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318 BCE
Aristotle describes life with the Scala Naturae
Aristotle's "scala naturae", meaning the natural ladder, was a organized and detailed classification of living things. Aristotle’s idea was that living things could be assigned a hierarchical position on this metaphorical ladder that would represent their degree of perfection and importance. He placed god, angels, and humans at the top and other living things of the known world on progressively lower levels. -
162 BCE
Galen of Pergamon describes the human body
Aelius Galenus, who was a prominent Greek physician, surgeon and philosopher in the Roman Empire. Galen had great expertise in anatomy, surgery, pharmacology and therapeutic methods. Since the dissection of humans was illegal in Rome, Galen was forced to dissect animals and treat wounded gladiators to learn more about the anatomy of the human body. Today, some practices promoted by Galen are still recognized as useful and well known. Link: http://www.famousscientists.org/galen/ -
Lamarck develops Hypothesis of evolution by means of acquired characteristics
Jean-Baptiste Lamarck, a French naturalist, is best known for his Theory of Inheritance of Acquired Characteristics, first presented in 1801. Lamarck's hypothesis states 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 evolution happens according to a predetermined plan and that the results have already been decided. Link: http://evolution.berkeley.edu/evolibrary/article/history_09 -
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The Voyage of the HMS Beagle
The Voyage of the HMS Beagle was a voyage Charles Darwin took with a large crew lead by captain Robert Fitzroy to survey the coast of lower south America. The voyage was planned to last only two years, but ended up lasting five years. Darwin made many discoveries and observations while on this historic voyage. Link: http://www.aboutdarwin.com/voyage/voyage03.html -
Alfred Russel Wallace published ideas of evolutionary processes
Alfred Russel Wallace, who was a British naturalist among other things, was best known for independently conceiving the ideas and theory of evolutionary processes through natural selection; his paper on the subject was jointly published with some of Charles Darwin's works in 1858. Wallace's research and works inspired Darwin to make and publish his own ideas On the Origin of Species later on. Link: http://evolution.berkeley.edu/evolibrary/article/history_14 -
"The Origin of species by means of Natural Selection" is published
Charles Darwin's scientific literary work on the origin of species is considered to be the foundation of evolutionary biology. In the book, Darwin discusses a theory he formed, Darwinism, which states that all species of organisms arise and develop through the natural selection of small, inherited variations that increase the individual's ability to compete, survive, and reproduce. Link: http://www.talkorigins.org/faqs/origin.html -
Louis Pasteur refutes spontaneous generation
Before the discovery of microbes, it was widely thought that life arose from nothing. This theory was known as spontaneous generation. By sterilizing cultures and keeping them isolated from the open air, Pasteur found that contamination of the media only occurred upon exposure to the outside environment, showing that some element was needed to give rise to life. Pasteur showed that life does not arise spontaneously. Link: http://www.talkorigins.org/faqs/abioprob/spontaneous-generation.html -
The Germ Theory of Disease is published
The germ theory of disease states that some diseases are caused by microorganisms. These small organisms that are too small to see without magnification, invade humans, animals, and other living hosts. Much of the work that led to a wide acceptance of the germ theory is down to Louis Pasteur, aided by the development of microscope techniques by Robert Koch which made microorganisms visible and identifiable. Link:http://www.sciencemuseum.org.uk/broughttolife/techniques/germtheory -
Gregor Mendel publishes works on inheritance of traits in pea plants
Gregor Johann Mendel, known as the father of genetics, through his work on pea plants discovered the fundamental laws of inheritance. He noticed 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. With his research, he then formed the laws of segregation, independent assortment, and dominance. Link: http://www.famousscientists.org/gregor-mendel/ -
