Nose Dive: Falcons & Gannets

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The Peregrine Falcon (Falco peregrinus) is famous for being one of the fastest animals in the world.  Image credit: Yale Peabody Museum / Curious Sengi.

Of all the powers of the animal world that humans have envied and engineered into submission, nothing has become a more overdone trope of this desire than the flight of birds.  In our endeavor to understand flight, we have broken down the components of aerodynamics into something we can quantify, calculate, and model.  This approach has obviously worked quite well for us.  Just think about how a Boeing 747 jumbo jet can haul passengers from the East to West Coast of America in about six hours.  The same journey would have taken wagon-driving pioneers months of life-threatening travel through forests, endless plains, deserts, snowy mountains, more deserts, and more mountains.

With our highly engineered view of flight, we tend to look back at living organisms and try to find elements of evolutionary design that seem perfectly adapted to certain modes of life.  For example, let’s take a look at the nostrils of two very different birds, the Peregrine Falcon (Falco peregrinus) and gannets (Family Sulidae).

The Peregrine Falcon is a small North American raptor famous for its incredible high-speed dives.  These dives, or stoops, are generally reported to clock in at 200 mph (320 km/h).  This makes the Peregrine one of the fastest animals on Earth, “a feathered bullet dropping out of the sky (Hagler 2012).”  Traveling at such speeds requires many modifications, including some less obvious ones like redirecting airflow into the nostrils for breathing.  It is repeatedly said that the force of air entering the nose at 200 mph would cause the lungs to explode.  In order to prevent this from happening, there are bony tubercles in the nares that act as baffles to safely regulate the passage of air into the respiratory system.  As a matter of fact — according to these often repeated anecdotes — the nostrils of Peregrine Falcons inspired the design of inlet cones for supersonic jet engines.

That’s a cool fact, but what does it really mean?

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The dive of the Peregrine Falcon is called the “stoop.”  During the stoop, the falcon strikes its prey — usually birds — with intense and often lethal force.  There are reports that the strike is enough to knock off the heads of prey animals.  Image credit: PBS Nature.

To begin with, traveling at high speeds will not cause lungs to explode.  Quite the opposite.  There are two physical principles to keep in mind here:  (1) the Bernoulli Effect where higher air speed results in lowered air pressure and (2) the energetically favored direction is always from high to low.  As the Peregrine Falcon reaches top speed during the stoop, the increasing air speed encountered by the nares will result in a drop in air pressure.  Inhalation relies upon relatively high pressure air outside the body rushing into the low pressure area of the lungs.  Eventually, the air pressure outside the stooping falcon will approach equilibrium with the air pressure inside the lungs, making breathing very difficult.  Think about how it is harder to breathe when facing into a strong wind, sticking your head out a car window on a freeway (not necessarily recommended), or riding a fast boat.  The presence of bony tubercles in the falcon’s nose act to slow down the airflow, increasing the air pressure, and allowing air to be drawn into the body.  Seems like a clever bit of evolutionary adaptation to extreme high speed flight.

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The bony tubercle appears as a bump in the center of the nostril of this Peregrine Falcon.  Image credit: Yale Peabody Museum / Curious Sengi.

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Compare the lack of a narial tubercle in an unrelated raptor, the Red-Tailed Hawk (Buteo jamaicensis calurus).  Image credit: Yale Peabody Museum / Curious Sengi.

This tidy story is somewhat disrupted once we take a look at the phylogenetic distribution of narial bony tubercles.  The Peregrine Falcon shares this morphological feature with all members of the Family Falconidae, which includes raptors of a wide variety of shapes, sizes, and flight abilities.  At one end of the spectrum is the Peregrine Falcon that knocks its bird prey out of the air.  At the other are the caracaras, which soar at a leisurely pace searching for carrion, much like vultures.  This leaves us with a puzzle:  if the tubercles within the nostrils of the Peregrine Falcon are adaptive for respiration at extreme flight speeds, why do all members of the Falconidae possess these tubercles?  It is possible that narial tubercles were present in the common ancestor of all Falconidae and, therefore, all its descendants still carry this feature.  Perhaps the tubercles evolved to serve a different function — such as sensing airspeed or temperature — and this existing structure was modified with a new purpose in the Peregrines.  The conclusion is that we do not fully understand why the bony tubercles of the nostril appear in the Falconidae and what adaptive purpose (if any) it may serve.

