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Period: 384 BCE to 322 BCE
Aristotle Scala Naturae
Aristotle was a Greek philosopher. He was the first to create a comprehensive system of Western philosophy, based on the idea of the scala naturae, the "Natural Ladder". He divided animals into two types: those with red blood, and those without blood. He was the first to give the first detailed classification of living things. http://palaeos.com/systematics/greatchainofbeing/scala_naturae.html Aristotle and the dawn of science Article was adapted from the UCMP page and Wikipedia -
162 BCE
Galen of Pergamon describes the human body
Galen was a brilliant philosopher and physician of his time. Unable to dissect humans he worked on sheep, pigs, dogs, goats and monkeys. Most of his observations of the human body were correct. He noted several cranial nerves, the chambers of the heart, the liver, and blood. As a continuation of earlier Hippocratic conceptions, Galenic physiology became a powerful influence in medicine for the next 1,400 years.
https://www.britannica.com/biography/Galen-of-Pergamum -
Lamarck develops Hypothesis of evolution by means of acquired characteristics
Lamarck proposed in his Philosophie Zoologique the theory that characteristics that were "needed" were acquired or diminished during the lifetime of an organism were then passed on to the offspring. Acquired characteristics are those changes in the structure or function of an organism that are the result of use, disuse, environmental influences, disease, mutilation. http://www.newworldencyclopedia.org/entry/Acquired_characteristiAcquired characteristics. -
HMS Beagle's voyage
H.M.S Beagle has the honor of being remembered today because of the five-year voyage of Darwin. Years prior to Darwin's voyage the ship had sailed on a number of scientific missions. It has also been used as a warship carrying canons. Only after it's four year voyage to explore the South American coast line did it return safely to England and pick up it's most noted passenger, who would go on to discover amazing theories.
http://www.amnh.org/exhibitions/darwin/a-trip-around-the-world/ -
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The Germ Theory of Disease
Germs - small particles unseen to the naked eye causing sickness and decay thought to be a kind of seed, or spore; the word “germ” derives from the Latin verb “to sprout.” These tiny particles were part of a Germ Theory made popular in Europe and North America, stated that microorganisms caused disease. It advanced medicine and reduction of the spread of diseases. The theory increased the social status of physicians.
http://ocp.hul.harvard.edu/contagion/germtheory.html -
Alfred Russel Wallace
He came to the conclusion that living things evolved after collecting almost 100,00 insects, birds and animal specimens. The thought process of how things evolved took him 3 years to process. He gave his old mentor, Darwin, his findings as a peer review. Darwin had come to the same conclusions years prior but now was willing to act on his findings. The two men co-wrote a paper in 1858.
http://www.npr.org/2013/04/30/177781424/he-helped-discover-evolution-and-then-became-e -
Louis Pasteur refutes spontaneous generation
Spontaneous generation is the theory that living organisms can come from nowhere, maggots from raw meat. Through experiments he proved that everything comes from somewhere, the air, a host, contamination. The theory of cells and germs helped people to believe in the theory that had been around for 2 millennia.
Https://www.boundless.com/microbiology/textbooks/boundless-microbiology-textbook/introduction-to-microbiology-1/introduction-to-microbiology-18/pasteur-and-spontaneous-generation-205-5188/ -
Natural Selection is published
Darwin was not the first to have thoughts of evolution, several before him had explored the theory. His observations were gained by his own experience on the Beagle, his 8 years of work on barnacles, and knowledge from friends. Darwin solved the problem of evolution by pointing to action that depended on nothing but diversity and chance. More individuals were born than could be supported by the environment, which meant that some had to die. Those that were better adapted would live. -
Mendel - works on inheritance of traits in pea plants
Taking 8 years and 10,000 pea plants Mendel discovered the theory of inheritance. He concluded that genes come in pairs and are passed down to offspring, one gene from each parent. He tracked the segregation of genes through generations and proved dominant and recessive genes. The Law of Independent Assortment spoke about how genes of different traits will line up independently of other genes, one not affecting another's chances to be expressed.
