Comparative Anatomy Lecture Notes PDF 2022-2023

COMPARATIVE ANATOMY (ANA3212) LECTURE NOTE By I.A. Tela Department of Anatomy, Faculty of Basic Medical Sciences, College of Health Science, Bayero University, Kano. Second Semester, 2022–23 Academic Session. Course...

COMPARATIVE ANATOMY (ANA3212) LECTURE NOTE By I.A. Tela Department of Anatomy, Faculty of Basic Medical Sciences, College of Health Science, Bayero University, Kano. Second Semester, 2022–23 Academic Session. Course outline Introduction Significance Brief History Ways to studying How to study Principles & Concepts Adaptation and natural selection Classification of mammals and their characteristics IA Tela 2 Introduction Comparative Anatomy is the study of the similarities and differences in the structures of different species. Also define as the branch of animal science (zoology) which deals with evolutionary trends on the basis of similarities and differences among animal types. Comparative Anatomy explores and establishes the correspondences between body parts of organisms from different species. It builds the concepts of the living structures and thus must not be confused with morphology (the study of the forms and their variations) nor with Evo-Devo (the study of the relations between genetics of the development and evolution). IA Tela 3 Introduction… IA Tela 4 Significance of Comparative Anatomy Evolutionary Relationships: Comparative anatomy provides valuable information about the evolutionary relationships between different species. By comparing the anatomical structures of organisms, scientists can infer common ancestry and evolutionary divergence. Homologous structures, which share a common origin, are essential in reconstructing evolutionary histories. Functional Morphology: Understanding the form and function of anatomical structures helps researchers deduce how different species have adapted to their environments. Comparative anatomy allows scientists to explore how structures serve specific functions and how they may have evolved to meet the needs of organisms in different ecological niches. Medical Applications: Comparative anatomy is foundational to the field of medicine. Studying the anatomy of different species helps researchers and medical professionals gain insights into human anatomy. This knowledge is crucial for medical education, surgical procedures, and developing a deeper understanding of human physiological systems. Biological Classification: Comparative anatomy is essential for classifying and categorizing living organisms. Similarities and differences in anatomical structures contribute to the development of taxonomies and phylogenetic trees, helping scientists organize and understand the diversity of life on Earth. IA Tela 5  Significance of Comparative Anatomy… Conservation Biology: Understanding the anatomical features of different species is vital for conservation efforts. Comparative anatomy aids in identifying key characteristics that are essential for the survival of a species. This knowledge is important for making informed decisions about conservation strategies and preserving biodiversity. Paleontology: Comparative anatomy is fundamental in the field of paleontology, where researchers study the anatomy of extinct organisms based on fossilized remains. By comparing these fossils to the anatomy of living organisms, scientists can gain insights into the evolutionary history and ecological roles of ancient species. Genetic Studies: Comparative anatomy complements molecular and genetic studies by providing a broader perspective on the relationships between organisms. Integrating anatomical comparisons with genetic data helps researchers build more comprehensive models of evolution and biological diversity. Education and Research: Comparative anatomy serves as a cornerstone in biology education. It provides students with a fundamental understanding of the principles of anatomy and evolution. Researchers continue to use comparative anatomy to investigate specific questions related to ecology, behavior, and the adaptive strategies of different organisms. IA Tela 6  Brief History Comparative Anatomy was first developed by Greek natural philosophers and physicians. It has had a rich interplay with Western culture since that time until the present. It can be traced back to the ancient Greeks who made scattered anatomical observations. The systematic study of the Comparative Anatomy of various types of animals began in earnest with the researches of the ancient Greek Aristotle. IA Tela 7  Pre-Aristotelian Greeks (500 BC) Although Aristotle was the first systematic