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Aristotle’s : An Overview Science in Time of

Megan Hertel

Department of Classics, University of Florida

Capstone Thesis

10 December 2019

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Abstract:

In his many works on zoology, Aristotle makes detailed observations about the , , and behaviors of a variety of that inhabit a wide range. While his works are important for science, Aristotle’s findings contain inaccuracies due to the challenges posed by the technology of the time. Firstly, Aristotle recognizes the unique characteristics of with high accuracy because they provide easy study specimens for his observations.

Next, he writes about , particularly that of cartilaginous fish, and identifies the unique morphological features of this taxon. Further, while Aristotle fails to grasp their mechanism for respiration, he discovers that whales, dolphins, and seals breathe through rather than . Additionally, Aristotle comes close to discovering how reproduce, yet misrepresents the of other insects. Also, he makes novel observations about and , especially in terms of their behavior. Lastly, Aristotle describes local and remote mammal in detail, but he errs in regard to the biology of foreign megafauna because he likely did not see these in person. Aristotle’s contributions to biology and zoology continue to impact these fields today, even inspiring new scientific hypotheses. Despite the errors in his ideas, Aristotle’s writings influence the field of zoology and the whole of science by raising unique ideas and introducing observational and logical data collection.

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In addition to his work on , Aristotle wrote a number of volumes on the biology, , and of animals ranging from the sea sponge to the elephant. In these works, Aristotle attempts to explain natural phenomena based on observation and logic. Due to the nascent state of science when these books were written, much of Aristotle’s zoology contains fundamental errors. Despite this, Aristotle made surprising discoveries that were far before their time. First, Aristotle identifies aquatic invertebrates and explains their morphologies, but he makes mistakes regarding their . Furthermore, he understands the differences between bony fish and cartilaginous fish, as well as the difference between these groups and marine mammals. In contrast, Aristotle fails to understand how insects reproduce because of their high mobility and small size. Yet, he grasps biological concepts about reptiles despite the challenges that the organisms pose for data collection. Likewise, Aristotle’s zoological works make assessments of behavior that were not appreciated until modern times. Finally, Aristotle describes the mammalian megafauna of Europe and Asia with the help of external sources, which leads to errors in his theories. Aristotle’s zoology makes profound impacts on the scientists that followed him and gives modern readers an idea of the state of science in the ancient world.

Aquatic Invertebrates:

Fundamentally, Aristotle divides animals into two basic groups: ἔναιµα, those with , and ἂναιµα, those that do not have blood. Aristotle’s blooded animals include , reptiles, birds, fish, and mammals, while bloodless animals include insects, mollusks, echinoderms (sea urchins, sea stars, and their kin), and (, pp. 22).

These divisions correspond with modern taxonomical classifications of and animals. are differentiated from invertebrates by the presence of a Hertel 4 notochord, a cartilaginous rod that supports the body of these organisms. Both of these taxa contain blood, though it comes in different forms in invertebrates; for example, the hemocyanin makes horseshoe crab blood blue, rather than the red blood that results from the presence of hemoglobin. In his works on zoology, Aristotle recognizes the differences between vertebrates and invertebrates without understanding what makes the two groups different.

Outside of bloodless and blooded animals, Aristotle characterizes some animals as intermediate forms between two groups. One of these includes sponges, sea stars, and corals, all of which Aristotle considers intermediate between animals and (Parts of Animals, pp. 23).

He does not consider these invertebrates as parts of his bloodless animals, but he does recognize the fact that they are living organisms and animals. Sponges are living, sessile organisms which can grow whole new sponges when they are cut into pieces ( of Animals, 548b6-7, 18-

19). As with the reproduction of other invertebrates, Aristotle is unclear about how sponges reproduce, since he says they are born spontaneously from crevices in rocks (,

548a24-25). Sponges can reproduce asexually through fragmentation—like Aristotle describes— but also through in broadcast spawning. Because two sponges do not have to come in contact or move to reproduce, Aristotle believes that sponges spontaneously appear without the assistance of other members of their species.

