Evolution
What is Evolution?
Evolution is the gradual change of species. It is believed that more than 3.5 million years ago, one primitive species assumed to be self-replicating lived on the planet earth. This molecule branched out to other diverse and new molecules. Evolution encompasses six components; natural selection, gradualism, Evolution, speciation, non-selective mechanism, and evolutionary change.
The first idea of Evolution is the genetic change of species that occurs over a period. It is believed that species tend to change from one generation to another. The transition from one generation is different compared to the change in the next generation. The mutation of the DNA occasions this change. This evolution change is gradual, which means that it requires a significant amount of time for the transition to be visible. Therefore, for substantial change to happen, generations must pass. This idea can be supported by the change that is evident in reptiles.
Evolution supports the idea of a single ancestry among the species on the earth. Although there are many species on the planet, all of them share fundamental traits. This means that all species had a common ancestry; the ancestor then passed those traits to its descendants. Currently, it is believed that there are over ten million species on the planet. If this were not so, there would only be one genetic species inexistent. This single ancestral species would be a highly evolved species of the first species.
The Evolution of different species from the first species is supported by the idea of splitting or speciation in Evolution. Speciation refers to the Evolution of diverse groups that cannot reproduce. These are groups of species that cannot exchange their genetic material. Usually, species do not split. It is believed that over 99 percent of species go into extinct without leaving any offspring.
On the flip side of speciation, is the idea of common ancestry. This idea suggests that we can always look back in time and trace our origin from a common ancestor. DNA sequences and fossils, the source of species, can be determined. When the fossils are studied, they point a connection to a common ancestor. When the DNA is sequenced, the similarity of their relationships can be derived. This relationship is critical in pointing out the evolutionary connection of the species.
Natural selection is Darwin’s most celebrated achievement intellectually. Selection tries to explain nature’s design in species that he does not attribute to the creation of the hand of supernatural force. Darwin explains that species tend to adapt to their different environment that they find themselves in. Gradual mutations happen that are helpful to the survival of species in their environment. Therefore, the variance of species on the planet is due to the situation that they find themselves in. Over time, adaptations that are not suitable for an environment tend to weed itself out. This discovery by Darwin is both striking and disturbing.
Natural selection acts like a tinkerer. It does not explain the genesis of things; instead it describes how species are depending on their current environment. It is a build-up knowledge of what is already available and explains why species are as they are. Natural selection upholds the idea that Evolution happens only through the habitation of species. Species tend to change based on their existing conditions to be able to adapt to that habitat. Consequently, when a species is taken to a new situation, it also evolves, thus causing Evolution.
How is evolutionary theory tested? This is a fundamental but difficult question to answer when it comes to Evolution. Scientists regard a theory to be scientific when it can be tested and verified. A theory is not just speculation; instead, it is a group of prepositions that are well thought out and try to explain facts. Therefore, for an argument to be considered accurate, its assertions and predictions ought to be tested time and again. The theory can become a fact when the time has accumulated so much evidence on its account, leaving no decisive opposition. Such an approach supports reason and is accepted across the board. Until new evidence is brought against the theory, it is regarded as fact.
The process of verifying a theory to be valid requires testing against existing facts and arguments. The challenge, therefore, is to test the evolutionary theory against the popular belief that life is created, and it cannot be changed. Two kinds of evidence exist; the first is derived from Darwin’s six components. Darwin’s six components are used in predictions of how ancient species ought to be found when they are subjected to study. The elements do not, in any way, predict how things will be in the future but instead reflects. A study of ancient species should reveal the following
- A study of fossil remains from ancient times should be able to provide some evidence of evolutionary change. Old rocks should contain minerals of primitive fossils, and younger rocks would contain organisms that resemble modern-day species. The study of these species ought to reveal changes over time. Some species may even show adaptations depending on the environments that they are found.
- A study of fossil records should reveal speciation. An ancestry should explain two or more kinds of species in subsequent generations.
- The dominant group of species ought to provide a link that shows common lineage. For example, fish can be linked to amphibians. The links can be used to predict the time when such diversions occur.
