Grade 12 Elite History of Evolutionary Thought PDF - M6/L1

0565618257 Grade 12 Elite Ms/ Reham Khaled M6/L1 History of Evolutionary Thought Term 1 ** In December 1831, Charles Darwin, set sail on a journey of a lifetime aboard the British naval vessel HMS Beagle....

0565618257 Grade 12 Elite Ms/ Reham Khaled M6/L1 History of Evolutionary Thought Term 1 ** In December 1831, Charles Darwin, set sail on a journey of a lifetime aboard the British naval vessel HMS Beagle. ied ** Darwin’s primary mission on his journey around the world was to serve as the ship’s naturalist—to collect and record the geological and biological diversity he saw during the voyage. ha ** As Darwin set sail on the HMS Beagle, he was a supporter of the long-held idea that species had remained unchanged since the time of creation. K ** During the 5-year voyage of the Beagle, Darwin’s observations challenged his belief that species do not change over time. am ** In fact, his observations of geological formations and species variation led him to propose a process by which species arise and change. 7 ** This process—evolution: proposed that genetic change occurs in a species over time, which leads to their genetic and phenotypic differences. 25 eh ** This process is due to natural, not supernatural, forces. /R ** This new view was not readily accepted by Darwin’s peers, but it 18 gained gradual credibility as a result of a scientific and intellectual revolution that began in Europe in the late 1800s. rs ** Today, 150 years since Darwin first published his idea of natural 56 selection. M ** The principle he proposed has been subjected to rigorous scientific tests. 6 ** So that it is now considered one of the unifying theories of biology. 05 ** Darwin’s theory of evolution by natural selection explains both the unity and the diversity of life on Earth, how all living organisms share a common ancestor, and how species adapt to various habitats and ways of life. 1  0565618257 Grade 12 Elite Ms/ Reham Khaled M6/L1 History of Evolutionary Thought Term 1 Mid-Eighteenth-Century Influences: ied  Plato said that every species on Earth has a perfect, or “essential,” form and species variation is imperfection of this essential form.  Aristotle saw that organisms vary in complexity and can be arranged based ha on their order of increasing complexity.  Georges-Louis Leclerc (1707–88), better known as Count Buffon, was a naturalist who worked most of his life writing a 44-volume natural history K series that described all known plants and animals. ** He provided evidence of evolution and proposed various causes, such as am environmental influence and the struggle for existence. ** Buffon’s support of evolution seemed to waiver, and often he professed to 7 believe in special creation and the fixity of species. 25 eh  Taxonomy: the science of classifying organisms.  Chief among taxonomists was Carolus Linnaeus (1707–78), who /R developed the binomial system of nomenclature (a two-part name 18 for a species, such as Homo sapiens) and a system of classification for living organisms.  Linnaeus believed in the fixity of species, that each species had an rs 56 “ideal” form.  He also believed in the scala naturae, a sequential ladder of life M where the simplest beings occupy the lowest rungs and the most complex and spiritual beings. 6 05  Comparative anatomy: the evaluation of similar structures across a variety of species.  Biologists of this time used comparative anatomy to classify organisms into groups.  By the late eighteenth century, scientists had discovered fossils.  Fossils: they were the remains of plants and animals from the past. 2  0565618257 Grade 12 Elite Ms/ Reham Khaled M6/L1 History of Evolutionary Thought Term 1  Explorers traveled the world and brought back newly discovered extant (still in existence) and fossil organisms to be compared to known living species. ied  At first, scientists believed that each type of fossil had a living descendant, but eventually some fossils did not seem to match well with known species.  Baron Georges Cuvier (1769–1832) was the first to suggest that some species known only from the fossil record had become extinct. ha ** Erasmus Darwin (1731–1802), Charles Darwin’s grandfather, was a physician and a naturalist. K ** His writings on both botany and zoology contained comments am and footnotes that suggested the possibility of evolution. ** He based his conclusions on changes in animals during 7 development, animal breeding by humans, and the presence of 25 eh vestigial structures. ** Vestigial structures: anatomical structures that apparently functioned in an ancestor but have since lost most or all of their /R 18 function in a descendant. ** Like Buffon, Erasmus Darwin thought that species might evolve, but he offered no mechanism by which this change might occur. rs 56 M Late-Eighteenth/Early-Nineteenth- 6 Century Influences: 05 ** Baron Georges Cuvier, a distinguished zoologist, used comparative anatomy to develop a system of classifying animals. ** He also founded the science of paleontology. ** paleontology: the study of fossils. 