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150 BCE
Galen of Pergamon describes the human body (150 A.D.)
Galen had great expertise in anatomy, surgery, pharmacology and therapeutic methods. He is famous for bringing philosophy into medicine, although most of his philosophical works have been lost.(https://www.famousscientists.org/galen/) -
Jan 1, 1546
The Germ Theory of disease is published
The germ theory of disease states that many diseases are caused by microorganisms. These small organisms, invade humans, animals, and other living hosts. Their growth and reproduction within their hosts can cause a disease. The germ theory was proposed by Girolamo Fracastoro in 1546, the nature of this doctrine prevented them from understanding how diseases actually progressed, with predictable consequences.(https://en.wikipedia.org/wiki/Germ_theory_of_disease) -
Lamarck develops Hypothesis of evolution by means of acquired characteristics
In 1801 Jean-Baptiste Lamarck developed the hypothesis that physiological modifications acquired by an organism can be inherited by the offspring. He belived that If an organism changes during life in order to adapt to its environment, those changes are passed on to its offspring. Lamarck also believed that body parts that are not being used, are gradually disappearing. Eventually, people will be born without these parts.(http://necsi.edu/projects/evolution/lamarck/lamarck/lamarck_lamarck.html) -
The Voyage of the HMS Beagle
In 1831, Charles Darwin received an astounding invitation: to join the HMS Beagle as ship's naturalist for a trip around the world. Darwin filled dozens of notebooks with careful observations on animals, plants and geology, and collected thousands of specimens, which he crated and sent home for further study.(http://www.amnh.org/exhibitions/darwin/a-trip-around-the-world/ ) -
Alfred Russel Wallace published ideas of evolutionary processes
Wallace spent eight years in the Malay Archipelago, traveling along the islands, he collected biological specimens for his own research and to sale. The first of article, published in 1855, concluded with the assertion that “every species has come into existence coincident both in space and time with a pre-existing closely allied species." (https://www.britannica.com/biography/Alfred-Russel-Wallace) -
The Origin of species by means of Natural Selection is published
In 1859 Charles Darwin published On the Origin of Species by Means of Natural Selection. By 1872, the book had run through six editions, and it became one of the most influential books of modern times. He traveled around South America for five years as an unpaid botanist and by the time he returned, he had developed an outstanding reputation as a field researcher and scientific writer. (http://www.history.com/this-day-in-history/origin-of-species-is-published) -
Louis Pasteur refutes spontaneous generation
Louis Pasteur boiled a meat broth in a flask that had a long neck that curved downward.Nothing grew in the broths unless the flasks were broken open,showing that the living organisms that grew in such broths came from outside,as spores on dust, rather than spontaneously generated within the broth.(https://www.boundless.com/microbiology/textbooks/boundless-microbiology-textbook/introduction-to-microbiology-1/introduction-to-microbiology-18/pasteur-and-spontaneous-generation-205-5188/) -
Gregor Mendel publishes works on inheritance of traits in pea plants
Gregor Mendel, through his work on pea plants, discovered the fundamental laws of inheritance. He deduced that genes come in pairs and are inherited as distinct units, one from each parent. Mendel tracked the segregation of parental genes and their appearance in the offspring as dominant or recessive traits.(http://www.dnaftb.org/1/bio.html) -
Hardy and Weinberg independently develop the Hardy- Weinberg equation for determining allele frequencies in populations
Godfrey Hardy and Wilhelm Weinberg went on to develop a simple equation that can be used to discover the probable genotype frequencies in a population and to track their changes from one generation to another. This has become known as the Hardy-Weinberg equilibrium equation. In this equation (p² + 2pq + q² = 1), p is defined as the frequency of the dominant allele and q as the frequency of the recessive allele.(http://anthro.palomar.edu/synthetic/synth_2.htm) -