Unlike in his discussion of sponges, Aristotle makes astute observations about sea urchins because they were easy for him to study. In Parts of Animals, he explains the internal and external anatomy of sea urchins, while only erring slightly. Aristotle delineates the motility of a ’s spines, its protective internal skeleton, and the five-rayed internal symmetry of a sea urchin’s prominent gonads (Parts of Animals, 679b26-30, 680b4-5). Additionally, he also describes their distinctive five-jawed feeding , comparing the ’s shape to that of a Hertel 5 lantern (History of Animals, 530b24-25; 531a3-6). Today, the jaws of a sea urchin are known as

Aristotle’s lantern due to this description. Furthermore, Aristotle correctly identifies the orientation of the sea urchin. He notes that they live oral-side down so that they can feed on benthic food sources (History of Animals, 530b19-23). This is an important discovery in understanding the feeding ecology and anatomy of a sea urchin; it also requires close observation, as their oral and aboral surfaces have only subtle differences. In general, Aristotle recognizes many of the characteristics that make sea urchins unique and that are vital to their taxonomic classification within the Phylum Echinodermata. On the other hand, Aristotle misunderstands the of a sea urchin’s spines as he explains that they use their spines for locomotion (Parts of Animals, 681a7-9). Instead, sea urchins move using their water vascular system and tube feet, in which water pressure extends and retracts flexible projections from inside the urchin’s internal shell. Aristotle did not recognize the tube feet as the urchin’s means of movement because his specimens were primarily dead. He makes multiple references to dissecting sea urchins or harvesting them to eat, which would not permit him to see movement or tube feet without chemical preservation (Parts of Animals, 680a1-3; History of Animals,

530b16). Aristotle tends to have a greater volume of accurate knowledge about organisms to which he in close proximity, compared to foreign species. He understands the biology, anatomy, and ecology of sea urchins so well because they are common near him and accessible.

Next, Aristotle categorizes , , and in their own group which he calls Malakia. In modern phylogenies, these same organisms belong to the Class Cephalopoda.

These organisms are differentiated from other bloodless animals by their soft bodies that cover their hard parts, if they have any at all (History of Animals, 523b22). Aristotle observes that cuttlefish have a substantial but porous “bone,” squids have a thin and cartilaginous pen, and Hertel 6 octopuses have no internal, rigid support (History of Animals, 524b23-31). Because belong to Phylum Mollusca, which also includes snails, oysters, and mussels, they secrete a shell. Unlike other mollusks, though, shells are internal. Another difference among cephalopods is that in addition to the eight arms with two rows of suckers each that the has around its mouth, squids and cuttlefish have two longer that they use to capture prey (History of Animals, 523b27-31). Also, octopuses have one arm that is bifurcated and used in copulation (History of Animals, 524a4-6). Aristotle refutes the theory of fishermen that the male octopus inserts this special into the siphon of the in to fertilize her eggs; rather, he suggests that this behavior connects the two together for some other method of copulation (, 720b33-36). Contrary to Aristotle’s counter-hypothesis, many species of cephalopods use their , an arm specialized for reproduction, to transfer packets of through the female’s siphon to her ovary. This behavior confused marine for centuries; the hectocotylus gets its name from in the 19th century, who classified the detached arms of male octopuses he found in the siphon of as a type of parasitic worm (Hardt 2016, pp. 126). Regardless of his errors in theory, Aristotle was able to observe the reproductive behavior of cephalopod mollusks without the assistance of modern technology. Aristotle presents his extensive knowledge on marine invertebrates throughout his zoological writings, which indicates his interest in the subject and the importance of marine invertebrates. Although Aristotle’s science is not accurate to modern standards in all cases, his observations of aquatic invertebrates pertain to ecologically relevant processes and represent the scientific knowledge of the time.

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Fish:

Next, Aristotle describes the other inhabitants of the ocean: fish. Aristotle spends much time discussing ; twenty percent of all of his writings pertain to fish, with much of that being spent on and rays (Ganias et al. 2016, pp. 1038). As with sea urchins, he studied fish so extensively because they were present close by and were the subject of fisheries.

Aristotle classifies fish as animals that live in the water, reproduce through laying eggs, and have fins rather than limbs (History of Animals, 504b13-14, 29-32). He further explains that fish inhale water through their mouths and send it through their gills to breathe (History of Animals,

504b29-32). This discovery informs Aristotle’s classification scheme, allowing him to recognize the difference between fish and marine mammals or reptiles. Furthermore, Aristotle says that no animals with gills also has lungs (Parts of Animals, 697a24-25). This is not the case; lungs are a primitive character in , and a number of extant fishes retain the ability to breathe air. For example, lungfishes which live in Australia, , and Africa today are obligate air breathers and must gulp air from the water’s surface to respire. Given that no air-breathing fish are native to regions near Greece, it makes that Aristotle would make the generalization that lungs and gills cannot coexist. Next, Aristotle makes astute observations about the digestive systems of fish; fish other than sharks and rays have projections off their stomach near the connection to the esophagus (History of Animals, 508b15-17). These projections that Aristotle observed are called pyloric caeca, and they contain digestive that help break down food for the fish. These observations on fish anatomy require intense studies of the internal workings of various fishes and provide important information on the differences between cartilaginous and bony fish. Buddington and Diamond cite Aristotle’s description of pyloric caeca in fish as the observation that inspired their study to determine the function of these (1986, pp. Hertel 8