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The bony tubercle is apparent in the nostril of this American Kestrel (Falco sparverius sparverius).  All members of the Family Falconidae share this morphological feature regardless of flight speed.  Image credit: Yale Peabody Museum / Curious Sengi.

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The bony tubercle is faintly visible in the skull of this Crested Caracara (Caracara cheriway cheriway).  Unlike the Peregrine, the Caracara is a slow, soaring bird often found on the ground and scavenging carrion.  It is possible that the bony tubercle changes in size and shape depending on the flight behavior, but this has not been proven yet.  Image credit: Yale Peabody Museum / Curious Sengi.

Perhaps we felt confident in stating the purpose of the Peregrine Falcon’s unusual nostrils because we saw how engineers solved the problem of regulating air intake in jet engines in a very similar way.  In the post-WWII years, military aircraft were breaking more speed records with an ever sophisticated understanding and use of rocketry, but aircraft could only travel so fast until the engines would choke and then stall.  It was soon discovered that instead of passing through the cylinder of the jet engine, air flow was being diverted away, taking with it the oxygen necessary for combustion.  This is the same problem caused by the Bernoulli Effect and the flow from high to low pressure discussed earlier.  The addition of cone-shaped structures in the engine’s inlet generates shockwaves that slow down airflow and allow the engines to continue running.  The inlet cone innovation made supersonic flight possible.  In 1947, Chuck Yeager was able to take a Bell X-1 experimental plane faster than the speed of sound, i.e., Mach 1, which is a blinding 768 mph (1235 km/h) at sea level.

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Schematic drawing of a cross-sectioned jet engine.  When faced with supersonic speeds, air entering into the engine (left) needs to be slowed down in order to pass through the engine and allow combustion to take place.  This slowing down of the airflow is achieved by the introduction of the inlet cone (labeled here as “inner body”).  Image credit: Phillip R. Hays via History of the Talos Ramjet Engine.

The similarity between the design of the inlet cone in supersonic jet engines and the bony tubercle in the nostrils of Peregrine Falcons make for another tidy story where Nature directly informed engineering.  Though I was unable to find any literature that proved experimental research was done on the aerodynamics of falcon nostrils, it does not preclude the possibility that a casual observation inspired an idea.

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SR-71 Blackbird was introduced in 1966 by Lockheed’s Skunk Works division, a secretive branch dedicated to advanced technology research. The Blackbird was indeed like nothing ever seen before in terms of aircraft design, prompting conspiracy theorists to claim it was reverse engineered from UFOs.  Definitely not alien technology, but note the presence of conical projections from the air intake of the engines mounted on the wings.  These inlet cones, similar to the bony tubercles seen in Peregrine Falcon nostrils, allowed the Blackbird to fly in excess of Mach 3.  So what came first:  did Nature inspire the engineering?  Or did engineering inspire our interpretation of the Peregrine Falcon?  The Blackbird was retired in the late 1990s. Image credit: Wikimedia Commons.

Another fast flyer encountering extreme physical forces are gannets.  These seabirds have been observed plunge diving from a height of about 100 feet (30 m), drawing their wings back and configuring their bodies into a tight, streamlined shape to pierce the surface of the water where they capture fish.  At the moment of impact with the water, gannets can be traveling at 54 mph (86.4 km/h, or 24 m/s).  (There are macabre data collected from 169 suicides of people jumping off the Golden Gate Bridge in San Francisco.  Impact velocity was calculated to be approximately 33 m/s.  Almost 100% of jumps were fatal, with a vast majority of deaths caused by the impact itself.)  Like the Peregrine Falcon, gannets have evolved a suite of features that allow them to cope with such intense hunting strategies.  As many human swimmers have experienced, how does the gannet dive without getting water up the nose?

