|The life sciences encompass all fields of scientific investigation of living organisms and living processes. The pursuit of life sciences may be described as the application of all of human\'s scientific disciplines to the elucidation of the processes behind life itself. The fields of medicine and agricultural science are applied life sciences, while large areas of geology and chemistry involve the study of the influence of life upon non-living matter.
Prehistoric man, no doubt, had an understanding of living organisms which enabled him to hunt, gather and domesticate those animals and plants which were of use to him. The earliest written records, such as Egyptian papyri from around 1500 Â BCE, indicate a degree of knowledge about diseases of man and animals, and the preservative and medicinal properties of particular herbs. The Chinese had developed a structured system of medicinal herbs (some of which are today proving useful in Western medicine) by 2800 Â BCE, and were using the silkworm for the large-scale production of silk. The Hindus in India had developed their own system of herbal medicines, and were knowledgeable about a variety of medical subjects, especially anatomy. However, it appears that the pre-Greek civilizations collected their knowledge of living processes primarily because the knowledge could be applied to medicine and agriculture. Furthermore, they believed that natural phenomena were the result of supernatural powers and were therefore often beyond human understanding. The ancient Greeks were the first to search for rational explanations for life; their ideas were based on a mixture of observation, guesswork and superstition, and focused on the question of what separated life from non-living matter, but came to dominate the development of Western science for over a millennium. Thales of Miletus, in the 7th century Â BCE, postulated that all living things were composed of water. This idea was expanded by his student Anaximander, who put forward the idea that life was composed from special mixtures of the four elements (fire, earth, water and air). The Greek philosopher who dominated the study of life was Aristotle (384-322 Â BCE), who made extensive observations of the living kingdom, classifying and dividing. Aristotle\'s philosophy was based on his belief that all living processes had a final cause or purpose.
After the decline of the ancient Greek civilization, the ideas of the Greek philosophers were developed by the Arabs, while science lay dormant in the West. When the Renaissance arrived, Western science was stimulated by the spread of academic ideas and the use of paper and then printing. A questioning environment developed and philosophers were encouraged and patronized by the wealthy; scientific societies, such as the Royal Society in England (founded in 1662), were established for debate between the learned; technical advances, especially the development of the microscope, enabled new fields of inquiry to be opened. Systematic approaches to classification and comparison clarified much existing knowledge, and new ideas were put forward by scientific philosophers which for the first time challenged the dominance of Greek philosophy.
In the 18th and 19th centuries, the progression of the life sciences continued to accelerate, stimulated by expeditions to the New World, such as those made by Captain Cook to Australasia (1768-79) and by Charles Darwin to South America in the 19th century. In the 20th century, progress continued as technology enabled the investigation of the genetic make-up of living organisms and the ultrastructure of their cells. Ecology has developed as a major new field of life science and has thrown new light on many older fields. The development of the life sciences continues and the systems which are studied grow increasingly complex along with the techniques used. However, the philosophical questions are little changed. RB
See also abiogenesis; biogenesis; biology; botany; science; scholasticism; zoology.Further reading John Bernal, Science in History; , Charles Singer, A Short History of Scientific Ideas.