Period: to
The Challenger Oceanography Expedition sails around the world
The challenger expedition was a scientific journey that made many discoveries to lay the foundation of oceanography. It was a voyage that lasted almost four years. The vessel, the HMS Challenger, was specifically designed to investigate the biology, geology and chemistry of the oceans and seafloor. It sailed from Portsmouth, England on December 21,1872 and forever changed the course of scientific history. Link: http://life.bio.sunysb.edu/marinebio/challenger.html -
Plasmodium falciparum is described as the causative agent of malaria
Plasmodium falciparum is a protozoan parasite usually found in the blood of a host that contracted malaria. It is one of the species of plasmodium that is a causative agent of malaria in humans. It is usually transmitted by the female Anopheles mosquito. French physician Charles Louis Alphonse Laveran was the first to discover the parasitic protozoan within the blood of infected victims with malaria in 1880. Link: https://www.cdc.gov/malaria/about/history/laveran.html -
Hardy and Weinberg independently develop the Hardy-Weinberg equation for determining allele frequencies in populations
The Hardy-Weinberg equation is the fundamental concept in population genetics made by G.H. Hardy and Wilhelm Weinberg. It is a mathematical equation describing the distribution and expression of alleles in a population. It also expresses the conditions under which allele frequencies are expected to change. It was formed by the duo in 1908. Link: http://anthro.palomar.edu/synthetic/synth_2.htm -
T. Hunt Morgan discovers sex-linkage
Sex linkage is the phenotypic expression of an allele that is dependent on the gender of the individual and is directly tied to the sex chromosomes. Genetic linkage was discovered for the first time by Thomas Hunt Morgan, who greatly expanded the understanding of sex-linkage, while experimenting with Drosophila melanogaster in 1910. Link: http://www.biologydiscussion.com/genetics/sex-linked-inheritance-sex-linkage-in-drosophila-and-man-with-diagram/5241 -
Neils Bohr develops the Bohr model of atom structure
In 1913, Niels Bohr and Earnest Rutherford introduced the Bohr model of atom structure. The model depicts the atom as a small, positively charged nucleus surrounded by electrons that travel in circular orbits around the nucleus. This is quite similar in structure to the Solar System. However, the attraction is provided by electrostatic forces rather than gravity. Link: http://abyss.uoregon.edu/~js/glossary/bohr_atom.html -
Frederick Griffith describes the process of transformation
The Transformation process was described in a ground breaking experiment in 1928 by Frederick Griffith. Griffith used two strains of Pneumococcus, a bacteria that infects mice. He used a type III-S and type II-R strain. In his experiment, Griffith noticed that bacteria were capable of transferring genetic information through a process known as transformation. Link: https://education.llnl.gov/bep/science/10/tLect.html -
Barbara McClintock describes transposons
Transposons, also known as "jumping genes", are sequences of DNA that move from one location in the genome to another. Geneticist Barbara McClintock was awarded the nobel prize in 1983 for her discovery of the mobile genetic elements. McClintock discovered that genes could move from place to place on a chromosome when she experimented with breeding maize plants in 1931. Link: http://www.nature.com/scitable/topicpage/barbara-mcclintock-and-the-discovery-of-jumping-34083 -
Theodosius Dobzhansky publishes Genetics and the Origin of Species
Genetics and the Origin of Species is a book published in 1937 by the evolutionary biologist, Theodosius Dobzhansky. The book is regarded as one of the most important works of modern evolutionary synthesis. The book included and familiarized the work of population genetics to other biologists, which in turn influenced their appreciation for the genetic basis of evolution. Link: http://www.pnas.org/content/94/15/7691.full -
Beadle and Tatum publish the 1 gene-1 enzyme hypothesis