http://www.dnaftb.org/1/bio.html -
HMS Challenger
Voyage of HMS Challenger lasted 1,000 days and covered more than 68,000 nautical miles. Many consider it to be the first oceanographic expedition because it yielded a wealth of information about the marine environment. The HMS Challenger originally was designed as a British warship outfitted with 17 guns and an engine capable of over 1,200 horsepower. The 200 foot ship was 3 masted and built of wood.
http://oceanexplorer.noaa.gov/explorations/03mountains/background/challenger/challenger.html -
Hardy-Weinberg equation for determining allele frequencies in populations
The definition of evolution was developed as a result of independent work by Hardy, a mathematician, and Weinberg, a physician. The Hardy-Weinberg equation is: p2 + 2pq + q2 = 1 where p the frequency of the "A" allele and q the frequency of the "a" allele in the population Which states that the amount of genetic variation in a population will remain constant from one generation to the next in the absence of disturbing factors. http://anthro.palomar.edu/synthetic/synth_2.htm -
T. Hunt Morgan discovers sex-linkage
In his lab of Drosophila melanogaster T. Morgan observed that a male fly had white eyes instead of the brilliant red eyes of the mass population. Through a series of breeding generation of specific flies he discovered sex-linked genes. During Initial experiments he thought to was a fatal gene of females but further data produced a 1:1:1:1 ratio.
http://www.nature.com/scitable/topicpage/thomas-hunt-morgan-and-sex-linkage-452 -
Bohr Atomic Model
Bohr proposed his 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. Bohr modified the Rutherford model by requiring that the electrons move in orbits of fixed size and energy. -
Nothing in Science Makes Sense Except in the Light of Evolution.
He was one of the principal architects of synthetic theory of evolution. He was an entomologist and zoologist with wide-ranging interests, he brought a rich background in systematics and study of natural populations with him when he came to learn genetics in the laboratory of T. H. Morgan. Utilizing his double background of with natural populations and in Mendelian genetics in writing what came to be the single most influential book in the formative period of the synthetic theory of evolution. -
Frederick Griffith: the process of transformation
While trying to develop a vaccine against the Spanish flu, English army doctor, discovered a process called transformation. He showed that bacteria were capable of transferring their genetic information. During his experiments he tested the effects of killed bacteria on living cells. He injected mice with one of two strains of Diplococcus pneumonia. When he mixed heat fixed killed and nonlethal strains the mice became infected.
http://www.brighthub.com/science/genetics/articles/43672.aspx -
Theodosius Dobzhansky - Genetics and the Origin of Species
After studying fruit fly's in a laboratory and getting results that said all genes in given species are identical, he began looking at the genes of wild fruit flies, traveling from Canada to Mexico to catch members of the species D. pseudoobscura. He found that different populations did not have identical sets of genes. Each population of flies he studied had markers in its chromosomes that differentiated it from other groups. http://evolution.berkeley.edu/evolibrary/article/history_20 -
One-gene One-Enzyme
Using the mold Neurospora Crassa, mutation-inducing x-ray, and a minimal growth medium, American geneticist George Wells Beadle and American biochemist Edward L. Tatum reported the one-gene one-enzyme theory. They discovered that each gene controls the synthesis of a single enzyme. This discovery won Beadle and Tatum the 1958 Nobel Prize for Physiology or Medicine.
https://www.britannica.com/science/one-gene-one-enzyme-hypothesis -
Barbara McClintock
McClintock challenged current concepts of what genes were capable of when she discovered that some genes could be mobile. Her studies of chromosome breakage in corn led her to discover a chromosome-breaking locus that could change its position within a chromosome. She went on to discover other such mobile elements, now known as transposons. In the 70’s this was also applied to viruses and bacteria.
