Horn (anatomy)

Anatomía animal de crecimientos en forma de cuerno.

A pair of horns on a male impala

Anatomy and physiology of an animal's horn

A horn is a permanent pointed projection on the head of various animals that consists of a covering of keratin and other proteins surrounding a core of live bone. Horns are distinct from antlers, which are not permanent. In mammals, true horns are found mainly among the ruminant artiodactyls,^{[not verified in body]} in the families Antilocapridae (pronghorn) and Bovidae (cattle, goats, antelope etc.). Cattle horns arise from subcutaneous connective tissue (under the scalp) and later fuse to the underlying frontal bone.^[1]

One pair of horns is usual; however, two or more pairs occur in a few wild species and in some domesticated breeds of sheep. Polycerate (multi-horned) sheep breeds include the Hebridean, Icelandic, Jacob, Manx Loaghtan, and the Navajo-Churro.

Horns usually have a curved or spiral shape, often with ridges or fluting. In many species, only males have horns. Horns start to grow soon after birth and continue to grow throughout the life of the animal (except in pronghorns, which shed the outer layer annually, but retain the bony core). Partial or deformed horns in livestock are called scurs. Similar growths on other parts of the body are not usually called horns, but spurs, claws, or hooves, depending on the part of the body on which they occur.

Other hornlike growths

The term "horn" is also popularly applied to other hard and pointed features attached to the head of animals in various other families:

• Giraffidae: Giraffes have one or more pairs of bony bumps on their heads, called ossicones. These are covered with furred skin.
• Cervidae: Most deer have antlers, which are not true horns and made of bone. When fully developed, antlers are dead bone without a horn or skin covering; they are borne only by adults (usually males, except for reindeer) and are shed and regrown each year.
• Rhinocerotidae: The "horns" of rhinoceroses are made of keratin, the same substance as fingernails, and grow continuously, but do not have a bone core.
• Chamaeleonidae: Many chameleons, most notably the Jackson's chameleon, possess horns on their skulls, and have a keratin covering.
• Ceratopsidae: The "horns" of the Triceratops were extensions of its skull bones, although debate exists over whether they had a keratin covering.
• Abelisauridae: Various abelisaurid theropods, such as Carnotaurus and Majungasaurus possessed extensions of the frontal bone which were likely covered in some form of keratinous integument.
• Horned lizards (Phrynosoma): These lizards have horns on their heads which have a hard keratin covering over a bony core, like mammalian horns.
• Insects: Some insects (such as rhinoceros beetles) have hornlike structures on the head or thorax (or both). These are pointed outgrowths of the hard chitinous exoskeleton. Some (such as stag beetles) have greatly enlarged jaws, also made of chitin.
• Canidae: Golden jackals were once thought to occasionally develop a horny growth on the skull, which is associated with magical powers in south-eastern Asia.^[2][3] Although no evidence of its existence has been found, it remains a common belief in South Asia.^[4][5][6]
• Azendohsauridae: the skull of the triassic azendohsaurid archosauromorph Shringasaurus possessed two massive, forward-facing conical horns, which were likely covered in cornified sheaths in life.
• Anhimidae: The horned screamer possesses an entirely keratinous spine, which is loosely connected to its skull.

Many mammal species in various families have tusks, which often serve the same functions as horns, but are in fact oversized teeth. These include the Moschidae (Musk deer, which are ruminants), Suidae (Wild Boars), Proboscidea (Elephants), Monodontidae (Narwhals) and Odobenidae (Walruses).Polled animals or pollards are those of normally-horned (mainly domesticated) species whose horns have been removed, or which have not grown. In some cases such animals have small horny growths in the skin where their horns would be – these are known as scurs.

On humans

Cutaneous horns are the only examples of horns growing on people.^[7]

Cases of people growing horns have been historically described, sometimes with mythical status. Researchers have not however discovered photographic evidence of the phenomenon.^[8] There are human cadaveric specimens that show outgrowings, but these are instead classified as osteomas or other excrescences.^[8]

The phenomenon of humans with horns has been observed in countries lacking advanced medicine. There are living people, several in China, with cases of cutaneous horns, most common in the elderly.^[9]

Some people, notably The Enigma, have horn implants; that is, they have implanted silicone beneath the skin as a form of body modification.^[10]

Animal uses of horns

Goat skull piece

African buffalo (both sexes have horns)

Animals have a variety of uses for horns and antlers, including defending themselves from predators and fighting members of their own species (horn fighting) for territory, dominance or mating priority.^[11][12] Horns are usually present only in males but in some species, females too may possess horns. It has been theorized by researchers that taller species living in the open are more visible from longer distances and more likely to benefit from horns to defend themselves against predators. Female bovids that are not hidden from predators due to their large size or open savannahlike habitat are more likely to bear horns than small or camouflaged species.^[13]

In addition, horns may be used to root in the soil or strip bark from trees. In animal courtship many use horns in displays. For example, the male blue wildebeest reams the bark and branches of trees to impress the female and lure her into his territory. Some animals such as goats with true horns use them for cooling with the blood vessels in the bony core allowing them to function as a radiator.^[14]

After the death of a horned animal, the keratin may be consumed by the larvae of the horn moth.

