Evoloution of Polar Bears (Lamarck vs Darwin) free essay sample

The intention of this paper is to compare these thesis and determine the most appropriate in relation this event. According to Lamarck’s theory, features can be strengthened or rid of completely through use or disuse over generations. For example, Jean Baptise Lamarck believed that the giraffes long neck was an acquired characteristic. After a lifetime of straining to reach up to eat leaves, a giraffe’s neck would elongate. Baptise thought that the offspring of these giraffes would then be born with longer necks. Lamarck’s theory has widely been disproved, especially with the discovery of heredity genetics. If the theory were correct, a man who works hard to get large muscles, would father naturally strong children. Though the physical side of the idea may be dismissed, many researchers are studying whether behavioural traits can be passed down from a parent to their young. Charles Darwin’s theory of Natural Selection is the process by which biological traits become either more or less regular in a species and is a key component of evolution. Natural Selection occurs when a subject has a feature that enables to be able to survive more easily than those without it. Take for example the Galapagos Finches (Darwin’s Finches). Found on the Galapagos Islands in the Pacific Ocean are a group of about 13 types of finches with different beaks living on separate islands. It is believed that these finches all came from the same ancestral bird, but different food sources caused them to develop different beaks. In 1977 a drought reduced the number of small seeds available for the birds, forcing them to rely on larger seeds and nuts, which were difficult for birds with smaller beaks to open. The number of birds unable to eat reduced as they died and gave way to harder beaked finches. Within a couple of generations they had evolved larger beaks. In 2003 another drought struck the Galapagos and as there were many large beaked finches, the food source of nuts dwindled, making the ability to eat smaller seeds an asset. The numbers of larger beaked birds dwindled as food became scarce, leaving the smaller birds to survive and reproduce. Darwin’s theory was not well received when first written in On the Origin of Species, though many scientists today use it as a basis for research in evolution. Both theories suggest that a species changes over time to be able to better adapt to an environment. Though Lamarck thought that the entire population of that species would evolve as one, i. e. all offspring changes together with same adaptation. Darwin concluded that only the specimen with the mutation or an altered version of a feature to evolve a species as they would be able to adapt and survive easier than those without it, thus causing the â€Å"unevolved† to die off while the â€Å"evolved† lived. Over many many generations the species keeps evolving until it has perfected the new trait, also becoming a new species as the animal they evolved from becomes extinct. Lamarck ultimately did not believe in extinction, as it was his view that the changes were striving for perfection, rather than the dying off of a species. Around 100-200 thousand years ago, the Arctic Ocean was completely frozen and glaciers covered most of Eurasia. It is understood that it was around this time that Brown Bears began to wander from their usual habitat in search of food. Approximately 125,000 years ago a population of Brown Bears split off from their ancestors most likely in competition for food. This population would have become isolated by glaciers and most died in the harsh conditions, though many were already developing attributes such as thicker, lighter coats to enable them to survive and breed. Over thousands of years they continued to evolve and develop to better suit the harsh environment of the Arctic. At first these bears would have scavenged seal remains at the edge of the water, but as they developed better shaped teeth and skulls, they began hunting the animals instead. White camouflaged them from prey in their snow covered environment, aiding them in hunting. Large feet with curved non-retractable claws aid in hunting and gripping, as well as evenly distributing their body weight over thin ice, and propelling them whilst swimming. Small hairs on the pads of the feet also give grip to icy landscapes and provide insulation. As can be seen in the diagram, the Polar Bears have developed blade like teeth to be able to tear flesh and strong canine teeth used to hold prey and cut the tough hide of seals. Since they swallow chunks of meat rather than chewing, molars are not necessary, making them much smaller than other bears. The design of the Polar Bear’s teeth make it easy to eat soft meats and the blubber of seals, though they cannot process bones and vegetation. The low elongated skull and high sitting eyes are ideal for aquatic life as it gives the advantage of being able to put their heads into breathing holes or the dens of seal pups. When Brown Bears went off in search of food and this population became stranded and forced to adapt, those with more suitable features such as thicker and lighter fur, and those with shaper teeth survived and reproduced while the others died from cold and or starvation. This matches Darwin’s theory of Natural Selection. If it were to match Lamarck’s theory, all Brown Bears would have evolved into Polar Bears as that was the intention of their design. When needed the Brown Bear changed with it’s environment with the survival of the fittest and the demise of those without the necessary traits to survive, and in turn gave proof to Charles Darwin’s theory of natural selection. As time goes on many species will continue to evolve and adapt, as well as many species will become extinct both because of Natural Selection and human intervention.