The one gene–one enzyme hypothesis was proposed by George Wells Beadle and Edward Lawrie Tatum in the US in 1941. The theory stated that each gene directly produces a single enzyme. This in turn consequently affects an individual step in a metabolic pathway. Both Beadle and Tatum won the Nobel Prize in 1958 for showing that genes control individual steps in metabolism. Link: http://www.historyofinformation.com/expanded.php?id=4325 -
Jacques Cousteau develops SCUBA
Jacques Yves Cousteau is considered to be "The father of scuba diving" among many other achievements. Cousteau and his partner Emille Gagnan co-invented a demand valve system that would supply divers with compressed air when they breathed. They named this modern demand regulator the Aqua-Lung and it allowed diving to be possible to anyone who was interested. -
Avery, MacLoed and McCarty determine that DNA is the molecule that carries the genetic code
In 1944, Oswald Avery, Colin MacLeod, and Maclyn McCarty, demonstrated that DNA is the substance that causes bacterial transformation and carries the genetic code in an experiment known as the Avery–MacLeod–McCarty experiments. The men used strands of purified DNA precipitated from solutions of cell components, to perform bacterial transformations. The trio proved that DNA, not protein, is the genetic molecule. Link:http://www.genomenewsnetwork.org/resources/timeline/1944_Avery.php -
Ensatina described as a ring species
Ensatina eschscholtzii has been described as a ring species by Robert Stebbins in the mountains surrounding the Californian Central Valley. The complex forms a horseshoe shape around the mountains, and though interbreeding can happen between each of the many populations around the horseshoe, the Ensatina eschscholtzii subspecies on the western end of the horseshoe cannot interbreed with the Ensatina klauberi on the eastern end. Link: http://www.actionbioscience.org/evolution/irwin.html -
Hershey-Chase experiments are published
The Hershey-Chase experiments were a series of experiments performed in 1952 by Alfred Hershey and Martha Chase which helped to prove that DNA is genetic material. Hershey and Chase showed that when bacteriophages, which are composed of DNA and protein, infect bacteria, their DNA enters the host bacterial cell, but most of their protein does not. Their contributions proved that DNA is hereditary material. Link: http://www.biology-pages.info/H/Hershey_Chase.html -
Rosalind Franklin works with DNA and X-Ray crystallography and develops “Image 51”
Photograph 51 was the name given to an X-ray diffraction image of DNA using X-Ray crystallography which was taken by Raymond Gosling and Rosalind Franklin in May 1952. Gosling was working as a PhD student under the supervision of Rosalind Franklin at King's College London at the MRC Biophysics unit in Sir John Randall's group. The photo was very important evidence in determining and identifying the structure of DNA. Link: http://www.insight.mrc.ac.uk/2013/04/25/behind-the-picture-photo-51/ -
Watson and Crick propose the double helix model of DNA structure
James Watson and Francis Crick, publish their paper proposing a double helix model with sides made of sugar phosphate and rungs of base pairs for the structure of DNA in the journal "Nature." Maurice Wilkins supported and aided them in their data. The trio of men ended up winning the Nobel Prize in 1962. Rosalind Franklin, whose data was key to solving the structure died before the Prize was awarded. Link:https://profiles.nlm.nih.gov/SC/Views/Exhibit/narrative/doublehelix.html -
Miller-Urey experiments published
The Miller–Urey experiments were chemical experiments, conducted by Stanley Miller and Harold Urey, that simulated the conditions thought at the time to be present on the early Earth billions of years ago, and tested the chemical origin of life under those conditions. It was conducted in 1952 at the University of Chicago and later the University of California, San Diego and published the following year. Link:https://ncse.com/files/pub/creationism/icons/gishlick_icons1.pdf -
Meselson and Stahl work with DNA replication
The Meselson–Stahl experiment was an experiment by Matthew Meselson and Franklin Stahl in 1958 which supported the hypothesis that DNA replication was semi-conservative. DNA replicates by semi-conservative replication, which means that one strand of the parent double helix is conserved in each new DNA molecule. Meselson and Stahl were the scientists who showed that DNA follows the semi-conservative model. Link: http://scienceprimer.com/meselson_stahl_experiment -
