Deep homologyIn evolutionary developmental biology, the concept of deep homology is used to describe cases where growth and differentiation processes are governed by genetic mechanisms that are homologous and deeply conserved across a wide range of species. In 1822, the French zoologist Étienne Geoffroy Saint-Hilaire dissected a crayfish, discovering that its body is organised like a vertebrate's, but inverted belly to back (dorsoventrally): I just found that all the soft organs, that is to say, the principal organs of life are found in crustaceans, and so in insects, in the same order, in the same relationships and with the same arrangement as their analogues in the high vertebrate animals .
Generation of AnimalsThe 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 collection of texts traditionally attributed to Aristotle (384 – 322BC). The work provides an account of animal reproduction, gestation and heredity. Generation of Animals consists of five books, which are themselves split into varying numbers of chapters. Most editions of this work categorise it with Bekker numbers.
Science in classical antiquityScience in classical antiquity encompasses inquiries into the workings of the world or universe aimed at both practical goals (e.g., establishing a reliable calendar or determining how to cure a variety of illnesses) as well as more abstract investigations belonging to natural philosophy. Classical antiquity is traditionally defined as the period between 8th century BC and the 6th century AD, and the ideas regarding nature that were theorized during this period were not limited to science but included myths as well as religion.
Four causesThe 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 that "we do not have knowledge of a thing until we have grasped its why, that is to say, its cause." While there are cases in which classifying a "cause" is difficult, or in which "causes" might merge, Aristotle held that his four "causes" provided an analytical scheme of general applicability.
Teleology in biologyTeleology in biology is the use of the language of goal-directedness in accounts of evolutionary adaptation, which some biologists and philosophers of science find problematic. The term teleonomy has also been proposed. Before Darwin, organisms were seen as existing because God had designed and created them; their features such as eyes were taken by natural theology to have been made to enable them to carry out their functions, such as seeing.
Tinbergen's four questionsTinbergen's four questions, named after 20th century biologist Nikolaas Tinbergen, are complementary categories of explanations for animal behaviour. These are also commonly referred to as levels of analysis. It suggests that an integrative understanding of behaviour must include ultimate (evolutionary) explanations, in particular: behavioural adaptive functions phylogenetic history; and the proximate explanations underlying physiological mechanisms ontogenetic/developmental history.
Function (biology)In evolutionary biology, function is the reason some object or process occurred in a system that evolved through natural selection. That reason is typically that it achieves some result, such as that chlorophyll helps to capture the energy of sunlight in photosynthesis. Hence, the organism that contains it is more likely to survive and reproduce, in other words the function increases the organism's fitness. A characteristic that assists in evolution is called an adaptation; other characteristics may be non-functional spandrels, though these in turn may later be co-opted by evolution to serve new functions.
History of AnimalsHistory of Animals (Τῶν περὶ τὰ ζῷα ἱστοριῶν, Ton peri ta zoia historion, "Inquiries on Animals"; Historia Animalium, "History of Animals") is one of the major texts on biology by the ancient Greek philosopher Aristotle, who had studied at Plato's Academy in Athens. It was written in the fourth century BC; Aristotle died in 322 BC. Generally seen as a pioneering work of zoology, Aristotle frames his text by explaining that he is investigating the what (the existing facts about animals) prior to establishing the why (the causes of these characteristics).
ZoologyZoology (zoʊˈɒlədʒi) is the scientific study of animals. Its studies include the structure, embryology, classification, habits, and distribution of all animals, both living and extinct, and how they interact with their ecosystems. Zoology is one of the primary branches of biology. The term is derived from Ancient Greek ζῷον, ('animal'), and λόγος, logos ('knowledge', 'study'). Although humans have always been interested in the natural history of the animals they saw around them, and used this knowledge to domesticate certain species, the formal study of zoology can be said to have originated with Aristotle.
