Cephalic index explained

Cephalic index should not be confused with encephalization.

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.

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 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]

Vertical cephalic index

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.

Medicine

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]

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".[13] Because of health issues brachycephaly is regarded in some countries as "qualzucht", which literally translates to "torture breeding"[14] [15] [16] [17] as it often leads to brachycephalic airway obstructive syndrome.

List of brachycephalic dogs

[18]

List of brachycephalic cats

[19] [20]

List of brachycephalic pigs

[21]

List of brachycephalic rabbits

[22]

Other

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.[23] [24]

List of mesaticephalic canines

List of mesaticephalic cats

Note: Almost all domestic felines are mesaticephalic

List of mesaticephalic rabbits

Other

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 canids

Note: Almost all canidae are dolichocephalic

List of dolichocephalic felines

List of dolichocephalic leporids

Other

See also

External links

Notes and References

  1. Killgrove K . 2005 . Bioarchaeology in the Roman World . Masters . UNC Chapel Hill . https://web.archive.org/web/20120328162246/http://www.piki.org/~kristina/Killgrove-2005-classics.pdf . 28 March 2012 . dead.
  2. Holloway RL . Head to head with Boas: did he err on the plasticity of head form? . Proceedings of the National Academy of Sciences of the United States of America . 99 . 23 . 14622–3 . November 2002 . 12419854 . 137467 . 10.1073/pnas.242622399 . 2002PNAS...9914622H . free .
  3. Sparks CS, Jantz RL . A reassessment of human cranial plasticity: Boas revisited . Proceedings of the National Academy of Sciences of the United States of America . 99 . 23 . 14636–14639 . November 2002 . 12374854 . 137471 . 10.1073/pnas.222389599 . free . 2002PNAS...9914636S . . See also the discussion in Holloway RL . Head to head with Boas: did he err on the plasticity of head form? . Proceedings of the National Academy of Sciences of the United States of America . 99 . 23 . 14622–14623 . November 2002 . 12419854 . 137467 . 10.1073/pnas.242622399 . free . 2002PNAS...9914622H .
  4. Gravlee CC, Bernard HR, Leonard WR . Heredity, environment, and cranial form: A reanalysis of Boas's immigrant data. American Anthropologist. March 2003. 105. 1. 125–138. 10.1525/aa.2003.105.1.125. 2018-03-23. 2027.42/65137. https://web.archive.org/web/20140730140427/http://www.gravlee.org/files/pdfs/gravlee03a.pdf. 30 July 2014. dead. free.
  5. Sparks CS, Jantz RL . Changing Times, Changing Faces: Franz Boas's Immigrant Study in Modern Perspective . American Anthropologist . 105 . 2 . 2003 . 333–337 . 10.1525/aa.2003.105.2.333 .
  6. Jantz RL, Logan MH . Why does head form change in children of immigrants? A reappraisal . American Journal of Human Biology . 22 . 5 . 702–707 . 2010 . 20737620 . 10.1002/ajhb.21070 . 12686512 .
  7. Book: Spradley MK, Weisensee K . Ancestry Estimation: The Importance, The History, and The Practice . Langley NR, Tersigni-Tarrant MT . Forensic Anthropology: A Comprehensive Introduction . Second . 2017 . 165–166 . CRC Press . 978-1-4987-3612-1 .
  8. Encyclopedia: length-height index . Merriam-Webster Medical .
  9. The Study of Vertical Cephalic Index (Length-Height Index) and Transverse Cephalic Index (Breadth-Height Index) of Andhra Region (India). 2013 . 10.3126/ajms.v3i3.4650 . Chandrashekhar . Chikatapu . Salve . Vishal Manoharrao . Asian Journal of Medical Sciences . 3 . 3 . 6–11 . free .
  10. Likus . Wirginia . Bajor . Grzegorz . Gruszczynska . Katrzyna . Baron . Jan . Markowski . Jaroslaw . Machnikowska-Sokolowska . Magdalena . Milka . Daniela . Lepich . Tomasz . February 4, 2014 . Cephalic Index in the First Three Years of Life: Study of Children with Normal Brain Development Based on Computed Tomography . TheScientificWorldJournal . 2014 . 502836 . 10.1155/2014/502836 . 24688395 . 3933399 . free .
  11. Nam . Heesung . Han . Nami . Eom . Mi Ja . Kook . Minjung . Kim . Jeeyoung . 2021-04-30 . Cephalic Index of Korean Children With Normal Brain Development During the First 7 Years of Life Based on Computed Tomography . Annals of Rehabilitation Medicine . English . 45 . 2 . 141–149 . 10.5535/arm.20235 . 33985316 . 2234-0645. 8137378 .
  12. Web site: Weerakkody . Yuranga . Cephalic index Radiology Reference Article Radiopaedia.org . 2023-04-06 . Radiopaedia . en-US.
  13. Web site: Brachycephalic Health. www.thekennelclub.org.uk. 2020-02-17.
  14. FOUR PAWS International: The suffering of dogs with genetic disorders
  15. Anne Fawcett, Vanessa Barrs, Magdoline Awad et al.: Consequences and Management of Canine Brachycephaly in Veterinary Practice: Perspectives from Australian Veterinarians and Veterinary Specialists
  16. Border Wars: Torture breeding
  17. FECAVA: Brachycephalic issues: shared resources
  18. Web site: Lowrey . Sassafras . June 10, 2022 . Brachycephalic Dog Breeds: A Guide to Flat-Faced Dogs . 2023-05-06 . American Kennel Club . en.
  19. Web site: Brachycephalic Breeds of Cats ASPCA Pet Health Insurance . 2023-03-13 . www.aspcapetinsurance.com . en.
  20. Web site: Breathing Problems in Flat-faced Cat Breeds Purina . 2023-03-13 . www.purina-arabia.com . en-AE.
  21. Geiger M, Schoenebeck JJ, Schneider RA, Schmidt MJ, Fischer MS, Sánchez-Villagra MR . Exceptional Changes in Skeletal Anatomy under Domestication: The Case of Brachycephaly . Integrative Organismal Biology . 3 . 1 . obab023 . 2021-08-14 . 34409262 . 8366567 . 10.1093/iob/obab023 .
  22. Web site: 24 March 2017 . Brachy breeds – not just dogs! Rabbits too .
  23. Book: Evans HE . 1994 . Miller's Anatomy of the Dog . 3rd . Philadelphia . Saunders . 9780721632001 . 132 . 827702042.
  24. Encyclopedia: mesaticephalic . Farlex Partner Medical Dictionary . 2012 . . 2 January 2019.