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). The index was once used to categorize human beings in the first half of the 20th century, but today it is used to categorize dogs and cats.
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.
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.
The usefulness of the cephalic index was questioned by Giuseppe Sergi, who argued that cranial morphology provided a better means to model racial ancestry. [1] 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 effect on the development of head shape. [2]
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. [3] 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." [2]
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. [4] 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. [4]
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. [5] 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. [6] [7]
The vertical cephalic index, also known as the length-height index, was a less-commonly measured head ratio. [8] [9] 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.
The cephalic index is also used in medicine, especially in the planning and effectiveness analysis of cranial deformity corrections. [10] The index is a useful tool in assessing the morphology of cranial deformities in clinical settings. [11] The index is used while looking at the fetal head shape, and can change in certain situations (ex. breech presentation, ruptured membranes, twin pregnancy). [12]
The cephalic index is used in the categorisation of animals, especially breeds of dogs and cats.
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". [13] Because of the health issues brachycephaly is regarded as torture breeding [14] [15] [16] [17] as it often leads to the brachycephalic airway obstructive syndrome.
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. [23] [24]
 |
| |
Note: Almost all domestic felines are mesaticephalic
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.
| |
Note: Almost all canidae are dolichocephalic
| |
Sighthounds are a type of hound dog that hunts primarily by sight and speed, unlike scent hounds, which rely on scent and endurance.
Brachycephaly is the shape of a skull shorter than average in its species. It is perceived as a cosmetically desirable trait in some domesticated dog and cat breeds, notably the pug and Persian, and can be normal or abnormal in other animal species.
Canine terminology in this article refers only to dog terminology, specialized terms describing the characteristics of various external parts of the domestic dog, as well as terms for structure, movement, and temperament. This terminology is not typically used for any of the wild species or subspecies of wild wolves, foxes, coyotes, dholes, jackals or the basal caninae. Dog terminology is often specific to each breed or type of dog. Breed standards use this terminology in the description of the ideal external appearance of each breed, although similar characteristics may be described with different terms in different breeds.
A snout is the protruding portion of an animal's face, consisting of its nose, mouth, and jaw. In many animals, the structure is called a muzzle, rostrum, or proboscis. The wet furless surface around the nostrils of the nose of many mammals is called the rhinarium. The rhinarium is often associated with a stronger sense of olfaction.
The Alaunt is an extinct type of dog which came in different forms, with the original possibly having existed in North Caucasus, Central Asia and Europe from ancient times.
The Dogue de Bordeaux, Bordeaux Mastiff, French Mastiff or Bordeauxdog is a large French mastiff breed. A typical brachycephalic mastiff breed, the Bordeaux is a very powerful dog, with a very muscular body.
Dog anatomy comprises the anatomical study of the visible parts of the body of a domestic dog. Details of structures vary tremendously from breed to breed, more than in any other animal species, wild or domesticated, as dogs are highly variable in height and weight. The smallest known adult dog was a Yorkshire Terrier that stood only 6.3 cm (2.5 in) at the shoulder, 9.5 cm (3.7 in) in length along the head and body, and weighed only 113 grams (4.0 oz). The heaviest dog was an English Mastiff named Zorba, which weighed 314 pounds (142 kg). The tallest known adult dog is a Great Dane that stands 106.7 cm (42.0 in) at the shoulder.
Progressive retinal atrophy (PRA) is a group of genetic diseases seen in certain breeds of dogs and, more rarely, cats. Similar to retinitis pigmentosa in humans, it is characterized by the bilateral degeneration of the retina, causing progressive vision loss culminating in blindness. The condition in nearly all breeds is inherited as an autosomal recessive trait, with the exception of the Siberian Husky (inherited as an X chromosome linked trait) and the Bullmastiff (inherited as an autosomal dominant trait). There is no treatment.
A field trial is a competitive event for gun dogs. Field trials are conducted for pointing dogs and setters, retrievers and spaniels, with each assessing the different types various working traits. In the United States, field trials are also conducted for basset hounds, beagles, and dachshunds.
Dolichocephaly is a term used to describe a head that is longer than average relative to its width. In humans, scaphocephaly is a form of dolichocephaly.
The English Water Spaniel is a breed of dog that has been extinct since the first part of the 20th century, with the last specimen seen in the 1930s. It was best known for its use in hunting waterfowl and for being able to dive as well as a duck. It is described as similar to a Collie or to a cross between a Poodle and a Springer Spaniel with curly fur and typically in a white and liver/tan pattern.
The cephalic index of a vertebrate is the ratio between the width and length of its cranium (skull). This ratio does not concern the muzzle or face, and thus is distinct from the craniofacial ratio, which compares the size of the cranium to the length of the muzzle. The two measures are often confused in descriptions of dog breeds.
The Pug is a breed of dog with the physically distinctive features of a wrinkly, short-muzzled face, and curled tail. An ancient breed, with roots dating back to 400 B.C., they have a fine, glossy coat that comes in a variety of colors, most often fawn or black, and a compact, square body with well developed and thick muscles all over the body.
Corneal dystrophies are a group of diseases that affect the cornea in dogs.
The Intelligence of Dogs is a 1994 book on dog intelligence by Stanley Coren, a professor of canine psychology at the University of British Columbia. The book explains Coren's theories about the differences in intelligence between various breeds of dogs. Coren published a second edition in 2006.
Richard L. Jantz is an American anthropologist. He served as the director of the University of Tennessee Anthropological Research Facility from 1998–2011 and he is the current Professor Emeritus of the Department of Anthropology at the University of Tennessee, Knoxville. His research focuses primarily on forensic anthropology, skeletal biology, dermatoglyphics, anthropometry, anthropological genetics, and human variation, as well as developing computerized databases in these areas which aid in anthropological research. The author of over a hundred journal articles and other publications, his research has helped lead and shape the field of physical and forensic anthropology for many years.
The Minuet is a hybrid mix of Persian and Munchkin cat breeds. Categorized by The International Cat Association (TICA) as a domestic hybrid, "developed from a deliberate cross between two existing domestic breeds, incorporating characteristics of both parental breeds into the new mix." The Minuet cat is characterized by its short legs, as a result of the dwarfism-mutation derived from the Munchkin breed.
Brachycephalic obstructive airway syndrome (BOAS), also known as brachycephalic airway obstructive syndrome (BAOS), brachycephalic airway syndrome (BAS), and brachycephalic syndrome (BS), is a pathological condition affecting short nosed dogs and cats which can lead to severe respiratory distress. There are four different anatomical abnormalities that contribute to the disease, all of which occur more commonly in brachycephalic breeds: an elongated soft palate, stenotic nares, a hypoplastic trachea, and everted laryngeal saccules. Because all of these components make it more difficult to breathe in situations of exercise, stress, or heat, an animal with these abnormalities may be unable to take deep or fast enough breaths to blow off carbon dioxide. This leads to distress and further increases respiratory rate and heart rate, creating a vicious cycle that can quickly lead to a life-threatening situation.
In the field of animal breeding and anatomy, a hypertype is the extreme accentuation of distinctive traits specific to a domesticated animal breed. This is particularly true of dogs, cattle and pigs, and more rarely of cats, horses, rabbits and other species. In companion animals, hypertype is favored by breeders and breed associations in direct connection with beauty and show competitions. Hypertype poses a problem when it leads to the selection of animals on aesthetic criteria that cause them suffering.
