THE ANATOMICAL RECORD 297:1973–1974 (2014)
Those Who Know What the Nose Knows JEFFREY T. LAITMAN* The Anatomical Record
Unlike people, all body parts are not beloved equally. Once I actually tested my brilliant hypothesis by simply asking my incoming medical school students what part of the body they were considering focusing on in their careers. A legion arose when I asked about the heart. Many snapped to attention when I called brain and nerves. All those over six feet stood tall when I mentioned knees and elbows and joints (got to love those frat brothers, future orthopedists all!). Even a few very bold souls acknowledged interest in the urinary tract and genitalia (I think it was the latter). Guts were a draw too; ears had their aficionados, as did throats, and eyes (those all wore glasses). A couple of coughing kids wheezed to attention when I called lungs. A few oddlooking folks even liked feet (I won’t go there). No one responded when I called “nose.” I thought that I had a chance with those few proudly wearing nose piercings but, no, no one for the nose. How interesting, I thought, that they would all eschew a career studying one of the most important— and incredibly alluring—structures of the mammalian body plan. After all, we, and our closest kin are airbreathing mammals and the portal for that lifeallowing gaseous mixture to enter our bodies is the nose. It’s the first thing we see in the mirror at the beginning of our day, and it is as plainly central to our existence, and as core to our functioning as, well, the nose on our faces. So, why no takers? There’s no clear answer, but it probably lies somewhere buried in the old adage that “familiarity breeds contempt.” We all know what the ol’ nose does, right? It’s just that funny thing between our chubby cheeks, below our sainted eyes and above our shapely lips. Just two holes for air to get into and out of our body. We don’t think about it much, except when its “stuffed”; when bleeding occasionally occurs, usually at most inopportune moments; or when unpleasant material drains out (often called catarrh; did you know that nasal mucus was originally thought to originate in the brain, specifically the pituitary, and this wasn’t debunked until the 17th century?; see Schneider, 1660; Lower, 1670). Our nose also frequently annoys us, and is particularly adept at sprouting unsightly “pimples” just before an important event (how does it know when these events are about to happen?). Just the unspectacular schnoz, the old honker, the Jimmy Durante special. Nothing of real interest here, right? My brilliant students could not have been more wrong! The nose is a lot more than two innocuous looking holes surrounded by some cartilage and assorted tissues and vessels. As brought to life in this Special Issue of The Anatomical Record, “The VerteC 2014 WILEY PERIODICALS, INC. V
brate Nose: Evolution, Structure, and Function,” Guest Edited by Baire Van Valkenburgh, Timothy Smith and Brent Craven (2014), the nose is a vast wonderland of labyrinths and bones, nerves and specialized tissues, vessels, and ducts, that have morphed and changed through evolution to accommodate specific requirements. This energetic nasal troika—Van Valkenburgh, an eminent vertebrate paleobiologist specializing in large, predatory mammals (she’s also a Dean; how interesting), with a particular focus on the interface of their olfaction and feeding adaptions; Tim Smith, arguably the leading comparative head and neck histologist in the world today whose research focuses on the microstructure of nasal tissues, with a particular fascination for the elusive vomeronasal organ (he’s also an incredible artist); and Brent Craven, one really smart guy, who combines anatomical knowledge with expertise in airflow dynamics to understand how animals incorporate and understand what they are smelling (he’s actually figured out why and how dogs perceive the world around them through their noses!). These good folks have melded their knowledge and passion with other like-minded souls who pick away at the diverse features of this multifaceted treasure trove to offer us this extraordinary view into their world. This Special Issue arose from a Symposium, “Inside the Vertebrate Nose: Evolution, Structure and Function,” supported in part by The Anatomical Record, held at the International Congress of Vertebrate Morphology in 2013 in Barcelona, Spain. There, as within these pages, the extraordinary complexity, development, and evolution of “a nose” was brought to life through the diversity of perspectives, material studied, and approaches employed. Indeed, what will strike one who is not a nasal cognoscenti as they wade into the articles herein is the extraordinary ways in which different vertebrates have “employed noses” to effectuate their lifestyles and, indeed, what constitutes a nose. What may seem simple is not always so. A theme that runs through this issue, and is heavily commented upon in a number of papers, concerns the
*Correspondence to: Jeffrey T. Laitman, Center for Anatomy and Functional Morphology, Icahn School of Medicine at Mount Sinai, Box 1007, One Gustave Levy Place, New York, NY 10029-6574. Tel: 212-241-562. Fax: 212-860-1174. E-mail: [email protected] Received 24 June 2014; Accepted 25 June 2014. DOI 10.1002/ar.23036 Published online in Wiley Online Library (wileyonlinelibrary. com).