8012). Centuries after their publication, Aristotle’s zoological works continue to impact science and inspire new discoveries. Also, Aristotle discusses fish sensory systems on multiple occasions, as they are a source of confusion for him. He notes that fish have the sense of sight and taste, but he could not find outward evidence of their of hearing or smell (History of

Animals, 533a32-34). For example, what appear to be nostrils on a fish are connected to olfactory sacs that do not connect to the (History of Animals, 533b1-4). Aristotle could not understand how sensory information from the nostrils of fish made its way to the brain. Fish have complex sensory systems that include the senses of sight, taste, touch, hearing, and smell.

These sensory systems differ from terrestrial vertebrate sensory systems because they are adapted for aquatic lifestyles. In regard to fish olfaction, the olfactory bulbs that Aristotle identified send sensory cues to the fish’s brain via olfactory sensory neurons. Despite not understanding how their senses work, Aristotle identifies evidence that fish can hear, smell, and taste. He reports that fishermen exploit these senses when they catch fish, by scaring them with the sounds of their oars or attracting them with their favorite bait (History of Animals, 533b22-

25). He admits that fish must be able to hear and smell even though he could not understand the mechanism. Aristotle trusts the popular knowledge of fishermen in this instance, and he gives a more complete view of ichthyology as a result.

One particular fish group that Aristotle discusses in depth are the cartilaginous fish.

Aristotle groups dogfishes, skates, rays, sharks, and “fishing-frogs” (anglerfish) in a clade he calls Selachia (History of Animals, 505a7-8). Modern phylogenies include all of these except the anglerfish in the Subclass Elasmobranchii, which belongs to Class Chondrichthyes, fish with cartilaginous skeletons. Due to their bony skeletons, anglerfish are not considered closely related to the other elasmobranchs that Aristotle describes. Aristotle recognizes that anglerfish have Hertel 9 bony skeletons and reproduce by laying eggs, unlike the rest of the organisms in Selachia

(History of Animals, 564b18-19). Ganias et al. assert that Aristotle groups the anglerfish with sharks and rays due to their depressiform body shape (2016, pp. 1047). It is surprising that

Aristotle classifies anglerfish as Selachia since he acknowledges many of the characteristics that indicate that the two groups are not closely related. Next, Aristotle establishes the group Selachia due to their rough skin without scales and cartilaginous skeletons (Parts of Animals, 697a7-9).

Elasmobranchs have rough-feeling skin due to their microscopic placoid scales, or dermal denticles, which have the same structure as their teeth. Given that placoid scales cannot be seen with the naked eye, Aristotle could not study elasmobranch scales as he could with the scales of other fish. Additionally, Selachia are distinguished from other fish because they are externally viviparous and internally oviparous (History of Animals, 489b12-13). While a majority of elasmobranchs are viviparous as Aristotle reports, all skates and approximately thirty percent of species lay eggs (Wourms and Demski 1993, pp. 8). Additionally, a number of viviparous elasmobranchs are not ovoviviparous as Aristotle describes, but rather nourish their through a placental connection. Many elasmobranch species reside in water too deep for

Aristotle to access or have defensive characters that make them dangerous to handle. Aristotle could not census the reproductive modes of all elasmobranchs due to the limitations of the time.

Also, Aristotle noted an organ only found in male elasmobranchs located near their cloaca

(History of Animals, 540b24-25). These are claspers, organs found in all male elasmobranchs that are used to transfer sperm to a female since all cartilaginous fishes reproduce by internal fertilization. Aristotle’s discovery of claspers distinguishes elasmobranchs from bony fish and gives further insight into their reproductive biology. Another anatomical distinguishing factor between Selachia and other fishes is that they do not have a covering (History of Animals, Hertel 10

505a1-2). All bony fishes have an operculum which covers their gill openings, while elasmobranchs have gill openings that are visible externally. Torpedo-fishes and sting rays have ventrally placed gill slits, a character which differentiates them from others in the group Selachia

