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Aristotle's biology is the theory of
biology Biology is the scientific study of life. It is a natural science with a broad scope but has several unifying themes that tie it together as a single, coherent field. For instance, all organisms are made up of cells that process hereditary ...
, grounded in systematic observation and collection of data, mainly zoological, embodied in Aristotle's books on the science. Many of his observations were made during his stay on the island of
Lesbos Lesbos or Lesvos ( el, Λέσβος, Lésvos ) is a Greek island located in the northeastern Aegean Sea. It has an area of with approximately of coastline, making it the third largest island in Greece. It is separated from Asia Minor by the na ...
, including especially his descriptions of the
marine biology Marine biology is the scientific study of the biology of marine life, organisms in the sea. Given that in biology many phyla, families and genera have some species that live in the sea and others that live on land, marine biology classifies ...
of the Pyrrha lagoon, now the Gulf of Kalloni. His theory is based on his concept of form, which derives from but is markedly unlike Plato's theory of Forms. The theory describes five major biological processes, namely metabolism,
temperature regulation Thermoregulation is the ability of an organism to keep its body temperature within certain boundaries, even when the surrounding temperature is very different. A thermoconforming organism, by contrast, simply adopts the surrounding temperature ...
, information processing, embryogenesis, and
inheritance Inheritance is the practice of receiving private property, titles, debts, entitlements, privileges, rights, and obligations upon the death of an individual. The rules of inheritance differ among societies and have changed over time. Officiall ...
. Each was defined in some detail, in some cases sufficient to enable modern biologists to create mathematical models of the mechanisms described. Aristotle's method, too, resembled the style of science used by modern biologists when exploring a new area, with systematic data collection, discovery of patterns, and inference of possible causal explanations from these. He did not perform experiments in the modern sense, but made observations of living animals and carried out dissections. He names some 500 species of bird, mammal, and fish; and he distinguishes dozens of insects and other invertebrates. He describes the internal anatomy of over a hundred animals, and dissected around 35 of these. Aristotle's writings on biology, the first in the history of science, are scattered across several books, forming about a quarter of his writings that have survived. The main biology texts were the '' History of Animals'', ''
Generation of Animals The ''Generation of Animals'' (or ''On the Generation of Animals''; Greek: ''Περὶ ζῴων γενέσεως'' (''Peri Zoion Geneseos''); Latin: ''De Generatione Animalium'') is one of the biological works of the Corpus Aristotelicum, the col ...
'', '' Movement of Animals'', ''
Progression of Animals ''Progression of Animals'' (or ''On the Gait of Animals''; el, Περὶ πορείας ζῴων; la, De incessu animalium) is one of Aristotle's major texts on biology. It gives details of gait and movement in various kinds of animals, as wel ...
'', '' Parts of Animals'', and '' On the Soul'', as well as the lost drawings of ''The Anatomies'' which accompanied the ''History''. Apart from his pupil, Theophrastus, who wrote a matching ''
Enquiry into Plants Theophrastus's ''Enquiry into Plants'' or ''Historia Plantarum'' ( grc-gre, Περὶ φυτῶν ἱστορία, ''Peri phyton historia'') was, along with his mentor Aristotle's ''History of Animals'', Pliny the Elder's '' Natural History'' a ...
'', no research of comparable scope was carried out in
ancient Greece Ancient Greece ( el, Ἑλλάς, Hellás) was a northeastern Mediterranean civilization, existing from the Greek Dark Ages of the 12th–9th centuries BC to the end of classical antiquity ( AD 600), that comprised a loose collection of cult ...
, though
Hellenistic In Classical antiquity, the Hellenistic period covers the time in Mediterranean history after Classical Greece, between the death of Alexander the Great in 323 BC and the emergence of the Roman Empire, as signified by the Battle of Actium in 3 ...
medicine in Egypt continued Aristotle's inquiry into the mechanisms of the human body. Aristotle's biology was influential in the medieval Islamic world. Translation of Arabic versions and commentaries into Latin brought knowledge of Aristotle back into Western Europe, but the only biological work widely taught in medieval universities was ''On the Soul''. The association of his work with medieval scholasticism, as well as errors in his theories, caused Early Modern scientists such as Galileo and William Harvey to reject Aristotle. Criticism of his errors and secondhand reports continued for centuries. He has found better acceptance among
zoologists This is a list of notable zoologists who have published names of new taxa under the International Code of Zoological Nomenclature. A * Abe – Tokiharu Abe (1911–1996) * Abeille de Perrin, Ab. – Elzéar Abeille de Perrin (1843–1910) * ...
, and some of his long-derided observations in
marine biology Marine biology is the scientific study of the biology of marine life, organisms in the sea. Given that in biology many phyla, families and genera have some species that live in the sea and others that live on land, marine biology classifies ...
have been found in modern times to be true.


Context


Aristotle's background

Aristotle (384–322 BC) studied at
Plato's Academy The Academy ( Ancient Greek: Ἀκαδημία) was founded by Plato in c. 387 BC in Athens. Aristotle studied there for twenty years (367–347 BC) before founding his own school, the Lyceum. The Academy persisted throughout the Hellenist ...
in Athens, remaining there for about 20 years. Like Plato, he sought
universals In metaphysics, a universal is what particular things have in common, namely characteristics or qualities. In other words, universals are repeatable or recurrent entities that can be instantiated or exemplified by many particular things. For exa ...
in his philosophy, but unlike Plato he backed up his views with detailed and systematic observation, notably of the natural history of the island of
Lesbos Lesbos or Lesvos ( el, Λέσβος, Lésvos ) is a Greek island located in the northeastern Aegean Sea. It has an area of with approximately of coastline, making it the third largest island in Greece. It is separated from Asia Minor by the na ...
, where he spent about two years, and the marine life in the seas around it, especially of the Pyrrha lagoon in the island's centre. This study made him the earliest scientist whose written work survives. No similarly detailed work on zoology was attempted until the sixteenth century; accordingly Aristotle remained highly influential for some two thousand years. He returned to Athens and founded his own school, the
Lycaeum The Lyceum ( grc, Λύκειον, Lykeion) was a temple dedicated to Apollo Lyceus ("Apollo the wolf-god"). It was best known for the Peripatetic school of philosophy founded there by Aristotle in 334 BC. Aristotle fled Athens in 323 BC, and ...
, where he taught for the last dozen years of his life. His writings on zoology form about a quarter of his surviving work. Aristotle's pupil Theophrastus later wrote a similar book on
botany Botany, also called , plant biology or phytology, is the science of plant life and a branch of biology. A botanist, plant scientist or phytologist is a scientist who specialises in this field. The term "botany" comes from the Ancient Greek w ...
, ''Enquiry into Plants''.