comparative anatomist, he had predecessors who observed and remarked on the anatomy of man and other animals. Their observations derived variously from the testimony of seamen, fishermen, hunters, butchers, farmers, soldiers and surgeons, as well as from animal sacrifice and even cutting animals open for medical inspection. There are a few scattered examples of anatomical observations of animals among the earliest Greek physicians and natural philosophers from about 500 BC onward. Animals are cut-opened for further knowledge regarding the structure and function of the body. IA Tela 8  Pre-Aristotelian Greeks (500 BC) Xenophanes of Colophon: (560BC), Described the fossilized remains of small marine animals and plants embedded in rocks far from the sea and even on mountain tops in the 6th century.  Pre-Aristotelian Greeks (500 BC)… Alcmaeon of Croton (500 BC) was the first to cut open the animal body for purposes of naturalistic research.  Pre-Aristotelian Greeks (500 BC)… Plato of Athens (427–348 BC): A Greek philosopher, Wrote a cosmological treatise entitled “Timaeus”, which includes important sections on the creation and anatomical structure of man, woman and animals of air (birds), land (footed and footless) and water (fish and shellfish).  Pre-Aristotelian Greeks (500 BC)… Democritus of Abdera (c. 460–400 BC), Compared fish to other (land) animals, reported that ‘common fish have no backbones (i.e. vertebrae)’. Authored the Hippocratic Medical tract on The Sacred Disease (c. 400 BC), Compared the brain of man to that of the domesticated farm animal (probata) or goat (aiges). Dissected the head of an epileptic goat to examine the pathological anatomy of animals other than man that are affected by the so-called sacred disease.  Aristotle of Stagira (384–322 BC) Aristotle of Stagira (384–322 BC): Wrote the first and most comprehensive treatises on comparative anatomy in antiquity, including the history of animals (HA), parts of animals (PA) and generation of animals (GA). conducted his animal research according to a scientific method; first, describing and classifying the phenomena of the objects under investigation (historia) and, second, inquiring into the underlying causes (aitia) of the phenomena described. He proposes that the best way to proceed with the comparative study of animals is to examine the parts of which they are composed, as ‘the parts of the body are not arranged in the same way in all animals, nor do all animals possess exactly the same parts’.  Aristotle of Stagira (384–322 BC)… Aristotle of Stagira (384–322 BC): He firstly studied the internal parts of animals other than man because of the difficulty accessing the internal anatomy of man. Second reason for the detailed comparative study of animals is the intellectual wonder and pure satisfaction that comes from studying the marvelous creatures constructed by nature. He mentioned 560 animal species altogether and investigated the anatomy of some 110 animals by means of dissection or vivisection, naturalistic observation and second-hand reports. He personally dissected 12 different species of mammals, 9 birds, 4 reptiles, 2 amphibians, 10 fish, an Ascidian, 7 molluscs, 3 arthropods, a sea urchin and a human fetus  Aristotle of Stagira (384–322 BC)… He provides a rough scheme of classification for comparing animals after, ✓ first, separating inanimate objects (apsycha) from plants which demonstrate the presence of the basic life (zôê) or soul (psychê) by sustaining and reproducing themselves (nutrition and generation) and, ✓ second, separating plants from animals by the addition of sensation (aisthêsis) and its corollary pleasure and pain to the basic functions of nutrition and reproduction. Aristotle’s first great division differentiates animals into two broad categories, the Blooded (enaima) and the Bloodless animals (anaima).  Post-Aristotle Philosophers After Aristotle, the epicentre of such research on anatomy soon passed from Athens to the Museum and Library in Alexandria, Egypt. At Alexandria, anatomical research was conducted by physicians and focused on the structure of man. Herophilus & Erasistratus Proposed a theory that sensation and voluntary motion were centred in the brain and conveyed to the body through at Alexandria.  Post-Aristotle Philosophers… Galen of Pergamum (AD 129–200/216). He wrote numerous anatomical treatises whose methodology. He developed sophisticated vivisection research methods such as ligaturing specific nerves in animals to observe the effect of the cut-off. He did detailed experiments on the branches of the vagus nerve, which goes from the brain down to the heart and loops back up. He discussed the anatomy of the monkey, urging that it could help physicians as human dissection was not permitted. Galen’s handbook in anatomy, the Anatomical Procedures, had been used for medical anatomy, but it was based on monkey dissections because Galen was not able to dissect humans in his culture.  