Evolution Biological evolution is the organisms evolve over new and adapted organism. variation and natural process may be minimal or anything from a slight major way of life change. diversification of many
process through which generations and become a This occurs through genetic selection. The result of the substantial and can be change in posture to a Through this process the unique species occurs.
The fossil record is history shown through fossils, it is the remains and imprints left behind from earlier, less evolved or extinct species, which over the thousands of years it has been in the earth has become fossilized in the earth and rock and preserved. Study of the fossil record is highly important for three main reasons that are paramount to the history of evolution. The progressive and evolutionary changes of a species or many species (after evolution) is preserved in these fossils and kept until it can be examined and placed into the evolutionary tree and fill in another piece of the puzzle. Over time successive generations may not all have changes, but once all the fossils are placed together in order of age, one can determine the evolutionary changes and the order in which they occurred. Fossils also provide geologists with a convenient and easy method of assigning an age to the strata in which they occur. This is another key factor in piecing together the evolutionary changes
that occurred in species. Lastly, fossil organisms, these organisms may provide information about the climate, terrain and conditions of the area this animal lived in at the time, which in turn helps scientists to understand why these species evolved the way they did and why others evolved differently and what the primary needs of these species were in order to survive. Through use of the fossil record one can piece together the histories and evolutionary needs of many vastly different species as well as understand everything that comes with evolving over generations and time. Natural selection is one of the main methods of evolution, through natural selection only the strongest, smartest and biggest animals are able to pass on their genes and produce offspring. Over time many animals of the same species will be born with slightly different traits and as a result of this natural selection will occur amongst that species when breeding is about to occur. Due to this only the most powerful males are given the chance to pass on their genetic code and produce offspring. Through natural selection only the traits that will improve chances of survival and reproduction are selected leaving
the weaker traits out therefore breeding stronger offspring and strengthening the species. A species is classified as a group of individuals who can produce fertile offspring. Speciation is also classified as a lineage-splitting event that can produce two or more new species. Geography and geographical barriers and aids play a major part in this, for example, if a colony of apes all began in a desert where they had lived for thousands of years, but then half went up into the mountains and later the pass they had taken became blocked off, and the other half stayed in the desert, but over time the desert transformed in a tropical rainforest, both groups of apes would evolve differently to suite their needs for survival and over time as their genes became completely different to each others if they ever met again they would not be able to produce fertile offspring, if any at all. There are five types of speciation; reproductive isolation in which species can no longer successfully mate together due to major genetic differences, post-zygotic isolation, through which the parents can form a zygote together but after that zygote, is finally born it’s lineage will end as it is infertile, pre-zygotic isolation, this happens before the egg is even fertilized by the father and can be a product of behavioural and geographical changes, allopatric speciation, this is when two animals from different areas evolve differently depending on the demands the environment puts on them, and lastly, sympatric speciation, this is when creatures from the same country can no longer successfully breed together. Evolution does occur. There is no doubt about it, through the fossil record we can map evolutionary changes and show others what happened and how it happened. Through science we have discovered speciation, natural selection and evolution. When the fossil record and these processes are combined the evidence is clear, evolution is fact, not fiction. Through the study of evolution we know that birds are descendants of reptiles and that every twenty minutes bacteria is evolving, over and over and over. All the evidence clearly states evolution is fact, not fiction.