(History of Animals, 505a3-6). Lateral versus ventral gill placement in elasmobranchs is an effective character with which to differentiate between sharks and rays. For example, sawfish, which are considered rays, and sawsharks, which are considered sharks, look virtually identical save the placement of their gill slits. Sawfish have ventral gill slits while sawsharks have lateral gill slits. These two elasmobranchs can be visually identified by this feature alone. With this observation on elasmobranch anatomy, Aristotle discovers a useful tool for taxonomic identification of these species. In History of Animals, Aristotle notes the methods of prey capture for torpedo rays and sting rays. Torpedo rays cause numbness in their prey and in humans, while both sting rays and torpedo fish bury themselves in the sand to ambush small fish (History of

Animals, 620b19-24). Torpedo rays, also called electric rays, can sense the electromagnetic fields produced by other fish, then send electric shocks to incapacitate their prey; they also do this to defend themselves from predators. Aristotle describes the unique prey-capture mechanism torpedo fish have even before the discovery of electricity. Additionally, rays are specially adapted to live on the seafloor due to their depressiform bodies. As Aristotle notes, rays dig themselves into the sand such that only their eyes are visible in order to hide from predators and to sneak up on their prey. Over the course of his writings, Aristotle records diverse zoological findings about elasmobranchs with scientific accuracy. This indicates Aristotle’s interest in the subject and the importance of sharks, skates, and rays in the of the Mediterranean Sea.

Aristotle discusses the ecology of eels at length because they were common locally and a cultured species at the time. Many species of eels are native to Greece including freshwater Hertel 11 species like the European eel and marine species such as the conger eel or Mediterranean moray.

Aristotle identifies many native species of eel, and they are among the species that he discusses most commonly (Ganias et al. 2016, pp. 1049). In addition to wild species of eels, Aristotle explains that fishermen in the region farm eels in tanks for food (History of Animals, 592a3-5).

Despite the proximity of his source material, Aristotle fails to understand the biology of eels.

According to Aristotle, they gain from rotting seaweed, mud, or from drinking freshwater (History of Animals, 570a20-22; 592a1-3). On the other hand, eels generally hunt small fish, crustaceans, sea urchins, and other prey species by hiding until they are able to strike.

This begs the question as to what ancient aquaculturists were feeding eels at this time, since

Aristotle gives no indication that he knows they are predators. Another source of inaccuracy about eels arises from a discussion about their reproduction; Aristotle states that eels arise spontaneously without the presence of eggs or sperm (History of Animals, 569a7-8). He justifies this by saying that eels appear when dried-up pools are refilled by rain, and when they are caught, they never contain eggs (History of Animals, 570a4-12). The observation that an aquatic can survive their water source drying up sounds like estivation, the process by which an organism can suspend their bodily functions in times of extreme climatic conditions. The only fish known to perform this behavior is the African lungfish (Protopterus annectens) which encloses itself in a hole lined with mucus to survive the dry season in Africa. It is possible that

Aristotle may have heard about estivation in lungfish from travelers to Africa, but this confusion about eel reproduction may come from the complex life history of certain eel species. Aristotle observes a facet of this in History of Animals; he states that eels migrate from freshwater rivers and marshes to the ocean periodically (569a8-9). European eels (Anguilla anguilla) are catadromous, meaning they migrate from freshwater to the ocean to . They travel Hertel 12 from their habitats in rivers in Europe to the Sargasso Sea in the Atlantic Ocean, where they die soon after they spawn. Once their eggs hatch, the eels proceed through multiple life stages before migrating to their freshwater adult habitats. European eels only reproduce once in their lives, which lead Aristotle to observe that they never contain eggs when caught; development of fertile eggs is a rare occurrence. The reproductive biology of European eels was not worked out until 1922, following the discovery of the larval and juvenile stages of A. anguilla (Schmidt). The migratory and infrequent of eel reproduction confounds

Aristotle’s observations and confused scientists for centuries. In total, Aristotle’s descriptions of ichthyology provide insight into the scientific endeavors and fishery activities of the Ancient

Greeks. His work on fish biology continues to inspire new scientific studies into modern times.

Marine Mammals:

In addition to invertebrates and fish, Aristotle also noticed other organisms that live in the ocean. Aristotle was the first person to recognize marine mammals including dolphins, baleen whales, porpoises, and seals as different from fishes (Evans et al. 2014, pp. 1073). He states that whales and dolphins use their lungs—not gills—to breathe and nourish their young with milk

(Parts of Animals, 697a16-19; History of Animals, 504b22-26). He also states the purpose of a cetacean’s blowhole: to eject seawater from their systems which they took-up while eating (Parts of Animals, 697a19-22). Aristotle notes the major characteristics that indicate that cetaceans are mammals, but he did not identify the actual purpose of their blowholes. A whale’s blowhole is its nostril which migrated to the top of its head in development; while in the water, cetaceans inhale and exhale through their blowhole. A cetacean’s blowhole does not connect to its throat at all.