Ancient Greek medicineAncient Greek medicine was a compilation of theories and practices that were constantly expanding through new ideologies and trials. The Greek term for medicine was iatrikē (Greek: ἰατρική). Many components were considered in ancient Greek medicine, intertwining the spiritual with the physical. Specifically, the ancient Greeks believed health was affected by the humors, geographic location, social class, diet, trauma, beliefs, and mindset. Early on the ancient Greeks believed that illnesses were "divine punishments" and that healing was a "gift from the Gods".
Spontaneous generationSpontaneous 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 from inanimate matter such as dust, or that maggots could arise from dead flesh. The doctrine of spontaneous generation was coherently synthesized by the Greek philosopher and naturalist Aristotle, who compiled and expanded the work of earlier natural philosophers and the various ancient explanations for the appearance of organisms.
Aristotelian physicsAristotelian physics is the form of natural science or natural philosophy described in the works of the Greek philosopher Aristotle (384–322 BC). In his work Physics, Aristotle intended to establish general principles of change that govern all natural bodies, both living and inanimate, celestial and terrestrial including all motion (change with respect to place), quantitative change (change with respect to size or number), qualitative change, and substantial change ("coming to be" [coming into existence, 'generation'] or "passing away" [no longer existing, 'corruption']).
Great chain of beingThe great chain of being is a hierarchical structure of all matter and life, thought by medieval Christianity to have been decreed by God. The chain begins with God and descends through angels, humans, animals and plants to minerals. The great chain of being (scala naturae, "Ladder of Being") is a concept derived from Plato, Aristotle (in his Historia Animalium), Plotinus and Proclus. Further developed during the Middle Ages, it reached full expression in early modern Neoplatonism.
SpiderSpiders (order Araneae) are air-breathing arthropods that have eight legs, chelicerae with fangs generally able to inject venom, and spinnerets that extrude silk. They are the largest order of arachnids and rank seventh in total species diversity among all orders of organisms. Spiders are found worldwide on every continent except for Antarctica, and have become established in nearly every land habitat. , 50,356 spider species in 132 families have been recorded by taxonomists.
Animal cognitionAnimal cognition encompasses the mental capacities of non-human animals including insect cognition. The study of animal conditioning and learning used in this field was developed from comparative psychology. It has also been strongly influenced by research in ethology, behavioral ecology, and evolutionary psychology; the alternative name cognitive ethology is sometimes used. Many behaviors associated with the term animal intelligence are also subsumed within animal cognition.
Blending inheritanceBlending inheritance is an obsolete theory in biology from the 19th century. The theory is that the progeny inherits any characteristic as the average of the parents' values of that characteristic. As an example of this, a crossing of a red flower variety with a white variety of the same species would yield pink-flowered offspring. Charles Darwin's theory of inheritance by pangenesis, with contributions to egg or sperm from every part of the body, implied blending inheritance.
Evolutionary developmental biologyEvolutionary developmental biology (informally, evo-devo) is a field of biological research that compares the developmental processes of different organisms to infer how developmental processes evolved. The field grew from 19th-century beginnings, where embryology faced a mystery: zoologists did not know how embryonic development was controlled at the molecular level. Charles Darwin noted that having similar embryos implied common ancestry, but little progress was made until the 1970s.
History of evolutionary thoughtEvolutionary thought, the recognition that species change over time and the perceived understanding of how such processes work, has roots in antiquity—in the ideas of the ancient Greeks, Romans, Chinese, Church Fathers as well as in medieval Islamic science.
OrthogenesisOrthogenesis, also known as orthogenetic evolution, progressive evolution, evolutionary progress, or progressionism, is an obsolete biological hypothesis that organisms have an innate tendency to evolve in a definite direction towards some goal (teleology) due to some internal mechanism or "driving force". According to the theory, the largest-scale trends in evolution have an absolute goal such as increasing biological complexity.
CuttlefishCuttlefish 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 of buoyancy. Cuttlefish have large, W-shaped pupils, eight arms, and two tentacles furnished with denticulated suckers, with which they secure their prey. They generally range in size from , with the largest species, the giant cuttlefish (Sepia apama), reaching in mantle length and over in mass.
