Lines of Evidence in Evolution

Evolution is the process by which all living things have developed from primitive organisms through changes occurring over billions of years, a process that includes all animals and plants. Exactly how evolution occurs is still a matter of debate, but there are many different theories and that it occurs is a scientific fact. Biologists agree that all living things come through a long history of changes shaped by physical and chemical processes that are still taking place. It is possible that all organisms can be traced back to the origin of Life from one celled organims.Human evolution is one of the most looked at aspects of anthropology.

To figure out how humans can adapt and develop there are many aspects that must be looked at, these aspects of evolution are called lines evidence of evolution, which deal with the physical and biological aspects of humans. These lines of evidence are the main things that are studied in order to understand evolution. The lines of evidence that are to be reviewed in this paper are Comparative anatomy, biogeography, molecular evolution, and fossil evidence. The first and line of evidence is the aspect of comparative anatomy.The study of comparative anatomy predates the modern study of evolution.

Early evolutionary scientists like “Buffon and Lamarck”(O’Neil, pre Darwinian theories) used comparative anatomy to determine relationships between species. Organisms with similar structures, they argued, must have gained these traits from a common ancestor. Today, comparative anatomy can serve as the first line of reasoning in determining the relatedness of species. Species can be related by determining if it has a comparative structure with another species.

These comparisons can be one of three types, these being homologous, analogous or vestigial structures.A homologous structure is a part of the body that has the same origin and structure, but may have a different function for different animals. For example the limbs of an animal can be used for flying, jumping or running. An analogous structure is the exact opposite, which is a function that is the same but the bones involved for that function are different. For example a bat and bird both fly, but have very different structure of wings. A vestigial structure is a part of the body that is not used by the animal because it is no longer useful and has diminished in size.

For example the pinky toe of a human, or the pelvic bone of the baleen whale. The field of biogeography is concerned with the distribution of species in relation both to geography and to other species. “Biogeography is a dynamic discipline that has led to expansive growth in our understanding of evolution” (Lieberman, 2003, 51). Biogeography involves two disciplines: historical biogeography, which is concerned with the origins and evolutionary histories of species on a long time scale, and ecological biogeography, which deals with the current interactions of species with their environments and each other on a much shorter time scale.Historical biogeographers depend heavily on evidence from other disciplines. Fossil records provide a large part of the information needed to determine past interactions.

Unlike historical biogeographers, ecological biogeographers make extensive use of current population information. They study the ways in which species develop and interact in the presence of other species and different environments. Molecular evolution is the evidence of evolution that shows that all living things are similar in one way or another. Our cells, and the cells of all organisms, are composed of molecular machines. These machines are built of component parts, each of which contributes a partial function or structural element to the machine.

How such sophisticated, multi-component machines could evolve has been somewhat mysterious, and highly controversial. ”(Lithgow, sciencedaily, 2009). At the cellular and molecular level living things are remarkably similar to each other. These fundamental similarities are most easily explained by the evolutionary theory that life shares a common ancestor.

All organisms are made of cells, which consist of membranes filled with water containing genetic material, proteins, lipids, carbohydrates, salts and other substances. The cells of most living things use sugar for fuel while producing proteins as building blocks and messengers. Different species share genetic homologies as well as anatomical ones. Roundworms, for example, share 25% of their genes with humans.

These genes are slightly different in each species, but their striking similarities nevertheless reveal their common ancestry. In fact, the DNA code itself is a homology that links all life on Earth to a common ancestor. Nothing is as dead as a fossil, yet the study of fossils is as lively as any branch of science. As the raw material for understanding the history of evolution, fossils never ceased to amaze and provoke.

”(Wade, 1, the Science Times Book of Fossils and Evolution). Fossils are the remains or traces of a plant or animal that have been preserved in the Earth's crust down to the present day. Fossils collected from all over the world are our most important source of information about the species that have existed on Earth since life began. The fossil record provides an historical account of the evolution of life.Fossils are parts or traces of ancient organisms that are usually preserved in sedimentary rock.

One way the age of a fossil can be determined is by noting its placement within the layers of the sedimentary rock it’s found in. Using the age of rocks and associated fossils, scientists have built a picture of apparent changes in groups of organisms from one geologic time period to another. In doing so, scientists have demonstrated linkages over time that support the idea that organisms have evolved and older species have given birth to more recent species, and so on throughout time.The evidence also shows that what have appeared to be gaps in the fossil record are due to incomplete data collection.

The more that we learn about the evolution of specific species lines, the more that these so-called gaps or missing links in the chain of evolution are filled with new fossil specimens. In conclusion, the lines of evidence that reviewed in this paper are Comparative anatomy, biogeography, molecular evolution, and fossil evidence. Comparative anatomy is a line of evidence because it shows that two very dissimilar animals can be from a common ancestor.This is proven by having homologous, analogous or vestigial structures. Biogeography, because the distribution of species over a long or short time frame, or historical and ecological geography. Molecular genetics, our DNA can be compared to that of all species to see how closely related we are.

This is done by comparing genes that are found in the DNA. Fossil records, because by studying fossils scientist can learn how old a species is and if it can be compared to that of another by similarities of their remains.These evidences are the most important, and also the most used by scientists when studying evolution. "There is grandeur in this view of life, with its several powers, having been originally breathed into a few forms or into one; and that, whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being evolved. " (Last words of Origin of Species, 1st Edition, Charles Darwin (1859))