A Case Study – Whales The evolution of whales has been a slow and lengthy process, much like any other species’ evolution over time. The evolution of whales began approximately three hundred and seventy-five million years ago. The evolutionary process began when the very first tetrapods – vertebrates with arms and legs – began leaving swamps and moving to dry and habitable lands, this would set the stage for many other species to evolve into what we know today, including whales. Although many of these creatures looked every bit a reptile they were not, instead they were the archaic precursors of what we today call mammals. By the time the first mammals would begin to evolve one hundred and seventy-five million years had passed, leaving dinosaurs as the dominant vertebrates, due to this looming and deadly race of creatures mammals were forced to breed and evolve in the shadows of the world and survive secretly and quietly. But, approximately sixtyfive million years ago a catastrophic event wiped out all the non-avian dinosaurs leaving the path clear for mammals to further evolve in to bigger and more dominant creatures. Another ten million years passed before the first whales began to form and take shape, although these cetaceans were not anything like the whales we know today, they were vastly different, even so that paleontologists had trouble identifying their relation to whales. For a long time no one can relate whales to their pre-mammal ancestors, but only three decades ago a huge number of fossils were found and completely filled in the gaps and therefore confirmed the lineage all modern day whales descend from. Whales did have a straight line of evolution descending from parent to child, and parent to child over and over, instead they had a miss-match of amphibious cetaceans that walked in both swamps, rivers, estuaries and the coastline of prehistoric Asia. These ancestors share no similarities whatsoever with modern day whales. When land in Alabama and Arkansas was cleared for inhabitants many round and circular bones were dug and used for many purposes, such as; fireplace hearths, corner stones, pillows for slaves and many more, but due to the excessive amount of bones in these areas many were removed and destroyed due to their annoyance and disturbance of those trying to cultivate the fields for farming and agriculture. Later in 1832 a hill in Arkansas collapsed revealing twenty-eight of these large round and circular bones in perfect sequence. At the time no one
knew what to do with these new-found bones or what to classify them as or where they came from, except for a small piece of information, due to the shells in the sediment which was attached to the bones scientists were able to conclude that this creature had roamed an ancient ocean, but no more information was conceived. Not too long after this previous discovery, a new and bigger one was made in Alabama, vertebrae, along with other fragments, including, skull, jaw, limbs, ribs and backbone were found, with some being in excess of one hundred feet in length. When studying these bones they were classed as belonging to the largest reptile that had ever lived, but this was in fact incorrect, this “reptile” had mammal-like teeth. In 1839 these bones were taken to London for further study where they were later identified through the microscopic structure of the inside of the creatures teeth, which ultimately led to the animal being declared a mammal. Only a few years later a scientist dropped a bone on to the floor, by accident, shattering it, but as he was retrieving the pieces he noticed the inner ear, now revealed and came to the conclusion that there was and is only one other animal with such an inner ear, whales, resulting in this extinct whale being named Basilosaurus. When Charles Darwin released book on the Theory of Evolution Natural Selection many quarreled how a whale-like creature would be formed. Charles Darwin then countered this with this quote, “In America the black bear was seen explorer Samuel] Hearne swimming for hours with widely mouth, thus catching, like a whale, in the water. Even in so extreme a as this, if the supply of insects constant, and if better adapted competitors did not already exist country, I can see no difficulty in a bears being rendered, by natural selection, more and more aquatic structure and habits, with larger larger mouths, till a creature was produced as monstrous as a At the time Darwin was widely critiqued for this statement with claiming that he proposed that were direct ancestors of whales.
his through about even
Soon after another extinct whale discovered and was classed as to Basilosaurus and named Squalodon, although for many these discoveries would sit alone none could identify their relation to day whales. The next discovery once again only find fully aquatic creatures, leaving no link between and sea, a greatly needed connection.
was related
North by [the open insects case were in the race of in their and whale.” many bears
years as modern would land
In 1981 a shocking discovery was found in the sands of Pakistan, this discovery delivered the transitional phase scientists had been hoping for for so
long. When this new discovery called, Pakicetus Inachus was made it did not have the specialized inner ear like all other cetaceans, which showed that it lived very early in the transitional phase. It was presented as a stumpylegged sea-like creature, trapped between the two worlds and still evolving. Throughout the 1990s many other skeletons were discovered and began filling in many more of the gaps in the evolution of whales leading more and more people to believe it was so. But when studies came out of the field of molecular biology they conflicted with the conclusions paleontologists had come to about whales. Later in 2001, the molecular biologists were proved correct with a bone confirmed and an ancestor of the whales changed from mesonychids to artiodactyls. In 2007 a student studying the bones of Indohyus broke of the outer ear, revealing the heavily mineralized inner ear, an adaptation shared by mammals that spend large periods of time in the water, this added another ancestor to the whale family tree, as well as finally rooting down the place of whales in the mammal evolutionary tree. New Scientist Magazine By Zac Waine