Comparative Anatomy in the Middle Ages During Late antiquity and throughout the early and later Middle Ages of Europe, Greek and Latin, natural history encyclopaedias and compilations, medical commentaries, epitomes and practical handbooks replaced the kind of original scientific research that had been conducted by Aristotle, the Hellenistic anatomists and Galen. With the conversion of the Roman emperor Constantine (AD 306–337) to Christianity and the subsequent cultural dominance of the Christian religion, many of these later works adopted a distinctive Christian interpretive framework.  Comparative Anatomy in the Middle Ages… Ancient pagan texts in science and medicine were reworked in empirical sciences Christian scholars often from a Christian point of view to bring them into harmony with the Holy Scripture. Christian commentators interpreted the contents of the sciences allegorically or metaphorically to wring (twist) some religiously or morally significant message from them.  Comparative Anatomy in the Middle Ages… Hexaemeral literature was the Christian scientific and biological literature. It was a large corpus of commentaries and homilies, written by generations of Christian theologians, on the 6 days of creation (hexaemeron) as told in the Hebrew Bible’s Genesis. The hexaemeral writings provided material for priests delivering sermons to the church-going masses.  Comparative Anatomy in the Middle Ages… Physiologus is a second Christian biological and natural historical tradition literature and comprised of a natural history compilation. It consists of the descriptions of animals that probably originated in Christian Greek Alexandria during the second century (c. AD 140) from Greek, Roman and Egyptian nature writings, folklore, fables and myths. It was eagerly adopted by western European Christian culture and translated into Latin in the fifth century (c. AD 430) and later into many European languages. The standard Physiologus contains 49 chapters, each of which deals with a separate animal.  Comparative Anatomy in the Middle Ages… Ibn Rushd, (1126–1198 AD): A Spanish Muslim philosopher Averroes completed his commentary on the Arabic translation of the Aristotle’s parts of animals (PA) and generation of animals (GA).  Comparative Anatomy in the Middle Ages… Gersonides (Levi ben Gershom, 1288–1344): A prominent Provençal Jewish scholar completed his super- commentary on the Hebrew version of Averroes’ Arabic commentary in 1323.  Comparative Anatomy in the Middle Ages… Both works deal with Aristotle’s discussion of the two problems that arise in classifying all the animals i.e. I. the problem of enumerating all subjects (the animals) falling under the investigation at hand, and II. the problem of the proper order of study. The two Medieval commentators favour a process of classification and discovery that combines both rational and sensory methods. They come to the conclusion that the systemization of the animal kingdom cannot escape the need for observation to grasp knowledge of them.  Comparative Anatomy in the Middle Ages… Latin translations of Arabic and Hebrew works brought into Europe from the Arab world formed the basis for a revival of learned biology and medicine in the Latin West during the 12th and 13th century after stagnating for nearly a millennium. The first spark of a renaissance in Greco-Arabic learning occurred in Monte Casino and Salerno in Southern Italy.  Comparative Anatomy in the Middle Ages… The later Middle Ages there was rise of the European universities during this period fuelled the demand for such books. This movement also led to the direct recovery of Aristotle’s works on comparative anatomy. Michael Scot (AD 1175–1235): reproduced the first Latin translation of Aristotle’s major biological works from the Arabic by around 1220. Comparative Anatomy During the Renaissance and Scientific Revolution Theodoros Gaza of Thessalonica (1400– 1476), made Aristotle’s anatomical works more accessible by translating them from Greek into Latin and publishing a printed edition in Venice in 1476. A printed edition of Magnus’ De animalibus libri XXVI was published in Rome in 1478. During the 16th century, comparative anatomy became a significant topic of research that went beyond retrieving ancient knowledge to discovering new knowledge.  