1974
LAITMAN
above question on “what is a nose?” More specifically, homologies are sought, traced, and described, with a particular focus on tracing developmental/ontogenetic features. Indeed, many of the papers discuss at length the formation and fate of the nasal capsule and the homologies of nasal bones, particularly the turbinates (the scroll-like bones that occupy the internal nasal region and are covered by respiratory and/or olfactory epithelium) among different species. For some of the papers these bones, often extensions of the ethmoid or maxilla, are used as “clues” to track down the evolutionary path of the animals under study. Some really interesting “sleuth-work” can be found in these pages! One of the strengths of this issue is the robust diversity of the species studied, a tribute to the Guest Editors’ efforts to offer a broad-spectrum view of the topic. Both a diversity of living and fossil species comes under the microscope, so to speak. The extant species explored include: marsupials, lagomorphs (rabbits, hares, and pikas; ever see a pika?), rodents, a menagerie of carnivores (bears, dogs, pinnipeds, cats, hyenas, civets; it seems half the zoo is here!), bats, deer, cetaceans, and many of our primate relatives (including some really odd-looking ones such as the aye-aye), including ourselves. Some of the most fascinating studies extracted information from dinosaurs (notably the Pachycephalosauridae, the thick headed guys, my new favorite dinos)—whose odd, hypermineralized skulls preserve large portions of the nasal region. Another fascinating study explores the nasal region of Brasilitherium (gotta love these names) an early, non-mammalian cynodont ancestor of mammals from the Late Triassic whose nose may reveal insights into both how the mammalian nasal cavity came to be and how mammals themselves came on the scene. Not to be outdone by dinos and pre-mammals, Neanderthal noses get their day in court as well, as we gain some insights into this very close, but very different, extinct human cousin. While the diversity of species explored will catch your attention, so too will the diversity of tools and approaches put in place to delve into the nosy questions asked. While comparative gross dissection, meticulous histologic analyses (some of these border on artwork) and craniometric analyses play an integral role, the use of cutting edge imaging technologies such as micro-CT affords approaches to material previously beyond view. The melding of these approaches also permits reconstructions (such as determining airflow dynamics in dinosaurs) and computational fluid dynamic (CFD) studies. The later, in particular, has played an important part in olfactionrelated research as well documented in some of the studies presented. The use of multiple species and a range of techniques and technologies have permitted this energetic band of “nose-ologists” to address some of the continuing global questions of major interest to those in the field. These include the aforementioned studies on turbinate homologies, or how parts of the “nasal
complex”—the expansive areas of the nose and their evaginations and pneumatizations such as the intricate naso-sinusal systems (see Laitman, 2008; Marquez, 2008) found in many species—came to be, and how they function. Similarly, the ever-debated question regarding how much of the nose is related to respiratory function and how much to olfaction is also put under the spotlight. The nose, as many studies make clear, is a mosaic, an inter-related realm of immigrant bits and pieces that each march to their own drummer. It’s a minimetropolis, with numerous structures crammed into constricted—yet highly prized—territory. Two of our key physiologic functions are housed here: the prime portal for entry and often initial processing of air, and a reception center for olfactory behavior. In addition, the holy highway know as the pharyngotympanic tube (better known as “Eustachian” tube; Eustachi, 1564; Bluestone, 2005) spans the nasopharynx and middle ear region in many species effectuating the aeration process (this is why the medical specialty is called “otorhinolaryngology,” or ENT, although, continuing the tradition of “dissing” the nose, it is usually referred to only as “otolaryngology”; noses just can’t get any respect!). How did the noses of the broad variety of vertebrates evolve to accommodate these crucial functions, how did they morph and change from their basal ancestors to do so, and how did they maximize the “New York City-esque” congestion of space to reach the finely tuned balance of territories they occupy, or occupied if extinct? While the riveting papers in this issue will assuredly raise as many questions as they answer, they achieve in throwing open the doors, and showing us all the centrality of comprehending this region in order to understand the very nature of vertebrates. That ol’, oft-disrespected, frequently unloved honker, it turns out, may actually hold within its treasure-laden, mucus-lined walls secrets to unraveling key questions on the evolution of vertebrates and their relatives. The nose, it seems, is definitely nothing to sneeze at.