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Image credit: BBC Earth.

Gannets are believed to bypass the problem by losing the external nares entirely.

As embryos in the egg, gannet nostrils develop identically to  many other bird species, with the nostril openings and immediate vestibular cavity sealed by a plug of epithelial tissue.  While this plug breaks down a little bit later in development to open up the nares, it remains in gannets.  Eventually, the gannets’ external nares are overgrown with bone and covered by the keratinous sheath of the beak, the rhamphotheca.  Interestingly, while the nostrils are completely occluded and there is no flow of air through the nasal cavity, gannets still retain well-developed olfactory structures.

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No external nares seen here on this Peruvian Booby (Sula variegata), which belongs to the same family as gannets.  The nostrils would be positioned near the base of the upper beak, but in gannets and boobies, the nostrils are completely covered over by bone growth and the keratinous sheath of the beak.  Image credit: Yale Peabody Museum / Curious Sengi.

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Nope, no nostrils in this view either! Image credit: Yale Peabody Museum / Curious Sengi.

How do gannets manage without nostrils?  Macdonald (1960) described secondary external nares — compensatory nostrils, if you will — formed by a gap at the corner of the mouth where the upper beak overhangs the lower.  This area of overhang is made from a bone called the jugal (equivalent to our cheekbone), which is covered by a hinged plate of keratin.  These two elements are loosely connected to the rest of the skull and are likely to collapse against the sides of the beak from the external pressure of water when diving, thus passively closing up these secondary external nares.

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Australasian Gannet (Morus serrator).  Note the keratinous plate of the beak underneath the black patch of the eye (it is a narrow triangular shape with a sharp point oriented anteriorly towards the tip of the beak).  Macdonald identifies this as the site of a secondary external naris, a permanent gap between the upper and lower beak covered by a collapsible “jugal operculum.”  Image credit: Yale Peabody Museum / Curious Sengi.

The total loss of nostrils in gannets seems to be a great way to prevent water from forcibly entering the nose during plunge diving and potentially causing damage or water entering the respiratory system.  However, Macdonald noticed some interesting patterns in other unrelated diving birds.  Cormorants (Family Phalacrocoracidae) certainly dive, but from the water’s surface, not from the air.  Despite this more gentle entry into the water, cormorant nostrils are small and almost completely occluded.  In contrast, the Brown Pelican (Pelecanus occidentalis) is a heavy-bodied plunge diver with open nostrils.  The nostrils are surrounded by a flap of skin that might push up against the nostril and seal it like a valve under external water pressure.

To say that the complete narial occlusion in gannets is directly correlated to plunge diving would be ignoring some of the complexities of the story.  We could interpret the near-total loss of nostrils in the cormorant as a remnant from a plunge diving ancestor.  Or it could evolved for a different reason entirely.  The alternative mechanism for closing up the nares in the Brown Pelican is suggestive that there is an adaptive advantage to not getting water up your nose when diving.  In addition, the employment of a different solution to the same problem suggests that there are negative trade-offs involved with losing nostrils.  For example, seabirds need salt-secreting glands to rid their bodies of the excess salt they ingest.  These glands usually empty out through the nostrils.  Gannets have relatively small salt-secreting glands and must discard concentrated salts from their mouths.

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Skull of the Northern Gannet (Morus bassanus).  During development, bone has overgrown the site of the external nares.  The long, thin bone projecting behind the mandible is the jugal.  Image credit: Yale Peabody Museum / Curious Sengi.

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Faced with only skeletal material of extinct animals, paleontologists must be extra careful in interpreting the function of anatomical structures and extrapolating behavior.  Even in a modern animal, like this Northern Gannet, it would be a dangerous oversimplification to state that occluded nostrils are directly related to plunge diving.  Image credit: Yale Peabody Museum / Curious Sengi.