Post-Aristotle Philosophers… Andreas Vesalius: (1514–1564): De humani corporis fabrica (On the Fabric of the Human Body) in 1543, which contained beautiful and wonderfully detailed woodblock illustrations. Vesalius’ illustrations represented anatomical structures and relations that were difficult to convey by words alone. In the Fabrica, Vesalius points out the places where human anatomy differs from the details that Galen’s text reports on monkeys. Comparative Anatomy During the Renaissance and Scientific Revolution… He gave point-by-point comparison between the human and the monkey ushered in a new age for anatomical science by presenting anatomical differences at a high degree of precision and set the stage for further detailed monographs that gave written and illustrated accounts of the anatomy of different animals. Examples of this work include Pierre Belon’s (1517–1564) monograph on fish, L’histoire naturelle de poissons marins (1551), Conrad Gesner’s (1516–1565) massive four-volume encyclopaedia on animals, Historiae animalium libri IV (1551–1557), Thomas Moufet’s on insects, Insectorum sive minimorum animalium theatrum (London, 1634 ) and Ulissi Aldrovandi’s (1522–1605) voluminous series of monographs that included one on comparative teratology, Monstrorum historia Comparative Anatomy During the Renaissance and Scientific Revolution… William Harvey (1578–1657): He published his Motion of the Heart and Blood, which advanced a new theory that the animal heart pumps blood which circulates through the arteries back to the heart through the veins. It made an extensive reference to experiments in different species to demonstrate how the heart works. He departs from his predecessors with his claim that vivisection is a method of discovery and justification of new knowledge (scientia) and not merely a means of collecting and expanding upon the list of observational fact (historia). Comparative Anatomy During the Renaissance and Scientific Revolution… Antoni van Leeuwenhoek (1632–1723): was especially active at publishing anatomical discoveries made with the microscope. Comparative Anatomy During the Renaissance and Scientific Revolution… Robert Boyle (1627–1691): published on how to preserve anatomical specimens in glass containers with alcohol. The new preservation techniques allowed anatomical museums to go beyond laying out dry bone and shell specimens for consideration and comparison to doing this for vessels, nerves, muscles and internal organs.  Evolutionary Ideas and Comparative Anatomy Carolus Linnaeus (1707–1778): advanced a way of naming and describing all life forms that would give comparative anatomy a systematic language within which any given organism would have its place. He saw all living things as belonging to the plant or animal kingdoms, with the kingdoms being divided into orders, which were in turn divided into genera, which consisted of different species. He argued that any plant or animal should be given a twofold name that consisted of one Latin word for its genus and one for its species. Thus, called Father of Taxonomy.  Evolutionary Ideas and Comparative Anatomy… Comte de Buffon (1707–1788): critiqued Linnaeus’ approach in his Histoire Naturelle, in which he argued that Linnaeus was overly abstract with some of his grouping being mere conventions. Both Linnaeus and Buffon developed theories of quasi- evolution, in which two species might form a hybrid species or one original species might produce several new species.  Evolutionary Ideas and Comparative Anatomy… These ideas influenced Erasmus Darwin (1731–1802) as he developed a more involved theory of how one species can evolve into another.  Evolutionary Ideas and Comparative Anatomy… In 1719, Russia’s Czar Peter the Great established one of the first government-sponsored large public museums.  Evolutionary Ideas and Comparative Anatomy… John Hunter (1728–1793): used dissection and preservation techniques to create a collection of specimens that sought to lay out the anatomy and physiology of all animals that existed.  Evolutionary Ideas and Comparative Anatomy… Jean Baptiste Lamarck (1744– 1829): published a work called Zoological Philosophy in 1809, in which he argued that complex species evolved from simpler ones.  Evolutionary Ideas and Comparative Anatomy… Etienne Geoffroy Saint-Hilaire (1772–1844): carried the theory of evolution further with a book called Philosophical Anatomy. He claimed that different animals share a common anatomical plan and use a given part altered in evolution in different animals a primary objective for identification in comparative anatomy. He also used a comparison of the parts’ connections, the examination of fetuses and the study of developmental malformations as methods of comparing the anatomy of different species and uncovering any underlying unity.  