LITRATURE CITED Bluestone CD. 2005. Eustachian tube: structure function role in otitis media. Hamilton, Ontario: BC Decker. Eustachi B. 1564. De auditus organis, p 148–164. In his, Opuscula Anatomica. Venice: V. Luchinus. Laitman JT. 2008. Harnessing the hallowed hollows of the head: the mysterious world of the paranasal sinuses. Anat Rec 291: 1346–1349. Lower R. 1670. Dissertatio de origine catarrh in qua ostenditur ilium non provenire a cerebro. p 221–239, in his: Tractatus de Corde. London: J. Redmayne. Marquez S. 2008. The paranasal sinuses: the last frontier in craniofacial biology. Anat Rec 291:350–361. Schneider CR. 1660. Liber Primus de Catarrhis. Wittebergae: T, Mevii & Schumacheri. Van Valkenburgh B, Smith TD, Craven BA. 2014. Tour of a labyrinth: exploring the vertebrate nose. Anat Rec 297:1975–1984.
Those Who Know What the Nose Knows JEFFREY T. LAITMAN* The Anatomical Record
Unlike people, all body parts are not beloved equally. Once I actually tested my brilliant hypothesis by simply asking my incoming medical school students what part of the body they were considering focusing on in their careers. A legion arose when I asked about the heart. Many snapped to attention when I called brain and nerves. All those over six feet stood tall when I mentioned knees and elbows and joints (got to love those frat brothers, future orthopedists all!). Even a few very bold souls acknowledged interest in the urinary tract and genitalia (I think it was the latter). Guts were a draw too; ears had their aficionados, as did throats, and eyes (those all wore glasses). A couple of coughing kids wheezed to attention when I called lungs. A few oddlooking folks even liked feet (I won’t go there). No one responded when I called “nose.” I thought that I had a chance with those few proudly wearing nose piercings but, no, no one for the nose. How interesting, I thought, that they would all eschew a career studying one of the most important— and incredibly alluring—structures of the mammalian body plan. After all, we, and our closest kin are airbreathing mammals and the portal for that lifeallowing gaseous mixture to enter our bodies is the nose. It’s the first thing we see in the mirror at the beginning of our day, and it is as plainly central to our existence, and as core to our functioning as, well, the nose on our faces. So, why no takers? There’s no clear answer, but it probably lies somewhere buried in the old adage that “familiarity breeds contempt.” We all know what the ol’ nose does, right? It’s just that funny thing between our chubby cheeks, below our sainted eyes and above our shapely lips. Just two holes for air to get into and out of our body. We don’t think about it much, except when its “stuffed”; when bleeding occasionally occurs, usually at most inopportune moments; or when unpleasant material drains out (often called catarrh; did you know that nasal mucus was originally thought to originate in the brain, specifically the pituitary, and this wasn’t debunked until the 17th century?; see Schneider, 1660; Lower, 1670). Our nose also frequently annoys us, and is particularly adept at sprouting unsightly “pimples” just before an important event (how does it know when these events are about to happen?). Just the unspectacular schnoz, the old honker, the Jimmy Durante special. Nothing of real interest here, right? My brilliant students could not have been more wrong! The nose is a lot more than two innocuous looking holes surrounded by some cartilage and assorted tissues and vessels. As brought to life in this Special Issue of The Anatomical Record, “The VerteC 2014 WILEY PERIODICALS, INC. V