T. Hunt Morgan discovers sex-linkage
In 1910, American geneticist Thomas Hunt Morgan peered through a hand lens at a male fruit fly, and he noticed it didn't look right. With this white-eyed fly, he would later confirm the chromosome theory. In doing so, Morgan would also be the first person to definitively link the inheritance of a specific trait with a particular chromosome.(https://www.nature.com/scitable/topicpage/thomas-hunt-morgan-and-sex-linkage-452) -
Neils Bohr develops the Bohr model of atom structure
In 1913 Bohr proposed his quantized shell model of the atom to explain how electrons can have stable orbits around the nucleus. The motion of the electrons in the Rutherford model was unstable because, according to classical mechanics and electromagnetic theory, any charged particle moving on a curved path emits electromagnetic radiation so, the electrons would lose energy and spiral into the nucleus.(http://abyss.uoregon.edu/~js/glossary/bohr_atom.html) -
Frederick Griffith describes the process of transformation
Frederick Griffith, established that there was a transforming principle in bacterial genetics in a ground-breaking experiment, performed in 1928.For this study, Griffith used two strains of Pneumococcus bacteria, type III-S and type II-R. Blood sampling showed that the blood of the dead mice contained both live type III-S and live type II-R bacteria.(https://explorable.com/transforming-principle) -
Theodosius Dobzhansky publishes genetics and the Origin of Species
Theodosius Dobzhansky, a Russian geneticist who published a book named “Genetics and the Origin of Species” in 1937 It is regarded as one of the most important works of the modern evolutionary synthesis. The book popularized the work of population genetics to other biologists, and influenced their appreciation for the genetic basis of evolution.(http://www.pbs.org/wgbh/evolution/library/06/2/l_062_04.html) -
Beadle and Tatum publish the 1 gene- 1 enzyme hypothesis
The one gene–one enzyme hypothesis, proposed by George Wells Beadle in the US in 1941, is the theory that each gene directly produces a single enzyme, which consequently affects an individual step in a metabolic pathway. In 1941, Beadle demonstrated that one gene in a fruit fly controlled a single, specific chemical reaction in the fruit fly, which one enzyme controlled.(https://embryo.asu.edu/pages/george-w-beadles-one-gene-one-enzyme-hypothesis) -
Ernst Mayr develops the biological species concept
The biological species concept is the most widely accepted species concept. When two organisms breed within a species, their genes pass into their combined offspring. As this process is repeated, the genes of different organisms are constantly shuffled around the species gene pool. The shared gene pool gives the species its identity. (https://www.blackwellpublishing.com/ridley/a-z/Biological_species_concept.asp) -
Jacques Cousteau develops SCUBA
In 1943 Jacques Cousteau co-invented the Aqua-Lung, a breathing device for scuba-diving. Around this time, compressed air cylinders were invented and Jacques and Emile experimented with snorkel hoses, body suits and breathing apparatus. In time, they developed the first aqua-lung device allowing divers to stay underwater for long periods of time.(http://www.biography.com/people/jacques-cousteau-9259496) -
Avery, McLeod and McCarty determine that DNA is the molecule that carries the genetic code
In 1944, experiments by Oswald Avery, Colin MacLeod, and Maclyn McCarty showed that DNA can transform the properties of cells, clarifying the chemical nature of genes. They identified DNA as the "transforming principle" while studying Streptococcus pneumoniae, bacteria that can cause pneumonia.(http://www.genomenewsnetwork.org/resources/timeline/1944_Avery.php) -
Barbara McClintock describes transposons
Barbara McClintock’s studies of chromosome breakage in maize led her to discover a chromosome-breaking locus that could change its position within a chromosome. McClintock went on to discover other such mobile elements, now known as transposons. She also found that depending on where they inserted into a chromosome these mobile elements could reversibly alter the expression of other genes.(http://www.pnas.org/content/109/50/20198.full) -
Hershey- Chase experiments are published
