6 July 2020- What is Biology?- Part 2

OTHER AREAS OF STUDY

Although the categories from yesterday represent the major subdivisions of biology, there are many other research areas. Some are based on life in specific environments. Marine biology, for example, looks at many aspects of ocean life, whereas soil biology focuses on organisms and processes occurring in soil.

Many other scientific disciplines also require knowledge of biology. For example, biochemistry, a subdivision of organic chemistry, focuses on subcellular chemical processes and requires a solid foundation in cell biology.

HISTORY

No one knows precisely when humans first began to acquire knowledge of the natural world. Most experts believe that humans had been domesticating many animals and cultivating crops long before written records were kept. The earliest records show that the Assyrians and Babylonians had some knowledge of agriculture and medicine as early as 3500 bc. By 2500 bc this knowledge was widely applied by the major civilizations of China, Egypt, and India.

THE GREEKS AND NATURAL LAW

The early Greeks were the first to formally investigate and describe the natural world. The concepts of cause and effect and that of a natural law that governs the universe were proposed around 600 bc. Some 200 years later, the Greek physician Hippocrates observed among other things the effect of the environment on human nature.

In the mid-4th century bc Aristotle presented the first system for classifying animals based on similarity of structure and function. His student Theophrastus drew up a scheme for classifying many of the plants. The writings of Galen, a Greek physician who lived in Rome during the 2nd century ad, influenced medicine for hundreds of years.

THE MIDDLE AGES

During the Middle Ages (roughly ad 500–1400), the center of biological studies shifted from Europe to the Middle East. The Islamic scholar al-Jahiz expanded on the observations of the Greeks. His multi-volume Book of Animals, discussed a variety of topics, such as the relationships among different animal groups and animal mimicry. The writings of the Persian physician Avicenna (Ibn Sina), based on the observations of Aristotle, helped revive European interest in biology.

A REBIRTH OF SCIENTIFIC LEARNING

Major biological advancements were made in Europe during the Renaissance (about ad 1300 to 1650). The serious study of anatomy emerged in the 1500s through the efforts of Leonardo da Vinci and Andreas Vesalius, who documented the relationships between the anatomies of humans and of other animals. Advances in anatomy and physiology were made by means of dissection of organisms during the 16th and 17th centuries.

Prior to the 16th century, it was commonly believed that organisms such as flies and worms arose from mud or other inanimate substrates. Although some scientists had previously disputed this idea of spontaneous generation, the concept remained untested. In 1668 the Italian physician Francesco Redi was the first to challenge the concept using a set of controlled experiments.

Interest in botany also increased during the 16th and 17th centuries. Numerous papers published by botanists such as Otto Brunfels of Germany and Gaspard Bauhin of Switzerland discussed horticulture and other plant-related topics.

DEVELOPMENT OF THE MICROSCOPE

The invention and development of the microscope in the 1600s generated an explosion of interest in biological studies. The value of this important new research tool was phenomenal. Unsuspected processes and organisms unknown to science were discovered in a flurry of biological investigation. Anthony van Leeuwenhoek reported his observations of single-celled animal-like creatures (protozoa) invisible to the naked eye. He subsequently observed spermatozoa, leading to new questions and interpretations of the male role in fertilization and reproduction. The concept of cells was introduced in 1665, when the English physicist Robert Hooke reported on the presence of tiny compartments in tissue he was studying under a microscope. Hooke named the compartments “cells.” Marcello Malpighi used the microscope to observe and describe many microscopic structures, including red blood cells. Many other contributions to biology were made during this period as a result of discoveries in this previously unseen microscopic world. 

BIOLOGICAL CLASSIFICATION

The publication in the 1750s of Carolus Linnaeus’ biological classification scheme for organisms was a major advance in biology. Linnaeus was one of the first taxonomists to organize living things in a simple and logical manner, using a system of binomial nomenclature (two-part names) that appealed to most scientists. The Linnaean system indicates both the degree of similarity and difference among species, and it persists today as the basis for naming living things.

EVOLUTIONARY THEORY

New biological theories developed rapidly during the 18th and 19th centuries and challenged many old ideas. The British naturalist Charles Darwin published his theory about evolution in the book On the Origin of Species by Means of Natural Selection (1859). Darwin’s ideas centered around observations he had made in the Galápagos Islands, an archipelago off the coast of Ecuador. Another British naturalist, Alfred Russel Wallace, made similar observations about animals in Indonesia, and the research of both scientists was presented simultaneously to their peers. Although Darwin’s efforts received wider attention, Wallace’s observations about the geographic distribution of plants and animals remain vital in modern studies of evolution.

The concept of natural selection and evolution revolutionized 19th-century thinking about the relationships between groups of plants and animals and about speciation (the origin of new species). Darwin provided sound scientific reasoning for the wealth of biological variability and similarity that exists among living things. Although genetics and the mechanisms of inheritance were unknown during Darwin’s time, he noted that certain life forms were more likely to survive than others, and proposed that this was influenced by variable traits (such as beak size in birds) that were passed from parents to offspring. This concept of natural selection provided the first scientific explanation of the variations observed in nature. Darwin also proposed that new species are formed—and others become extinct—by a gradual process of change and adaptation made possible by this natural variability. Although Darwin’s ideas provoked tremendous controversy, they influenced biology more than any other concept and today are generally accepted by the scientific community.

MECHANISM OF HEREDITY

The mechanism that produced the heritable variation needed for natural selection was discovered in the mid-19th century by Gregor Mendel. An Austrian monk interested in plant breeding, Mendel’s experiments with garden peas revealed that the peas inherited characteristics from their parents in a mathematically predictable fashion. His findings introduced the concept of the gene as the unit of inheritance, or heredity. Although Mendel published his results in 1866, the significance of his studies remained obscure until 1900. The rediscovery of Mendel’s work and the discovery of chromosomes in the early 20th century spurred development of studies of genetics and heredity and strengthened science’s understanding of evolution.

MODERN DEVELOPMENTS

During the 20th century biology changed from a predominantly descriptive science to one keenly founded upon experimentation and deductive reasoning. Such discoveries as the use of antibiotics to treat infectious disease and insulin to treat diabetes as well as increased knowledge about cell development were among the many important advances made over the past 100 years or so. A key turning point in biology was the discovery in 1953 of the structure of DNA and the subsequent unraveling of the genetic code of life. These discoveries aided science’s understanding of genetic diseases in plants and animals and allowed for unprecedented discoveries in molecular biology. Advances in the technology for copying and manipulating DNA ushered in the age of biotechnology with practical applications in agriculture, industry, and medicine. It also enabled efforts to decipher the entire genetic code (genome) of many organisms. As genetic sequencing became faster and less expensive, it spurred biological research in such areas as the study of gene expression and function in biological processes.

Some developments had negative effects on the natural world, however. Increased urbanization and industrialization destroyed many habitats and threatened the existence of countless species, while pollution and the emergence of new infectious diseases such as AIDS endangered public health.

The growth of biotechnology also raised concerns over its potential hazards to health and the environment and the need to monitor and regulate its use.

That's it for today. Tomorrow, we will look at chemistry, in a two-parter (At least, it might be a two-parter!). Until next time, stay curious, and stay sciencey!