Aristotle confuses the blowhole’s purpose because when a whale exhales, warm air coming from the lungs condenses when it meets cold air outside the body which forms a spout of mist. He Hertel 13 misconstrues this expulsion of mist as the whale removing seawater from its body. Overall,

Aristotle recognizes the criteria that make cetaceans unique from fish and furthers science by officially describing marine mammals.

Aristotle also describes another marine mammal: the seal. As with cetaceans, Aristotle describes seals as an intermediate form between quadrupeds and fish, as they both have lungs and live in the water (Parts of Animals, 697b1-4). He also recognizes that they have four limbs that are modified into flippers (Parts of Animals, 697b5-8). Seals are marine mammals that have the basic of terrestrial mammals, modified with to aquatic life. Unlike his other accurate observations, Aristotle reports that seals have nails on the ends of their flippers and tails like deer (History of Animals, 498a33-35; 498b14-15). Additionally, based on the way they move, Aristotle deduces that seals have cartilaginous bones (History of Animals, 567a9-10).

It is surprising how strange Aristotle’s description of seals is, given the likelihood that he would have seen one in person. Prior to the twentieth century, Mediterranean monk seals (Monachus monachus) were plentiful from the North Atlantic to the Black Sea, particularly in the Aegean and Ionian Seas around Greece (Karamanlidis et al. 2015, pp. 3). Johnson and Lavigne assert that not much more has been learned about the Mediterranean monk seal since Aristotle’s description of them in History of Animals, although they have been exploited and observed by humans throughout this time (1999, pp. 2-3). Scientists made little progress on Mediterranean monk seal zoology because of where they live; their foraging includes relatively deep neritic waters up to 200 meters deep, and they often breed in marine caves which can only be accessed from the water (Karamanlidis et. al. 2015., pp. 6). Without Scuba systems or submersible technologies, Aristotle was unable to gain close access to seals to observe them. On the other hand, Aristotle reports that seals bear their young on beaches in large groups (History of Hertel 14

Animals, 566b27-32). Moreover, Ancient Greeks harvested Mediterranean monk seals for food and fur during Aristotle’s time (Karamanlidis et al. 2015., pp. 30). Both of these facts make it unclear as to why Aristotle was unable to observe seals in greater detail. Regardless of his various inaccuracies, Aristotle furthers scientific knowledge substantially when he identifies marine mammals in his writings.

Terrestrial Invertebrates:

Aristotle makes the greatest scientific errors in his descriptions of insects. He observes that insects shed their exoskeletons and that they all have six legs (History of Animals, 601a3-4;

Parts of Animals, 683b4-5). Arthropods, such as insects and crustaceans, perform ecdysis

(molting) in order to grow, and this character unites the phylum. The number of legs distinguishes insects from the related group (spiders, scorpions, and kin). Both of these characters that Aristotle isolates define the differences between insects and other taxa. On the other hand, he insists that some insects are born without input from parents but from a number of different substances including wood, dew, dung, and mud (History of Animals, 551a1-12). The idea of in insects arises because insects are small, making observation difficult (McCartney 1920, pp. 109). Highly mobile insects pose a challenge to an observer with no background knowledge; they are small and fast, which makes it difficult to track their movements and behavior for any length of time. An adult insect lays her eggs on a particular material, as flies lay their eggs in animal dung for example, but Aristotle only observes the larva emerging once the eggs hatch. As with the eel’s reproduction, multi-stage life histories that accompany habitat shifts cause confusion in Aristotle’s zoological theories.

Aristotle attempts to reconcile spontaneous generation in bees with his observations of their social hierarchy. In Generation of Animals, Aristotle discusses the reproductive mode of Hertel 15 bees by discounting some popular theories and proposing his own. He starts by refuting the idea that bees collect their young from an external source, like they collect pollen to make honey

(Generation of Animals, 759a32-34). Instead, Aristotle proposes that some bees arise without copulation, and that different types of bees can produce different castes of offspring. Aristotle explains that the caste he calls kings can produce other kings or the caste called bees (Generation of Animals, 760a3-4). Bees produce drones without copulating with a male (Generation of

Animals, 759b28-29). In fact, queen bees reproduce sexually with drones, the males of the colony, to produce female offspring—a worker or a new queen. The queen’s unfertilized eggs develop into male offspring. Worker bees do not reproduce at all. Thus, Aristotle made astute observations about the complex of bees; some bees (queens and workers) arise from copulation, while drones are born by . Following Aristotle’s description of reproduction, this concept was not officially described until the 19th century

(Prete 1990, pp. 273). Although his theory on the reproduction of bees is not completely correct,

Aristotle explains the novel reproductive method of honey bees without devoted study or manipulative experiments. The life histories of terrestrial invertebrates confound Aristotle’s theories on , but he also introduces new concepts that were not appreciated at the time.

