The cephalic index or cranial index is a number obtained by taking the maximum width (biparietal diameter or BPD, side to side) of the head of an organism, multiplying it by 100 and then dividing it by their maximum length (occipitofrontal diameter or OFD, front to back). It is used to categorize dog and cat breeds. In humans, it serves diagnostic purposes for some disorders. It has also been used in the modelling of human migrations to categorize remains.
Historic use in anthropology Early anthropology
The cephalic index was used by anthropologists in the early 20th century as a tool to categorize human populations. It was used to describe an individual's appearance 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 historians attempted to use ancient remains to model population movements in terms of racial categories. American anthropologist Carleton S. Coon also used the index in the 1960s, by which time it had been largely discredited.
In the cephalic index model, human beings were characterized by having either a dolichocephalic (long-headed), mesaticephalic (moderate-headed), or brachycephalic (short-headed) 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 (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.
Controversy
The usefulness of the cephalic index was questioned by the Italian anthropologist Giuseppe Sergi, who argued that cranial morphology provided a better means to model racial ancestry. Also, the Jewish anthropologist 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 effect 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 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's original data using new statistical techniques and concluded that there was a "relatively high genetic component" of head shape. See also the discussion in 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's data and concluded that most of Boas's original findings were correct. Moreover, they applied new statistical, computer-assisted methods to Boas's data and discovered more evidence for cranial plasticity. In a later publication, Gravlee, Bernard and Leonard reviewed Sparks's and Jantz's analysis. They argue that Sparks and Jantz misrepresented Boas's claims, and that Sparks's and Jantz's data 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's 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.
Vertical cephalic index The vertical cephalic index, also known as the length-height index, was a less-commonly measured head ratio. In the vertical cephalic index model, humans beings were characterized by having either a chamaecranic (low-skulled), orthocranic (medium high-skulled), or hypsicranic (high-skulled) cephalic index or cranial index.
Medicine The cephalic index is also used in medicine, especially in the planning and effectiveness analysis of cranial deformity corrections. The index is a useful tool in assessing the morphology of cranial deformities in clinical settings. The index is used while looking at the fetal head shape, and can change in certain situations (e.g. breech presentation, ruptured membranes, twin pregnancy). It can be measured for prenatal infants in the womb using obstetric ultrasound, and a value of 78.3% ± 8% (±2 standard deviations) is considered normal.
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". Because of health issues brachycephaly is regarded in some countries as "qualzucht", which literally translates to "torture breeding"FOUR PAWS International: The suffering of dogs with genetic disordersAnne Fawcett, Vanessa Barrs, Magdoline Awad et al.: Consequences and Management of Canine Brachycephaly in Veterinary Practice: Perspectives from Australian Veterinarians and Veterinary SpecialistsBorder Wars: Torture breedingFECAVA: Brachycephalic issues: shared resources as it often leads to brachycephalic airway obstructive syndrome.
List of brachycephalic dogs
Affenpinscher American Bulldog American Bully Bernese Mountain Dog Boston Terrier Boxer Brussels Griffon Bulldog Bullmastiff Cane Corso Cavalier King Charles Spaniel Apple-headed Chihuahua Chow Chow Dogo Argentino Dogue de Bordeaux English Mastiff English Bulldog Fila Brasileiro French Bulldog Japanese Chin King Charles Spaniel Lhasa Apso Lowchen Neapolitan Mastiff Newfoundland Olde English Bulldogge Pekingese Perro de Presa Canario Pit bull Pug Pyrenean Mastiff Rottweiler Shar-Pei Shih Tzu St. Bernard Tibetan Spaniel Tosa