Aristotelian forms

Aristotle's biology is constructed on the basis of his theory of form, which is derived from Plato's theory of Forms, but significantly different from it. Plato's Forms were eternal and fixed, being "blueprints in the mind of God". Real things in the world could, in Plato's view, at best be approximations to these perfect Forms. Aristotle heard Plato's view and developed it into a set of three biological concepts. He uses the same Greek word, (''eidos''), to mean first of all the set of visible features that uniquely characterised a kind of animal. Aristotle used the word γένος (génos) to mean a kind. For example, the kind of animal called a bird has feathers, a beak, wings, a hard-shelled egg, and warm blood. Aristotle further noted that there are many bird forms within the bird kind – cranes, eagles,
crow A crow is a bird of the genus '' Corvus'', or more broadly a synonym for all of ''Corvus''. Crows are generally black in colour. The word "crow" is used as part of the common name of many species. The related term "raven" is not pinned scientific ...
s,
bustard Bustards, including floricans and korhaans, are large, terrestrial birds living mainly in dry grassland areas and on the steppes of the Old World. They range in length from . They make up the family Otididae (, formerly known as Otidae). Bust ...
s,
sparrows Sparrow may refer to: Birds * Old World sparrows, family Passeridae * New World sparrows, family Passerellidae * two species in the Passerine family Estrildidae: ** Java sparrow ** Timor sparrow * Hedge sparrow, also known as the dunnock or he ...
, and so on, just as there are many forms of fishes within the fish kind. He sometimes called these ''atoma eidē'', indivisible forms. Human is one of these indivisible forms: Socrates and the rest of us are all different individually, but we all have human form. Finally, Aristotle observed that the child does not take just any form, but is given it by the parents' seeds, which combine. These seeds thus contain form, or in modern terms information. Aristotle makes clear that he sometimes intends this third sense by giving the analogy of a
woodcarving Wood carving is a form of woodworking by means of a cutting tool (knife) in one hand or a chisel by two hands or with one hand on a chisel and one hand on a mallet, resulting in a wooden figure or figurine, or in the sculptural ornamentation ...
. It takes its form from wood (its material cause); the tools and carving technique used to make it (its efficient cause); and the design laid out for it (its ''eidos'' or embedded information). Aristotle further emphasises the informational nature of form by arguing that a body is compounded of elements like earth and fire, just as a word is compounded of letters in a specific order.


System


Soul as system

As analysed by the evolutionary biologist
Armand Leroi Armand Marie Leroi (born 16 July 1964) is a New Zealand-born Dutch author, broadcaster, and professor of evolutionary developmental biology at Imperial College in London. He received the Guardian First Book Award in 2004 for his book ''Muta ...
, Aristotle's biology included five major interlocking processes: # a metabolic process, whereby animals take in matter, change its qualities, and distribute these to use to grow, live, and reproduce # a cycle of
temperature regulation Thermoregulation is the ability of an organism to keep its body temperature within certain boundaries, even when the surrounding temperature is very different. A thermoconforming organism, by contrast, simply adopts the surrounding temperature ...
, whereby animals maintain a steady state, but which progressively fails in old age # an information processing model whereby animals receive sensory information, alter it in the seat of sensation, and use it to drive movements of the limbs. He thus separated sensation from thought, unlike all previous philosophers except Alcmaeon. # the process of
inheritance Inheritance is the practice of receiving private property, titles, debts, entitlements, privileges, rights, and obligations upon the death of an individual. The rules of inheritance differ among societies and have changed over time. Officiall ...
. # the processes of embryonic development and of
spontaneous generation Spontaneous generation is a superseded scientific theory that held that living creatures could arise from nonliving matter and that such processes were commonplace and regular. It was hypothesized that certain forms, such as fleas, could arise f ...
The five processes formed what Aristotle called the soul: it was not something extra, but the system consisting exactly of these mechanisms. The Aristotelian soul died with the animal and was thus purely biological. Different types of organism possessed different types of soul. Plants had a vegetative soul, responsible for reproduction and growth. Animals had both a vegetative and a sensitive soul, responsible for mobility and sensation. Humans, uniquely, had a vegetative, a sensitive, and a rational soul, capable of thought and reflection.


Processes


Metabolism

Aristotle's account of metabolism sought to explain how food was processed by the body to provide both heat and the materials for the body's construction and maintenance. The metabolic system for live-bearing tetrapods described in the ''Parts of Animals'' can be modelled as an open system, a branching tree of flows of material through the body. The system worked as follows. The incoming material, food, enters the body and is concocted into blood; waste is excreted as urine, bile, and faeces, and the element fire is released as heat. Blood is made into flesh, the rest forming other earthy tissues such as bones, teeth, cartilages and sinews. Leftover blood is made into
fat In nutrition, biology, and chemistry, fat usually means any ester of fatty acids, or a mixture of such compounds, most commonly those that occur in living beings or in food. The term often refers specifically to triglycerides (triple est ...
, whether soft
suet Suet is the raw, hard fat of beef, lamb or mutton found around the loins and kidneys. Suet has a melting point of between 45 °C and 50 °C (113 °F and 122 °F) and congelation between 37 °C and 40 °C (98.6& ...
or hard lard. Some fat from all around the body is made into semen. All the tissues are in Aristotle's view completely uniform parts with no internal structure of any kind; a cartilage for example was the same all the way through, not subdivided into atoms as
Democritus Democritus (; el, Δημόκριτος, ''Dēmókritos'', meaning "chosen of the people"; – ) was an Ancient Greek pre-Socratic philosopher from Abdera, primarily remembered today for his formulation of an atomic theory of the universe. N ...
(c. 460–c. 370 BC) had argued. The uniform parts can be arranged on a scale of Aristotelian qualities, from the coldest and driest, such as hair, to the hottest and wettest, such as milk. At each stage of metabolism, residual materials are excreted as faeces, urine, and bile.


