THE ORIGIN OF MYTH: Discover The Living Proof Of Our Ancient Past - Vol. 1
Oleta Blaylock
Paleontology is the study of the history of life on Earth as based on fossils. Fossils are the remains of plants, animals, fungi, bacteria, and single-celled living things that have been replaced by rock material or impressions of organisms preserved in rock.
Evolutionary Biology
Many paleontologists are also evolutionary biologists. Evolutionary biology is the study of the origin, development, and changes (evolution) in species over time. Other scientists that contribute to evolutionary biology are geologists and geneticists.
THE ORIGIN OF MYTH: Discover the Living Proof of Our Ancient Past - Vol. 1
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Fossils and Myths
Ancient cultures did not always understand what fossils were, and adapted their discovery to fit with myths and stories.
China is rich in dinosaur fossils. Dinosaurs are ancient reptiles whose bones share characteristics with both reptiles and birds. Ancient Chinese people often interpreted dinosaur skeletons as the remains of flying dragons!
Fossilized remains of dwarf elephants have been found on several Mediterranean islands. Dwarf elephants grew to only 2 meters (6 feet) tall. Their skulls are about the same size as a human skull, with a large hole in the middle where the living animal's trunk is. In the ancient Mediterranean cultures of Greece and Rome, the remains of dwarf elephants were often interpreted as the remains of cyclopes, a type of feared, one-eyed giant.
Mary Anning
The 19th-century British fossil collector Mary Anning proved you don't have to be a paleontologist to contribute to science. Anning was one of the first people to collect, display, and correctly identify the fossils of ichthyosaurs, plesiosaurs, and pterosaurs. Her contributions to the understanding of Jurassic life were so impressive that in 2010, Anning was named among the 10 British women who have most influenced the history of science.
Soaking Up History
The oldest fossils ever discovered are stromatolites, the remains of ancient cyanobacteria, or blue-green algae. The oldest animal fossils ever discovered are sponges. Prehistoric sponges have been discovered on the Arabian Peninsula and Australia.
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Malaria is caused by infection with protozoan parasites belonging to the genus Plasmodium transmitted by female Anopheles species mosquitoes. Our understanding of the malaria parasites begins in 1880 with the discovery of the parasites in the blood of malaria patients by Alphonse Laveran. The sexual stages in the blood were discovered by William MacCallum in birds infected with a related haematozoan, Haemoproteus columbae, in 1897 and the whole of the transmission cycle in culicine mosquitoes and birds infected with Plasmodium relictum was elucidated by Ronald Ross in 1897. In 1898 the Italian malariologists, Giovanni Battista Grassi, Amico Bignami, Giuseppe Bastianelli, Angelo Celli, Camillo Golgi and Ettore Marchiafava demonstrated conclusively that human malaria was also transmitted by mosquitoes, in this case anophelines. The discovery that malaria parasites developed in the liver before entering the blood stream was made by Henry Shortt and Cyril Garnham in 1948 and the final stage in the life cycle, the presence of dormant stages in the liver, was conclusively demonstrated in 1982 by Wojciech Krotoski. This article traces the main events and stresses the importance of comparative studies in that, apart from the initial discovery of parasites in the blood, every subsequent discovery has been based on studies on non-human malaria parasites and related organisms.
Malaria is an ancient disease and references to what was almost certainly malaria occur in a Chinese document from about 2700 BC, clay tablets from Mesopotamia from 2000 BC, Egyptian papyri from 1570 BC and Hindu texts as far back as the sixth century BC. Such historical records must be regarded with caution but moving into later centuries we are beginning to step onto firmer ground. The early Greeks, including Homer in about 850 BC, Empedocles of Agrigentum in about 550 BC and Hippocrates in about 400 BC, were well aware of the characteristic poor health, malarial fevers and enlarged spleens seen in people living in marshy places. For over 2500 years the idea that malaria fevers were caused by miasmas rising from swamps persisted and it is widely held that the word malaria comes from the Italian mal'aria meaning spoiled air although this has been disputed. With the discovery of bacteria by Antoni van Leeuwenhoek in 1676, and the incrimination of microorganisms as causes of infectious diseases and the development of the germ theory of infection by Louis Pasteur and Robert Koch in 1878-1879, the search for the cause of malaria intensified. Scientific studies only became possible after the discovery of the parasites themselves by Charles Louis Alphonse Laveran in 1880 and the incrimination of mosquitoes as the vectors, first for avian malaria by Ronald Ross in 1897 and then for human malaria by the Italian scientists Giovanni Battista Grassi, Amico Bignami, Giuseppe Bastianelli, Angelo Celli, Camillo Golgi and Ettore Marchiafava between 1898 and 1900. Excellent histories of this disease include those by Celli [1], Stephens [2], Scott [3], Russell [4], Foster [5], Garnham [6, 7], Harrison [8], Bruce-Chwatt [9], Desowitz [10], McGregor [11], Poser & Bruyn [12] and Schlagenhauf [13].