Nirenberg cracks the genetic code
In 1961 Marshall W. Nirenberg, a young biochemist at the National Institute of Arthritic and Metabolic Diseases, discovered the first "triplet" which was a sequence of three bases of DNA that codes for one of the twenty amino acids that serve as the building blocks of proteins. Finally in 1966, the genetic code was cracked by Marshall Nirenberg, Har Khorana and Severo Ochoa. Nirenberg won and shared the Nobel prize. Link: https://www.nobelprize.org/educational/medicine/gene-code/history.html -
Endosymbiosis is described by Lynn Margulis
Lynn Margulis is an American biologist whose serial Endosymbiotic theory of eukaryotic cell development revolutionized the modern concept of how life arose on Earth. The Endosymbiotic theory, is an evolutionary theory of the origin of Eukaryotic cells from Prokaryotic organisms. In 1967, Margulis advanced and substantiated the theory with undeniable microbiological evidence. Link: http://evolution.berkeley.edu/evolibrary/article/history_24 -
Apollo 11 lands on the moon
On July 20th, 1969, Apollo 11 was marked in history as the first spaceflight that successfully put humans on the moon. The Lunar module, "Eagle", made a successful land on the lunar surface. Crew members Neil Armstrong, Buzz Aldrin, and Michael Collins were the men behind the historical space mission. Link: https://www.nasa.gov/mission_pages/apollo/apollo11.html -
CRISPr/CAS 9 is identified and described
CRISPR-Cas9 is a unique technology that enables geneticists and medical researchers to edit parts of the genome. It does this by removing, adding or altering sections of the DNA sequence.
It is currently the simplest, most versatile and precise method of genetic manipulation. It's discovery caused a revolution in science. It was first discovered in the 1970s. Link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4343198/ -
Ernst Mayr develops the Biological Species Concept
Ernst Mayr, one of the 20th century's leading evolutionary biologists, proposed the biological species concept is the most widely accepted species concept. It defines species in terms of interbreeding. For instance, Ernst Mayr defined a species as follows: "species are groups of interbreeding natural populations that are reproductively isolated from other such groups". Link: http://www.genetics.org/content/167/3/1041 -
The Sanger Technique is developed
The Sanger Technique is a method of DNA sequencing based on the selective incorporation of chain-terminating dideoxynucleotides by DNA polymerase during in vitro DNA replication. Two sequencing techniques were developed independently in the 1970s. The method developed by Fred Sanger used chemically altered "dideoxy" bases to terminate newly synthesized DNA fragments at specific bases. Once size-separated, the DNA can be read. Link: https://www.dnalc.org/view/15922-Early-DNA-sequencing.html -
Theodosius Dobzhansky publishes “Nothing in Science Makes Sense Except in the Light of Evolution.”
"Nothing in Science Makes Sense Except in the Light of Evolution", was an essay written by Theodosius Dobzhansky in 1973. The Essay Criticized anti-evolution creationism and espousing theistic evolution and offered arguments for evolution . The essay greatly criticized religious thoughts, beliefs, and views about many fields of science and the world. The essay was first published in the "American Biology Teacher". Link:https://www.pbs.org/wgbh/evolution/library/10/2/text_pop/l_102_01.html -
Australopithicus afarensis nicknamed “lucy” fossil discovered
Lucy is the common name of AL 288-1, which was several hundred pieces of bone fossils representing 40 percent of the skeleton of a female of the hominin species Australopithecus afarensis. Lucy was found by Donald Johanson and Tom Gray on the November 24, 1974, at the site of Hadar in Ethiopia. Link: http://australianmuseum.net.au/australopithecus-afarensis -
Deep sea hydrothermal vents and associated life around them are discovered
Hydro thermal vents are caused by a fissure in our planet's surface from which geothermal heated water flows. Hydro thermal vents are commonly found near active volcano sites, areas where tectonic plates are moving apart, ocean basins, and hot spots. In 1977, scientist exploring the Galapagos Rift came to contact with these vents and with them, found an ocean floor teeming with life. Link: http://nationalgeographic.org/media/deep-sea-hydrothermal-vents/ -
