Timeline of Major Discoveries in Biology

Aristotle classified animals into species based on those that had red blood cells and those that did not. The animals with red blood were mostly vertebrates, while the “bloodless” animals were labeled cephalopods. Despite the relative inaccuracy of his hypothesis, Aristotle’s classification was regarded as the standard system for hundreds of years. This is important to biology because it shows how people perceived animals and it helped people understand them.

French physician, writer and translator Charles Estienne published "De Dissectione partium corporis humani libri tres." It would have been the first work to show detailed illustrations of dissection in serial progression, the first to discuss and illustrate the total human body, instructions how to mount a skeleton and the first to set the anatomical figures in a fully developed panoramic landscape. Estienne affected biology by showing us the basic knowledge about humans and the human anatomy.

Girolamo Fracastoro, (born c. 1478, Verona, Republic of Venice, Italian physician, poet, astronomer, and geologist, proposed a scientific germ theory of disease. He is best known for Syphilis in his book "Syphilis sive morbus Gallicus" in 1530. He named the disease, Syphilis. He made an intense study of epidemic diseases. he provided the medical justification for the removal of the council to the papal state of Bologna by pointing out the danger of plague in the north Italian town of Trent.

Fracastoro stated that each epidemic disease is caused by a different type of rapidly multiplying minute body and that these bodies are transferred from the infector to the infected in three ways: by direct contact, by carriers such as soiled clothing and linen, and through the air. Fracastoro's statement was the first scientific statement of the true nature of contagion, infection, disease germs, and modes of disease transmission. This helped us understand germs and diseases and their causes.

Dutch spectacle makers, Zaccharias Janssen and his father Hans started experimenting with lenses. They put several lenses in a tube and made a very important discovery. The object near the end of the tube appeared to be greatly enlarged, much larger than any simple magnifying glass could achieve by itself. They had just invented the compound microscope (which is a microscope that uses two or more lenses). This invention led to the further discoveries of cells and cell structures.

The cell was first discovered and named by Robert Hooke in 1665. He remarked that it looked strangely similar to cellula or small rooms which monks inhabited, thus deriving the name. However what Hooke actually saw was the dead cell walls of plant cells (cork) as it appeared under the microscope. The cell walls observed by Hooke gave no indication of the nucleus and other organelles found in most living cells. This ignited the spark of the cell theory discovery.

The first blood transfusion involving a human being is performed. What is not in dispute is the year, 1667, and the patient – a 15 year old boy who had been bled so much by his doctor that he required an infusion of blood. The source is also not under dispute: Whoever the physician was, he used a sheep's blood. And, somehow, the kid recovered. This inspired more human blood transfusions which eventually led to saving people's lives, and is still used today to help people recover.

Redi went on to do another experiment, this time placing fresh meat in two different jars once again, but one jar was left open while the other was covered with a cloth. Days later, the open jar contained maggots, whereas the covered jar contained no maggots. He did note that maggots were found on the exterior surface of the cloth that covered the jar. Redi successfully demonstrated that the maggots came from fly eggs and thereby helped to disprove spontaneous generation.

In 1668, Francesco Redi, an Italian scientist, designed a scientific experiment to test the spontaneous creation of maggots by placing fresh meat in each of two different jars. One jar was left open and the other was closed with a lid, the jar that was open contained maggots and flies but the closed one contained nothing but the meat. People then argued that there were no maggots in the closed jar because air couldn’t get it.

Anton van Leeuwenhoek built a simple microscope with one lens and used it to examine blood, yeast, insects, etc. He invented new methods for grinding and polishing microscope lens that allowed for up to 270 diameters magnitude. He was the first to observe bacteria and protozoa. His researches on lower animals refuted the doctrine of spontaneous generation, and his observations helped lay the foundations for the sciences of bacteriology and protozoology.