In order to understand the historical events it is necessary to summarise briefly our current state of knowledge. Malaria is caused by infection with five species of Plasmodium the life cycles of which are very similar (Figure 1).
Infection begins when (1) sporozoites, the infective stages, are injected by a mosquito and are carried around the body until they invade liver hepatocytes where (2) they undergo a phase of asexual multiplication (exoerythrocytic schizogony) resulting in the production of many uninucleate merozoites. These merozoites flood out into the blood and invade red blood cells where (3) they initiate a second phase of asexual multiplication (erythrocytic schizogony) resulting in the production of about 8-16 merozoites which invade new red blood cells. This process is repeated almost indefinitely and is responsible for the disease, malaria. As the infection progresses, some young merozoites develop into male and female gametocytes that circulate in the peripheral blood until they are (4) taken up by a female anopheline mosquito when it feeds. Within the mosquito (5) the gametocytes mature into male and female gametes, fertilization occurs and a motile zygote (ookinete) is formed within the lumen of the mosquito gut, the beginning of a process known as sporogony. The ookinete penetrates the gut wall and becomes a conspicuous oocyst within which another phase of multiplication occurs resulting in the formation of sporozoites that migrate to the salivary glands of a mosquito and are injected when the mosquito feeds on a new host.
Our understanding of the life cycle of the malaria parasites did not proceed in the logical order just outlined but more like a jigsaw in which the various pieces were painstakingly put into place and, like a jigsaw, often involved mistakes and false starts. The story begins with the discovery of the stages in the blood. Many textbooks merely state that 'in 1880 Laveran discovered the malaria parasite' words that do not give this discovery the credit it deserves. In order to understand the background of this discovery it is necessary to go back to the 1870s. The discoveries of Pasteur and Koch had precipitated a search for a bacterial cause for many diseases including malaria. By 1879 the miasma theory was going out of favour and the two theories vying for contention were whether the microorganisms responsible were transmitted (1) by air and inhalation or (2) by water and ingestion. The leading theory was that proposed by the Italian Corrado Tommasi-Crudeli and the German, Theodor Albrecht Edwin Klebs, an eminent microbiologist who had been the first person to see the bacteria responsible for typhoid and diphtheria. Tommasi-Crudeli and Klebs claimed that they had isolated from the waters of the Pontine Marshes, where malaria was prevalent, a bacterium, Bacillus malariae, which when isolated in culture and injected into rabbits caused febrile infections accompanied by enlarged spleens reminiscent of malaria [14]. It was against this background that Charles Louis Alphonse Laveran, an unknown French army officer working in Algeria, challenged the perceived wisdom and began in his own words 'to follow the pigment'. Beginning with the known fact that the spleens of malaria patients contained pigment he began to look for pigment in the fresh unstained blood of patients and observed it first in leucocytes and then in or on red blood cells. Looking more carefully, he observed several different forms of erythrocytic organism including crescents, spherical motionless bodies with pigment, spherical moving bodies with pigment and bodies that extruded flagella-like structures all of which he thought were on the outside of the red cells. These observations are particularly interesting because Laveran not only used fresh blood but also a dry objective with a maximum magnification of 400 diameters. He also suggested a course of events that began with clear spots that grew, acquired pigment and filled the corpuscle which then burst coinciding with the fevers associated with malaria. Laveran meticulously examined the blood of 200 patients and in 148 observed the crescentic bodies in all cases of malaria but never in those without malaria. He also noted that quinine removed these stages from the blood. Laveran quickly realised that he had found a parasitic protozoan which he called Oscillaria malariae. He presented his findings to the French Academy of Medical Sciences in December 1880 [15] but failed to persuade any of the eminent microbiologists, zoologists or malariologists of the day that he was seeing anything other than disintegrating red blood cells. Nevertheless he persevered and by 1884 had convinced the leading Italian malariologists including Bignami, Golgi and Marchiafava that malaria was caused by a protozoan and not a bacterium [16]. His biggest triumph came in the same year when he also convinced the more cynical microbiologists Louis Pasteur, Charles Edouard Chamberland and Pierre Paul mile Roux. Robert Koch, one of the most influential microbiologists of his time, however, remained sceptical until 1887. Nevertheless in some quarters the miasma theory persisted and as late as 1895 the American R. C. Newton, a supporter of Tommasi-Crudeli, wrote that 'Aerial and aquatic transportation of malaria has been proved' [17]. (This paper is worth reading in full because, although based on what we now know to be false premises, it contains a mass of interesting information about the prevention of malaria such as the use of screens or mosquito nets to exclude insects, closing doors at night and lighting fires out of doors). Laveran was awarded the Nobel Prize for Medicine in 1907 and his discoveries are described in some detail by the Sergent brothers [18] and Bruce-Chwatt [19] as well as in the various histories of malaria listed above.
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