Zoology or animal biology is the branch of biology that studies the animal kingdom, including the structure, embryology, evolution, classification, habits and distribution of all living and extinct animals and how they interact with their ecosystems.
The history of zoology traces the study of the animal kingdom from antiquity to modern times. Although the concept of zoology as the only coherent field emerged much later, zoological sciences arose from natural history dating back to the works of Aristotle and Galen in the ancient Greco-Roman world. This ancient work was developed in the Middle Ages by Muslim doctors and scholars like Albertus Magnus. During the Renaissance and early modern times, zoological thought was revolutionized in Europe by a renewed interest in empiricism and the discovery of many new organisms. Vesalius and William Harvey, who used experimentation and careful observation in physiology, and naturalists like Carl Linnaeus and Buffon, began to classify the diversity of life and the fossil record as well as the development and behavior of organisms. Microscopy revealed the previously unknown world of microorganisms, laying the foundation for cellular theory. The growing importance of natural theology, partly as a response to the emergence of mechanical philosophy, stimulated the growth of natural history (though it rooted the design argument).
During the eighteenth and nineteenth centuries, zoology became an increasingly professional scientific discipline. Explorers-naturalists like Alexander von Humboldt investigated the interaction between organisms and their environment, and the ways in which this relationship depends on geography, laying the groundwork for biogeography, ecology, and ethology. Naturalists began to reject essentialism and to consider the importance of extinction and the mutability of species. Cell theory provided a new perspective on the fundamental basis of life.