In 1952, Alfred Hershey and Martha Chase published a demonstration stating that DNA was the genetic material not protein. The Hershey–Chase experiment was carried out with a virus, the virus was called bacteriophage T2, and it infects bacteria. (http://bcs.whfreeman.com/webpub/Ektron/Hillis%20Principles%20of%20Life2e/Animated%20Tutorials/pol2e_at_0901_The_Hershey-Chase_Experiment/pol2e_at_0901_The_Hershey-Chase_Experiment.html) -
Rosalind Franklin works with DNA and X-ray crystallography and develops "image 51"
Photo 51 is a fuzzy X -ray showing a strand of DNA taken from human calf tissue. This image was captured by an English chemist named Rosalind Franklin in 1952. This was the clearest shot of life's building blocks ever seen up to that point, and the first one that seemed to prove once and for all the double-helix structure of DNA.(http://www.livescience.com/2912-photo-51-changed-world.html) -
Watson and Crick propose the double helix model of DNA structure
The discovery in 1953 of the double helix, the twisted-ladder structure of deoxyribonucleic acid (DNA), by James Watson and Francis Crick marked a milestone in the history of science and gave rise to modern molecular biology, which is largely concerned with understanding how genes control the chemical processes within cells.The double helix has not only reshaped biology, it has become a cultural icon.(https://profiles.nlm.nih.gov/SC/Views/Exhibit/narrative/doublehelix.html ) -
Miller- Urey experiments published
The Miller-Urey experiment was an experiment that simulated hypothetical conditions present on the early Earth in order to test what kind of environment would be needed to allow life to begin. The experiment is considered to be the classic experiment on the origin of life. It was conducted in 1953 by Stanley L. Miller and Harold C. Urey at the University of (Chicago.http://www.juliantrubin.com/bigten/miller_urey_experiment.html) -
Meselson and Stahl work with DNA replication
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Nirenberg cracks the genetic code
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Endosymbiosis is described by Lynn Margulis
In the late 1960s Margulis studied the structure of cells.Mitochondria,for example,are wriggly bodies that generate the energy required for metabolism.To Margulis, they looked remarkably like bacteria. She knew that scientists had been struck by the similarity ever since the discovery of mitochondria at the end of the 1800s. (http://evolution.berkeley.edu/evolibrary/article/history_24) -
Theodosius Dobzhansky publishes "Nothing in Science Makes sense except in the light of evolution"
Theodosius Grigorevich Dobzhansky was a noted geneticist,and evolutionary biologist.His article which was published in 1973“Nothing in the science makes sense except in the light of evolution”has the meaning that seen in the light of evolution,biology is intellectually the most satisfying and inspiring science. Without that light it becomes a pile of sundry facts some of them interesting or curious but making no meaningful picture as a whole. (https://en.wikiquote.org/wiki/Theodosius_Dobzhansky) -
Australopithecus afarensis nicknamed "Lucy" fossil discovered
“Lucy” was the nickname of a partial skeleton discovered in 1974 by Donald Johanson in Hadar, Ethiopia. This relatively complete female skeleton, is the most famous individual from this species. Lucy was only about 110 centimeters tall but was a fully grown adult when she died. She was bipedal which means she could walk on two legs but she probably also spent a lot of time climbing trees in search of food or shelter. (https://australianmuseum.net.au/australopithecus-afarensis) -
Spliceosomes were discovered and described
A spliceosome is a large and complex molecular machine found primarily within the splicing speckles of the cell nucleus of eukaryotic cells. In 1977, work by the Sharp and Roberts labs revealed that genes of higher organisms are split or present in several distinct segments along the DNA molecule. The split gene structure was found when adenoviral mRNAs were hybridized to endonuclease cleavage fragments of single stranded viral DNA.(https://en.wikipedia.org/wiki/Spliceosome) -
The Sanger technique is developed
In 1977, Frederick Sanger developed the classical “rapid DNA sequencing” technique, now known as the Sanger method, to determine the order of bases in a strand of DNA.