Interpreting the function of anatomical structures is always going to be more nuanced than saying “structure X is perfectly adapted to serve purpose Y.”  The biological world is far removed from the world of engineering design.  In our interpretations, we have to take into account the baggage and constraints imposed by evolutionary history, experimentally prove that a given structure does have a function that enhances performance, and keep in mind that trade-offs exist.

References

Hagler, Gina.  2012.  Modeling Ships and Space Craft:  The Science and Art of Mastering the Oceans and Sky.  New York:  Springer.

Macdonald, Helen.  2006.  Falcon.  London:  Reaktion Books.

Macdonald, J.D.  1960.  “Secondary External Nares of the Gannet.”  Journal of Zoology 135 (3):  357 – 363.

Ropert-Coudert, Yan et al. 2004.  “Between air and water:  the plunge dive of the Cape Gannet Morus capensis.”  Ibis 146:  281 – 290.

Scholz, Floyd.  1993.  Birds of Prey.  Mechanicsburg, PA:  Stackpole Books.

Scothorne, R.J.  1958.  “On the anatomy and development of the nasal cavity of the gannet (Sula bassana L.).”  Journal of Anatomy 92 (4): 648.

Snyder, Richard G. & Clyde C. Snow.  1967.  “Fatal Injuries Resulting from Extreme Water Impact.”  Aerospace Medicine 38 (8):  779 – 783.

Supersonic speed.”  Wikipedia: The Free EncyclopediaJou.  Wikimedia Foundation, Inc.  Last modified 21 August 2016.  Web.  Accessed 25 August 2016.

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Tenuously Tame: Humans and Hyenas

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The Striped Hyena (Hyaena hyaena).  Though hyenas are generally seen as denizens of the African savanna, this species has a distribution through northern Africa, the Middle East, and Central Asia through to India.  Image credit: Smith, Charles Hamilton. No year. “The Naturalist’s Library: Mammalia, Dogs.” Volume II. London: Chatto & Windus. Via Biodiversity Heritage Library.

The hyena has suffered from an unsavory reputation as a frightening,  loathsome creature.  Medieval rehashings of ancient Classical texts describe the hyena as an ungodly hermaphrodite that skulks about in tombs to feed upon the dead, as well as having the power to imitate the human voice to lure out victims into the night.

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Medieval imaging of a hyena scavenging upon a human corpse.  This illumination comes from the Aberdeen Bestiary, which was produced in England around 1200.  Image credit: University of Aberdeen.

In 1833, Lieutenant Colonel William H. Sykes (1790 – 1872) wrote to the Zoological Society of London to refute the “popular error” that the Striped Hyena (Hyaena hyaena; cited as H. vulgaris by Sykes) was “ferocious and untameable” based on his personal experience with an individual he acquired in India and transported to the London Zoo (“the Gardens”):

Two years have elapsed since I placed in the Gardens of the Society the above-mentioned cub (a female), which has now attained its full growth, and I am happy to be enabled to confirm the opinions I formerly advanced.  In India it was allowed to run about my house, and on board ship it was released from its cage two or three times a day, to play with the sailors and gambol with the dogs.  It early recognised my person and voice, and would obey when called; and in generally was as playful and good-humored as a puppy.  My visits to it in the Gardens have been rare, and at long intervals, nor have I ever carried it food; I anticipated, therefore, that it would outgrow its early associations, and that I should be to it as any other stranger; but it has always greeted me not only as an acquaintance, but as an old friend. . . .

On Sunday last it was asleep in its cage when I approached.  On calling to it by its name it looked up, distinguished me in the crowd, started on its legs, and on my applying my hand to its mouth to smell to, threw itself down against the bars, rubbed its head, neck, and back against my hand, and then started on its legs and bounded about its cage, uttering short cries.  On ceasing to speak to it, and moving away, it stopped, and looked wistfully after me, nor resumed its motions until I addressed it again.  Its manifestations of joy were so unequivocal, as to excite the surprise of a great number of bystanders.  As these pleasing traits in the disposition of a calumniated animal appeared so new to those who surround me on that occasion, they may possibly be deemed of sufficient interest to be worthy of. . . . record in our Proceedings.

