anatomy Anders Retzius (1796–1860) and first used in physical anthropology to classify ancient human remains found in Europe. The theory became closely associated with the development of racial anthropology in the 19th and early 20th centuries, when prehistorians attempted to use ancient remains to model population movements in terms of racial categories.

Humans are characterized by having either a dolichocephalic (long headed), mesaticephalic (moderate headed), or brachycephalic (short headed) cephalic index/cranial index.


Cephalic indices are grouped as in the following table:

Technically, the measured factors are defined as the maximum width of the bones that surround the head above the supramastoid crest (behind the cheekbones), and the maximum length from the most easily noticed part of the glabella (between the eyebrows) to the most easily noticed point on the back part of the head.


The usefulness of the cephalic index was questioned by Giuseppe Sergi, who argued that cranial morphology provided a better means to model racial ancestry. Also, Franz Boas studied the children of immigrants to the United States in 1910 to 1912, noting that the children's cephalic index differed significantly from their parents', implying that local environmental conditions had a significant impact on the development of head shape.

Boas argued that if craniofacial features were so malleable in a single generation, then the cephalic index was of little use for defining race and mapping ancestral populations. Scholars such as Earnest A. Hooton continued to argue that both environment and heredity were involved. Boas did not himself claim it was totally plastic.

In 2002, a paper by Sparks and Jantz re-evaluated some of Boas' original data using new statistical techniques and concluded that there was a "relatively high genetic component" of head shape. Ralph Holloway of Columbia University argues that the new research raises questions about whether the variations in skull shape have "adaptive meaning and whether, in fact, normalizing selection might be at work on the trait, where both extremes, hyperdolichocephaly and hyperbrachycephaly, are at a slight selective disadvantage."

In 2003, anthropologists Clarence C. Gravlee, H. Russell Bernard, and William R. Leonard reanalyzed Boas' data and concluded that most of Boas' original findings were correct. Moreover, they applied new statistical, computer-assisted methods to Boas' data and discovered more evidence for cranial plasticity. In a later publication, Gravlee, Bernard and Leonard reviewed Sparks' and Jantz' analysis. They argue that Sparks and Jantz misrepresented Boas' claims, and that Sparks' and Jantz' data actually support Boas. For example, they point out that Sparks and Jantz look at changes in cranial size in relation to how long an individual has been in the United States in order to test the influence of the environment. Boas, however, looked at changes in cranial size in relation to how long the mother had been in the United States. They argue that Boas' method is more useful, because the prenatal environment is a crucial developmental factor.

Modern use in animal breeding

The cephalic index is used in the categorisation of animals, especially breeds of dogs and cats.

Brachycephalic animals

A brachycephalic skull is relatively broad and short (typically with the breadth at least 80% of the length). Dog breeds such as the pug are sometimes classified as "Extreme Brachycephalic".

List of brachycephalic dogs

  • Affenpinscher
  • American Staffordshire Terrier
  • Boston Terrier
  • Boxer
  • Brussels Griffon
  • Bulldog
  • Bullmastiff
  • Cane Corso
  • Chihuahua (apple-headed)
  • Chow Chow
  • Dogo Argentino
  • Dogue de Bordeaux
  • English Mastiff
  • French Bulldog
  • Japanese Chin
  • King Charles Spaniel
  • Lhasa Apso
  • Neapolitan Mastiff
  • Newfoundland
  • Pekingese
  • Presa Canario
  • Pug
  • Shar-Pei
  • List of brachycephalic cats

  • British Shorthair
  • Exotic Shorthair
  • Himalayan cat
  • Persian cat
  • Scottish Fold
  • List of brachycephalic rabbits

  • Jersey Wooly
  • Lionhead rabbit
  • Lop rabbit
  • Mesaticephalic animals

    A mesaticephalic skull is of intermediate length and width. Mesaticephalic skulls are not markedly brachycephalic or dolichocephalic. When dealing with animals, especially dogs, the more appropriate and commonly used term is not "mesocephalic", but rather "mesaticephalic", which is a ratio of head to nasal cavity. The breeds below exemplify this category.

