Noteworthy Events in Science History

By srochester
  • 322 BCE

    Aristotle describes life with the Scala Naturae

    (384-322 BCE)
    Aristotle described and classified life (using the Scala Naturae) as follows:
    - Man
    - Mammals
    - Cetaceans
    - Cephalopods (and Fish)
    - Crustaceans
    - Other Arthropods
    - Other Mollusks
    This was seen as the order of the least to most (with humans as the highest) on the "natural ladder".
  • 216

    Galen of Pergamon describes the human body

    During the life of Galen (from 129-216 CE), he dissected and studied many animals. He also "distinguished seven pairs of cranial nerves, described the valves of the heart, and observed the structural differences between arteries and veins'.

  • Lamarck develops Hypothesis of evolution by means of acquired characteristics

    Lamarck believed that "if an organism changes during the life in order to adapt to its environment, those changes are passed on to its offspring". He hypothesized this because of giraffes and their long necks.

  • The Voyage of the HMS Beagle

    Charles Darwin set sail on the HMS Beagle and traveled the coast of South America (including the Galápagos) while writing about what he encountered.

  • Alfred Russel Wallace published ideas of evolutionary processes

    In 1855, Alfred Russel Wallace published the idea that "every species has come into existence coincident both in space and time with pre-existing closely allied species".

  • The Origin of species by means of Natural Selection is published

    Charles Darwin published "The Origin of Species by Means of Natural Selection" in which he argued that organisms evolve through natural selection (this basically states that organisms adopt traits that allow them to survive over organisms that do not).

  • Louis Pasteur refutes spontaneous generation

    Louis Pasteur refuted spontaneous generation by conducting an experiment using beef broth. He proved it by boiling broth to sterilize it. He showed that the boiled, sterile broth would stay sterile unless exposed to air, concluding that generation did not happen spontaneously.

  • Gregor Mendel publishes works on inheritance of traits in pea plants

    Gregor Mendel conducted experiments on pea plants that showed the presence of hereditary traits.

  • The Challenger Oceanography Expedition sails around the world

    The Challenger Expedition of 1872 - 1976 was "first expedition organized specifically to gather data on a wide range of ocean features".

  • The Germ Theory of Disease is published

    Louis Pasteur determined that germs cause diseases after he killed germs in milk, and then sealed it, which prevented the milk from going sour.

  • Plasmodium falciparum is described as the causative agent of malaria

    In the late 1800s, the human malaria parasite p. faciparum was found and discovered.

  • Hardy and Weinberg independently develop the Hardy-Weinberg equation for determining allele frequencies in populations

    G. H. Hardy and Wilhelm Weinberg created the equation:
    p2 + 2pq + q2 = 1 The letters correspond to alleles and the numbers correspond to their frequencies.

  • T. Hunt Morgan discovers sex-linkage

    After studying fruit flies, T. Hunt Morgan discovered that males have a different chromosome than females do.

  • Neils Bohr develops the Bohr model of atom structure

    Neils Bohr developed the Bohr model which allows for a visual of electrons and the electron orbital.

  • Frederick Griffith describes the process of transformation

    Frederick Griffin used infected mice to show that bacteria can change and transform.

  • Theodosius Dobzhansky publishes Genetics and the Origin of Species

    "Genetics and the Origin of Species" merges Darwinian and Mendelian ideas to create a new idea regarding evolution. The idea used evidence from genetics and had an emphasis on alleles.

  • Beadle and Tatum publish the 1 gene-1 enzyme hypothesis

    In 1941, George Beadle and Edward Tatum conducted an experiment that tested and showed that one gene "specifies the production of one enzyme".

  • Jacques Cousteau develops SCUBA

    Jacques Cousteau and Emile Gagnan improved upon an already existing device (SCUBA) invented by Yves Paul Gaston Le Prieur. They took the SCUBA device and added a diving regulator to it to make diving more efficient.

  • Avery, MacLoed and McCarty determine that DNA is the molecule that carries the genetic code

    Avery, MacLoed, and McCarty experimented on mice using bacteria, DNA, and RNA. After some testing, their experiment showed that DNA (not RNA) aided in transformation.

  • Barbara McClintock describes transposons

    In 1945, Barbara McClintock discovered transponsons which are "class of genetic elements that can “jump” to different locations within a genome".

  • The first atomic bomb is used in war

    The Manhattan Project oversaw the creation of the first atomic bomb to be used in war. This bomb was dropped on the cities of Hiroshima and Nagasaki in Japan to get them to surrender.