I take occasion to repeat my conviction, that association with man, constant kindness, and abundance of food, will suffice not only to modify, and indeed eradicate, the worst traits in the disposition of any animals of the higher classes, but give birth to others of which their natures were not deemed susceptible.

The affectionate reunion described by Sykes is reminiscent of what dog owners observe in their pets.  Hyenas are a branch on the feline side of the carnivore family tree, though very much their own distinct lineage.  However, their similarity to canines as intelligent, social group hunters points them towards tameness.  Legge (2011) cites a San Diego Zoo keeper saying that Striped Hyenas could be practically pets to individuals who care for them from a very young age, which collaborates Sykes’ experience.

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Scientist, conservationist, and writer Delia Owens with a Brown Hyena (Hyaena brunnea).  With her husband, Mark Owens, Delia published an account of their years of research in an acclaimed memoir, “Cry of the Kalahari.”  Being a neutral presence — neither a threat nor a source of food — brought the Owens into a respectful living relationship with a number of individual large carnivores.  Image credit:  Namibiana Buchdepot.

There is some tantalizing evidence that hyenas were either domesticated or kept in captivity in ancient Egypt.  These animals were most commonly depicted in artwork as being led or carried as offerings.  There are even several images of hyenas being force-fed to be fattened for slaughter and consumption.  These images can be hard to interpret — do they represent real scenes or imaginings of elaborate, fantasized banquets for the elite?  The only physical evidence comes from a significantly later period, from the Workmen’s Village at Tell el-Amarna where bones with butchering marks were discovered.  It is not known if the butchered animals were captive or wild-caught, but it was clear that the hyena’s star had fallen and they were no longer part of the upper echelons of society.  Legge (2011) even corroborates this with artwork from the same period that relegates hyenas to mere victims in hunting scenes.

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Drawing of a bas-relief from the Fifth Dynasty (ca. 2500 BCE).  The distinct profile of high shoulders and low hindquarters identifies these animals as hyenas.  They are closely handled by men who are force-feeding the animals in the center of the image sequence.  Image credit: Legge (2011).

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Detail of a bas-relief from the Tomb of Kagemni, Mastaba 25 in Saqqara, Egypt (early Sixth Dynasty, after 2347 BCE).  Here a hyena is bound but gently fed by an attendant.  The poultry depicted in the upper left corner suggests the hyenas were being fattened up with choice meats.  Even today, hyena flesh is occasionally consumed for its magical properties and rich, sweet taste.  Image credit: AKG Images.

Archaeologists and anthropologists recognize that humans and hyenas share a long history, one beyond the days of the Old Kingdom of Egypt.  The relationship may go as far back as 4.4 million years ago, to the early Pliocene.  The Aramis site in Ethiopia has revealed a host of fossils, including an early hyena, Crocuta dietrichii.  But most lauded were the bones of an early hominine, Ardipithecus ramidus, nicknamed “Ardi.”  What was significant about Ardi was that, despite being trampled after death, her skeleton was relatively intact.  Grim as it is, it was worth celebrating since all previously known ardipithecine remains were just bits of undigested teeth and heavy bone.  Zoologist Hans Kruuk would remark that the incredible scavenging and digestive powers of the hyena has depleted much of the fossil record of early humans.

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This particular specimen of Ardipithecus ramidus, named “Ardi”, was the first good look we had of this early human predecessor.  Image credit: Wikipedia.

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The fate Ardi avoided by a quick burial in a mudslide.  The powerful digestive capability of the hyena draws out nearly all organic content, leaving nothing but pure mineral apatite from the bones.  Image credit: Smithsonian Magazine.