http://www.pnas.org/content/109/50/20198.full -
Ernst Mayr develops the Biological Species Concept
He argued for what came to be called the Biological Species Concept, that a species consists of populations of organisms that can reproduce with one another and that are reproductively isolated from other populations, though he was not the first to define species on the basis of reproductive compatibility. It has been argued that the BSC is a natural consequence of the effect of sexual reproduction of natural selection.
https://en.wikipedia.org/wiki/Species_problem#Biological_species_concept -
Jacques Cousteau SCUBA
Gagnan and Cousteau patented an aqualung prototype. This included a regulator, two tanks of compressed air, a mouth piece and hoses. In 1947, Cousteau, was able to set a free dive world record going to a depth of 300 feet. Aqualung is a demand valve that would supply compressed air to a diver when they took a breath. This invention greatly increased the exploration of the ocean allowing drivers to move more freely and swim deeper. Also decreasing the energy used to pull a breath. -
Avery, MacLoed and McCarty determine that DNA is the molecule that carries the genetic code
In a time when scientist thought it was proteins that had the function of carrying genetic information three scientist were discovering that DNA is the substance that causes bacterial transformation. Through a culmination of experiments from 1930's to 1940's they were able to identify the properties responsible for the transformation phenomenon first described in Griffith's experiment of 1928.
https://en.wikipedia.org/wiki/Avery%E2%80%93MacLeod%E2%80%93McCarty_experiment -
Miller-Urey Experiment
Using the elements thought to be present on early Earth Miller and assistant Urey simulated conditions needed to produce life. Those elements, water, methane, ammonia and hydrogen, were sealed inside a sterile five-liter glass flask. Then attached to a 500ml flask filled with water. Continuous electrical sparks simulating lighting were fired at the water and gaseous mixtures.
https://en.wikipedia.org/wiki/Miller%E2%80%93Urey_experiment -
Hershey-Chase experiments
Alfred Hershey and Martha Chase confirmed DNA is genetic material through a series of experiments. Winning them the Nobel Prize in Physiology or Medicine. Using bacteria cells, DNase, and isotopes (S35 and P32) they concluded that DNA, not protein, was genetic material. This finding has numerous applications in forensic science, crime investigation and genealogy. After publication it led to more detailed investigation of DNA and the discovery of it's shape. -
Photo 51
Rosalind Franklin was the supervisor in charge of Raymond Gosling PhD student, who captured an X-ray diffraction image of DNA that came to be known as Photograph 51. Without Rosalind Franklin's permission or knowledge Maurice Wilkins showed James Watson the photo, helping to prove the double helix shape of DNA and earning them the Nobel Prize in Physiology or Medicine in 1962, four years after Rosalind Franklin passed away. byhttps://en.wikipedia.org/wiki/Photo_51 -
Watson and Crick Discover double standed DNA helix
Using Chargaff's rule that A=T and C=G go together Watson and Crick make cardboard cut outs of each chemical compound. They began moving the pieces around on their desk like a puzzle and with some help of fellow scientist they were able to determine the double-stranded helix structure of DNA They discovered that most DNA is right handed and the double helix is anti-parallel to each other.
http://www.nature.com/scitable/topicpage/discovery-of-dna-structure-and-function-watson-397 -
Meselson and Stahl work with DNA replication
Meselson and Stahl ran some experiments which supported the hypothesis that DNA replication was semiconservative. In semiconservative replication, when the double stranded DNA helix is replicated, each of the two new double-stranded DNA helices consisted of one strand from the original helix and one newly synthesized. Using an isotope of nitrogen to distinguish between parent and newly copied DNA they grew several generation of E. Coli. This changed the weight and made monitoring possible. -
Endosymbiosis: Lynn Margulis
Since the discovery of mitochondria at the end of the 1800’s scientist have thought that there has been a resemblance to bacteria. Margulis agreed with this thought and set out to prove that mitochondria began from bacteria that lived in a permanent symbiosis within the cell. When DNA was seen inside chloroplasts, she was not surprised. She spent much time honing her argument that symbiosis was a major force in the evolution of cells.