Reptiles:

Aristotle makes reference to many types of reptiles in his works on zoology including lizards, snakes, , tortoises, and sea turtles. He classifies reptiles as quadrupeds that lay eggs or animals without feet (Parts of Animals, pp. 22). One example of Aristotle’s work on reptiles is his assessment of the . He states that a chameleon changes its colors because of its fear (Parts of Animals, 692a24-27). Aristotle is credited with the discovery of Hertel 16 color change in , and there is some truth to his explanation of why they perform this behavior (Ligon 2015, pp. 2). Chameleons change their color for communication and expression of emotion, rather than the common misconception that they do so for . The common chameleon (Chamaeleo chamaeleon) is native to the Greek islands of Crete, Samos, and Chios and is slow-moving, which allows for easy observation and accurate theories from Aristotle.

Unlike the chameleon, the Nile lives in a distant land, moves fast, and poses a danger to humans. Contrary to this, Aristotle makes interesting observations about this .

According to Aristotle, crocodiles have poor eyesight in the water but better eyesight above the water (History of Animals, 503a11-12). Fleishman et al. tested this hypothesis in 1988 and found that crocodilians are unable to focus their eyes while underwater, leaving their eyesight much better above the water line (pp. 441). Aristotle could not have performed the histological studies that proved his hypothesis. Rather he likely came to this conclusion based on eyesight, as both crocodilian and human eyes function in a similar way. Furthermore, crocodiles spend their days in the water and nights on land in order to conserve heat (History of Animals, 503a12-15).

Nile crocodiles regulate their body temperatures behaviorally by moving to the warmer land at night when the water cools. Crocodiles, and all reptiles, are poikilothermic which means their internal temperatures match the ambient environmental temperatures. While he does not notice this fact outright, Aristotle notices the importance of thermoregulation in reptiles. Aristotle writes less frequently about reptiles than he does about other groups, but what he does include is accurate and ecologically important. He notices important features about reptiles, regardless of their habitat or temperament.

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Birds:

Aristotle establishes that birds lay eggs, have a beak and , and migrate to nest or to find appropriate environmental conditions (Parts of Animals, 692b9-17; History of Animals,

597a1-5). Aristotle reports the nesting times, number of offspring, migrations, feeding ecology, and many other criteria for a number of bird species, many of which are difficult to positively identify today. In addition, Aristotle speaks on some interesting behavior of various birds. For example, he reports that cuckoos sometimes lay their eggs in the nests of other birds, then eat the other bird’s eggs (History of Animals, 563b30-32). Although they do not eat the other eggs as

Aristotle reports, Edward Jenner observed common cuckoos (Cuculus canorus), whose range spans across Eurasia, performing brood in 1788 (pp. 221). These cuckoos lay their eggs in the nests of other birds and let them raise their offspring. Aristotle made revolutionary observations about interspecific bird interaction that were not appreciated until much later in the . Furthermore, according to Aristotle, bird song is learned; if a bird is raised away from their parents, its song differs (History of Animals, 536b14-19). Today, animal behaviorists use this study method to differentiate between learned and innate behaviors. In a cross-fostering experiment, scientists switch the juveniles of two different species or and allow the juveniles to be raised by parents of a different species. If the juvenile matches the behavior of their cross-fostered parents (like Aristotle reports with bird song), the juvenile learned the behavior from their new parents. Modern scientists use the same methods to test animal behavior hypotheses as Aristotle.

In addition, Aristotle claims that the ostrich is an intermediate form between quadrupeds and birds. Ostriches have eyelashes and hooves rather than toes on their feet (Parts of Animals,

697b18-23). They cannot fly due to their unique feathers (Parts of Animals, 697b16-18). To Hertel 18

Aristotle, these characteristics deviate from the qualities of a bird and align more with that of a quadruped. Other than the erroneous statement that they have hooves, the qualities Aristotle describes are adaptations to the dry, savanna habitat where ostriches live. Ostriches reach a maximum speed of forty miles per hour, and this might contribute to Aristotle’s (or his source’s) confusion about their feet.