Evolutionary Ideas and Comparative Anatomy… Johann Goethe (1749–1832): in Germany developed an approach to studying morphology and explored the possibility of evolution.  Evolutionary Ideas and Comparative Anatomy… Georges Cuvier (1769–1832): was highly critical of Lamarck’s account. He offered an exhaustive exploration of animal morphology and argued that the animal body can be seen as having two types of functions, the ‘Animal functions’ which are executed by the neuromuscular system that lets the organism move around the world, and the ‘Vital functions’ which are executed by the internal organs that maintain the animal’s basic life.  Evolutionary Ideas and Comparative Anatomy… Henry Gray: in 1858 published the Anatomy textbook that would become the book of choice in schools and hospitals for human medicine (Gray’s Anatomy), first established his reputation by winning an essay on the comparative anatomy of optic nerves.  Evolutionary Ideas and Comparative Anatomy… Richard Owen (1804–1892): sorted through the anatomical collection of John Hunter, promoted the use of a new term, ‘homology’ for the anatomical analogies Geoffroy had found in different species.  Evolutionary Ideas and Comparative Anatomy… Robert Chambers (1802– 1871):Published an article called Vestiges of the Natural History of Creation. Chambers’ work emphasized the evidence for the fact that evolution has occurred.  Evolutionary Ideas and Comparative Anatomy… Charles Darwin’s (1809–1882): wrote on Origin of Species convinced many scientists that evolution occurs by a process he called natural selection. He argued that all presently living beings can be traced back to between 1 and 10 organic progenitors.  Evolutionary Ideas and Comparative Anatomy… Sigmund Freud: fully immersed himself in evolutionary neurology and in 1879 published a paper on the spinal ganglia and cord of a species of lampreys  Evolutionary Ideas and Comparative Anatomy… Willi Hennig (1913–1976): worked on mosquitoes and other invertebrates, published a work Foundations of a Theory of Phylogenetic Systematics, which sought to revolutionized comparative anatomy by putting it on a more rigorous foundation grounded in the epistemology of logical empiricism.  Evolutionary Ideas and Comparative Anatomy… Thomas Kaufman and Rudolf Raft (1983): published a monograph on the study of embryos, genes and evolution. During the 1990s, advances in techniques for studying molecular developmental genetics increased the interest in the study of the interplay between developmental biology and evolution.  Evolutionary Ideas and Comparative Anatomy… In 2000, the Society for Integrative and Comparative Biology formed a Division of Evolutionary Developmental Biology.  Ways to Study Comparative Anatomy Comparative Embryology/Embryogenesis Gross morphology Comparative histology & Molecular genetics Fossils IA Tela 50 COMPARATIVE EMBRYOLOGY OR EMBRYOGENESIS IA Tela 51  The History of Comparative Embryology… However, in 1672, Marcello Malpighi published the first microscopic account of chick development. For the first time, the neural groove (precursor of the neural tube), the muscle-forming somites, and the first circulation of the arteries and veins—to and from the yolk—were identified  The History of Comparative Embryology… With the discovery of Malpighi, there begin one of the great debates in embryology whether the organs of the embryo are formed de novo (“from scratch”) at each generation (epigenesis), or whether the organs are already present, but in miniature form, within the egg (or sperm), (preformation). The epigenesis was supported by Aristotle and Harvey while the preformation was reinvigorated with support from Malpighi, who showed that the unincubated chick egg already had a great deal of structure. According to the preformationist view, all the organs of the adult were prefigured in miniature within the sperm or (more usually) the egg, therefore, organisms were not seen to be “developed,” but rather “unrolled.”  