http://evolution.berkeley.edu/evolibrary/article/history_24 -
Nirenberg cracks the genetic code
Together with his colleague Johann Matthaei, he tried to figure out how the genetic information hidden in the DNA strand could be read out as protein. Using only the nucleotide uracil in the cell-free system it produced a protein that contained a single letter, the amino acid F, phenylalanine. By showing that a strand of U triplets was the template for the amino acid phenylalanine they cracked the first letter of the code.
https://www.nobelprize.org/educational/medicine/gene-code/history.html -
Apollo 11 lands on the moon
Apollo 11 landed on the moon with Neil Armstrong and Buzz Aldrin. On July 19th Armstrong, Aldrin, and Collins had to travel 240,000 miles over 76 hours to enter into the lunar orbit. Armstrong and Aldrin broke away from Collins and landed on the sea of Tranquility 2 hours later. The round trip to the moon and back cost $24 Billion, and took about 400,000 engineers, techs, and scientists. The expense was approved by the president’s mandate to beat the Soviets in the great space race. -
Lucy's Story
Lucy was found by Donald Johanson and Tom Gary at the site of Hadar in Ethiopia. Weighing in at 60 to 65 pounds in life Lucy was only about three and a half feet tall. It is estimated that she lived about 3.18 million years ago. The remains were named after the song Lucy in the sky with diamonds by the Beatles. Her finial resting place is the Paleoanthropology Laboratories in the National Museum of Ethiopia.
http://www.history.com/news/famed-lucy-fossils-discovered-in-ethiopia-40-years-ago -
Spliceosomes
The work by the Sharp and Roberts labs revealed that genes of higher organisms are spliced in several distinct segments along the DNA molecule.The spliceosome has been described as one of "the most complex macromolecular machines known," "composed of as few as 300 proteins in lower eukaryotes or more then a thousand distinct proteins in higher eukaryotes.
http://www.evolutionnews.org/2013/09/the_spliceosome_1076371.html
https://en.wikipedia.org/wiki/Spliceosome -
Sanger Technique
Sanger sequencing is a method of DNA sequencing first commercialized by Applied Biosystems, based on the selective incorporation of chain-terminating by DNA polymerase. Developed by Frederick Sanger and colleagues it was the most widely used sequencing method for approximately 39 years. https://unlockinglifescode.org/sites/default/files/1977.jpg -
Ensatina Ring Species.
A great living example of speciation is the Ensatina eschscholtzii. This salamander represents evolution as you follow the two lineages into two main groups. One population moved south and evolved with new colors, patterns, and adaptations to meet it's new environment. Discovered and cataloged by Robert Stebbins in 1977.
http://evolution.berkeley.edu/evolibrary/article/0_0_0/devitt_02 -
Deep sea hydrothermal vents and associated life around them are discovered
While exploring the Galapagos Rift scientist noticed a series of temperature spikes and discovered deep sea hydrothermal vents. The temperature would go from near freezing to 400 degrees C in short distances because of the vents. Each vent has it's own mineral content, temperature, ecosystem, and magma flow level. The conversion of mineral rich hydrothermal fluid is what is key to this unique ecosystem.
http://nationalgeographic.org/media/deep-sea-hydrothermal-vents/ -
Kary Mullis develops Polymerase Chain Reaction
Mullis was working for Cetus Corp. as a chemist. That spring, according to Mullis, he was driving his vehicle late one night with his girlfriend when he had the idea to use a pair of primers to bracket the desired DNA sequence and to copy it using DNA polymerase; a technique which would allow rapid amplification of a small strand of DNA. Cetus took Mullis off his usual projects to concentrate on PCR full-time.[18] Mullis succeeded in demonstrating PCR.
https://en.wikipedia.org/wiki/Kary_Mullis -
CRISPr/CAS 9
Clustered regularly interspaced short palindromic repeats (CRISPR) are segments of prokaryotic DNA containing short repetitions of base sequences. The CRISPR/Cas system is a prokaryotic immune system that confers resistance to foreign genetic elements such as those present within plasmids and phages and provides a form of acquired immunity. Bioethical concerns have been expressed about the prospect of using this biotechnology for editing the human germline.
