Evolution: how why and when
Evolution: how why and when
What Is Evolution?
Biological evolution refers to the changes that occur in a population over time. These changes are produced at the genetic level as organisms’ genes mutate and/or recombine in different ways during reproduction and are passed on to future generations. Sometimes, individuals inherit new characteristics that give them survival and reproductive advantages in their local environments. These characteristics tend to increase in occurrence in the population, while those that are harmful decrease in frequency. This process of making more of the best and getting rid of the worst is known as “natural selection” or “survival of the fittest”. Some people think that any change in an organisms’ body or genetic makeup is evolution. However, this is not true. Non-genetic changes that occur during an organism’s life span, for example increases in muscle tissue due to exercise cannot be passed on to the next generation and are not examples of evolution.
Are all species related?
Yes. Scientists today believe that all organisms share an ancestor somewhere in their history. When this theory is put into a chart it looks much like a tree. Therefore scientists have named this “chart” the “Tree of Life”. Every branch of the “tree” represents a different species, and everywhere the branch forks or splits represents the common ancestor that binds two species together.
How do organisms evolve?
Individual organisms don’t evolve. Populations evolve. Because individuals in a population vary, some in the population are better able to survive and reproduce given a particular set of environmental conditions. These individuals generally survive and produce more offspring, thus passing their advantageous traits on to the next generation. Over time, the population changes.
What do genes have to do with evolution?
First of all, to understand what genes have to do with evolution you must understand what genes are and how they work. Genes are the portions of an organism’s DNA that carry the code responsible for the makeup of that particular organism. Genes are responsible for the way an organism looks, acts, and genes can determine whether or not an organism will have many diseases or birth defects.
When organisms reproduce they “pass down” a fraction of the genes that they carry themselves. Not always, but most of the time the “bad” genes are naturally discarded or over-powdered in the reproduction process. This is because the bad genes are usually recessive which means that the offspring has to receive two of the “bad” genes in order to carry that trait. I am not saying that all recessive genes are “bad” genes. (An example of a recessive gene in humans is blonde hair.) Genes that are stronger than recessive genes are known as dominate. (Brown hair is an example of a dominant gene in humans).
Now that you understand what genes are and how they work I will explain what they have to do with evolution. As I explained before, the parents of that offspring contribute the genes the offspring receives. Thus, giving the offspring the genes that they will pass on to their children. From generation to generation, well-understood molecular mechanisms reorganize, duplicate, and alter genes in a way that produces genetic variation. This variation is the raw material for evolution.
For example, scientists estimate that the common ancestor shared by humans and chimpanzees lived some 5 to 8 million years ago. Humans and bacteria obviously share a much more distant common ancestor, but our relationship to these single-celled organisms is no less real. Indeed, DNA analyses show that although humans share far more genetic material with primates than we do with single-celled organisms, we still have more than 200 genes in common with bacteria.
It is important to realize that describing organisms as relatives does not mean that one of those organisms is an ancestor of the other, or, for that matter, that any existing species is the ancestor of any other existing species. A person may be related to blood relatives, such as cousins, aunts, and uncles, because they share with them one or more common ancestors, such as a grandparent, or great-grandparent. But those cousins, aunts, and uncles are not their ancestors. In the same way, humans and other living primates are related, but none of these living relatives is a human ancestor.
Is evolution a random process?
Evolution is not a random process. The genetic variation on which natural selection acts may occur randomly, but natural selection itself, is not random at all. The survival and reproductive success of an individual is directly related to the way its inherited traits function in the context of its local environment. Whether or not an individual survives and reproduces depends on whether it has genes that produce traits that are well adapted to its environment.
Does evolution prove there is no God?
No. Many people, from evolutionary biologists to important religious figures like Pope John Paul II, contend that the time-tested theory of evolution does not refute the presence of God. They acknowledge that evolution is the description of a process that governs the development of life on Earth. Like other scientific theories, including Copernican theory, atomic theory, and the germ theory of disease, evolution deals only with objects, events, and processes in the material world. Science has nothing to say one way or the other about the existence of God or about people’s spiritual beliefs.
Is evolution a “real” science?
Yes. Evolution is a “real” science. Is it perfect? No, definitely not. There are still many factors in the theory of evolution that don’t quiet work. However, many schools have started to exclude evolution in their curriculum. Therefore causing students to not learn the basics of evolution. This is a problem that the Kansas Board of Education has just recognized. They have just recently reinstated evolution into Kansas’s Public School Science Standards of Academics.