Special enzymes are used to synthesize short pieces of DNA, which end when a selected “terminating” base is added to the stretch of DNA being synthesized. Frederick Sanger shared the 1980 Nobel Prize in Chemistry for his contributions to DNA-sequencing methods. (https://unlockinglifescode.org/timeline/11) -
Deep Sea hydrothermal vents and associated life around them are discovered
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Kary Mullis develops Polymerase Chain Reaction
Kary Mullis received a Nobel Prize in chemistry in 1993, for his invention of the polymerase chain reaction. A method of amplifying DNA, PCR multiplies a single, microscopic strand of the genetic material billions of times within hours. The process has multiple applications in medicine, genetics, biotechnology, and forensics. PCR,because of its ability to extract DNA from fossils, is in reality the basis of a new scientific discipline, paleobiology. (https://www.karymullis.com/biography.shtml) -
Tommie Lee Andrews is convicted of rape
Tommie Lee Andrews, 24 years old, was convicted of breaking into the home of a 27-year-old Orlando woman, raping and stabbing her on May 9, 1986. The woman identified Mr. Andrews during the trial as her attacker. Michael Baird, a senior scientist at Lifecodes, and David Houseman, a research biologist, testified that the DNA in the semen and in Mr. Andrews' blood matched. (http://www.nytimes.com/1988/02/06/us/rapist-convicted-on-dna-match.html) -
The Innocence project is founded
The Innocence Project is a non-profit legal organization that is committed to exonerating wrongly convicted people through the use of DNA testing and to reforming the criminal justice system to prevent future injustice. The Innocence Project was founded in 1992 by Barry Scheck and Peter Neufeld.(https://www.innocenceproject.org/about/) -
Dolly the sheep is cloned
Dolly the sheep was cloned at the Roslin Institute in Midlothian, Scotland, and lived there until her death when she was six years old. Her birth was announced on February 22, 1997. The sheep was originally code-named "6LL3". The technique that was made famous by her birth is somatic cell nuclear transfer, in which a cell is placed in a de-nucleated ovum, the two cells fuse and then develop into an embryo. (https://www.sciencedaily.com/terms/dolly_the_sheep.htm) -
Sahelanthropus tchadensis fossil discovered
Sahelanthropus tchadensis is one of the oldest known species in the human family tree which lived in West-Central Africa. Walking upright may have helped this species survive in diverse habitats, including forests and grasslands. A research team of scientists led by French paleontologist Michael Brunet uncovered the fossils in 2001. The fossils found are nine pieces of cranial bones. (http://humanorigins.si.edu/evidence/human-fossils/species/sahelanthropus-tchadensis) -
Human Genome is fully sequenced
On April 14, 2003 the National Human Genome Research Institute, the Department of Energy and their partners in the International Human Genome Sequencing Consortium announced the successful completion of the Human Genome Project. A genome is an organism's complete set of DNA, which is a chemical compound that contains the genetic instructions needed to develop and direct the activities of every organism. (https://www.genome.gov/11006943/human-genome-project-completion-frequently-asked-questions/) -
Homo denisova fossil discovered
In the summer of 2008, Russian researchers dug up a sliver of human finger bone from an isolated Siberian cave. At the time the team stored it away for later testing,The genetic data, published online, reveal that the bone may belong to a previously unrecognized, extinct human species that migrated out of Africa long before our known relatives.(http://www.nature.com/news/2010/100324/full/464472a.htm) -
Richard L Bible is executed
In May 1987, Bible was released from prison after serving a sentence imposed in 1981 for kidnapping and sexual assault. Thirteen months later, nine year-old Jennifer Wilson went missing Her naked body was found three weeks later hidden under a tree, with her hands tied behind her back. In one of the first DNA cases, blood smeared on a shirt and worn by Bible at his arrest was tested and found to be the blood of Jennifer. (http://www.clarkprosecutor.org/html/death/US/bible1259.htm) -
CRISPr/ CAS 9 is identified and described
CRISPR/Cas9, is a gene-editing technique that can target and modify DNA with groundbreaking accuracy. Invented in 2012 by scientists at the University of California, Berkeley. (https://motherboard.vice.com/en_us/article/what-is-crisprcas9-and-why-is-it-suddenly-everywhere)