brate Nose: Evolution, Structure, and Function,” Guest Edited by Baire Van Valkenburgh, Timothy Smith and Brent Craven (2014), the nose is a vast wonderland of labyrinths and bones, nerves and specialized tissues, vessels, and ducts, that have morphed and changed through evolution to accommodate specific requirements. This energetic nasal troika—Van Valkenburgh, an eminent vertebrate paleobiologist specializing in large, predatory mammals (she’s also a Dean; how interesting), with a particular focus on the interface of their olfaction and feeding adaptions; Tim Smith, arguably the leading comparative head and neck histologist in the world today whose research focuses on the microstructure of nasal tissues, with a particular fascination for the elusive vomeronasal organ (he’s also an incredible artist); and Brent Craven, one really smart guy, who combines anatomical knowledge with expertise in airflow dynamics to understand how animals incorporate and understand what they are smelling (he’s actually figured out why and how dogs perceive the world around them through their noses!). These good folks have melded their knowledge and passion with other like-minded souls who pick away at the diverse features of this multifaceted treasure trove to offer us this extraordinary view into their world. This Special Issue arose from a Symposium, “Inside the Vertebrate Nose: Evolution, Structure and Function,” supported in part by The Anatomical Record, held at the International Congress of Vertebrate Morphology in 2013 in Barcelona, Spain. There, as within these pages, the extraordinary complexity, development, and evolution of “a nose” was brought to life through the diversity of perspectives, material studied, and approaches employed. Indeed, what will strike one who is not a nasal cognoscenti as they wade into the articles herein is the extraordinary ways in which different vertebrates have “employed noses” to effectuate their lifestyles and, indeed, what constitutes a nose. What may seem simple is not always so. A theme that runs through this issue, and is heavily commented upon in a number of papers, concerns the
*Correspondence to: Jeffrey T. Laitman, Center for Anatomy and Functional Morphology, Icahn School of Medicine at Mount Sinai, Box 1007, One Gustave Levy Place, New York, NY 10029-6574. Tel: 212-241-562. Fax: 212-860-1174. E-mail: [email protected] Received 24 June 2014; Accepted 25 June 2014. DOI 10.1002/ar.23036 Published online in Wiley Online Library (wileyonlinelibrary. com).
1974
LAITMAN
above question on “what is a nose?” More specifically, homologies are sought, traced, and described, with a particular focus on tracing developmental/ontogenetic features. Indeed, many of the papers discuss at length the formation and fate of the nasal capsule and the homologies of nasal bones, particularly the turbinates (the scroll-like bones that occupy the internal nasal region and are covered by respiratory and/or olfactory epithelium) among different species. For some of the papers these bones, often extensions of the ethmoid or maxilla, are used as “clues” to track down the evolutionary path of the animals under study. Some really interesting “sleuth-work” can be found in these pages! One of the strengths of this issue is the robust diversity of the species studied, a tribute to the Guest Editors’ efforts to offer a broad-spectrum view of the topic. Both a diversity of living and fossil species comes under the microscope, so to speak. The extant species explored include: marsupials, lagomorphs (rabbits, hares, and pikas; ever see a pika?), rodents, a menagerie of carnivores (bears, dogs, pinnipeds, cats, hyenas, civets; it seems half the zoo is here!), bats, deer, cetaceans, and many of our primate relatives (including some really odd-looking ones such as the aye-aye), including ourselves. Some of the most fascinating studies extracted information from dinosaurs (notably the Pachycephalosauridae, the thick headed guys, my new favorite dinos)—whose odd, hypermineralized skulls preserve large portions of the nasal region. Another fascinating study explores the nasal region of Brasilitherium (gotta love these names) an early, non-mammalian cynodont ancestor of mammals from the Late Triassic whose nose may reveal insights into both how the mammalian nasal cavity came to be and how mammals themselves came on the scene. Not to be outdone by dinos and pre-mammals, Neanderthal noses get their day in