About this sample
About this sample
Words: 1731 |
9 min read
Published: Jun 20, 2019
Words: 1731|Pages: 4|9 min read
Scientific theory is an observed and tested phenomenon, governed by a set of rules, facts and well sustainable explanation. However, this differs from how we normally think of a theory because a theory is basically formed from a hypothesis attempting to relate facts to each other on the grounds of speculation. However, a hypothesis is an observable, proposed idea or explanation. In the case of the law of Parsimony, Occam’s Razor states that “entities should not be multiplied beyond necessity”, therefore in science we should not make assumptions of things that are surplus to requirement. In the case of multiple hypothesis, the law of parsimony is a general guideline applied, it suggests that we look for the simplest, clearer hypothesis, with empirical evidentiary support first, in order remove the unnecessary assumptions. Parsimony is used more specifically in taxonomy to produce the least number of groups in phylogenetic trees, to avoid over group. Scientists need to communicate their latest findings and inform their colleagues and the public of new data. They may present these findings at conferences where a group of their peers can listen to the presentations, at universities or through journals and popular media. The main outlet that scientists use to communicate their results is through publishing it in journals, they are placed in archive, so it can be read and referenced in the future. Some journals go through something called peer reviewing, this is when your article becomes published after other scientists have reviewed and deem it to be of good standard and quality. This builds the scientist's reputation and gives a wide audience, making it easier for other scientists in their field to be easily accessed and refer to their findings while doing similar researches, such as researches on descent from common ancestors.
It is a known fact that each species that live today is as a result of evolution of pre-existing species throughout their lineage, if follow the ancestry of two modern day species at one point they're will be intersection with the two lineage on the family tree of life, indicative of a common ancestor, therefore all organisms today are all descendants of species that no longer exists and the closer the species are from their common descendant the more related they are. When the whole idea for common descent was proposed, Darwin had no genetics understanding, but today we see when scientist compare genomes of different species they fumed similarity in the numbers of chromosomes and their location, with fossil evidence they were also able to find similarities amongst different species bone structure and their assemblages.
A typical example of descent from a common ancestor is horse evolution, no evolution of any other species is as well documented as the horse lineage, this is due to an abundance of fossils found throughout North America from over 50 million years ago, this allows us to reconstruct much of the horse family tree. The rise of the horses embodies the “survival of the fittest” phrase, since along this lineage there were some branches that ran dead due, the story of horse evolution is one of constant adaptation and radiation in response to changes in North Americas climate. The Hyracotherium (Eohippus) was the first equine animal that raised about 55 million years ago, it was as big as a fox, hind legs longer than the foreleg with toes that were each capped with separate hooves (four on forelimb and three on hindlimb), omnivorous teeth, with in its 20 million years in existence, its first complete fossil was found in 1876, this forest creature have risen to the equidae. With diversification the equid family had more than a dozen genera that roamed the northern hemisphere, unlike the one genus that remains today, the eques (modern horses, donkey and zebra). By the Eocene, the climate was dry, giving way to a mosaic of dry grassland, in this environment it is believed that the descendant of eohippus first appeared, the mesohippus, which quickly diversified into another genus the miohippus. These two roamed the earth at the time but they were both different to the eohippus as they were beginning to adapt to the changes occurring to North America's landscape. They're preserved teeth shows that they had more molars and higher crest to aid in the grinding of kore fibrous foods like grass, unlike the eohippus. There fossil bodies also indicated that they were beginning to get much longer legs, which might have helped them to make faster strides, even their fourth front toe had disappeared as the middle to disappeared, it is believed that this was necessary support the larger mass they now had. Mid Oligocene the smaller mesohippus disappeared leaving the larger miohippus, which later radiated into many different species into the miocene epoch. This time there was much swampy area, the parahippus, descendant of the miohippus paleontologist were able to learn about one of their species, it is said to be the first horse to be a hypsodont, which gave a greater advantage for living on the plains, when it came to eating grass that wears away the teeth. From the perahippus