Temperature regulation

Aristotle's account of temperature regulation sought to explain how an animal maintained a steady temperature and the continued oscillation of the thorax needed for breathing. The system of regulation of temperature and breathing described in ''Youth and Old Age, Life and Death'' 26 is sufficiently detailed to permit modelling as a
negative feedback Negative feedback (or balancing feedback) occurs when some function of the output of a system, process, or mechanism is fed back in a manner that tends to reduce the fluctuations in the output, whether caused by changes in the input or by othe ...
control system (one that maintains a desired property by opposing disturbances to it), with a few assumptions such as a desired temperature to compare the actual temperature against. The system worked as follows. Heat is constantly lost from the body. Food products reach the heart and are processed into new blood, releasing fire during metabolism, which raises the blood temperature too high. That raises the heart temperature, causing lung volume to increase, in turn raising the airflow at the mouth. The cool air brought in through the mouth reduces the heart temperature, so the lung volume accordingly decreases, restoring the temperature to normal. The mechanism only works if the air is cooler than the reference temperature. If the air is hotter than that, the system becomes a positive feedback cycle, the body's fire is put out, and death follows. The system as described damps out fluctuations in temperature. Aristotle however predicted that his system would cause lung oscillation (breathing), which is possible given extra assumptions such as of delays or non-linear responses.


Information processing

Aristotle's information processing model has been named the "centralized incoming and outgoing motions model". It sought to explain how changes in the world led to appropriate behaviour in the animal. The system worked as follows. The animal's
sense organ A sense is a biological system used by an organism for sensation, the process of gathering information about the world through the detection of stimuli. (For example, in the human body, the brain which is part of the central nervous system rec ...
is altered when it detects an object. This causes a perceptual change in the animal's seat of sensation, which Aristotle believed was the heart ( cardiocentrism) rather than the brain. This in turn causes a change in the heart's heat, which causes a quantitative change sufficient to make the heart transmit a mechanical impulse to a limb, which moves, moving the animal's body. The alteration in the heat of the heart also causes a change in the consistency of the joints, which helps the limb to move. There is thus a causal chain which transmits information from a sense organ to an organ capable of making decisions, and onwards to a motor organ. In this respect, the model is analogous to a modern understanding of information processing such as in
sensory-motor coupling Sensory-motor coupling is the coupling or integration of the sensory system and motor system. Sensorimotor integration is not a static process. For a given stimulus, there is no one single motor command. "Neural responses at almost every stage of ...
.


Inheritance

Aristotle's inheritance model sought to explain how the parents' characteristics are transmitted to the child, subject to influence from the environment. The system worked as follows. The father's semen and the mother's menses have movements that encode their parental characteristics. The model is partly asymmetric, as only the father's movements define the form or ''eidos'' of the species, while the movements of both the father's and the mother's uniform parts define features other than the form, such as the father's eye colour or the mother's nose shape. Aristotle's theory has some symmetry, as semen movements carry maleness while the menses carry femaleness. If the semen is hot enough to overpower the cold menses, the child will be a boy; but if it is too cold to do this, the child will be a girl. Inheritance is thus particulate (definitely one trait or another), as in
Mendelian genetics Mendelian inheritance (also known as Mendelism) is a type of biological inheritance following the principles originally proposed by Gregor Mendel in 1865 and 1866, re-discovered in 1900 by Hugo de Vries and Carl Correns, and later popularized ...
, unlike the
Hippocratic Hippocrates of Kos (; grc-gre, Ἱπποκράτης ὁ Κῷος, Hippokrátēs ho Kôios; ), also known as Hippocrates II, was a Greek physician of the classical period who is considered one of the most outstanding figures in the history of ...
model which was continuous and blending. The child's sex can be influenced by factors that affect temperature, including the weather, the wind direction, diet, and the father's age. Features other than sex also depend on whether the semen overpowers the menses, so if a man has strong semen, he will have sons who resemble him, while if the semen is weak, he will have daughters who resemble their mother.


Embryogenesis

Aristotle's model of embryogenesis sought to explain how the inherited parental characteristics cause the formation and development of an embryo. The system worked as follows. First, the father's semen curdles the mother's menses, which Aristotle compares with how
rennet Rennet () is a complex set of enzymes produced in the stomachs of ruminant mammals. Chymosin, its key component, is a protease enzyme that curdles the casein in milk. In addition to chymosin, rennet contains other enzymes, such as pepsin and ...
(an enzyme from a cow's stomach) curdles milk in
cheesemaking Cheesemaking (or caseiculture) is the craft of making cheese. The production of cheese, like many other food preservation processes, allows the nutritional and economic value of a food material, in this case milk, to be preserved in concentr ...
. This forms the embryo; it is then developed by the action of the ''pneuma'' (literally, breath or spirit) in the semen. The ''pneuma'' first makes the heart appear; this is vital, as the heart nourishes all other organs. Aristotle observed that the heart is the first organ seen to be active (beating) in a hen's egg. The ''pneuma'' then makes the other organs develop.


Method

Aristotle has been called unscientific by philosophers from Francis Bacon onwards for at least two reasons: his scientific style, and his use of explanation. His explanations are in turn made cryptic by his complicated system of causes. However, these charges need to be considered in the light of what was known in his own time. His systematic gathering of data, too, is obscured by the lack of modern methods of presentation, such as tables of data: for example, the whole of '' History of Animals'' Book VI is taken up with a list of observations of the life histories of birds that "would now be summarized in a single table in ''
Nature Nature, in the broadest sense, is the physical world or universe. "Nature" can refer to the phenomena of the physical world, and also to life in general. The study of nature is a large, if not the only, part of science. Although humans are p ...
'' – and in the Online Supplementary Information at that".


