In his 1898 science fiction novel, The War of The Worlds, H.G. Wells attributes the demise of the Martian invaders to the lowly bacterium. Yet the concept of an invisible yet microscopic adversary, potent enough to bring about the fall of an invincible aggressor had been around for a long time.
Around 100 BC, the Roman scholar Marcus Varro first postulated the existence of unseen organisms which spread disease, calling these animalcules. He suggested that these were so small that they would float in the air and enter the bodies of humans and animals through the nose and mouth. His insight however was not much noted, and it was not until a millennium later in 1025 that the Persian polymath Ibn Sina published the idea of contagion in his Canon of Medicine, proposing that certain ailments such as tuberculosis are transferred from subject to subject by some unseen vector.
One of the first epidemiologists was the Italian physician Girolamo Fracastoro, who suggested that epidemics are caused by the transfer of tiny spores which transmit the infection from host to host through direct contact and/or over long distances. His publication De Contagione relied on data from the transmission of syphilis and typhus.
The first experimental evidence for the existence of microorganisms came from work by the Dutch scientists and entrepreneur Antonie Phillips van Leeuwenhoek during the 1670s. He designed single-lensed microscopes with which he observed the animalcules first postulated by Varro almost 2000 years previously. His studies ranged from bacteria and blood cells, to muscle fibres and the flow of blood through capillaries. At this time the English natural philosopher Robert Hooke conducted his own studies on microbial life, which he published in his book Micrographia introducing the concept of the cell.
Up until the 19th century the scientific and medical community believed in the concept of spontaneous generation, whereby microorganisms spontaneously came into existence. This contentious point was finally debunked by the French microbiologist Louis Pasteur in 1860. He showed that boiled broths exposed to air but isolated by a filter remained sterile and free of microorganisms when compared to those exposed to air directly. This led to the development of pasteurisation which is used to this day in sterilising food for long term preservation. Pasteur also developed the principles of microbial fermentation and vaccination, making ground-breaking progress in disease prevention. He also created the first vaccines for rabies and anthrax.
These advances in microbiology paved the way for our understanding of the fundamentals of life itself. In the early 1800s, the Swede Karl Rudolphi and German Johann Link had managed to show that cells possessed definite structures with independent walls. This led to the development of cell theory by the scientists Theodor Schwann and Matthias Schleiden which stated that the cell is the most basic unit of life from which all living organisms are made, and which is created from pre-existing cells. Our understanding of cell structure and function improved during the mid-1800s with a knowledge of semipermeable membranes (which selectively allow certain molecules through) and the advent of colloidal chemistry (where molecules bind with water).
By 1869 the Swiss chemist Friedrich Miescher was trying to establish the nature of the proteins within white blood cells but instead it led to his discovery of the nuclein composed of an enigmatic substance. The first ground-breaking efforts into understanding its composition were made by the Russian chemist Phoebus Levene. He identified the three main components of the nucleotide bases as well as the carbohydrate components of ribose nucleic acid (RNA) and deoxyribonucleic acid (DNA). The groundwork was ready for the American and British molecular biologists James Watson and Francis Crick to propose the double-helix structure of the DNA molecule.
Today our understanding of DNA sequences and associated functions within the nuclei of cells is known as genomics. It has enabled the modern researcher to make progress in fields ranging from fertility, to battling cancers and fighting infections and diseases.
Since ancient times our societies have faced repeated attacks from the microscopic world in the form of epidemics and pandemics. The Justinian Plague of 541 AD cost the lives of half the people in Europe. Over the years however, progress in medical understanding and practice have helped mitigate the consequences. Initially progress was slow, but with the development of antibiotics in the early 1900s and anti-viral drugs more recently, we have become more successful in minimising the impact of such tragedies. Hopefully as our biological and pharmacological technologies and understanding improve further, we will may one day stay ahead of the next bacterium or virus to make its presence felt, and avoid the same fate as the Martians in H.G. Wells’ novel.
Little Einstein’s Corner - Soapy Water
With the recent epidemic, we have been told to wash our hands with soap. Why do we need to do this? The reason is that viruses are protected by a fatty or oily case, and soap breaks this so destroying the harmful bug. In our experiment we will see the difference soap makes.
You will need:
* Two small clear plastic water bottles with lids
* Two cups of water
* Half a cup of oil
* Washing up liquid
* A tablespoon
* A watch or timer
* A permanent marker
Using the marker, label one of the water bottles Oil+Water and the other Oil+Water+Soap.
Fill both bottles with a cup of water and then add a quarter of a cup of oil.
Seal the bottle marked Oil+Water with its cap and then add three tablespoons of the washing up liquid to the other bottle. Seal this one also.
Shake both bottles for about 30 seconds and then leave them both for 20 minutes.
Look at the bottles. The one with only oil and water has two separate liquid layers. This is oil floating on water.
The one with the soap is a single liquid made up of oil and water mixed into one. The oil has been broken up, as it would have been had it been surrounding a virus.