Human uses of horns

Water buffalo horn used as a hammer with cleaver to cut fish in southeast China

• Horned animals are sometimes hunted so their mounted head or horns can be displayed as a hunting trophy or as decorative objects.
• Some cultures use bovid horns as musical instruments, for example, the shofar. These have evolved into brass instruments in which, unlike the trumpet, the bore gradually increases in width through most of its length—that is to say, it is conical rather than cylindrical. These are called horns, though now made of metal.
• Drinking horns are bovid horns removed from the bone core, cleaned, polished, and used as drinking vessels. (This is similar to the legend of the cornucopia.) It has been suggested that the shape of a natural horn was also the model for the rhyton, a horn-shaped drinking vessel.^[15]
• Powder horns were originally bovid horns fitted with lids and carrying straps, used to carry gunpowder. Powder flasks of any material may be referred to as powder horns.
• Shoehorns were originally made from slices of bovid horn, which provided the right curving shape and a smooth surface.
• Antelope horns are used in traditional Chinese medicine.
• Horns consist of keratin, and the term "horn" is used to refer to this material, sometimes including similarly solid keratin from other parts of animals, such as hoofs. Horn may be used as a material in tools, furniture and decoration, among other uses. In these applications, horn is valued for its hardness, and it has given rise to the expression hard as horn. Horn is somewhat thermoplastic and (like tortoiseshell) was formerly used for many purposes where plastic would now be used. Horn may be used to make glue.
• Los arcos de cuerno son arcos hechos de una combinación de cuerno, tendones y generalmente madera. Estos materiales permiten almacenar más energía en un arco corto que la madera sola.
• Los cuernos y las puntas de cuernos de diversos animales se han utilizado durante siglos en la fabricación de balanzas, empuñaduras o mangos para cuchillos y otras armas y, a partir del siglo XIX, para las balanzas de las pistolas .
• Los botones de cuerno pueden estar hechos de cuernos e históricamente también pezuñas, que son de un material similar. La parte no ósea del cuerno o la pezuña se puede ablandar calentándola a una temperatura justo por encima del punto de ebullición del agua, luego se moldea en moldes de metal, o la parte inferior hueca del cuerno se puede cortar en espiral a lo largo y luego aplanarla en forma de prensa entre tablas de madera, nuevamente después de calentar, y luego corte con una sierra de corona o herramienta similar en espacios en blanco redondos u otras formas que se terminan en un torno o a mano. Los botones de palanca se fabrican cortando las puntas sólidas de los cuernos y perforándolas. Los botones de asta y los botones hechos con pezuñas no son técnicamente botones de cuerno, pero a menudo se denominan así en el lenguaje popular. Los cuernos de ganado vacuno, búfalo de agua y oveja se utilizan para la fabricación de botones comerciales, y también de otras especies, de forma local y no comercial.
• Los peines de cuerno eran comunes en la época anterior a la sustitución por el plástico y todavía se fabrican.
• Todavía se fabrican estuches para agujas de cuerno y otras cajas pequeñas, especialmente de cuerno de búfalo de agua. De vez en cuando se encuentra cuerno utilizado como material en cajas de rapé antiguas.
• Las tiras de cuerno para incrustar madera son una técnica tradicional.
• Especialmente en Asia se fabrican horquillas de cuerno tallado y otras joyas, como broches y anillos, también para el comercio de souvenirs.
• El cuerno se utiliza en obras de arte para tallas pequeñas y detalladas. Es un material fácil de trabajar y pulir, es fuerte y duradero y, en la variedad adecuada, hermoso.
• Los palillos de cuerno se encuentran en países asiáticos desde las tierras altas de Nepal y el Tíbet hasta la costa del Pacífico. Normalmente no son el material común, sino que son artículos decorativos de mayor calidad. De manera similar, se siguen fabricando otros cubiertos de cuerno, en particular cucharas, para decoración y otros fines.
• Los dados largos hechos de cuerno que tienen una forma alargada como una varilla con cuatro caras numeradas y dos extremos pequeños sin numerar continúan fabricándose en Asia, donde se utilizan tradicionalmente en juegos como Chaupar (Pachisi) y muchos otros.
• El cuerno a veces se encuentra en bastones , mangos y varas de bastones. En este último uso, los elementos de bocina pueden cortarse en segmentos cilíndricos cortos mantenidos unidos por un núcleo metálico.
• Las deidades con cuernos aparecen en diversas formas en muchas religiones y mitologías del mundo.
• Los cascos con cuernos surgen en diferentes culturas, más con fines rituales que de combate.
• Los cuernos fueron tratados y cortados en tiras para hacer ventanas semitransparentes en la arquitectura vernácula de la Edad Media.

descornado

En algunos casos, los parques naturales pueden decidir quitar los cuernos de algunos animales (como los rinocerontes) como medida preventiva contra la caza furtiva . Los cuernos de los animales se pueden cortar de forma segura sin dañar al animal (es similar a cortar las uñas de los pies). ^{[16] [17] [18]} Cuando el animal iba a ser cazado furtivamente, generalmente se mata al animal, ya que se le dispara primero. Sin embargo, los guardaparques pueden decidir tranquilizar al animal en lugar de quitarle el cuerno. ^{[ se necesita aclaración ]}