In 1674 he likely observed protozoa for the first time and several years later bacteria. Those “very little animalcules” he was able to isolate from different sources, such as rainwater, pond and well water, and the human mouth and intestine. He also calculated their sizes. Started research in microorganisms through the idea of a single celled organism.

Edme Mariotte hypothesizes that plants obtain nourishment from air and water as well to make energy. This is important because it paved the way to developing the definition of photosynthesis. From his studies of plants, he concluded that they synthesize materials by chemical processes that vary from plant to plant—a theory verified long after his time. He also observed the pressure of sap in plants and compared it to blood pressure in animals.

Gesner, Belone and Aldrovandus classified the animals in a little different way than that of Aristotle. John Ray was the first naturalist to give the modern concept of species and tried to classify the animals. He published Quadrupeds and Reptiles in 1693 and divided the two classes based on toes covered with horny hoofs and toes having only nails. He classified the living things based on structure. This approach was most important as compared with the approach of his predecessors.

In 1735, Carl Linnaeus published his Systema Naturae, which contained his taxonomy for organizing the natural world. Linneaus proposed three kingdoms, which were divided into classes. From classes, the groups were further divided into orders, families, genera and species. Another rank beneath species distinguished highly similar organisms. A modified version of the Linnaean classification system is still used to identify and categorize animals and plants today.

When identifying an object, Linnaeus first looked at whether it was animal, vegetable, or mineral. These three categories were the original domains. Domains were divided into kingdoms, which were broken into phyla–animals and divisions–plants and fungi. Phyla or divisions were broken into classes, which were divided into orders, families, genera and species. Species were divided into subspecies. In botany, species were divided into varietas (singular: variety) and forma (singular: form).

Edward Jenner is well known around the world for his innovative contribution to immunization and the ultimate eradication of smallpox. Jenner's work is widely regarded as the foundation of immunology. In May 1796, Jenner encountered a young dairymaid, Sarah Nelms, who had fresh cowpox lesions. Using material from her lesions, Jenner inoculated James Phipps.

The child developed a mild fever and lost his appetite, but after ten days he was in good spirits. In July, Jenner inoculated the boy again, this time with fresh smallpox. No disease developed and Jenner concluded that protection was complete. He named this procedure variolae vaccinae (“smallpox of the cow”) which has been Anglicized and shortened today to “vaccination.”

Gideon Mantell and his wife made the unique discovery His wife took a walk one day and she passed a pile of broken rock on the roadside, she noticed an unusual object embedded in a piece of rock, She realized it was a fossil. The wife showed her husband. Mantell realized he has found the remains of an extinct giant reptile like an Iguana and named it the 'Iguanodon' meaning 'iguana tooth'. He shared his news in 1825. We learn how species have evolved with this discovery.

Cell theory, developed by Matthias Schleiden and Theodor Schwann, states that all organisms are composed of one or more cells, that cells are the fundamental unit of structure and function in all living organisms, that all cells come from preexisting cells, and that all cells contain the hereditary information necessary for regulating cell functions and for transmitting information to the next generation of cells. This is important because it became the definition of life in biology and science.

Rudolph Virchow built on the existing cell theory. He was one of the first to accept the work of Robert Remak, who showed the origins of cells was the division of pre-existing cells. He did not initially accept the evidence for cell division, believing that it occurs only in certain types of cells. He published Remak's work as his own. It is a rejection of the concept of spontaneous generation. This was significant to biology because it proved that cells only come from pre-existing cells.

The theory of evolution by natural selection is the process by which organisms change over time as a result of changes in heritable physical or behavioral traits. This allows an organism to better adapt to its environment, help it survive and have more offspring. Evolution by natural selection is one of the best substantiated theories in the history of science. This has helped us understand the theory of life and has become the foundation to genetics, immunology, and other biological sciences.

