Transcript Evolution
Evolution By Fehmi Alkas What is evolution ? • Evolution is the change in the inherited traits of a population of organisms through successive generations.(1) • Primary mechanism by which evolution occurs is natural selection. Charles Robert Darwin •Born in England in 1809. •Developed the Theory of Evolution with contributions from Alfred Russell Wallace. •Differentiation among birds in different zones gave him the idea that in a particular environment, only the species that are best adapted to that environment are likely to survive. This is known as natural selection. •Published On The Origin of Species in 1859. •Widely criticised by the Fundametalists. Mutations • Mutations are random changes in an organism’s DNA that can have various effects. • Mutations can have a wide range of effects : Some of them are fatally impairing but most have no or little effect on the organism. • A little proportion of mutations actually cause a change that will make the organism more fit to survive. It is these mutations that evolution mainly depends on. Natural Selection • In any environment, there will be some subspecies that will have superior traits to the mainstream population e.g. Better vision or hearing. • These subspecies will have a lower probability of being predated as they can sense predators from a greater distance and run away more easily. • In time, all the members of the species will be the better type. • Example X : Normal, Y: Better Sight 90 X, 10 Y Y: 10 % Predation or Next Generation 70 X, 8 Y Y: 10.3 % Predation or Next Generation 50 X, 7 Y Y: 12.3 % Key points to natural selection • Not all of the offspring produced by a generation survives. In fact, most of the offspring produced by a generation is going to die before producing any offspring themselves. • It does not mean that the better organisms will always survive and the less functional ones will die. • An almost perfect organism can still die sue to factors purely dependent on luck e.g. Velociraptor, Tyrannosaurus Rex and Carcharodon Megalodon were among the deadliest predators ever roamed the Earth but nonetheless they are extinct. • Evolution does not happen overnight : It takes thousands, even million years for a small change in the general population to happen. • It does not advance in definitive steps : It rather advances in small, smooth steps that eventually give result to something fundamentally different. Therefore, it’s a continuous process.(2) • It does not result in freak creatures : An intermediate between an ape and a human is NOT an ape with the arm of a human. It is more likely to be an ape with the ability to stand on two feet or an ape with decreased fur. References • http://en.wikipedia.org/wiki/Charles_Darwin • http://en.wikipedia.org/wiki/Evolution • http://www.wisegeek.com/contest/how-doesevolution-work.htm • http://necsi.org/projects/evolution/evolution/5parts /evolution_5parts.html