Scientific style

Aristotle did not do experiments in the modern sense. He used the ancient Greek term ''pepeiramenoi'' to mean observations, or at most investigative procedures, such as (in ''Generation of Animals'') finding a fertilised hen's egg of a suitable stage and opening it so as to be able to see the embryo's heart inside. Instead, he practised a different style of science: systematically gathering data, discovering patterns common to whole groups of animals, and inferring possible causal explanations from these. This style is common in modern biology when large amounts of data become available in a new field, such as
genomics Genomics is an interdisciplinary field of biology focusing on the structure, function, evolution, mapping, and editing of genomes. A genome is an organism's complete set of DNA, including all of its genes as well as its hierarchical, three-dim ...
. It does not result in the same certainty as experimental science, but it sets out testable hypotheses and constructs a narrative explanation of what is observed. In this sense, Aristotle's biology is scientific. From the data he collected and documented, Aristotle inferred quite a number of
rules Rule or ruling may refer to: Education * Royal University of Law and Economics (RULE), a university in Cambodia Human activity * The exercise of political or personal control by someone with authority or power * Business rule, a rule perta ...
relating the life-history features of the live-bearing tetrapods (terrestrial placental mammals) that he studied. Among these correct predictions are the following. Brood size decreases with (adult) body mass, so that an
elephant Elephants are the largest existing land animals. Three living species are currently recognised: the African bush elephant, the African forest elephant, and the Asian elephant. They are the only surviving members of the family Elephantidae a ...
has fewer young (usually just one) per brood than a mouse. Lifespan increases with gestation period, and also with body mass, so that elephants live longer than mice, have a longer period of gestation, and are heavier. As a final example, fecundity decreases with lifespan, so long-lived kinds like elephants have fewer young in total than short-lived kinds like mice.


Mechanism and analogy

Aristotle's use of explanation has been considered "fundamentally unscientific". The French playwright
Molière Jean-Baptiste Poquelin (, ; 15 January 1622 (baptised) – 17 February 1673), known by his stage name Molière (, , ), was a French playwright, actor, and poet, widely regarded as one of the greatest writers in the French language and world ...
's 1673 play '' The Imaginary Invalid'' portrays the
quack Quack, The Quack or Quacks may refer to: People * Quack Davis, American baseball player * Hendrick Peter Godfried Quack (1834–1917), Dutch economist and historian * Joachim Friedrich Quack (born 1966), German Egyptologist * Johannes Quack ...
Aristotelian doctor Argan blandly explaining that opium causes sleep by virtue of its dormitive leep-makingprinciple, its ''virtus dormitiva''. Argan's explanation is at best empty (devoid of mechanism), at worst
vitalist Vitalism is a belief that starts from the premise that "living organisms are fundamentally different from non-living entities because they contain some non-physical element or are governed by different principles than are inanimate things." Wher ...
. But the real Aristotle did provide biological mechanisms, in the form of the five processes of metabolism, temperature regulation, information processing, embryonic development, and inheritance that he developed. Further, he provided mechanical, non-vitalist analogies for these theories, mentioning
bellows A bellows or pair of bellows is a device constructed to furnish a strong blast of air. The simplest type consists of a flexible bag comprising a pair of rigid boards with handles joined by flexible leather sides enclosing an approximately airtigh ...
, toy carts, the movement of water through porous pots, and even automatic puppets.


Complex causality

Readers of Aristotle have found the
four causes The four causes or four explanations are, in Aristotelian thought, four fundamental types of answer to the question "why?", in analysis of change or movement in nature: the material, the formal, the efficient, and the final. Aristotle wrote t ...
that he uses in his biological explanations opaque, something not helped by many centuries of confused exegesis. For a biological system, these are however straightforward enough. The material cause is simply what a system is constructed from. The goal ( final cause) and formal cause are what something is for, its
function Function or functionality may refer to: Computing * Function key, a type of key on computer keyboards * Function model, a structured representation of processes in a system * Function object or functor or functionoid, a concept of object-oriente ...
: to a modern biologist, such teleology describes
adaptation In biology, adaptation has three related meanings. Firstly, it is the dynamic evolutionary process of natural selection that fits organisms to their environment, enhancing their evolutionary fitness. Secondly, it is a state reached by the po ...
under the pressure of natural selection. The efficient cause is how a system develops and moves: to a modern biologist, those are explained by
developmental biology Developmental biology is the study of the process by which animals and plants grow and develop. Developmental biology also encompasses the biology of regeneration, asexual reproduction, metamorphosis, and the growth and differentiation of stem c ...
and physiology. Biologists continue to offer explanations of these same kinds.


Empirical research

Aristotle was the first person to study biology systematically. He spent two years observing and describing the zoology of
Lesbos Lesbos or Lesvos ( el, Λέσβος, Lésvos ) is a Greek island located in the northeastern Aegean Sea. It has an area of with approximately of coastline, making it the third largest island in Greece. It is separated from Asia Minor by the na ...
and the surrounding seas, including in particular the
Pyrrha In Greek mythology, Pyrrha (; Ancient Greek: Πύρρα) was the daughter of Epimetheus and Pandora and wife of Deucalion of whom she had three sons, Hellen, Amphictyon, Orestheus; and three daughters Protogeneia, Pandora II and Thyia. Accordi ...
lagoon in the centre of Lesbos. His data are assembled from his own observations, statements given by people with specialised knowledge such as
beekeeper A beekeeper is a person who keeps honey bees. Beekeepers are also called honey farmers, apiarists, or less commonly, apiculturists (both from the Latin '' apis'', bee; cf. apiary). The term beekeeper refers to a person who keeps honey bees i ...
s and fishermen, and less accurate accounts provided by travellers from overseas. His observations on
catfish Catfish (or catfishes; order Siluriformes or Nematognathi) are a diverse group of ray-finned fish. Named for their prominent barbels, which resemble a cat's whiskers, catfish range in size and behavior from the three largest species alive ...
,
electric fish An electric fish is any fish that can generate electric fields. Most electric fish are also electroreceptive, meaning that they can sense electric fields. The only exception is the stargazer family. Electric fish, although a small minority, in ...
('' Torpedo'') and
angler fish The anglerfish are fish of the teleost order Lophiiformes (). They are bony fish named for their characteristic mode of predation, in which a modified luminescent fin ray (the esca or illicium) acts as a lure for other fish. The luminescence c ...
are detailed, as is his writing on
cephalopod A cephalopod is any member of the molluscan class Cephalopoda (Greek plural , ; "head-feet") such as a squid, octopus, cuttlefish, or nautilus. These exclusively marine animals are characterized by bilateral body symmetry, a prominent head, a ...
s including the
octopus An octopus ( : octopuses or octopodes, see below for variants) is a soft-bodied, eight- limbed mollusc of the order Octopoda (, ). The order consists of some 300 species and is grouped within the class Cephalopoda with squids, cuttlef ...
,
cuttlefish Cuttlefish or cuttles are marine molluscs of the order Sepiida. They belong to the class Cephalopoda which also includes squid, octopuses, and nautiluses. Cuttlefish have a unique internal shell, the cuttlebone, which is used for control o ...
and
paper nautilus The argonauts (genus ''Argonauta'', the only extant genus in the family Argonautidae) are a group of pelagic octopuses. They are also called paper nautili, referring to the paper-thin eggcase that females secrete. This structure lacks the gas-f ...
. He reported that fishermen had asserted that the octopus’s hectocotyl arm was used in sexual reproduction. He admitted its use in mating 'only for the sake of attachment', but rejected the idea that it was useful for generation, since "it is outside the passage and indeed outside the body". In the 19th century, biologists found that the reported function was correct. He separated the aquatic mammals from fish, and knew that sharks and
ray Ray may refer to: Fish * Ray (fish), any cartilaginous fish of the superorder Batoidea * Ray (fish fin anatomy), a bony or horny spine on a fin Science and mathematics * Ray (geometry), half of a line proceeding from an initial point * Ray (gr ...
s were part of the group he called ''Selachē'' (roughly, the modern zoologist's selachians). Among many other things, he gave accurate descriptions of the four-chambered stomachs of ruminants, and of the ovoviviparous embryological development of the dogfish. His accounts of about 35 animals are sufficiently detailed to convince biologists that he dissected those species, indeed vivisecting some; he mentions the internal anatomy of roughly 110 animals in total.