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Hyenas were part of the Paleolithic human imagination.  Drawing of a Cave Hyena (Crocuta crocuta spelea) discovered in Chauvet Cave in France.  The images in Chauvet have been dated to be at least 32,000 years old.  Image credit: Wikipedia.

We evolved alongside these creatures, eating them and being eaten by them.  We watched hyenas, kept them at bay, and sometimes admired them.  During this long (and continuing) standoff between give and take, we have in some ways entered into a domesticated partnership.  Scholars such as Reed (1986) view domestication as a two-way, “cooperative, symbiotic process” that requires a change in both the wild animal and to ourselves when we put down our weapons.  This tenuous taming between hyenas and humans is still actively seen today in modern Africa.

Multiple studies have revealed that the Spotted Hyenas’ (Crocuta crocuta) indifference for areas of human habitation have defined a coexistence, a two-way domestication.  Hyenas are allowed to roam the city streets, where they consume nearly all organic garbage, including feces, and are therefore viewed as important agents of urban sanitation.  Some people will purposefully feed the animals to maintain their interest in sticking around.  In contrast, hyenas make no distinction between kitchen scraps and human remains.  Christian and Islamic burying grounds are often surrounded by high walls, or the body is otherwise protected in sturdy coffins or shelters.  But during times of intense stress such as epidemics, famines, and massacres,  hyenas may be tolerated as a practical means of disposing of corpses.  In his dissertation, Baynes-Rock (2012) observed the convoluted relationships between the people of the city of Harar, Ethiopia and hyenas.  This included the existence of two official hyena feeding places to attract wildlife tourism.  The operators of these businesses drive customers out at dusk to a designated area (usually a stretch of empty dirt road), call for the hyenas to come, and feed them chunks of meat as customers watch and take photographs in the beam of car headlights.  Feeding hyenas for tourist money most likely arose secondarily from feeding them just enough to deflect these scavengers from turning their attention to killing livestock or family members.  Baynes-Rock captured a remarkable statement from one of the men running the feeding operation:  he was always worried that when he called, the hyenas may not come.  Even with the familiar promise of an easy meal at the same time and same place, hyenas were never fully dependent or dependable.

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Advertisement for the Aboker feeding place.  Image credit: Baynes-Rock (2012).

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Sofi feeding place.  Hyenas are being fed pieces of meat on sticks.  Paying customers are allowed the privilege, but the photos here are of family members running the feeding operation.  These animals are treated with familiarity and they sometimes even enter the home, but they are left to wander freely through the surrounding land.  Image credit:  Baynes-Rock (2012).

Finally, there are the “Hyena Men” (Gadawan Kura) of Nigeria.  For most of the year, these men are regular farmers at the mercy of the fields and sky.  But they are also engaged in a hereditary profession of making and selling herbal medicines from town to town.  And like all good traveling medicine men, they need a good show to draw the customers in.  The Gadawan Kura perform street shows with hyenas, baboons, and snakes — all animals associated with fear, witchcraft, and superstition.  To have power over such animals imbues a mystique that enhances medicine sales and brings in much-needed income.  Video footage of these street performances show hyenas muzzled and on the end of heavy chains, jerked about, picked up, and spun around.  Whatever moments we saw before, where the animals are cared for as valuable assets and the calm moments of affection, are quickly forgotten.  It becomes painfully clear that the men have control over these animals and their priority is making money to support their families.  Though it can be hard to watch, it is undoubtedly representative of most human-animal relationships throughout all history.  In the First World concept of domestication and tameness, our pets absorb our love and affection, satisfying our egos.  With the hyena, there is a mutual understanding of the necessary partnership, of independent and sometimes conflicting interests.  In the proximity, there is still wildness and an acknowledgement of the danger that comes from both beast and human.

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Gadawan Kura in costume.  Image credit: Pieter Hugo via So Bad So Good.

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Training to handle hyenas, baboons, and snakes is a family tradition.  Image credit: Pieter Hugo via So Bad So Good.