In 1861, Louis Pasteur developed a process for purifying milk, etc. He hypothesized that microbes come from cells of organisms on dust particles in the air, not the air itself. Pasteur put broth in several special S-shaped flasks that he made himself. Each flask was boiled and placed at various locations, warm and cold places, light and dark, inside and outside, etc. The special shape of the flask was designed to trap dust particles containing bacteria.

it would do this by leading them down the tube leading to the flask in an ‘s’ shape. The dust particles containing bacteria were too heavy to be lifted above the bump leading to the flask, so they collected at the bottom of the tube. The broth did not turn cloudy, microbes were not found in it but there was dust collected at the neck of the flask. Pasteur’s flask let air in but kept microbes out. This proved that microbes travel on dust and only come from other microbes.

Gregor Mendel, through his work on pea plants, concluded that genes came in pairs and are inherited from each parent. Three Laws make up up the law of inheritance; law of segregation, independent assortment and dominance. His law shows that offspring are connected to their biological parents and ancestors. His work is well known for being the foundation of genetics in biology.

Eduard Strasburger was the first to provide an accurate description of the embryonic sac in gymnosperms and angiosperms along with a demonstration of double fertilization in the angiosperms. He set forth the basic principles of mitosis in his papers, and in each edition following it, he clarified and modified the description of the process until in the third edition, he enunciated one of the modern laws of plant cytology: that new nuclei can arise only from the division of other nuclei.

Strasburger devised the terms cytoplasm and nucleoplasm to describe the cell body and nucleus. Next, he showed that during fertilization in the flowering plants, the nucleus is the primary structure concerned in heredity. Walther Flemming was a German anatomist who had similar discoveries. He was the first to observe and describe the behavior of chromosomes in the nucleus during normal cell division in animal cells. Their work of cell division led to greater and further understanding of cells.

Edouard van Beneden discovered how chromosomes organized meiosis. He explained with Walther Flemming and Edward Strasburger, the facts of mitosis. Beneden's discovery is important because meiosis aids in genetics diversity. Beneden's discovery had an effect on biology because it gave us a better understanding on how offspring are connected to their parents. Plus a few extra features on meiosis but most importantly pairing and genetic recombination homologous chromosomes.

Ivan Pavlov became interested in studying reflexes when he noticed that dogs drool with the proper stimulus, such as food. In one of his experiments, Pavlov struck a bell whenever the dogs were fed. Since the bell was closely associated to food, after some time, the dogs would drool at the sound of a bell with no other stimulus. His discovery showed that environmental effects could eventually trigger a reflex. Pavlov’s work paved the way for a new, more objective method of studying behavior.

Theodor Boveri experimented with sea urchin eggs to demonstrate that individual chromosomes uniquely impact development. Since sea urchins can be fertilized with two sperm, he showed that daughter cells of the double union possess variable numbers of chromosomes. He found that the individual chromosomes would then possess different qualities. We learn more about how species get their genetics and what they are responsible for.

Walter Sutton worked with marine life forms and had also become familiar with the process of meiosis. In meiosis, the number of chromosomes is reduced by half in sperm and egg cells, with the original number being restored in the fertilized egg. Sutton stated that this association may constitute the Mendelian Law of heredity.
It correctly explains the mechanism underlying the laws of Mendelian inheritance by identifying chromosomes with the paired factors identified by Mendel’s laws.

Frederick Frost Blackman conducted research on plant physiology in particular photosynthesis. Blackman proposed the law of limited factors. According to this law when a process depends on a number of factors, its rate is limited by the pace of the slowest factor. His law of limiting factors determines the rate of photosynthesis and helped us to understand plants and their processes.

Katsusaburo Yamagiwa and Koichi Ichikawa conducted an experiment based on their research about cancer. The experiment involved applying coal tar to the skin of lab rabbits to prove that chemicals can cause cancer. He succeeded in producing cancerous growths in rabbits' ears after the repeated application of coal-tar. This has helped scientists discover that coal tar, tobacco, and asbestos are cancer causing agents, which has saved many people's lives from cancer by warning them of the risks.

