New Sci enti st Special Issue!
LIFEGOESON- EVOLUTION MAYEDITION- 2017
- Is Darwin's Theory of Evolution True? - Natural Selection - Fossil Record and more!
ONLY - $6.99! ?One general law, leading to the advancement of all organic beings, namely, multiply, vary, let the strongest live and the weakest die?. - Charles Darwin
By Nikhil Dulat
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NOVEMBER27,1859
DARWIN'SDEFINITION OFEVOLUTION -THEORIGINOF SPECIES
Charles Darwin proposed the Theory of Evolution by natural selection in 1859 in his first book ?On the Origin of Species?. This book has been deemed as the foundation of evolutionary biology. Darwin elucidates the Theory of Evolution by natural selection as an organism changing over time as a consequence of variation changes in heritable, (genes that have been passed down from an organisms parents that encode for certain characteristics presented within that organism) physical and behavioral traits. These changes in traits allow an organism to better adapt to its natural environment aiding the survival of the species as well as potentiating its ability to reproduce. Further, these changes can subsequently result in the generation of biodiversity, which is more overtly the generation of new species as well as the differentiation between subtypes of species within animal populations.
Charles Darwin, 1859, The Origin of Species ? ?I can see no difficulty in a race of bears being rendered, by natural selection, more aquatic in their structure and habits, with larger and larger mouths, till a creature was produced as monstrous as a whale?.
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WHAT LANDMAMMALSTO WHALES? TROUBLES DID DARWIN FACE? In Darwin?s Origin of Species he proposes that whales originated from land mammals via the process of natural selection. More explicitly, he suggested that whales evolved from North American black bears. These bears were known to catch insects by swimming in the water with their mouths wide open.
Darwin?s proposed idea had a bad reception and received an immense amount of public and scientific criticism. This was largely due to the fact evolutionist ideas contradicted religious beliefs regarding genesis. Due to the humiliation that he felt from the public, Darwin removed his passage on black bears from later publications of his book. Scientists now believe that Darwin had the correct idea regarding the evolution of whales, but the wrong original animal and should have considered hippotamuses or cows.
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NATURAL SELECTION -WHATISIT? The theory of evolution by natural selection is one of the greatest supported theories in the history of science and is one of the basic mechanisms of evolutions. Clear evidence has supported the idea of natural selection through a wide variety of scientific disciplines ? more specifically: geology, paleontology, development biology and genetics. Natural selection can be broken down into five steps: Variation, Inheritance, Selection, Time and Adaptation. DNA, which is comprised, of genes from parents is transferred to their offspring. The genes on the DNA encode for traits expressed within that offspring. For e.g. Eye colour. This is known as Variation and Inheritance. Certain environments are unable to support unlimited populations. Due to the fact that many resources are limited, more organisms are born than can survive. Eventually certain animals that do not have access to food resources for example will eventually die and become extinct. Small variations in their expressed traits can help a species survive for e.g. chameleons and their camouflaging. This is known as Selection/survival and reproduction. Eventually, in generation after generation, advantageous traits help some individuals survive and reproduce. These traits are then passed on to greater numbers of offspring. After just a few generations or after thousands, depending on the circumstances, such traits become common within the population. This is known as Time and Adaption.
Darwin, C (1859), The Origin of Species ? ?One general law, leading to the advancement of all organic beings, namely, multiply, vary, let the strongest live and the weakest die?.
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- HOWDOESNATURAL SELECTIONRELATETO POPULATIONCHANGEOVER TIME? Antibiotic resistance is the key consequence of evolution via natural selection. The antibiotic action is an environmental pressure. Certain bacteria contains a mutation, allowing them to survive and ultimately live on to reproduce. The bacteria will then pass this trait off to their offspring, which will eventually result in a fully resistant generation. This relates to how natural selection is a simple biological mechanism that both large and small populations of living things, can change and revolutionize over time.
Dar w in's Fin ch es
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CASESTUDY/EXAMPLEOFNATURALSELECTION THEORIGINOFBIRDS BYNIKHILDULAT The Origin of Birds has been a major historical topic within evolutionary biology, that has been debated and questioned by many scientists over countless decades. In the late 19th century, after the discovery of the primitive bird known as Archaeopteryx in Germany, a close relationship has been established between both dinosaurs and birds. Scientists have discovered that many birds share numerous similarities and comparabilities with dinosaurs, along with certain unique skeletal features.
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In 1970, paleontologists uncovered that the Archaeopteryx shared unique features with small carnivorous dinosaurs known as theropods. Based on mutual features, scientists reasoned that perhaps the theropods were indeed, the ancestors of birds. When paleontologists built evolutionary trees to study the question, they were even more convinced. As many birds evolved from these theropod dinosaurs, many of their features were modified. Sufficient evidence of evolution through birds and dinosaurs has delivered scientists with arguable theories on the origin of birds which leads us to ponder these theories and sources on their reliability, consistency and dependability.