Terrestrial Mammals:

Finally, Aristotle describes terrestrial mammal zoology for all types of species—from the smallest mouse to the elephant. He calls these viviparous quadrupeds—four-footed animals that give to live young. Aristotle spends a lot of time discussing the biology and husbandry of domesticated animals such as horses, pigs, cows, goats, and . Additionally, Aristotle gives descriptions of foreign megafauna from Africa and India largely based on secondary sources. As a result, these observations have errors because Aristotle was not able to perform his own studies. Contrary to this, Aristotle provides interesting ecological insights on these foreign mammals.

First, Aristotle gives a detailed description of the biology, ecology, and anatomy of elephants, while also dispelling rumors about the animal. According to Aristotle, elephants have four teeth for grinding food on either side of their mouth in addition to two tusks (History of

Animals, 501b31-33). They are born with teeth but without their tusks (History of Animals,

502b2-3). In fact, elephants have four molars in total in their mouth at any one time, in addition to their two large incisors; also, they are born with both teeth and small tusks. Next, Aristotle claims that both male and female elephants have tusks, but they are curved upwards in males and downward in females (History of Animals, 502a1-2). Both African and Asian elephants of both sexes have tusks, though tusks occur more often in the male Asian elephants versus female Asian Hertel 19 elephants (Shoshani 1978, pp. 21). Aristotle attempts to describe a sexual dimorphism in elephants that does not exist with this statement. The shape of an elephant’s tusk does not vary between sexes, but may vary between individuals (Shoshani 1978, pp. 21). Next, elephants use their trunks for many different purposes including feeding, grasping objects, and as a snorkel while wading in water (History of Animals, 497b26-30). An elephant uses the prehensile

“fingers” on the end of its trunk in order to grasp and handle objects with its trunk. In regard to reproduction, Aristotle states that elephants gestate for approximately two years, and they tend to have one calf at a time (History of Animals, 546b10-11). in elephants lasts between eighteen and twenty-two months, the longest-known gestation in the animal (Shoshani

1978, pp. 25). In his description of elephant biology, Aristotle slightly overestimates gestation times but recognizes the unusual nature of this fact. Additionally, Aristotle reports that elephants can live between two and three hundred years, but he expresses skepticism at this number

(History of Animals, 596a11-12). In reality, elephants can live between sixty and eighty years, when they tend to die from starvation after their teeth are worn down completely (Shoshani

1978, pp. 21). This is one of the few outright erroneous facts that Aristotle gives about the elephant. There are a number of arguments about Aristotle’s sources for his knowledge on the elephant; for example, Alexander the Great may have sent an elephant back to Aristotle from his campaign in India or he may have seen live elephants at a menagerie in Macedon (Bigwood

1993, pp. 549). On the other hand, it is more likely that Aristotle draws from secondary sources such as Ctesias about the elephant. Aristotle names Ctesias, who traveled in India, as his source when dispelling the rumor that elephant semen become as hard as amber when it dries

(Generation of Animals, 736a3-4). Because he draws so heavily from secondary sources about Hertel 20 elephants, Aristotle’s errors likely stem from errors in the source material or from Aristotle’s misreading of the literature.

Next, Aristotle lists the attributes of a hippopotamus in History of Animals and compares them to the qualities of many other species. He states that the hippopotamus has a mane like a horse, cloven-hooves like an ox, the tail of a pig, and the neigh of a horse (History of Animals,

502a9-13). This description reads more like that of a mythical than the other morphological descriptions that Aristotle has given thus far. This comparison-based description relates the unknown form of the hippopotamus into shapes familiar to someone from Greece.

This passage can be traced back to Herodotus’s Histories, but Herodotus also borrows his description from another author, Hecataeus (Owen 1838, pp. 217; Brown 1965, pp. 62).

Aristotle’s description of the hippopotamus passed through many sources before it made its way to his zoological works, and as a result, the description does not offer accurate information about the species. Hippopotami are large, dangerous, and from a far off region, all of which add to the challenge that Aristotle and his sources face in observing them.

Furthermore, Aristotle cites Ctesias when he describes the martichoras, or mantichore.

These fantastic animals come from India, have the face and ears of a human, and have three rows of teeth in their jaws (History of Animals, 501a26-30). Also, the martichoras has a scorpion-like tail that can shoot barbs (History of Animals, 501a31-33). Because Aristotle reports his source by name, he likely did not believe or at least doubted these descriptions of the martichoras

(Bigwood 1993, pp. 539). As with the hippopotamus, Aristotle uses familiar forms to describe the foreign martichoras to give a frame of reference for the reader. Later sources align the martichoras with the tiger (Beagon 2014, pp. 423). Due to the dangerous nature of a tiger, Hertel 21 observations may have been confused by distance and or communication issues, resulting in the fantastic description of the martichoras.