Classification

Aristotle distinguished about 500 species of birds, mammals and fishes in ''History of Animals'' and '' Parts of Animals''. His system of classification, one of the earliest in scientific taxonomy, was influential for over two thousand years. Aristotle distinguished animals with blood, ''Enhaima'' (the modern zoologist's
vertebrates Vertebrates () comprise all animal taxa within the subphylum Vertebrata () ( chordates with backbones), including all mammals, birds, reptiles, amphibians, and fish. Vertebrates represent the overwhelming majority of the phylum Chordata, ...
) and animals without blood, ''Anhaima'' (
invertebrates Invertebrates are a paraphyletic group of animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This is a grouping including all animals apart from the chordate ...
). Animals with blood included live-bearing tetrapods, ''Zōiotoka tetrapoda'' (roughly, the mammals), being warm, having four legs, and giving birth to their young. The
cetacea Cetacea (; , ) is an infraorder of aquatic mammals that includes whales, dolphins, and porpoises. Key characteristics are their fully aquatic lifestyle, streamlined body shape, often large size and exclusively carnivorous diet. They propel the ...
ns, ''Kētōdē'', also had blood and gave birth to live young, but did not have legs, and therefore formed a separate group (''megista genē'', defined by a set of functioning "parts"). The birds, ''Ornithes'' had blood and laid eggs, but had only 2 legs and were a distinct form (''eidos'') with feathers and beaks instead of teeth, so they too formed a distinct group, of over 50 kinds. The egg-bearing tetrapods, ''Ōiotoka tetrapoda'' ( reptiles and
amphibians Amphibians are four-limbed and ectothermic vertebrates of the class Amphibia. All living amphibians belong to the group Lissamphibia. They inhabit a wide variety of habitats, with most species living within terrestrial, fossorial, arbore ...
) had blood and four legs, but were cold and laid eggs, so were a distinct group. The snakes, ''Opheis'', similarly had blood, but no legs, and laid dry eggs, so were a separate group. The fishes, ''Ikhthyes'', had blood but no legs, and laid wet eggs, forming a definite group. Among them, the selachians ''Selakhē'' (sharks and rays), had
cartilage Cartilage is a resilient and smooth type of connective tissue. In tetrapods, it covers and protects the ends of long bones at the joints as articular cartilage, and is a structural component of many body parts including the rib cage, the neck an ...
s instead of bones. Animals without blood were divided into soft-shelled ''Malakostraka'' (
crabs Crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting " tail" (abdomen) ( el, βραχύς , translit=brachys = short, / = tail), usually hidden entirely under the thorax. They live in all th ...
,
lobsters Lobsters are a family (Nephropidae, synonym Homaridae) of marine crustaceans. They have long bodies with muscular tails and live in crevices or burrows on the sea floor. Three of their five pairs of legs have claws, including the first pair, ...
, and
shrimps Shrimp are crustaceans (a form of shellfish) with elongated bodies and a primarily swimming mode of locomotion – most commonly Caridea and Dendrobranchiata of the decapod order, although some crustaceans outside of this order are referre ...
); hard-shelled ''Ostrakoderma'' ( gastropods and
bivalves Bivalvia (), in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class of marine and freshwater molluscs that have laterally compressed bodies enclosed by a shell consisting of two hinged parts. As a group, biv ...
); soft-bodied ''Malakia'' (
cephalopods A cephalopod is any member of the molluscan class Cephalopoda (Greek plural , ; "head-feet") such as a squid, octopus, cuttlefish, or nautilus. These exclusively marine animals are characterized by bilateral body symmetry, a prominent head, a ...
); and divisible animals ''Entoma'' (
insects Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (head, thorax and abdomen), three pairs of ...
, spiders, scorpions,
tick Ticks (order Ixodida) are parasitic arachnids that are part of the mite superorder Parasitiformes. Adult ticks are approximately 3 to 5 mm in length depending on age, sex, species, and "fullness". Ticks are external parasites, living by ...
s). Other animals without blood included
fish lice The family Argulidae, whose members are commonly known as carp lice or fish lice, are parasitic crustaceans in the class Ichthyostraca. It is the only family in the monotypic subclass Branchiura and the order Arguloida, although a second family, ...
, hermit crabs,
red coral Precious coral, or red coral, is the common name given to a genus of marine corals, ''Corallium''. The distinguishing characteristic of precious corals is their durable and intensely colored red or pink-orange skeleton, which is used for ma ...
, sea anemones, sponges,
starfish Starfish or sea stars are star-shaped echinoderms belonging to the class Asteroidea (). Common usage frequently finds these names being also applied to ophiuroids, which are correctly referred to as brittle stars or basket stars. Starfish ...
and various worms: Aristotle did not classify these into groups.