The Four Principles of Karl Ernst von Baer Karl Ernst von Baer made observations on the embryos of many species and noted marked similarities, or homologies, in the development of all vertebrates. He formulated four (4) principles of comparative embryology. i. general features appear before specialized features. ii. general features progressively develop into more specialized features. iii. embryos of more evolved/advanced animals diverge more and more from those of more primitive animals. iv. embryos of higher animals resemble the embryos, but not the adults of more primitive animals. Von Baer’s work was later used by Charles Darwin to support his theory of evolution. Comparative Embryology/Embryogenesis Embryogenesis is a developmental process that usually begins once the egg has been fertilized. It involves multiplication of cells (by mitosis) and their subsequent growth, movement, and differentiation into all the tissues and organs of a living organism. Comparative embryology is the comparison of embryo development across species. All embryos pass from single cells to multi-celled zygotes, clumps of cells called morulas, and hollow balls of cells called blastulas , gastrulas, before they differentiate, creating the organs and systems of the body. IA Tela 55  Comparative Embryology/Embryogenesis… This could give evolutionary trend between different species e.g., Sea urchins, frogs, humans etc that similar at early development. The middle layer of gastrula gives rise to excretory system in all animals e.g. Sea urchins, Coelenterates, frogs, and kidneys in human. In higher animals it give rise to the blood, muscles and bones. The ectoderm gives rise to the outer covering of all animals, and in the frogs, humans and higher animals it gives rise to nervous system. IA Tela 56  Gross Morphology One of the most important goals of evolutionary biology is to better understand the diversity of organismal body forms that exist in nature, and how these body forms relate to the organism’s ecology and life history. It involves the use of many physical features on the outsides of the body of the animal body. For instance, humans have four limbs each with five digits, two forward facing camera eyes, and a mouth full of teeth of different shapes compared to fruit flies have six limbs plus two wings, two compound eyes, and a proboscis for a mouth.  Gross Morphology… Also, although the limbs of vertebrates have diverged functionally into the wings of bats, the arms of humans, the forelimbs of reptiles and the fins of whales, they are nevertheless homologous. The general skeletal structure is similar in each, despite large differences in individual bone size and shape. However, the fruit flies do not have any limbs. IA Tela 58  Comparative Histology & Molecular genetic This involves study of cells and tissues. It also involves the study of cells at molecular level and genetic makeup of an organism and look for their differences which provides clues to their evolutionary lineage. Animals are composed of cell types that are specialized for functions as diverse as nutrient uptake, contraction, light perception and hormone secretion. It involves the use of light and electron microscopy techniques to identify homologous cell types between closely related species. IA Tela 59  Comparative Histology & Molecular genetic… For example, it was found that the surface-enlarged, light-sensitive cilia of ciliary photoreceptors in humans and worms harbour orthologous opsins, and that the stripes of striated muscle cells in various animals are composed of the same cytoskeletal proteins which is indicative of homology.  Fossils Fossils are the preserved remains or traces of animals, plants, and other organisms from the past. It ranges in age from 10,000 to 3.48 billion years old. The fossils vary in size from microscopic, like single-celled bacteria, to gigantic, like dinosaurs and trees.  Fossils… Fossils, constitute the morphological, or anatomical, record. By comparing the anatomies of both modern and extinct species, paleontologists can infer the lineages of those species. This approach is most successful for organisms that had hard body parts, such as shells, bones or teeth. The resulting fossil record tells the story of the past and shows the evolution of form over millions of years. Fossils are the preserved remains or traces of animals, plants, and other organisms from the past.  Fossils… The totality of fossils, both discovered and undiscovered, and their placement in fossiliferous (fossil-containing) rock formations and sedimentary layers (strata) is known as the fossil record. Trace Fossils consist of the marks left behind by the organism while it was alive, such as footprints or feces. It is also called ichnofossils  Fossils… Past life may also leave some markers that cannot be seen but can be detected in the form of biochemical signals; these are known as chemofossils or biomarkers.  Principles of Comparative Anatomy Symmetry & Segmentation Cephalization Body plans IA Tela 65