    List of mesaticephalic canines

  • Alaskan Malamute
  • American Cocker Spaniel
  • Australian Cattle Dog
  • Australian Shepherd
  • Basenji
  • Beagle
  • Bearded Collie
  • Beauceron
  • Belgian Malinois
  • Belgian Sheepdog
  • Bernese Mountain Dog
  • Bichon Frisé
  • Black and Tan Coonhound
  • Border Collie
  • Border Terrier
  • Brittany
  • Cairn Terrier
  • Canadian Eskimo
  • Cardigan Welsh Corgi
  • Chesapeake Bay Retriever
  • Chihuahua (deer-headed)
  • Chinese Crested
  • Chinook
  • Chow Chow
  • Clumber Spaniel
  • Dalmatian
  • English Cocker Spaniel
  • English Foxhound
  • English Springer Spaniel
  • Field Spaniel
  • Finnish Laphund
  • Finnish Spitz
  • German Shorthaired Pointer
  • German Spitz - Klein & Mittel
  • Golden Retriever
  • Irish Setter
  • Japanese Spitz
  • Keeshond
  • Komondor
  • Kuvasz
  • Labrador Retriever
  • Maltese
  • Miniature Pinscher
  • Norfolk Terrier
  • Norwegian Laphund
  • Norwich Terrier
  • Papillon
  • Pembroke Welsh Corgi
  • Phalène
  • Pomeranian
  • Rottweiler
  • Šarplaninac
  • St. Bernard
  • Samoyed
  • Siberian Husky
  • Vizsla
  • Weimaraner
  • West Highland White Terrier
  • Yorkshire Terrier
  • List of mesaticephalic cats

  • American Shorthair
  • Russian Blue
  • Egyptian Mau
  • Ocicat
  • Manx
  • Russian White, Black and Tabby
  • Bengal cat
  • Siberian cat
  • Donskoy
  • Turkish Van
  • Note: Most cat landraces are mesaticephalic.

    List of mesaticephalic rabbits

  • Dutch rabbit
  • Mini Rex
  • Polish rabbit
  • Satin Rabbit
  • Mini Satin
  • Hotot Dwarf
  • New Zealand rabbit
  • Netherland Dwarf
  • American Sable
  • Dolichocephalic animals

    A dolichocephalic skull is relatively long skull (typically with the breadth less than 80% or 75% of the length).

    List of dolichocephalic canids

  • Afghan Hound
  • Airedale Terrier
  • American Staghound
  • Azawakh
  • Basset Hound
  • Bedlington Terrier
  • Bloodhound
  • Borzoi
  • Bull Terrier
  • Cesky Terrier
  • Chart Polski
  • Chippiparai
  • Cirneco dell'Etna
  • Coyote
  • Dachshund
  • Doberman Pinscher
  • English Bull Terrier
  • Galgo Español
  • German Shepherd
  • Great Dane
  • Gray wolf
  • Greyhound
  • Hortaya Borzaya
  • Ibizan Hound
  • Irish Wolfhound
  • Italian Greyhound
  • Kangaroo Dog
  • Kanni
  • Khalag Tazi
  • Longdog
  • Lurcher
  • Magyar Agár
  • Manchester Terrier
  • Miniature Bull Terrier
  • Mudhol Hound
  • Old Croatian Sighthound
  • Peruvian Hairless Dog
  • Pharaoh Hound
  • Poodle
  • Portuguese Podengo
  • Rajapalayam
  • Rampur Greyhound
  • Rough Collie
  • Saluki
  • Serbian Hound
  • Scottish Collie
  • Scottish Deerhound
  • Scottish Terrier
  • Shetland Sheepdog
  • Siberian Husky
  • Silken Windhound
  • Sloughi
  • Smooth Fox Terrier
  • Taigan
  • Whippet
  • Whippet (longhaired)
  • Wire Fox Terrier
  • List of dolicocephalic felines

  • Abyssinian
  • Oriental Bicolor
  • Oriental Longhair
  • Oriental Shorthair
  • Savannah
  • Siamese
  • Sphynx
  • Peterbald
  • Balinese
  • List of dolicocephalic leporids

  • English Spot
  • English Lop
  • Belgian Hare
  • References

    Cephalic index Wikipedia

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