Scale of being

Aristotle stated in the ''History of Animals'' that all beings were arranged in a fixed scale of perfection, reflected in their form (''eidos''). They stretched from minerals to plants and animals, and on up to man, forming the '' ''scala naturae'' or great chain of being''. His system had eleven grades, arranged according to the potentiality of each being, expressed in their form at birth. The highest animals gave birth to warm and wet creatures alive, the lowest bore theirs cold, dry, and in thick eggs. The system was based on Aristotle's interpretation of the four elements in his ''
On Generation and Corruption ''On Generation and Corruption'' ( grc, Περὶ γενέσεως καὶ φθορᾶς; la, De Generatione et Corruptione), also known as ''On Coming to Be and Passing Away'' is a treatise by Aristotle. Like many of his texts, it is both scie ...
'':
Fire Fire is the rapid oxidation of a material (the fuel) in the exothermic chemical process of combustion, releasing heat, light, and various reaction Product (chemistry), products. At a certain point in the combustion reaction, called the ignition ...
(hot and dry);
Air The atmosphere of Earth is the layer of gases, known collectively as air, retained by Earth's gravity that surrounds the planet and forms its planetary atmosphere. The atmosphere of Earth protects life on Earth by creating pressure allowing for ...
(hot and wet); Water (cold and wet); and Earth (cold and dry). These are arranged from the most energetic to the least, so the warm, wet young raised in a womb with a placenta were higher on the scale than the cold, dry, nearly mineral eggs of birds. However, Aristotle is careful never to insist that a group fits perfectly in the scale; he knows animals have many combinations of attributes, and that placements are approximate.


Influence


On Theophrastus

Aristotle's pupil and successor at the
Lyceum The lyceum is a category of educational institution defined within the education system of many countries, mainly in Europe. The definition varies among countries; usually it is a type of secondary school. Generally in that type of school the ...
, Theophrastus, wrote the '' History of Plants'', the first classical book of
botany Botany, also called , plant biology or phytology, is the science of plant life and a branch of biology. A botanist, plant scientist or phytologist is a scientist who specialises in this field. The term "botany" comes from the Ancient Greek w ...
. It has an Aristotelian structure, but rather than focus on formal causes, as Aristotle did, Theophrastus described how plants functioned. Where Aristotle expanded on grand theories, Theophrastus was quietly empirical. Where Aristotle insisted that species have a fixed place on the ''scala naturae'', Theophrastus suggests that one kind of plant can transform into another, as when a field sown to wheat turns to the weed
darnel ''Lolium temulentum'', typically known as darnel, poison darnel, darnel ryegrass or cockle, is an annual plant of the genus ''Lolium'' within the family Poaceae. The plant stem can grow up to one meter tall, with inflorescence in the ears and pur ...
.


On Hellenistic medicine

After Theophrastus, though interest in Aristotle's ideas survived, they were generally taken unquestioningly.Annas, "Classical Greek Philosophy", 2001, p. 252. In Boardman, John; Griffin, Jasper; Murray, Oswyn (ed.) ''The Oxford History of the Classical World''. Oxford University Press. It is not until the age of
Alexandria Alexandria ( or ; ar, ٱلْإِسْكَنْدَرِيَّةُ ; grc-gre, Αλεξάνδρεια, Alexándria) is the second largest city in Egypt, and the largest city on the Mediterranean coast. Founded in by Alexander the Great, Alexandri ...
under the
Ptolemies The Ptolemaic dynasty (; grc, Πτολεμαῖοι, ''Ptolemaioi''), sometimes referred to as the Lagid dynasty (Λαγίδαι, ''Lagidae;'' after Ptolemy I's father, Lagus), was a Macedonian Greek royal dynasty which ruled the Ptolemaic K ...
that advances in biology resumed. The first medical teacher at Alexandria,
Herophilus of Chalcedon Herophilos (; grc-gre, Ἡρόφιλος; 335–280 BC), sometimes Latinised Herophilus, was a Greek physician regarded as one of the earliest anatomists. Born in Chalcedon, he spent the majority of his life in Alexandria. He was the first sci ...
, corrected Aristotle, placing intelligence in the brain, and connected the nervous system to motion and sensation. Herophilus also distinguished between
vein Veins are blood vessels in humans and most other animals that carry blood towards the heart. Most veins carry deoxygenated blood from the tissues back to the heart; exceptions are the pulmonary and umbilical veins, both of which carry oxygenated ...
s and
arteries An artery (plural arteries) () is a blood vessel in humans and most animals that takes blood away from the heart to one or more parts of the body (tissues, lungs, brain etc.). Most arteries carry oxygenated blood; the two exceptions are the p ...
, noting that the latter pulse while the former do not.


On Islamic zoology

Many classical works including those of Aristotle were transmitted from Greek to Syriac, then to Arabic, then to Latin in the Middle Ages. Aristotle remained the principal authority in biology for the next two thousand years. The ''
Kitāb al-Hayawān The ''Kitāb al-Ḥayawān'' ( ar, كتاب الحيوان, , ''LINA saadouni'') is an Arabic translation for hayawan (Arabic: , maqālāt). '' Historia Animalium'': treatises 1–10; '' De Partibus Animalium'': treatises 11–14; ''De Generation ...
'' (كتاب الحيوان, ''Book of Animals'') is a 9th-century
Arabic Arabic (, ' ; , ' or ) is a Semitic language spoken primarily across the Arab world.Semitic languages: an international handbook / edited by Stefan Weninger; in collaboration with Geoffrey Khan, Michael P. Streck, Janet C. E.Watson; Walte ...
translation of ''History of Animals'': 1–10, ''On the Parts of Animals'': 11–14, and ''Generation of Animals'': 15–19. The book was mentioned by
Al-Kindī Abū Yūsuf Yaʻqūb ibn ʼIsḥāq aṣ-Ṣabbāḥ al-Kindī (; ar, أبو يوسف يعقوب بن إسحاق الصبّاح الكندي; la, Alkindus; c. 801–873 AD) was an Arab Muslim philosopher, polymath, mathematician, physician ...
(d. 850), and commented on by
Avicenna Ibn Sina ( fa, ابن سینا; 980 – June 1037 CE), commonly known in the West as Avicenna (), was a Persian polymath who is regarded as one of the most significant physicians, astronomers, philosophers, and writers of the Islamic ...
(Ibn Sīnā) in his '' Kitāb al-Šifā'' (کتاب الشفاء, ''The Book of Healing'').
Avempace Abū Bakr Muḥammad ibn Yaḥyà ibn aṣ-Ṣā’igh at-Tūjībī ibn Bājja ( ar, أبو بكر محمد بن يحيى بن الصائغ التجيبي بن باجة), best known by his Latinised name Avempace (;  – 1138), was an ...
(Ibn Bājja) and
Averroes Ibn Rushd ( ar, ; full name in ; 14 April 112611 December 1198), often Latinized as Averroes ( ), was an Andalusian polymath and jurist who wrote about many subjects, including philosophy, theology, medicine, astronomy, physics, psychology ...
(Ibn Rushd) commented on ''On the Parts of Animals'' and ''Generation of Animals'', Averroes criticising Avempace's interpretations.