Frits Zernike invented the phase-contrast microscope, an instrument that permits the study of internal cell structure without the need to stain and kill the cells. While studying the flaws that occur in some diffraction gratings because of the imperfect spacing of engraved lines, he discovered the phase-contrast principle. He noted that he could distinguish the light rays that passed through different transparent materials. This has made it possible to study living cells and cell division.

These experiments led them to propose a direct link between genes and enzymatic reactions, known as the one gene-one enzyme hypothesis. Beadle and Tatum's idea of one gene-one enzyme is the idea that each gene encodes a single enzyme. Scientists know now that this hypothesis is generally correct. This hypothesis was able to be proved, or somewhat proved, by other scientists. It gave a foundation or starting point for the link between genes and enzymes.

George Beadle and Edward Tatum were both scientists in the field of genetics but discovered the role of genes in regulating biochemical events within cells. In their 1940 experiment, they exposed moldy bread to x-rays, which caused mutations. In a series of experiments, they showed that these mutations caused changes in specific enzymes involved in metabolic pathways (a linked series of chemical reactions within a cell).

This Avery-MacLeod-McCarty discovery showed society that DNA contains our hereditary information. This was exciting news in the world of biology because scientists were beginning to understand DNA function and structure.

In 1944, Oswald Avery discovered that DNA carries a cell’s genetic material and can be altered through transformation. His experiment in 1940 involved injecting mice with a live yet harmless form of pneumococcus and with an inert but lethal form. Although expected to live, the mice died. With the assistance of Colin MacLeod and Maclyn McCarty, Avery was able to fix the problems in his experiment of 1944. This trio discovered that DNA is the substance that causes bacterial transformation.

Jonas Salk discovered and developed one of the first successful polio vaccines. The subjects of his experiment were resident children in institutions for the disabled. Salk tested vaccines for all three strains of polio, some in combination, and some on their own. Salk's experiment concluded that vaccine recipients produced antibodies to the virus type in the vaccine they were given. Salk's vaccine saved many people's lives. People were able to be protected from polio because of Salk's vaccine.

Francis Crick and James Watson discovered the chemical structure of DNA. They discovered that the structure of DNA was a double-helix polymer, or a spiral of two DNA strands, each containing a long chain of monomer nucleotides, wound around each other. According to their research, DNA replicated itself by separating into individual strands, each of which became the template for a new double helix.

Crick and Watson's discovery was publicly announced on April 25th, 1953. The article completely changed what people thought of biology and medicine and gave rise to modern molecular biology. Their discovery yielded ground-breaking insights into the genetic code and protein synthesis. Their discovery did not affect much in their time, but now it is used for many things such as genetic fingerprinting and modern forensics.

Robert H. Whittaker proposed the five-kingdom classification which is still commonly used today. All living organisms are divided into five kingdoms: Monera (small, single celled), Protista (single-celled eukaryotes), Mycota (Fungi), Metaphyta (Kingdom Plantae, eukaryotic multicellular plants), Metazoa (Kingdom Animalia, heterotrophic, eukaryotic multicellular). Whittaker’s five-kingdom classification made it easier for us to make predictions of life forms that are similar to one another.

A team of scientists were digging in an isolated spot in the Afar region of Ethiopia. Paleoanthropologist Donald Johanson spotted a small part of an elbow bone. He immediately recognised it as coming from a human ancestor. And there was more. It was immediately obvious that the skeleton was a momentous find, because the sediments at the site were known to be 3.2 million years old. It was the most ancient human ever found, and most complete. This discovery proved the theory of human evolution.

Chemoautotrophs are organisms that are able to fix inorganic carbon using a chemical energy obtained through the oxidation of reduced compounds. There has been an increasing knowledge that deep-sea vent chemoautotrophs display remarkable physiological and phylogenetic diversity. Genomic analysis also suggested that there are previously unrecognizable evolutionary links between deep-sea vent chemoautotrophs and important human/animal pathogens. They can be used to purify substances.

