It is human nature to be curious about the things around us. More importantly, humans have always been interested in other living beings, especially animals. Zoology is the scientific approach to studying animals. It is related to biology, as it studies the structure and physiology of animals, as well as all other aspects of their lives. From cavemen hunting those that were seen as prey animals, to the modern-day study, humans have always seen the differences and similarities in animals.
Even as early as 400 B.C., people began classifying animals into groups and studying how they reproduced differently as well as their habitats. Aristotle was the first to be recognized doing this, observing development of various species of animals. He made note of asexual and sexual reproduction, the similarities in embryos from different species and that even dissimilar structures may have comparable functions. He wrote the Historia Animalium describing animals of Greece and Asia Minor.
Pliny the Elder, in Roman times, wrote his 37-volume Historia Naturalis, including four volumes of zoology. Unfortunately there was little fact and more myth in this book. However, a Greek physician named Galen, dissected farm animals, monkeys and other mammals and was able to accurately describe many features, even though some that were applied to humans were incorrect. His ideas involving the movement of blood were inaccurate though many people believed it for hundreds of years. Not until the 17th century did an English physician, named William Harvey, establish the truth of blood circulation.
The 12th century German scholar St. Albertus Magnus reintroduced the work of Aristotle. Leonardo da Vinci did anatomical studies that were quite advanced for the age in which he lived. He dissected and compared human and animal structure and noted similarities, though he was not recognized for this in his time. Andreas Vesalius became known as the father of anatomy as he circulated his writings and set the principles for comparative anatomy.
In the 1700s, Carolus Linnaeus (sometimes called Carl Linnaeus or Carl von Linne) created the binomial nomenclature using the genus name followed by species name. He also developed the system of classifying organisms using Kingdom, Class, Order, Genus, and Species and was the originator of the male and female symbols used today. The word "cell" began being used in the 17th century by Robert Hooke, but not until 1839 did Matthias Schleiden and Theodor Schwann prove the cell is the common structural unit found in all living things.
The 1800s brought about Charles Darwin’s theory of evolution through natural selection. He is considered the father of evolutionary theory. His five year voyage of the Beagle in the 1830s is his most famous, as he was able to observe living things of South America and Australia. Then in 1838 he created his theory of evolution by natural selection after studying the transmutation of species. Though he mostly kept this theory to himself, in 1858 Russel Wallace came up with a similar theory and this led to Darwin publishing his The Origin of Species by Means of Natural Selection in 1859.
With modern zoology, genetics has been developed after discovery of genes which control hereditary factors for all living things. Ecological studies have been conducted to show how organisms interact with their environment. Cytology studies of cells in living beings and genetics has become easier with technology. From these developments, zoology has branched to include paleontology, ethology, behavioral ecology, animal physiology, and even disciplines that are specific to different species such as mammalogy and herpetology. Some studies include evolutionary and molecular biology. It is quite amazing that humans went from simply noticing prey animal habits in order to hunt properly, to discovering cells, genetic makeup, and how some animals changed over time. As humans advance, so will their understanding of the world around them and how everything came to be as it is.