On medieval science

When the Christian
Alfonso VI of Castile Alphons (Latinized ''Alphonsus'', ''Adelphonsus'', or ''Adefonsus'') is a male given name recorded from the 8th century (Alfonso I of Asturias, r. 739–757) in the Christian successor states of the Visigothic kingdom in the Iberian peninsula. ...
retook the
Kingdom of Toledo The Kingdom of Toledo ( es, Reino de Toledo) was a realm in the central Iberian Peninsula, created after the capture of Toledo by Alfonso VI of León in 1085. It continued in existence until 1833; its region is currently within Spain. Back ...
from the Moors in 1085, an Arabic translation of Aristotle's works, with commentaries by
Avicenna Ibn Sina ( fa, ابن سینا; 980 – June 1037 CE), commonly known in the West as Avicenna (), was a Persian polymath who is regarded as one of the most significant physicians, astronomers, philosophers, and writers of the Islamic ...
and
Averroes Ibn Rushd ( ar, ; full name in ; 14 April 112611 December 1198), often Latinized as Averroes ( ), was an Andalusian polymath and jurist who wrote about many subjects, including philosophy, theology, medicine, astronomy, physics, psychology ...
emerged into European medieval scholarship.
Michael Scot Michael Scot ( Latin: Michael Scotus; 1175 – ) was a Scottish mathematician and scholar in the Middle Ages. He was educated at Oxford and Paris, and worked in Bologna and Toledo, where he learned Arabic. His patron was Frederick II o ...
translated much of Aristotle's biology into Latin, c. 1225, along with many of Averroes's commentaries.
Albertus Magnus Albertus Magnus (c. 1200 – 15 November 1280), also known as Saint Albert the Great or Albert of Cologne, was a German Dominican friar, philosopher, scientist, and bishop. Later canonised as a Catholic saint, he was known during his life ...
commented extensively on Aristotle, but added his own zoological observations and an encyclopedia of animals based on
Thomas of Cantimpré Thomas of Cantimpré (Latin: Thomas Cantimpratensis or Thomas Cantipratensis) (Sint-Pieters-Leeuw, 1201 – Louvain, 15 May 1272) was a Flemish Catholic medieval writer, preacher, theologian and a friar belonging to the Dominican Order. He is be ...
. Later in the 13th century,
Thomas Aquinas Thomas Aquinas, OP (; it, Tommaso d'Aquino, lit=Thomas of Aquino; 1225 – 7 March 1274) was an Italian Dominican friar and priest who was an influential philosopher, theologian and jurist in the tradition of scholasticism; he is known w ...
merged Aristotle's metaphysics with Christian theology. Whereas Albert had treated Aristotle's biology as science, writing that experiment was the only safe guide and joining in with the types of observation that Aristotle had made, Aquinas saw Aristotle purely as theory, and Aristotelian thought became associated with scholasticism. The scholastic natural philosophy curriculum omitted most of Aristotle's biology, but included ''On the Soul''.


On Renaissance science

Renaissance zoologists made use of Aristotle's zoology in two ways. Especially in Italy, scholars such as
Pietro Pomponazzi Pietro Pomponazzi (16 September 1462 – 18 May 1525) was an Italian philosopher. He is sometimes known by his Latin name, ''Petrus Pomponatius''. Biography Pietro Pomponazzi was born in Mantua and began his education there. He completed h ...
and
Agostino Nifo Agostino Nifo ( Latinized as Augustinus Niphus; 1538 or 1545) was an Italian philosopher and commentator. Life He was born at Sessa Aurunca near Naples. He proceeded to Padua, where he studied philosophy. He lectured at Padua, Naples, Rome, and P ...
lectured and wrote commentaries on Aristotle. Elsewhere, authors used Aristotle as one of their sources, alongside their own and their colleagues' observations, to create new encyclopedias such as
Konrad Gessner Conrad Gessner (; la, Conradus Gesnerus 26 March 1516 – 13 December 1565) was a Swiss physician, naturalist, bibliographer, and philologist. Born into a poor family in Zürich, Switzerland, his father and teachers quickly realised his tale ...
's 1551 '' Historia Animalium''. The title and the philosophical approach were Aristotelian, but the work was largely new. Edward Wotton similarly helped to found modern zoology by arranging the animals according to Aristotle's theories, separating out folklore from his 1552 ''De differentiis animalium''.


Early Modern rejection

In the Early Modern period, Aristotle came to represent all that was obsolete, scholastic, and wrong, not helped by his association with medieval theology. In 1632, Galileo represented
Aristotelianism Aristotelianism ( ) is a philosophical tradition inspired by the work of Aristotle, usually characterized by deductive logic and an analytic inductive method in the study of natural philosophy and metaphysics. It covers the treatment of the socia ...
in his '' Dialogo sopra i due massimi sistemi del mondo'' (Dialogue Concerning the Two Chief World Systems) by the
strawman A straw man (sometimes written as strawman) is a form of argument and an informal fallacy of having the impression of refuting an argument, whereas the real subject of the argument was not addressed or refuted, but instead replaced with a false o ...
Simplicio ("Simpleton"). That same year, William Harvey proved Aristotle wrong by demonstrating that blood circulates. Aristotle still represented the enemy of true science into the 20th century. Leroi noted that in 1985,
Peter Medawar Sir Peter Brian Medawar (; 28 February 1915 – 2 October 1987) was a Brazilian-British biologist and writer, whose works on graft rejection and the discovery of acquired immune tolerance have been fundamental to the medical practice of tissue ...
stated in "pure seventeenth century" tones that Aristotle had assembled "a strange and generally speaking rather tiresome
farrago Farrago is a Latin word, meaning "mixed cattle fodder", used to refer to a confused variety of miscellaneous things. As a name, it may refer to: * ''Farrago'' (plant), a genus of plants in the family Poaceae * ''Farrago'' (magazine), student newsp ...
of hearsay, imperfect observation, wishful thinking and credulity amounting to downright gullibility".