https://en.wikipedia.org/wiki/CRISPR -
Tommie Lee Andrews
Tommie Lee Andrews was the first person convicted of a sex crime using DNA sequencing as evidence. The DNA technicians could not match the entire genetic code to the rapist's--that would be technically impossible. They used semen left at the crime scene and blood samples taken fro Tommie to run the DNA sequencing. The DNA data base was established in Virginia after this case and within 9 years the other 49 states passed laws to make a data base and require DNA sampling of felons. -
Richard L Bible
While on vacation 9 year old Jennifer was abducted and sexually assaulted by Richard Bible. DNA evidence found on his shirt matching Jennifer tied hi to the crime. Hair samples found at the scene also matched Richard. Till they day he was executed for his crime he maintained he was innocent and said DNA evidence would clear him.
http://archive.azcentral.com/news/articles/2011/06/30/20110630arizona-execution-richard-lynn-bible.html -
The Innocence Project is founded
The Innocence Project, founded in 1992 by Peter Neufeld and Barry Scheck at Cardozo School of Law, exonerates the wrongly convicted through DNA testing and reforms the criminal justice system to prevent future injustice. To date, 347 people in the United States have been exonerated by DNA testing, including 20 who served time on death row. They not only take on cases to get people exonerated but they get involved with cases to explain DNA testing.
http://www.innocenceproject.org/about/ -
Dolly the sheep is cloned
July 5, 1996 a special sheep was born to three mothers. One ho provided they egg that would have the DNA removed, one mom who donated the mammary cell where the DNA was collected from and the surrogate who gave birth. Dolly was born, named after Dolly Parton because it was a mammary cell. She lived till February 14, 2003 when lung cancer and arthritis got the best of her.
https://en.wikipedia.org/wiki/Dolly_(sheep) -
Human genomes is fully sequenced.
Human genome typing is the process used to map the DNA sequence of an organism’s genome one at a time. In 1999 the entire 22nd chromosome of humans were sequenced. In 1998 scientist were able to sequence the whole genome of a nematode. In the ‘70’s the Maxam-Gilbert sequencing and Sanger sequencing were the preferred manual methods used and it was slow and painstaking, with the invention of automated methods in the ‘90’s we were able to make incredible advancements. -
Sahelanthropus tchadensis fossil
A research team of scientist led by French paleontologist Michael Brunet uncovered a fossil belonging to the oldest known species in the human family tree. They discovered 9 pieces of the cranial bone. Based on the flat teeth it is suggested that seeds, grass, and plants were the likely diet. Based on the foramen magnum it proves they walked in an upright fashion. -
Reproductive isolation as a consequence of adaptive divergence in Drosophila pseudoobscrura
We studied a set of four laboratory populations of D. melanogaster that have been selected for rapid development for over 300 generations, and have also evolved reduced body size relative to the four ancestral control populations. We tested for RI between the selected populations and their ancestral controls, and found evidence for two complementary asymmetric pre and postmating barriers to effective reproduction.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3539013/ -
The Denisova genome
When a finger bone was discovered in a cave it was thought to belong to one of the Neandertals living there about 30,000 and 48,000 years ago. However in May of 2010 when the mitochondrial DNA was tested it was estimated that the finger lived about 1 million years ago. Later an upper molar was discovered giving more information genetically and about the way of life for the people of the past.
http://www.talkorigins.org/faqs/homs/denisova.html -
Plasmodium falciparum is described as the causative agent of malaria
Malaria parasites are micro-organisms that belong to the genus Plasmodium. There are 156 species but only four are considered true parasites of humans. In addition there is one species that naturally infects macaques which has recently been recognized to be a cause of zoonotic malaria in humans. The malaria life cycle consists of two hosts the fist being the mosquito and the second being humans. Most commonly found in tropical areas.
https://www.cdc.gov/malaria/about/biology/parasites.html