Lastly, in History of Animals, Aristotle makes anatomical observations about various type of primates. He first differentiates between monkeys and ; members of the former group have tails while apes do not (History of Animals, 502a19). Aristotle was the first to classify primates based on their tails, and this criterion persists today (Ashley Montagu 1940, pp. 87).

Next, he states that apes resemble humans externally based on their body shape and internally based on (History of Animals, 502a24-31). Apes differ from humans in that they have more hair, walk on all fours, and have feet with elongate palms that they use like hands (History of Animals, 502a26-28; 502b15-19). Aristotle does not compare the ’s appearance to a combination of many different animals as he does with other organisms such as the hippopotamus, but rather he only draws comparisons between apes and humans. Long before

Charles Darwin hypothesized the evolutionary relationship between the Great Apes and humans,

Aristotle noticed the similarities between these closely related taxa. Aristotle’s work on mammal biology sheds light on the zoological knowledge of his time; it includes domestic animals and fantastic foreign animals that may have seemed unreal at the time. In his writings, Aristotle attempts to give a complete picture of the animals of the world, even if he had never seen them himself.

Aristotle’s Impacts:

Aristotle’s work on zoology continues to have a lasting impact on modern zoology. For example, Coonen cites Aristotle’s use of the words γένος and εἶδος as the origin of “genus” and

“species” which are vitally important for Linneaus’s (1977, pp. 734).

Furthermore, the names that Aristotle gives to various organisms are preserved in their scientific Hertel 22 names and common names. For instance, Aristotle refers to crabs, lobsters, and crayfish as

Malacostraca, which today is a taxonomic class that contains these crustaceans (Voultsiadou and

Vafidis 2007, pp. 107). Some common names include Aristole’s lantern, the feeding organ of sea urchins, and Aristotle’s catfish, a Silurian fish endemic to Greece. Aristotle’s zoology inspires modern naming conventions in important ways, including taxonomic groups, scientific names, and common names for many species.

In addition, Aristotle’s works on establish ecological observations that were not resolved until the modern era. For example, Aristotle notes that large, live-bearing animals do not tend to produce many offspring, although they would be able to hold more offspring in their bodies than small animals (Generation of Animals, 771a21-26). The inverse is also true; he notes that small animals tend to have many small offspring (Generation of Animals,

771a21-26). He states that this is a matter of differential investment. Large animals put more energy into growing in size than they put into their reproductive output, and the opposite is true for small animals (Generation of Animals, 771a28-31). Though he could not necessarily explain this phenomenon completely, Aristotle took note of an important ecological theory about alternative life histories in the animal kingdom. In 1967, Robert MacArthur and E.O. Wilson described r/K Selection Theory to explain this phenomenon. An r-strategist matures fast and has many small offspring with little parental investment, while a K-strategist matures slowly and has a few competent offspring with high parental investment (MacArthur and Wilson 1967). These two life histories each have their own advantages and disadvantages that maximize an organism’s reproductive success in different ways. As Aristotle describes, the difference between r-selected and K-selected species lies in different energy investment. Rather than investment in somatic versus gonadal growth, r-selected species invest more energy in producing a great Hertel 23 number of offspring with less energy invested per offspring. K-selected species invest a high level of energy in one offspring rather than investing little energy in many offspring. Long before modern scientists could explain alternative life history strategies in animals, Aristotle recognized the need to resolve the abnormalities in his observations about the reproductive strategies of some organisms. Thousands of years after the publication of Aristotle’s writings on natural history, he continues to impact the way scientists study zoology and inspire innovations in the study of animals.

Despite the errors in Aristotle’s zoological theories, his writings are important for understanding the state of science in the ancient world. Modern scientists continue to learn from

Aristotle’s species descriptions and ecological theories long after the publication of his books. In his writings on animals, Aristotle comments on the biology and anatomy of all types of terrestrial and aquatic animals from near Greece and from the rest of the world. For example, he was the first person to identify that dolphins, whales, and seals are not fish. Additionally, Aristotle attempts to explain insect reproduction, where he faces challenges due to his data collection methods. Finally, Aristotle tries to give a well-rounded census of global fauna by including descriptions of animals from Africa and Asia alongside domesticated Greek animals. Throughout his writings, Aristotle revolutionizes scientific thought through observation, , and logical reasoning, and these works continue to impact science today.

Hertel 24

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