Cephalic index
The cephalic index or cranial index is the ratio of the maximum width of the head of an organism multiplied by 100 divided by its maximum length. The index is also used to categorize animals, especially dogs and cats.
Historic use in anthropology
Early anthropology
The cephalic index was widely used by anthropologists in the early 20th century to categorize human populations. 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 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. Carleton S. Coon also used the index in the 1960s.
Humans are characterized by having either a dolichocephalic, mesaticephalic, or brachycephalic cephalic index or cranial index.
Indices
Cephalic indices are grouped as in the following table:Females | Males | Scientific term | Meaning | Alternative term |
< 75 | < 75.9 | dolichocephalic | 'long-headed' | |
75 to 83 | 76 to 81 | mesaticephalic | 'medium-headed' | mesocephalic; mesocranial |
> 83 | > 81.1 | brachycephalic | 'short-headed' | brachycranial |
Technically, the measured factors are defined as the maximum width of the bones that surround the head above the supramastoid crest, and the maximum length from the most easily noticed part of the glabella to the most easily noticed point on the back part of the head.
Controversy
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.
Jantz and Sparks responded to Gravlee et al., reiterating that Boas' findings lacked biological meaning, and that the interpretation of Boas' results common in the literature was biologically inaccurate. In a later study, the same authors concluded that the effects Boas observed were likely the result of population-specific environmental effects such as changes in cultural practices for cradling infants, rather than the effects of a general "American environment" which caused populations in America to converge to a common cranial type, as Boas had suggested.
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. Dog breeds such as the pug are sometimes classified as "Extreme Brachycephalic".List of brachycephalic dogs
- Affenpinscher
- American Bulldog
- Apple headed Chihuahua
- Boston Terrier
- Boxer
- Brussels Griffon
- Bulldog
- Bullmastiff
- Cane Corso
- Cavalier King Charles Spaniel
- Chow Chow
- Dogo Argentino
- Dogue de Bordeaux
- English Mastiff
- English Bulldog
- French Bulldog
- Japanese Spaniel
- King Charles Spaniel
- Lhasa Apso
- Lowchen
- Mal-shi
- Mini Shar Pei
- Neapolitan Mastiff
- Newfoundland
- Olde English Bulldogge
- Pekingese
- Perro de Presa Canario
- Pit bull
- Pug
- Shar-Pei
- Shih Tzu
- Tibetan Spaniel
- Tosa
- Zuchon
List of brachycephalic cats
- British Shorthair
- Exotic Shorthair
- Foldex
- Himalayan cat
- Persian cat
- Scottish Fold
List of brachycephalic pigs
- Middle White
List of brachycephalic rabbits
- Jersey Wooly
- Lionhead rabbit
- Lop rabbit
- Netherland Dwarf rabbit
Other
- Giant panda
- Ross seal
- Spectacled Bear
Mesaticephalic animals
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
- African Wild Dog
- Alaskan Malamute
- Almost all Spaniels
- Almost all Spitz, except for the Chow Chow
- American Eskimo Dog
- American Foxhound
- 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
- Cardigan Welsh Corgi
- Chesapeake Bay Retriever
- Pear and Deer headed Chihuahua
- Chinese Crested
- Chinook
- Curly-Coated Retriever
- Dalmatian
- Dhole
- English Foxhound
- Field Spaniel
- Finnish Lapphund
- Finnish Spitz
- Flat-Coated Retriever
- German Shorthaired Pointer
- German Wirehaired Pointer
- German Spitz
- Golden Retriever
- Irish Setter
- Komondor
- Labrador Retriever
- Miniature Pinscher
- Pomeranian
- Miniature, Toy and Teacup Poodle
- Most terriers
- Mudi
- Pembroke Welsh Corgi
- Puli
- Rottweiler
- Samoyed
- Siberian Husky
- St. Bernard
- Vizsla
- Weimaraner
- Wirehaired Vizsla
- Mexican hairless dog
List of mesaticephalic cats
- American Shorthair
- American Bobtail
- Bengal cat
- Birman
- Bombay cat
- Burmese cat
- Chartreux
- Chausie
- Cymric cat
- Devon Rex
- Donskoy
- Egyptian Mau
- Felid hybrids
- Felis, or Small cats
- Lion
- Maine Coon
- Manx
- Munchkin cat
- Norwegian forest cat
- Ocelot
- Ocicat
- Pallas cat
- Panthera hybrid
- Ragdoll
- Russian Blue
- Russian White, Black and Tabby
- Selkirk Rex
- Siberian cat
- Tiger
- Toyger
- Turkish Angora
- Turkish Van
List of mesaticephalic rabbits
- Dutch rabbit
- Mini Rex
- Polish rabbit
- New Zealand rabbit
- American Sable
Other
- American Black Bear
- Brown Bear
- Guinea Pig
- Polar bear
- Spotted Hyena
- Sun Bear
Dolichocephalic animals
List of dolichocephalic canids
- Afghan Hound
- Airedale Terrier
- Azawakh
- Basset Hound
- Bedlington Terrier
- Bloodhound
- Borzoi
- Bull terrier
- Cesky Terrier
- Coyote
- Dachshund
- Doberman Pinscher
- Fox Terrier
- Galgo Español
- German Shepherd
- Great Dane
- Greyhound
- Irish Terrier
- Irish Wolfhound
- Italian Greyhound
- Kangaroo Dog
- Kanni
- Kerry Blue Terrier
- Khalag Tazi
- Longdog
- Lurcher
- Manchester Terrier
- Miniature Bull Terrier
- Peruvian Hairless Dog
- Pharaoh Hound
- Poodle
- Rampur Greyhound
- Red Fox
- Rough Collie
- Russian Black Terrier
- Saluki
- Schnauzer
- Scottish Deerhound
- Scottish Terrier
- Sealyham Terrier
- Serbian Hound
- Shetland Sheepdog
- Silken Windhound
- Sloughi
- Smooth Collie
- Taigan
- Welsh Terrier
- Whippet
- Wolf
List of dolichocephalic felines
- Abyssinian
- Colorpoint Shorthair
- Oriental Bicolor and Tricolor
- Oriental Longhair
- Oriental Shorthair
- Savannah
- Siamese
- Somali
- Sphynx
- Javanese
- Peterbald
- Balinese
List of dolichocephalic leporids
- English Spot
- English Lop
- Belgian Hare
Other
- Aardwolf
- Bontebok
- Brown Hyena
- Domestic horse
- Fur seal
- Hartebeest
- Leopard seal
- Raccoon
- Sea lion
- Sloth Bear
- Striped Hyena
- Wild boar
- Wildebeest