court as well, as we gain some insights into this very close, but very different, extinct human cousin. While the diversity of species explored will catch your attention, so too will the diversity of tools and approaches put in place to delve into the nosy questions asked. While comparative gross dissection, meticulous histologic analyses (some of these border on artwork) and craniometric analyses play an integral role, the use of cutting edge imaging technologies such as micro-CT affords approaches to material previously beyond view. The melding of these approaches also permits reconstructions (such as determining airflow dynamics in dinosaurs) and computational fluid dynamic (CFD) studies. The later, in particular, has played an important part in olfactionrelated research as well documented in some of the studies presented. The use of multiple species and a range of techniques and technologies have permitted this energetic band of “nose-ologists” to address some of the continuing global questions of major interest to those in the field. These include the aforementioned studies on turbinate homologies, or how parts of the “nasal
complex”—the expansive areas of the nose and their evaginations and pneumatizations such as the intricate naso-sinusal systems (see Laitman, 2008; Marquez, 2008) found in many species—came to be, and how they function. Similarly, the ever-debated question regarding how much of the nose is related to respiratory function and how much to olfaction is also put under the spotlight. The nose, as many studies make clear, is a mosaic, an inter-related realm of immigrant bits and pieces that each march to their own drummer. It’s a minimetropolis, with numerous structures crammed into constricted—yet highly prized—territory. Two of our key physiologic functions are housed here: the prime portal for entry and often initial processing of air, and a reception center for olfactory behavior. In addition, the holy highway know as the pharyngotympanic tube (better known as “Eustachian” tube; Eustachi, 1564; Bluestone, 2005) spans the nasopharynx and middle ear region in many species effectuating the aeration process (this is why the medical specialty is called “otorhinolaryngology,” or ENT, although, continuing the tradition of “dissing” the nose, it is usually referred to only as “otolaryngology”; noses just can’t get any respect!). How did the noses of the broad variety of vertebrates evolve to accommodate these crucial functions, how did they morph and change from their basal ancestors to do so, and how did they maximize the “New York City-esque” congestion of space to reach the finely tuned balance of territories they occupy, or occupied if extinct? While the riveting papers in this issue will assuredly raise as many questions as they answer, they achieve in throwing open the doors, and showing us all the centrality of comprehending this region in order to understand the very nature of vertebrates. That ol’, oft-disrespected, frequently unloved honker, it turns out, may actually hold within its treasure-laden, mucus-lined walls secrets to unraveling key questions on the evolution of vertebrates and their relatives. The nose, it seems, is definitely nothing to sneeze at.
LITRATURE CITED Bluestone CD. 2005. Eustachian tube: structure function role in otitis media. Hamilton, Ontario: BC Decker. Eustachi B. 1564. De auditus organis, p 148–164. In his, Opuscula Anatomica. Venice: V. Luchinus. Laitman JT. 2008. Harnessing the hallowed hollows of the head: the mysterious world of the paranasal sinuses. Anat Rec 291: 1346–1349. Lower R. 1670. Dissertatio de origine catarrh in qua ostenditur ilium non provenire a cerebro. p 221–239, in his: Tractatus de Corde. London: J. Redmayne. Marquez S. 2008. The paranasal sinuses: the last frontier in craniofacial biology. Anat Rec 291:350–361. Schneider CR. 1660. Liber Primus de Catarrhis. Wittebergae: T, Mevii & Schumacheri. Van Valkenburgh B, Smith TD, Craven BA. 2014. Tour of a labyrinth: exploring the vertebrate nose. Anat Rec 297:1975–1984.