3  0565618257 Grade 12 Elite Ms/ Reham Khaled M6/L1 History of Evolutionary Thought Term 1 ** and was quite skilled at using fossil bones to deduce the structure of an animal. ied ** Cuvier was a staunch advocate of the fixity of species and special creation, but his studies revealed that the assembly of fossil varieties changed suddenly between different layers of sediment, or strata, within a geographic region. ha ** He reconciled his beliefs with his observations by proposing that sudden changes in fossil variation could be explained by a series of local catastrophes, or mass extinctions, followed by repopulation by species from surrounding areas. K ** The result of these catastrophes was a turnover in the assembly of life- am forms that occupied a particular region over time. 7 ** Some of Cuvier’s followers suggested that there had been worldwide catastrophes and God had created new sets of species to repopulate the 25 eh world. ** This explanation of the history of life came to be known as catastrophism. /R 18  Jean-Baptiste de Lamarck (1744–1829) was the first biologist to offer a testable hypothesis that explained how evolution occurs via adaptation to the environment. rs  Lamarck’s ideas about descent were entirely different from those of 56 Cuvier. M  After studying the succession of fossilized life-forms in the Earth’s strata, Lamarck proposed that more complex organisms are descended from less complex organisms. 6  He mistakenly concluded, however, that increasing complexity is the 05 result of a natural motivating force—a striving for perfection—that is inherent in all living organisms. ** To explain the process of adaptation to the environment, Lamarck proposed the idea of inheritance of acquired characteristics. 4  0565618257 Grade 12 Elite Ms/ Reham Khaled M6/L1 History of Evolutionary Thought Term 1 ** Inheritance of acquired characteristics: that the environment can produce physical changes in an organism during its lifetime that are inheritable. ied ** One example he gave is that the long neck of giraffes developed over time because their necks grew longer as they stretched to reach food in tall trees, and this longer neck was then passed on to their offspring. ha ** His hypothesis of inheritance of acquired characteristics has never been supported by experimentation. ** The molecular mechanism of inheritance explains why—phenotypic changes acquired during an organism’s lifetime do not result in genetic changes that can be passed to subsequent generations. K am 7 25 eh /R 18 rs 56 M 6 05 :::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::: ** Geologist James Hutton (1726–97) proposed a theory of slow, uniform geological change. 5  0565618257 Grade 12 Elite Ms/ Reham Khaled M6/L1 History of Evolutionary Thought Term 1 ** Charles Lyell (1797–1875), the foremost geologist of Darwin’s time, made Hutton’s ideas popular in his book Principles of Geology. ied ** Hutton explained that the Earth is subject to slow but continuous cycles of rock formation and erosion, not shaped by sudden catastrophes. ** He proposed that erosion produces dirt and rock debris that is washed into ha the rivers, transported to the oceans, and deposited in thick layers, which are converted over time into sedimentary rock. K ** These layers of sedimentary rocks, which often contain fossils, are then uplifted from below sea level to form land during geological upheavals. am  Hutton concluded that extreme geological changes can be explained by slow natural processes, given enough time. 7  Lyell went on to propose the theory of uniformitarianism.  The theory of uniformitarianism: which states that the natural 25 eh processes witnessed today are the same processes that occurred in the past.  Hutton’s general ideas about slow and continual geological change /R 18 are still accepted today, although modern geologists realize that rates of change have not always been uniform through history. ** Thomas Malthus (1766–1834) was an economist who studied the factors rs that influence the growth and decline of human populations. 56 M ** In 1798 Malthus published An Essay on the Principle of Population, in which he proposed that the size of human populations is limited only by the quantity of resources, such as food, water, and shelter, available to support it. 6 ** He related famine, war, and epidemics to the problem of populations 05 overstretching their limited resources. ** Darwin, after reading Malthus’s essay in 1838, applied similar principles to animal populations—that is, animals tend to produce more offspring than can survive, and competition for limited resources in the environment is the element that determines survival. 6  0565618257 Grade 12 Elite Ms/ Reham Khaled M6/L1 History of Evolutionary Thought Term 1 ** Darwin thus used Malthus’s principle to formulate his idea of natural selection. ied Kha am 7 25 eh /R 18 rs 56 M 6 05 :::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::: H.W 7 0565618257 Grade 12 Elite Ms/ Reham Khaled M6/L1 History of Evolutionary Thought Term 1 ied Kha am 7 25 eh /R 18 rs 56 M 6 05 8  0565618257 Grade 12 Elite Ms/ Reham Khaled M6/L1 History of Evolutionary Thought Term 1 ied Kha am 7 25 eh :::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::: /R 18 rs 56 M 6 05 9