The Evolution of Flight in Birds - Research Proposal Example

The Evolution of Flight in Birds Grade (Oct. 30th, The Evolution of Flight in Birds The of theevolution of Flight in Birds is a controversial topic to present day, owing o the fact that different theories have evolved in a bid to try and explain how the birds’ flight evolved, but none of them has been found to offer a satisfactory explanation. While some of the theories hold that evolution of Flight in Birds started from the-trees-down, others have held that it started from ground-upwards (Burgers & Chiappe, 1999). The proponents of the view that flight in birds started from the trees downwards holds that; since birds are arboreal, they developed their flight through gliding, which basically is a natural concept applying the forces of gravity (Noberg, 2002). On the other hand, the proponents of the ground-to-up theory of evolution of flight in birds holds that the wings were first applied to catch insects and not primarily for flying, thus it is in the process of trying to use wings to reach the insects upwards, that the flight tendencies developed, and finally the birds were able to fly (Speakman, 2001). While each of the above theory seems to hold some ground, it makes the understanding of evolution of flight in birds so elusive, such that there is no telling what to believe anymore. Nevertheless, these are just mere believes that have not been backed by any scientific data or evidence, thus remains just theoretical explanations of the evolution of flight in birds, requiring that more scientific and well grounded explanations should be developed. The major issue that brings the complexity of the explanation of the evolution of flight in birds, is the issue of why, considering the fact that evolution is a field that does not deal with the question why, only concerning itself with what is and how it might have come about, but not for what reasons (Schluter, 2001). Therefore, the first step to reaching a conclusion on how the evolution of flight in birds came about must start with their ancestral origin or lineages as explained by the theory of evolution (Burgers & Chiappe, 1999). The theory of evolution holds that the ancestors of the flying animals must have been the glider; the arboreal glider that is characteristic of the modern ones that are non-aquatic, to mean that flight must have then evolved from an arboreal ancestor (Noberg, 2002). Nevertheless, without wings there can be no flight. Thus, the first question that needs to be answered, while addressing the issue of the evolution of flight in birds, is the concept of wings and wings development. Scientists have come to an agreement that wings either evolved for exaptations or adaptations (Norell, 2007). The exaptations theory holds that wings were used by the earlier ancestors of the birds for a different function, and then developed to be used for flight in the later descendants (Norell, 2007). Thus, according to this theory, wings were initially meant for protecting the birds against cold, by offering warmth. On the other hand, the adaptation theory holds that wings were originally developed for powering flight, thus flight in birds did not evolve, but was their initial state of being (Seebacher, 2003). The arboreal hypothesis is one major theory that has been established to explain how evolution of flight in birds occurred, providing that the ancestors of birds lived in trees, and then glided into flapping, thus supposing that the evolution of flight in birds started from up-to-down (Dial, 2003). According to the arboreal hypothesis, the ancestors of birds could climbed the tree through the usual ways that the other animals climb trees, but coming down the trees was achieved through running down the tree trunk, which made the ancestors of the birds flap their wings (Dial, 2003). Eventually, the flapping of the wings resulted in the ability of the wings to power flight when they were continually and powerfully flapped. The cursorial hypothesis is yet another theory that tries to explain the evolution of flight in birds, holding that the claws of birds could not support ascending up the tree (Dial, 2003). Thus, according to this theory, the ancestors of birds used their powerful legs to run first, while having their arms outstretched, an occurrence that then made the wind currents cause the arms of the ancestors to flap, thus taking the ancestors airborne (Speakman, 2001). The wing-assisted incline running hypothesis is yet another theory that has been developed to offer an explanation in relation to the evolution of flight in birds (Noberg, 2002). According to this theory, the early dinosaurs had feathered limbs, which might have enabled them to run uphill or along other vertical inclines in order to escape their predators (Schluter, 2001). Thus, according to this theory, it is the half-running and half-flapping activities of the dinosaurs that eventually developed into the ability to fly (Dial, 2003). This theory has indicated that the ability to fly developed gradually, with the wings and feathers initially being meant for protecting the animals against cold weather and water, after which the development of flapping came as a necessity adaptations when such animals started to be chased by their predators (Dial, 2003). Thus, before managing to fly, the wings first developed the traction for high speed, which would propel the animals forward so that they escape from the predators (Dial, 2003). Eventually, the high speed developed into frantic flapping, which the combined with the wind currents caused the animals to get airborne (Burgers & Chiappe, 1999). Therefore, the initial ancestors of the birds had strong legs and weaker wings, since it is the legs rather than the wings that enabled the animals to run. However, with the need for high speed, the wings developed to become stronger for the purpose of keeping he animals well grounded and with good balance during the time of running away from the enemies (Daily Mail, 2012). The grounding and stabilizing effect of the wings then paved way for high speed of the animals, which caused them to flap their wings frantically in the process. Eventually, the wings became adapted for flying. Recent research A study of chicks at the University of Montana has shown that they flap their wings frantically as they run away from any perceived danger, a process that enables the chicks to run faster and even develop the capacity to move vertically at a high speed (Dial, 2003). It is this finding that has served to strengthen the cursorial hypothesis, by showing that the ancestors of birds could have first started with running on the ground at a fast speed while flapping their wings, an occurrence that eventually enabled them to mover vertically and eventually able to fly (Dial, 2003). Another recent research from the Universities of Bristol and Yale has shown that feathers in the dinosaurs, which are believed to be the ancestors of birds were arranged in layers for the purpose of offering the dinosaurs with heat insulation (Daily Mail, 2012). This research has indicated that the dinosaurs simply applied the feathered wings for heat insulation, and it is not until a million years after the first ancestors of the birds applied the wings for heat preservation, that the wings then emerged for display, then for camouflage purposes and finally for flapping to allow the dinosaurs to fly (Daily Mail, 2012). Describe future research The various theories that have been offered to explain the evolution of flight in birds have tried to explain how the birds came to start flying (Dial, 2003). However, there is little focus on the question of why the wings evolution occurred, owing to the fact that if the wings served their initial purposes well, then, they need not have evolve for different adaptations. In this respect, the future researches should focus on the question of why the evolution of the wings occurred from their initial adaptations to their current use. This way, the pending question of why; which is a pertinent question for creating understanding of flight in birds will be addressed. References Burgers, P. & L. M. Chiappe. (1999). The wings of Archaeopteryx as a primary thrust generator. Nature 399: 60-62. Daily Mail. (2012, November 21). Birds first evolved wings for warmth rather than flight, new findings suggest. The Daily Mail. Available at: http://www.dailymail.co.uk/sciencetech/article-2236373/Birds-evolved-wings-warmth-flight-new-findings-suggest.html Dial, K. P. (2003). Wing-assisted incline running and the evolution of flight. Science 299:402-404. Noberg, U. M. L. (2002). Structure, form, and function of flight in engineering and the living world. Journal of Morphology 252:52-81. Norell, M. A. (2007). A basal dromaeosaurid and size evolution preceding avian flight. Science 317: 1378-1381. Schluter D. (2001). Ecology and the origin of species. Trends in Ecology and Evolution 16:372–380 Seebacher, F. (2003). Dinosaur body temperatures: the occurrence of endothermy and ectothermy. Paleobiology 29: 105-122. Speakman, J. R.(2001). The evolution of flight and echolocation in bats: another leap in the dark. Mammal Review 31: 111-130. Read More