- THEROPOD DINOSAUR
- ARCHAEOPTERYX/PRIMITIVE BIRD
- CURRENT DAY BIRD
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SPECIATION - WHATISIT? The concept of speciation is very simple to understand. Speciation is simply, the formation of new and distinctive species formed over the cause of evolution.
- HOWDOGENESANDENVIRONMENTALFACTORS INTERACTTOAFFECTTHESURVIVALOF ORGANISMSINAPOPULATION? Both genes and environmental factors can interact to affect the overall survival of organisms in a population. In our society today, it is relevant to notice that the environment provides many raw materials for the synthetic processes controlled by genes. A common example of this would be that animals are able to obtain several of the amino acids for their proteins as part of their diets.
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Both of these diagrams show the different variations of species across the bird family and how the main founder species is the main bird in which all of the other birds inherit certain similarities and genetic features.
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2. BIOGEOGRAPHY
EVIDENCE 1.PALEONTOLOGY Paleontology is the study of prehistoric life including fossils, footprints and past climatic events. As organisms die, they are incorporated into the ground as fossils/bones. This allows scientists to study these fossils years later when retrieving them under the many surface layers on the earth. Over the years, new layers are formed and fossils form on top of each other. Scientists can then use the fossil record to form a biological timeline. Visually, fossil records can show scientists the sequence of historical changes in organisms and how these organisms have adapted and evolved over long periods of time. Scientists can then use radiometric dating techniques to determine the age of the fossils and rocks.
Biogeography shows scientists how and where certain species are distributed across earth. This is what first suggested to Charles Darwin that certain species evolve from a common ancestor. Darwin later observed that the animals of the Galapagos Islands were very similar and alike to the animals on the South American mainland, but very dissimilar to animals on other islands that had similar environments. From this, he then concluded that the animals on the Galapagos Islands had in fact migrated from South America and after a long period of time, became new species as the populations adapted to their new environment. This also helps explain why there are no polar bears in the Antarctic and no penguins in the Arctic despite both places being both very icy and cold.
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MOREEVIDENCE... 3. COMPARATIVEEMBRYOLOGY Comparative embryology is purely the study of how different types of organisms compare to one another during their fetal stages. Below is an image that shows the similarities in organism components between fish and reptiles, birds and humans.
4. COMPARATIVEANATOMY Comparative anatomy is the study of certain similarities and differences in the anatomy of different species. A common example of comparative anatomy is the similar bone structures in forelimbs of cats, whales, bats, and humans. Paleontologists believe
that both wales and dolphins evolved from land animals. The body structure of both animals indicate the similarities. Further, paleontologists believe that whale and dolphin flippers are reminiscent of the two front legs of a 4 legged animal. Whilst the tail of a 4 legged animal is resonant of the lower limbs (small internal back limbs) of a whale or dolphin. Scientists believe that studying certain similarities and traits amongst species could help accentuate a further understanding of evolution.
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THEFOSSIL RECORD
Dendrochronology is a dating method that studies tree rings to determine how old the tree is as well as the distinctive atmospheric conditions and their temporalities through which the tree developed. Dendrochronology utilizes the knowledge that a tree produces a new ring every year and that the thickness of that ring is a reflection of the climate in which the tree is situated. Dendrochronology is arguably one of the most accurate ways to date ancient objects.
Fossil record refers to the placement of fossils throughout the surface layers of the Earth. The older the fossil is, the deeper it is buried within the Earths crust. The fossil record provides evidence on the origin of life. Scientists believe that both Earth and life on Earth have existed for over 3.5 billion years due to the presence of prokaryotic cells upon the earth at that time.
Relative dating methods conveys organisms that lived together as well as the order in which fossils occurred, however it does not give an exact age of the fossil. Relative dating uses the Law of Superposition, which is the idea of sedimentary layers deposited in a time sequence whereas the older rock remains on the bottom whilst the younger rock stays at the top.
On the other hand absolute dating methods are used to determine an actual date in years for the age of an object. Absolute dating methods are carried out in a laboratory. Absolute dates must coincide with dates from other relative methods in order to be valid.
The molecular clock estimates the number of genetic mutations between two species closely related to each other and utilizes an average genetic mutation rate to determine the amount of time that has surpassed since the speciation of those two species. Where fossilisation minimally occurs, for example with jelly fish, the molecular clock is the only feasible dating method. However, a limitation of this method is that the average genetic mutation rate is ambiguous, whereby genes can go through periods with significant mutation and periods without.
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RESOURCES
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