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Contact with animals begins at an extremely early age.  Children, adults, and animals all drink a secret herbal potion to protect them from injury.  Image credit: Pieter Hugo via So Bad So Good.

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Image credit: Pieter Hugo via So Bad So Good.

References

Aberdeen University Library.  1995.  “Folio 11v Translation and Transcription.”  The Aberdeen Bestiary.  Accessed 16 August 2016.

Baynes-Rock, Marcus.  2012.  Hyenas like Us:  Social Relations with an Urban Carnivore in Harar, Ethiopia.  Dissertation.  Macquarie University.  Accessed 17 August 2016.

Gade, Daniel W.  2006.  “Hyenas and Humans in the Horn of Africa.”  Geographical Review 96 (4):  609 – 632.

Legge, A.J.  2011.  “The Hyaena in Dynastic Egypt:  Fancy Food or Fantasy Food?”  International Journal of Osteoarchaeology 21:  613 – 621.

Perkins, Dexter Jr.  1973.  “The Beginnings of Animal Domestication in the near East.” American Journal of Archaeology 77 (3):  279 – 282.

Reed, Charles A.  1986.  “Wild Animals Ain’t So Wild, Domesticating Them Not So Difficult.”  Expedition 28(2):  8 – 15.

Sykes, W.H.  1833.  “On a Remarkable Instance of affectionate Attachment in the common Hyaena (Hyaena vulgaris, Cuv.).”  Proceedings of the Zoological Society of London:  76.

 

Pigs Without Hams

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Image credit: Pinterest.

In 1833, a letter from a Briton abroad was read before the Zoological Society of London.  The contents of this rather unusual correspondence was later published in the society’s journal:

A note from Col. Hallam was read. . . . of two individuals of a race of pigs with only two legs, the hinder extremities being entirely wanting.  The latter, Col. Hallam states, were observed ‘at a town on the coast in the Tanjore country [in India], in the year 1795:  they were from a father and mother of similar make, and the pigs bred from them were the same.’

So, three successive generations of pigs missing hindlimbs. . . .  essentially, pigs lacking hams.

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Pig born without hindlimbs in 2011 in Anhui Province, China.  Image credit: Quirky China News / Rex Features via Daily Mail.

The congenital absence of entire limbs is a relatively rare condition termed amelia.  The lack of one or more limbs at birth is merely a symptom resulting from a variety of different causes, both internal and external.  Developmental abnormalities can be genetic (internal) or they can arise from exposure to toxins, chemical substances, physical trauma, and radiation at crucial points during pregnancy (external).  In addition, amelia can occur along with a suite of other deformities, especially in the face, or it can appear by itself in an otherwise healthy, normal individual.

It is these latter cases — adorable baby animals with missing limbs yet a plucky attitude — that have been enthusiastically picked up by news media.  In 2010, an amelic piglet was born in Henan Province, China and named Zhu Jianqiang (“Strong-Willed Pig”), eventually reaching quasi-celebrity status worldwide.  The pig’s owner, Wang Xihai, is quoted as saying:  “My wife asked me to dump it but I refused as it’s a life.  I thought I should give it a chance and unexpectedly it survived healthily (Daily Mail Reporter, 1 October 2010).”  He even helped the pig learn how to walk balanced on its forelegs in a handstand, which it did with great success in about a month.  At the time of the original news report, Zhu Jianqiang was still going strong and had obtained a healthy (albeit ham-less) weight of 110 pounds (50 kilograms).

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Zhu Jianqiang, “Strong-Willed Pig”, has learned to move around by balancing on forelimbs alone.  It is unknown what caused this developmental anomaly, especially given the health and normal anatomy of the pig’s parents and siblings.  There are some reports of amelia occurring if the pregnant sow consumes tobacco stalks (Nicotiana tabacum), but that is not confirmed in this case here.  Image credit:  Quirky China News / Rex Features via Daily Mail.