19th century revival

Zoologists working in the 19th century, including Georges Cuvier, Johannes Peter Müller, and
Louis Agassiz Jean Louis Rodolphe Agassiz ( ; ) FRS (For) FRSE (May 28, 1807 – December 14, 1873) was a Swiss-born American biologist and geologist who is recognized as a scholar of Earth's natural history. Spending his early life in Switzerland, he rec ...
admired Aristotle's biology and investigated some of his observations. D'Arcy Thompson translated ''History of Animals'' in 1910, making a classically-educated zoologist's informed attempt to identify the animals that Aristotle names, and to interpret and diagram his anatomical descriptions.
Charles Darwin Charles Robert Darwin ( ; 12 February 1809 – 19 April 1882) was an English naturalist, geologist, and biologist, widely known for his contributions to evolutionary biology. His proposition that all species of life have descended fr ...
quoted a passage from Aristotle's ''Physics'' II 8 in '' The Origin of Species'', which entertains the possibility of a selection process following the random combination of body parts. Darwin comments that "We here see the principle of natural selection shadowed forth". However, two things mitigate against this interpretation. Firstly, Aristotle immediately rejected the possibility of such a process of assembling body parts. Secondly, according to Leroi, Aristotle was in any case discussing ontogeny, the Empedoclean coming into being of an individual from component parts, not phylogeny and natural selection. Darwin considered Aristotle the most important early contributor to biological thought; in an 1882 letter he wrote that "Linnaeus and Cuvier have been my two gods, though in very different ways, but they were mere schoolboys to old Aristotle."


20th and 21st century interest

Zoologists have frequently mocked Aristotle for errors and unverified secondhand reports. However, modern observation has confirmed one after another of his more surprising claims, including the
active camouflage Active camouflage or adaptive camouflage is camouflage that adapts, often rapidly, to the surroundings of an object such as an animal or military vehicle. In theory, active camouflage could provide perfect concealment from visual detection. Activ ...
of the octopus and the ability of elephants to snorkel with their trunks while swimming. Aristotle remains largely unknown to modern scientists, though zoologists are perhaps most likely to mention him as "the father of biology"; the MarineBio Conservation Society notes that he identified "
crustaceans Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean group c ...
, echinoderms, mollusks, and fish", that
cetaceans Cetacea (; , ) is an infraorder of aquatic mammals that includes whales, dolphins, and porpoises. Key characteristics are their fully aquatic lifestyle, streamlined body shape, often large size and exclusively carnivorous diet. They propel them ...
are mammals, and that marine vertebrates could be either
oviparous Oviparous animals are animals that lay their eggs, with little or no other embryonic development within the mother. This is the reproductive method of most fish, amphibians, most reptiles, and all pterosaurs, dinosaurs (including birds), and ...
or viviparous, so he "is often referred to as the father of
marine biology Marine biology is the scientific study of the biology of marine life, organisms in the sea. Given that in biology many phyla, families and genera have some species that live in the sea and others that live on land, marine biology classifies ...
". The evolutionary zoologist
Armand Leroi Armand Marie Leroi (born 16 July 1964) is a New Zealand-born Dutch author, broadcaster, and professor of evolutionary developmental biology at Imperial College in London. He received the Guardian First Book Award in 2004 for his book ''Muta ...
has taken an interest in Aristotle's biology. The concept of homology began with Aristotle, and the evolutionary developmental biologist Lewis I. Held commented that


Works

Aristotle did not write anything that resembles a modern, unified textbook of biology. Instead, he wrote a large number of "books" which, taken together, give an idea of his approach to the science. Some of these interlock, referring to each other, while others, such as the drawings of ''The Anatomies'' are lost, but referred to in the ''History of Animals'', where the reader is instructed to look at the diagrams to understand how the animal parts described are arranged. Aristotle's main biological works are the five books sometimes grouped as ''On Animals'' (De Animalibus), namely, with the conventional abbreviations shown in parentheses: * ''History of Animals'', or ''Inquiries into Animals'' (Historia Animalium) (HA) * ''
Generation of Animals The ''Generation of Animals'' (or ''On the Generation of Animals''; Greek: ''Περὶ ζῴων γενέσεως'' (''Peri Zoion Geneseos''); Latin: ''De Generatione Animalium'') is one of the biological works of the Corpus Aristotelicum, the col ...
'' (De Generatione Animalium) (GA) * '' Movement of Animals'' (De Motu Animalium) (DM) * '' Parts of Animals'' (De Partibus Animalium) (PA) * ''Progression of Animals'' or ''On the Gait of Animals'' (De Incessu Animalium) (IA) together with '' On the Soul'' (De Anima) (DA). In addition, a group of seven short works, conventionally forming the '' Parva Naturalia'' ("Short treatises on Nature"), is also mainly biological: * '' Sense and Sensibilia'' (Sense) * ''
On Memory ''On Memory'' ( Greek: Περὶ μνήμης καὶ ἀναμνήσεως; Latin: ''De memoria et reminiscentia'') is one of the short treatises that make up Aristotle's '' Parva Naturalia''. It is frequently published together, and read toget ...
'' * ''
On Sleep ''On Sleep'' (or ''On Sleep and Sleeplessness''; Greek Περὶ ὕπνου καὶ ἐγρηγόρσεως; Latin: ''De somno et vigilia'') is a text by Aristotle, one of the '' Parva Naturalia''. Topics The common sense "In another pl ...
'' * '' On Dreams'' * ''
On Divination in Sleep ''On Divination in Sleep'' (or ''On Prophesying by Dreams''; grc-gre, Περὶ τῆς καθ᾽ ὕπνον μαντικῆς; Latin: ''De divinatione per somnum'') is a text by Aristotle in which he discusses precognitive dreams. The treatis ...
'' * '' On Length and Shortness of Life'' * '' On Youth, Old Age, Life and Death, and Respiration''De Juventute et Senectute, De Vita et Morte, De Respiratione


Notes


References


Sources

* * * * * * * * * * {{Use dmy dates, date=April 2017 History of biology Philosophy of Aristotle History of zoology Ancient Greek science