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. The spliceosome is assembled from snRNAs and protein complexes. The spliceosome removes introns from a transcribed pre-mRNA, a type of primary transcript. This process is generally referred to as splicing. It was discovered in 1977. -
Kary Mullis develops Polymerase Chain Reaction
The Polymerase chain reaction is a technique that allowed scientists to make millions of copies of a scarce sample of DNA. The technique used thermocycling to rapidly copy segments of DNA and it revolutionized biology. The technique was created by Nobel Prize winner Kary Mullis while working as a chemist at the Cetus Corporation, a biotechnology firm in Emeryville, California in 1985. Link:http://siarchives.si.edu/research/videohistory_catalog9577.html -
Tommie Lee Andrews is convicted of rape
Tommie Lee Andrews is a serial rapist who became the first American to ever be convicted in a case that used DNA evidence. The police sent two samples to a New York lab for testing. Semen found at the crime scene and Andrews's blood were sent for testing. The Lab Isolate DNA from each sample and compared the two which were found to be a matched. Andrews was sentenced to 22 years in prison for his crimes. Link: http://articles.latimes.com/1997-03-02/local/me-33996_1_serial-rapist -
“Reproductive isolation as a consequence of adaptive divergence in Drosophila pseudoobscrura” is published.
Diane M. B. Dodd published an important book documenting her experiments with Drosophila pseudoobscrura (fruit flies). Dodd experimented with a population of fruit flies which was divided into two, with one of the populations fed with starch based food and the other with maltose based food. After the populations had diverged over many generations, the groups were again mixed. Dodd observed that the flies continued to prefer mating with others from the same original population. -
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. Link: http://www.truthinjustice.org/ips.htm -
Dolly the sheep is cloned
Dolly the Sheep, an ewe, was the first mammal to have been successfully cloned from an adult cell. Her birth was announced on February 22, 1997. The sheep was cloned at the Roslin Institute in Midlothian, Scotland, and she lived there until her death at just six years old. Link:http://news.bbc.co.uk/onthisday/hi/dates/stories/february/22/newsid_4245000/4245877.stm -
Sahelanthropus tchadensis fossil discovered
Sahelanthropus tchadensis is one of the oldest known species found in the human family tree. This species was believed to have lived sometime between 7 and 6 million years ago in West-Central Africa (Chad). A research team of scientists who were led by French paleontologist, Michael Brunet, uncovered the nine cranial specimens in the African country Chad in 2002. Link: http://australianmuseum.net.au/sahelanthropus-tchadensis -
Human genome is fully sequenced
The Human Genome Project, led by James Watson and Francis Collins, accomplished the massive goal of determining the sequence of chemical base pairs which make up human DNA, and of identifying and mapping all of the genes of the human genome from both a physical and functional standpoint. Link: https://www.genome.gov/11006943/human-genome-project-completion-frequently-asked-questions/ -
Homo denisova fossil discovered
Homo denisova is an extinct species of human in the genus Homo. It's fossils were discovered in 2008 in the Denisova Cave, located in southwestern Siberia, in the Altai Mountains near the border with China and Mongolia. The fossils of large molar teeth were unknown at the time but were eventually classified by December 2010 as the remains of an ancient homo genus species and were named Denisovans, after the cave they were discovered in. Link: http://www.talkorigins.org/faqs/homs/denisova.html -
Richard L Bible is executed
Richard Lynn Bible was the convicted murder, kidnapper, and molester of nine year old Jennifer Wilson. Wilson's body was found hidden under a tree covered with branches with her hands tied behind her back in Flagstaff, Arizona. Bible was found to be the culprit when DNA evidence of blood smeared on his shirt matched the blood of the victim. Bible's hair was also found at the crime scene. Bible was soon executed for his crimes. Link: http://www.clarkprosecutor.org/html/death/US/bible1259.htm