List of brachycephalic cats
British Shorthair Burmese cat Exotic Shorthair Himalayan cat Persian cat Scottish Fold White tiger
List of brachycephalic pigs
Middle White Neijiang
List of brachycephalic rabbits
Lionhead rabbit Lop rabbit Netherland Dwarf rabbit Dwarf Papillon rabbit Dwarf Hotot rabbit Jersey Wooly rabbit American Fuzzylop rabbit
Other Alligator Australian Lowline brachycephalic Arabian horse Elephant European bison Giant panda Niata cattle Otter Raccoon dog Ross seal Sloth Spectacled bear Sun bear Tortoise Walrus Wombat
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 canids
Note: Almost all canidae are mesaticephalic ("medium-headed") African Wild Dog Airedale Terrier Alaskan Malamute almost all spaniels Field Spaniel almost all terriers American Pit Bull Terrier (some lines do have mesaticephalic faces) Bedlington Terrier Cesky Terrier Irish Terrier Kerry Blue Terrier Russian Black Terrier Scottish Terrier Sealyham Terrier Welsh Terrier American Foxhound Appenzeller Sennenhund Australian Cattle Dog Australian Shepherd Basset Hound Beagle Bearded Collie Beauceron Belgian Sheepdog Black and Tan Coonhound Bloodhound Border Collie Chesapeake Bay Retriever Chinook Coyote Curly-Coated Retriever Dalmatian Dhole Dingo English Foxhound Flat-Coated Retriever German Shepherd Dog German Shorthaired Pointer German Wirehaired Pointer Golden Retriever Irish Setter Komondor Labrador Retriever Mudi Puli Serbian Hound Schnauzer Siberian Husky Vizsla Weimaraner Wirehaired Vizsla Wolf
List of mesaticephalic cats
Note: Almost all domestic felines are mesaticephalic
Abyssinian American Shorthair American Bobtail Bengal cat Birman Bombay cat Burmese cat Chartreux Chausie Cheetah Colorpoint Shorthair Cymric cat Egyptian Mau Felid hybrids Felis, or small cats Maine Coon Manx Mountain Lion Munchkin cat Norwegian forest cat Ocicat Pallas's cat Ragdoll Russian Blue Russian White, Black and Tabby Selkirk Rex Siberian cat Somali Toyger Turkish Angora Turkish Van
List of mesaticephalic rabbits Dutch rabbit Mini Rex Polish rabbit New Zealand rabbit American Sable
Other Aardwolf American black bear Brown bear Brown hyena Crocodile Fur seal Guinea pig Hyrax Leopard seal Raccoon Sea lion Spotted hyena Striped hyena Tasmanian devil
Dolichocephalic animals
A dolichocephalic skull is relatively long-headed (typically with the breadth less than 80% or 75% of the length).
Note: Almost all representatives of the infraphylum Gnathostomata (with rare exceptions) are dolichocephalic.
List of dolichocephalic canines
Afghan Hound American Eskimo Dog Azawakh Basenji Bichon Frisé Borzoi Bull Terrier Cardigan Welsh Corgi pear- and deer-headed Chihuahuas Chinese Crested Dachshund Doberman Pinscher Finnish Lapphund Finnish Spitz Fox Terrier Galgo Español German Spitz Great Dane Greyhound Irish Wolfhound Italian Greyhound Kangaroo hound Kanni Khalag Tazi Long dog Lurcher Manchester Terrier Miniature Bull Terrier Miniature Pinscher most spitz, except for the Chow Chow Pembroke Welsh Corgi Peruvian Inca Orchid Pharaoh Hound Pomeranian Poodle (Miniature and Toy) Poodle (Standard) Rampur Greyhound Rough Collie Saluki Samoyed Scottish Deerhound Shetland Sheepdog Silken Windhound Sloughi Smooth Collie Taigan Whippet Xoloitzcuintle
List of dolichocephalic felines
Balinese Devon Rex Donskoy Jaguar Javanese Leopard Lion Ocelot Oriental Bicolor and Tricolor Oriental Longhair Oriental Shorthair Panthera hybrid Peterbald Sabertooth cats Savannah Siamese Snow leopard Sphynx Tiger
List of dolichocephalic leporids English Spot English Lop Belgian Hare All true hares
Other
Baboon Bontebok Cow Dinosaur (including birds) Dolphin Domestic horse Donkey Gharial Grevy's zebra Hartebeest Kangaroo Mule Onager Plains zebra Polar bear Sloth bear Thylacine Warthog Whale Wild boar Wildebeest
See also Cephalic index in cats and dogs Craniometry Phrenology Human skull
References
External links
Cephalic index Brachycephalic Experienced Veterinarians Database