  • Ensatina described as a ring species

    Robert Stebbins described the different patterns of Ensatina salamanders that varied by geographical location.

  • Hershey-Chase experiments are published

    Alfred Hershey and Martha Chase, using E. coli and a centrifuge, concluded that DNA, and not protein as previously believed, was the source of genetic information.

  • Rosalind Franklin works with DNA and X-Ray crystallography and develops “Image 51”

    Using X-ray crystallography, Rosalind Franklin was able to show the 3D shape of DNA.

  • Miller-Urey experiments published

    Stanley Miller and Harold Urey conducted experiments using water, ammonia, methane, and hydrogen in a flask. After some testing, the result of their chemical experiment supported the idea that "complex chemicals needed for living things to develop could be produced naturally on the early Earth".

  • Watson and Crick propose the double helix model of DNA structure

    James Watson and Francis Crick discovered the double helix structure of DNA which gave insight to protein synthesis and the genetic code.

  • Meselson and Stahl work with DNA replication

    The Meselson and Stahl experiment showed the semi-conservative nature of DNA.

  • Nirenberg cracks the genetic code

    Marshall Nirenberg discovered the first "triplet"—a sequence of three bases of DNA that codes for one of the twenty amino acids. He then went on the crack the entire genetic code.

  • Endosymbiosis is described by Lynn Margulis

    In 1967, Lynn Margulis' explains endosymbiosis, in regards to, "the origins of eukaryotic cell organelles such as mitochondria in animals and fungi and chloroplasts in plants".

  • Apollo 11 lands on the moon

    The Apollo 11 spacecraft launched on July 16, 1969 carrying Buzz Aldrin, Neil Armstrong, and others. After about 4 days, the spacecraft successfully landed and Neil Armstrong became the first person to ever step foot on the moon.

  • 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 basically critiquing anti-evolution sentiments.

  • Australopithicus afarensis nicknamed “lucy” fossil discovered

    The upright-walking hominid skeleton named "Lucy" was discovered in Ethiopia by Donald Johanson and Tom Gray. Lucy is dated to be around 3 million years old.

  • The Sanger Technique is developed

    Developed in 1977, the Sanger Technique is "the process of selective incorporation of chain-terminating dideoxynucleotides by DNA polymerase during in vitro DNA replication".

  • Deep sea hydrothermal vents and associated life around them are discovered

    In 1977, scientists found vents gushing warm fluid on the seafloor.

  • Kary Mullis develops Polymerase Chain Reaction

    In 1983, Kary Mullis developed the Polymerase Chain Reaction which was "based on the natural processes a cell uses to replicate a new DNA strand. Only a few biological ingredients are needed for PCR. The integral component is the template DNA—i.e., the DNA that contains the region to be copied, such as a gene. As little as one DNA molecule can serve as a template".

  • Spliceosomes were discovered and described

    At California Institute of Technology, spliceocomes (which removes introns from transcribed pre-mRNA) were identified.

  • Tommie Lee Andrews is convicted of rape

    Serial rapist, Tommie Lee Andrews, became the first American to be convicted using DNA evidence.

  • “Reproductive isolation as a consequence of adaptive divergence in Drosophila pseudoobscrura” published.

    Eight populations of Drosophila pseudoobscura (a fruit fly species) were studied in attempt to "gain insight into the process of development of reproductive isolation".

  • The Innocence Project is founded

    Founded in 1992, the Innocence Project seeks out to exonerate wrongful convictions using DNA evidence.

  • Dolly the sheep is cloned

    In 1996, Dolly the sheep became the first mammal (a complex multi-cellular organism)to be cloned.

  • Sahelanthropus tchadensis fossil discovered.

    This species lived between 6 and 7 million years ago, making it one of the oldest known species (in the family tree of a human). With ape and human like features, fossils from this species were found by a researching team in 2001.

  • Human genome is fully sequenced

    The National Human Genome Research Institute, The Department of Energy, and the International Human Genome Sequencing Consortium announced that they had successfully sequenced the human genome.

  • CRISPr/CAS 9 is identified and described

    Discovered around 2005, CRISPr - CAS 9 technology allows geneticists to add or alter parts of the DNA sequence.

  • Homo denisova fossil discovered

    In 2010, scientists discovered ancient skulls that are thought to belong to an eastern variant of Neanderthals called Denisovans.

  • Richard L Bible is executed

    Richard L. Bible was executed in 2011, making him the first murder case to use DNA technology in Arizona.