Luis Alvarez and his son's theory suggested that the extinction of 70% of all the species, even dinosaurs, called cretaceous- Paleogene extinction event was caused by an impact of a huge asteroid. This theory was argued 10 years after Alvarez died and other evidence was found. Later on, many scientists choose to accept the theory and put more research into it to help explain what happened. This theory gives us a sense of what could have happened before humans inhabited the earth.

The first approved gene therapy procedure was performed on four-year-old girl who was born with a rare genetic disease. She was immunocompromised and vulnerable to every infection. In the gene therapy procedure, doctors removed white blood cells from her body, inserted the missing gene, and then replaced the modified blood cells back into her bloodstream. This proved that gene therapy is possible and showed scientists how to perform the gene therapy.

Dolly the sheep was the first mammal to be cloned from an adult cell. Animal cloning from an adult cell is much more difficult than an embryonic cell. Scientists worked and worked and eventually produced Dolly. She was the only sheep born from 277 other attempts. Dolly was cloned from a cell that was taken from the mammary gland that came from a Finn Dorset sheep and an egg cell from Scottish Black face sheep. This Showed what scientists can do in the future with genetics.

The Human Genome Project published the draft sequence, which covers more than 90% of the human genome, and initial analysis of the human genome. The sequence shows the exact order of DNA's four bases (A, T, C, and G) along the human chromosomes and includes everything such as eye colour, height, and disease. This discovery opened the doors for replicating organs.

President Obama lifted Bush administration’s limits on human embryonic stem cell research and issued an executive order intended for advancement. Obama followed up with a statement prompting that this would not open doors to cloning for human reproduction. This was a huge win for scientists as it increases research opportunities with the potential of new discoveries.

In the near future, I think a cure for diabetes may be developed, or at least a better way to manage it. Scientists have been working with cell therapy and making artificial organs to replace the missing insulin-producing cells. This discovery would help many people affected by diabetes and may also affect the money companies make off of diabetes victims, blood testing strips and pumps are expensive.

This wouldn't exactly affect me directly, but it would affect my sister. She has type 1 diabetes and would improve her quality of life, and would also help her to save some of her money.

In my opinion, 1667 Blood, 1796 Immunization and 1915 Cancer are related and connected because in each of those events, people and/or animals are being tested and researched on to try and make a discovery and help prevent different diseases. 1667 Blood, a 15 year old boy was tested on with sheep's blood and then the first blood transfusion was made. 1796 Immunization, an 8 year old boy was injected over a series of several days and afterward a few months to cure smallpox.

The first protection against a infectious disease was made. 1902 Cancer, a rabbit was tested on to discover if chemicals can cause cancer and it was proven that it can cause cancer. All these different times in life have aided in new discoveries and prevention against very harmful diseases, as well as a practice that can help save lives.

The 3 that stand out to me, in my opinion are Blood (1667), Immunization (1796) and Cancer (1915). In my honest opinion these are the 3 that are the most significant discoveries because lives were changed during these events. We were able to take an amazing leap and save many many lives with these discoveries. Some people need blood transfusions every so often to be able to stay balanced and maintain a normal life. Many people do not believe in immunizations but there are many benefits to them

in the process. Without Edward Jenner who injected a young boy who had smallpox we may not have the same tools and information that we have today. Jenner saved that little boy's life and so many others because of the discovery he made and his work of perfecting a cure to an infectious disease. If Katsusabura Yamagiwa did not perform tests on a rabbit to cause skin cancer, we may not have discovered that coal tar, tobacco, and asbestos are cancer causing agents.

Without the information that Yamagiwa collected, many lives could have been lost to cancer that was caused by chemicals, and nobody would have known what was causing it for some time. There are so many dangerous diseases out there in the world and in my opinion I think without these 3 discoveries, many more lives would have been lost due to diseases that could have been treated through immunization and blood transfusions and chemically caused cancer.