lineage fossil records show that a new genus had evolved, called the merychippus (the first true equine), it was a lot bigger, the long horse-like head, its legs were especially adaptive to running on hard ground, all its weight was supported on 3 toes by springy ligaments, forelegs were much longer and stronger due to the bones that were fused together. Several descendants of the merychippus later, they became monodactyl, having this one large to would reduce the stress caused by their increasing weight. Then there was the Pliocene Epoch, where one of the single toe equines finally gave rise to Equus (genus of the modern day horse), the oldest species found being Equus simplicidens, it had around the size of a modern horse, similar teeth, fully fused leg bones for better protection and locomotion, long face and neck for better feeding and developed stay-mechanism an adaptation for standing for long periods. They later crossed over into different continents, during this time all the three toed horses died out as well as most monodactyl. At the end of the Pleistocene most of the large mammals including Equus went extinct in North America, its believed that the hunting by early humans, the competition for food by other bigger animals and the climatic change due to the end of the last ice age. However, the migrated horses were able to survive in other continent that supported their favorable environments, that were able to repopulate North America. In 2013 a group of researchers were able to obtain DNA sequence of a horse's leg bone buried in permafrost that’s about 560 to 780 000 yrs. old. They compared the sequence with that of a 43000-yr. old Pleistocene horse, a Przewalksis horse, and along with 5 modern horses and a donkey, when the difference amongst the genomes were analyzed, they found that the last common ancestor of them existed 4 to 4.5 million yrs. ago.
The whole idea of survival of the fittest was contributed by Charles Darwin, where he believed that organisms will change over time to best survive in their environment, this is a biological fact, but the theory is how they change over time. Charles Darwin was the first to propose that this change happens through a process of natural selection, basically nature choses what survive and what goes extinct. On a voyage between 1831 and 1836 he noticed that the same species of organism had a lot of similarities. This prompted him to publish his book on the origin of species by natural selection in 1859. To understand natural selection you must have a population of organisms where there are variations, there must be change in the environment, this May allow some organisms with particular traits to be better suited for the environment, because they have they have higher fitness they live long enough to reproduce and pass that variation to their offspring, the ones that does not have a suited variation are going to die and they’re genes are going to die out of the population. This suitable variation becomes adaptation. More of the better gene population increases creating a population well suited for its environment. A famous observation of natural selection was made by a biologist named Kent Well on the peppered moth (black and white color), most moths looked like that with just a few if the darker variation. The peppered gave those one with a peppered appearance to camouflage easily from predators on the barks than the darker ones, giving them higher fitness. During the industrial revolution, something happened to the environment, coal dust landed on the moth’s habitat making it darker, this in turn gave the darker moth an advantage, they were then the fittest ones causing them to successfully reproduce more, increasing its population and the peppered moths which were now exposed to predator, their population decreased.
When these organisms evolve from their ancestors, there is a remnant of features that served a function in an organism’s ancestor, but since we are no longer living in similar circumstances like our ancestors that require them, they are called vestigial structures since they aren’t always organs. For instance in humans the coccyx is believe to be an evolved tail now operates as anchor in the lower body, the wisdom teeth are extra teeth that helped our ancestors digest uncooked and unprocessed food, also the appendix now only stores bacteria to aid in digestion, also in animals such as a whale we see evidence that the ancestor was a terrestrial animal with the pelvis and femur bone found in the whales body.
Whether organisms may be different in ways of their mobility, with keen observation we can see that certain structures of these varying species are alike whether they swing, walk, fly or swim. These similarities in their bone structure which suggests that they all came from the same ancestor. When the forearms of a bat, whale horse and humans are observed we can see they all have similar bones, similar number of bones and arrangement. This is known as homology and pays an important role in supporting evolution, in a nut shell evolution aims to prove that every organism we see today, diversified from one single organism over a long period today, and only the fittest continues to prevail.
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