Galería

• 
  Erkencho , instrumento musical elaborado a partir de un cuerno
• 
  Una oveja de las Hébridas con un cuerno en un lado y dos en el otro.
• 
  Cuerno de búfalo de agua ( Bubalus bubalis )
• 
  Collar de cuernos Art Nouveau de Elizabeth Bonté
• 
  Cuernos montados en antílope sable , en el Museo Zoológico, Dinamarca
• 
  Cuernos, colmillos y astas en el Museo Nacional de Escocia

Ver también

• dios cornudo
• Ganado sin cuernos
• Carey
• Shofar
• Signo de los cuernos  – Gesto con la mano
• Conservación y restauración de objetos de hueso, cuerno y asta  – Preservación de colecciones patrimoniales

Referencias

1. Nasoori, Alireza (2020). "Formación, estructura y función de huesos extraesqueléticos en mamíferos". Reseñas biológicas . 95 (4): 986–1019. doi :10.1111/brv.12597. PMID  32338826. S2CID  216556342.
2. Bocetos de la historia natural de Ceilán por Sir James Emerson Tennent, publicados por Longman, Green, Longman y Roberts, 1861. Archivado
3. Mamíferos de Nepal: (con referencia a los de India, Bangladesh, Bután y Pakistán) por Tej Kumar Shrestha, publicado por Steven Simpson Books, 1997, ISBN 0-9524390-6-9 
4. Pardikar, Rishika (26 de abril de 2020). "En la India, los chacales son cazados furtivamente por sus cuernos 'mágicos' e inexistentes". Desplazarse hacia adentro . Consultado el 24 de febrero de 2024 .
5. Sekar, Sandhya (20 de abril de 2020). "Un cuento de cuernos de chacal inexistentes y su venta online". Mongabay-India . Consultado el 24 de febrero de 2024 .
6. Sharma, Chandra Prakash; Singh, Preeti; Srinivas, Yellapu; Madhanraj, Anandraj; Rawat, Gopal Singh; Gupta, Sandeep Kumar (2022). "Unraveling the mystery of confiscated "jackal horns" in India using wildlife forensic tools". International Journal of Legal Medicine. 136 (6): 1767–1771. doi:10.1007/s00414-022-02773-6. ISSN 1437-1596. PMID 35102447.
7. Alston, Isabella (2014-08-01). Anatomical Anomalies. TAJ Books International. ISBN 9781844063789.
8. Tubbs, R. Shane; Smyth, Matthew D.; Wellons, John C. III; Blount, Jeffrey P.; Oakes, W. Jerry (June 2003). "Human horns: a historical review and clinical correlation". Neurosurgery. 52 (6): 1443–1448. doi:10.1227/01.NEU.0000064810.08577.49. PMID 12762889. S2CID 24254020. (Literature Reviews)
9. "Mysteriöse Krankheit: Hilfe für den Baummenschen". Stern. 2007-11-22. Archived from the original on 2011-08-25.
10. Johann, Hari (2002-03-11). "Johann Hari on the bizarre world of radical plastic surgery". London: Guardian News and Media. Retrieved 2010-05-04.
11. Valerius Geist; Fritz R. Walther; International Union for Conservation of Nature and Natural Resources (1974). The Behaviour of Ungulates and Its Relation to Management: The Papers of an International Symposium Held at the University of Calgary, Alberta, Canada, 2-5 November 1971. International Union for Conservation of Nature and Natural Resources.
12. Edward O. Wilson (1 January 1980). Sociobiology. Harvard University Press. pp. 119–. ISBN 978-0-674-81624-4.)
13. "Why Female Water Buffalo Have Horns but Impala Do Not?".
14. Taylor, Charles R. (1966). "The Vascularity and Possible Thermoregulatory Function of the Horns in Goats". Physiological Zoology. 39 (2): 127–139. doi:10.1086/physzool.39.2.30152426. ISSN 0031-935X.
15. Chusid, Hearing Shofar: The Still Small Voice of the Ram's Horn, 2009, Chapter 3-6 - Ram's Horn of Passover <http://www.hearingshofar.com Archived 2010-03-28 at the Wayback Machine>. The book also posits that the ancient Hebrews and neighboring tribes used horns as weapons and as utensils.
16. "How chopping off their horns helps save rhinos from poachers". The Guardian. 2018-05-31. Archived from the original on 2023-05-11.
17. Cortar cuernos para salvar a los rinocerontes de los cazadores furtivos
18. Descornar rinocerontes

enlaces externos

• Un sitio con información sobre la historia del cuerno de vaca como instrumento musical.
• MacGregor, Arturo. Hueso, asta, marfil y cuerno: la tecnología de materiales esqueléticos desde la época romana . Barnes and Noble, 1985. [Reimpreso en 2016, Routledge] Esta es una monografía académica sobre el tema del cuerno y otros materiales esqueléticos, profusamente ilustrada y con extensas referencias académicas y de historia del arte.