The absence of hindlimbs has been popularly reported not only in pigs, but also in other domesticated animals.  A Florida kitten named Anakin was found in 2012 without pelvis or hind legs and yet “. . . . he plays and scurries around by balancing on his forelegs, which he positions under his middle, and balancing with his tail (Hartwell).”  An English Bulldog was born to a Arkansas breeder in 2015 with a truncated spine, no pelvis, and only vestigial hindlimbs.  This pup, Bonsai, became a Facebook darling and a crowdfunding campaign raised over $24,000 to support medical expenses.

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Bonsai the bulldog puppy.  Image credit: Daily Mail.

Like the pigs in Colonel Hallam’s 1833 report, existence without hindlimbs did not prevent these animals from living out their lives well into adulthood.  At least in the case presented by Hallam, this included the somewhat mentally inconceivable act of breeding between two limb-less pigs.  However, this carnival of cute oddities should not draw us into comfortable complacency.  The congenital loss of limbs is the result of catastrophic disturbances in development.  Many times, the results are fatal, if not outright cruel.  For an amelic calf, veterinarians decided to euthanize the otherwise healthy animal because it could only drag itself around on its belly, causing raw skin abrasions.  Bonsai the puppy was born with vestigial remnants of hindlimbs that had to be surgically removed.  Also, Bonsai’s unsupported posture was putting pressure on internal organs — hardly good news for a bulldog, a breed already highly compromised with respiratory and other health problems.  Needless to say, animals like Bonsai, Anakin, and Zhu Jianqiang will need extensive human care.

Bulldog Amelia_1

X-ray of Bonsai after surgical removal of his vestigial hindlimbs.  Image credit: Daily Mail.

There is a sense of renewal at the delivery of a newborn.  What we expect to find is something tiny, yet utterly new and perfect in every way.  This is the body before the hard knocks of life, before battle wounds, poorly considered tattoos, run-ins with power tools.  Congenital deformities can feel like a betrayal of these expectations.  The birth of “monstrous” animals and babies were once seen as ominous signs that something was terribly amiss in the world.  Such fearful portents may no longer signal religious heresies or political upheaval, but we must still think carefully about what they mean.  We must be able to understand the difference between something so deep and hidden within our cells it is beyond our control, and warnings from an environment under siege.  We must reconsider what is “normal”, what constitutes a meaningful life, and realize how our immediate culture defines those terms for us.

References

Daily Mail Reporter.  “Hogging the limelight:  Meet Zhu Jianqiang, the two-legged pig who’s become a celebrity in China.”  Daily Mail 1 October 2010.  Accessed 2 August 2016.

—–.  “Hamstand:  ‘Gymnast’ piglet born without hind legs learns to walk on two front trotters.” Daily Mail 28 November 2011.  Accessed 2 August 2016.

Hallam.  1833.  “Letter on a singular Race of Pigs.”  Proceedings of the Zoological Society of London:  16.

Hartwell, Sarah.  “Feline Medical Curiosities:  The Limbs.”  Messybeast Cats:  Curious Cats and Medical Anomalies.  Accessed 2 August 2016.

Hiraga, Takeo et al.  1991.  “Anatomical Findings of Apodia in a Calf.”  Journal of Veterinary Medical Science 53 (6):  112 – 1127.

MacFarlan, Tim.  “Cute bulldog puppy born with genetic conditions that mean he has no bottom half.”  Daily Mail 10 July 2015.  Accessed 2 August 2016.

Merck Sharp & Dohme Corporation.  “Overview of Congenital and Inherited Anomalies.”  The Merck Veterinary Manual.  Accessed 2 August 2016.

Mosbah, E. et al.  2012.  “Congenital Limb Deformities in Some Farm Animals.”  Proceedings of the 5th Animal Wealth Research Conference in the Middle East  North Africa.  Pp. 23 – 38.

Szczerbal, I. et al.  2006.  “Chromosome Instability in a Calf with Amelia of Thoracic Limbs.”  Veterinary Pathology 43 (5):  789 – 792.