Biology

Introduction

For thousands of years scientists from different countries have been contributing important discoveries and ideas that shaped a modern science. This chapter looks at some important discoveries in the field of biology.

Where did it all begin?

Biology is the study of living organisms. People have been studying the plants and animals around them for thousands of years.  Many of the ancient civilisations were dependent on agruculture to sustain them. In order to develop agriculture, people had to know which plants were edible, which plants grew at certain times of the year and how to capture and train animals.  

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Thousands of years ago, there were no separate branches of science like there are today. For the people of the ancient civilisations, religion and science were one and the same thing. For example, in in some civilisations, people believed that the crops would only grow if the gods were happy. As civilisations began to develop, however, people began to look at the world differently. As this was happening, branches of science such as astronomy, physics, medicien, biology and chemistry began to emerge.

Some of the early scientists include Anaximander, a Greek philosopher, is credited with the first written work on natural science. Xenophanes was another scientist from Ancient Greece. He was one of the first people to record his observations of fossils. Fossils are traces of ancient plants and animals preserved in rock. Xenophanes believed the presence of fossils indicated that water has been present in the area at some point in the past.  A famous Ancient Greek doctor, Hippocrates, was the first person to observe and record that the human body contains different types of fluids.

The biological terms genus and species are Latin translations of Greek words first used by the Ancient Greek scientist Aristotle. The Ancient Greeks were not the only ancient people to make biological discoveries. The Ancient Arabs were also very advanced in their scientific thinking and copiled detailed medical encyclopaedias.  

The microscope was one of the most significant medical inventions and remains an important tool even today. A microsope is an optical instrument which allows scientists to see particles that are too small to be seen by the naked eye. The first microscope was invented by Hans Janssen and his son Zacharias in the sixteenth century. This first microscope was simply a tube with a magnifying glass on each end. It magnified objects to between three and nine times their actual size

Later, in the seventeenth century, the microscope was improved by the English scientist Robert Hook. After studying pieces of cork (plant tissue) under the microscope he noticed that they were all made up of units that he called cells.

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Anton van Leeuwenhoek also made further improvements to the microscope in the seventeenth century. He was the first scientist to describe some bacteria that he obtained from his own teeth, as well as some protozoans which he took from his local pond.

An eighteenth century scientist Carolus Linnaeus came up with a way of classifying all living things. We still use this classification system today.  The cell theory was officially formulated in the nineteenth century by German scientists Matthias Schleiden and Theodor Schwann. Cell theory states that:

• All living things are made up of cells
• All cells come from pre-existing cells
• The cell is the smallest form of life.

In 1859, Charles Darwin published his work called The Origin of Species. Modern understanding of the evolution of living things is based on Darwin's research and publications. According to Darwin's theory of evolution, living organisms change over the generations as a result of natural selection. Natural selection means that the forms of an organism that have best adapted to their environment are the ones that will survive and reproduce.

Louis Pasteur was a nineteenth century French biologist and chemist. He came up with the germ theory of disease stating that microorganisms are the cause of many diseases. In 1865, Gregor Mendel, an Austrian monk, published a paper on genetics. Mendel showed that the inheritance of the characteristics of living organisms follows particular laws, which were later named after him.

Scientists like Oparin, Miller and Urey came up with the theory of abiogenesis, which is the formation of living forms from non-organic (non-living) matter. These scientists recreated the environment of planet Earth when it was newly formed in a laboratory. When gases containing inorganic elements, like hydrogen, oxygen, nitrogen and carbon were heated with water and energised by electrical discharge or by UV radiation, they formed small organic molecules.

In 1953, scientists James Watson and Francis Crick  discovered the structure of the DNA molecule. DNA stands for Deoxyribonucleic Acid. DNA contains the genetic instructions for making living organisms. The discovery of the DNA molecule led to the development of new branches of science, such as genetic engineering. Genetic engineering is a technology used to genetically change living cells in order to make them produce new chemicals or perform new functions. Genetic engineering is used today in agriculture and to make medicines.

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