- The study of the species reveals the genetic variation of the various traits. This variation is one of the evidence of Evolution happening.
- The study should reveal imperfect species and imperfect adaptation. Imperfection cannot happen when a creator is involved.
- Natural selection and how it plays out, especially in the wild, should also be established.
All this information gathered should somehow lead to the conclusion that, indeed, Evolution is true.
Written in the rocks
Fossils have existed since ancient times; their formation, however, is not straightforward. A set of unique circumstances is critical in its composition. The remains of a species ought to find its way into a water body and sink at the bottom. The remains then should be covered by sediments. These unique circumstances ensure that the remains don’t decay or scattered away by scavengers. Taking all these factors into consideration, it is without a doubt that fossil records are incomplete. It is estimated that only one percent of species is evident on fossil records. This is hardly a good sample but enough to study Evolution.
Fossil records do not support the creation theory, but it gives a sequence of Evolution. Biologists are particularly interested in the transitions that exist between species. These transitions are critical in pointing to the common ancestry of organisms. Fossil records reveal three things. It supports Evolution and the gradual change of lineages together with transitional links that exist between organisms. Secondly, fossil records give a clear indication of transitions forms of species. Lastly, fossil records provide an understanding of the old species and the current.
Fossil records offer little basis for natural selection. It is impossible to imagine that a grand designer would remodel old species to come up with new features. Each species should be modeled from the ground up and not remodel what is already in existence. Unique traits in species cannot come from thin air.
Remnants
Organisms are manuscripts that tell history, in this case, evolutionary history. A vestige is an organism that has adaptation features that match its ancestors. Over time, these features lose their usefulness or functionality. The loss of these features is believed to be due to Evolution. An excellent example of such a feature is an appendix in human beings and a flight in Ostrich. With regards to Evolution, it is believed that the human appendix is of no value to us but was critically important to our ancestors. The appendix is simply the remains of an organ that was used for our ancestors who ate leaves.
Atavism is the reappearance of a trait or something that featured in the ancestors. Mammals can be born with extra toes, tail, or fingers. They differ from vestiges because they occur occasionally, and they do not happen to every species. In some species, dead genes are also expected. These are silenced genes that were once useful, too, but are no longer evident. It is believed that human beings carry more than 2000 of these genes.
In Evolution, a perfect design does not exist. Organisms are imperfect, which a true mark of Evolution is. The microorganisms may seem to fit in their environment, but they keep evolving to adapt to their environment. The male reproductive system is a perfect example to illustrate this. The descent of male testes results in the weakening of the abdominal cavity, which may lead to Hernia. The male species are further disadvantaged because they are at risk of having an enlarged prostate later in life. This enlargement squeezes the urethra resulting in severe and painful urination.
Geography of life
Evolution is not only crucial in explaining the origin and form of plants and animals, but also their distribution across the planet. The evidence of Evolution across the globe is very compelling that the proponents of creation theory are yet to dispute it. The proponents of creation theory are, however, to explain why different types of plants and animals have similar features in two different places. This unique phenomenon is attributed to convergent Evolution.
Convergent Evolution explains that species share a similarity in habitat experience similar reactions and pressures from the environment that they find themselves in. Therefore, such species converge to similar adaptations. This convergence causes them to have the same behaviors and features even though they do not have a relation.
Convergent Evolution supports three components in the evolution theory; natural selection, common ancestry, and speciation. If indeed Evolution happened, species that live in a particular area ought to be descendants of species that lived in that very same place. What this means, if extraction of specific rocks was to be done in a particular area, fossils that resemble present species should be found. This scenario is not the case.
How does creation theory explain this? The proponents of the creation theory are hard-pressed to define these patterns clearly. The argument may be forced to propose that creations and successive extinctions took place all over the world. New sets of these creations species were then made to resemble the older species that lived in the same area. This suggestion is hard to imagine.
The conclusion, therefore, of biogeography is this; the diversity of plants and animals in the continent explains Evolution. The distribution of life across the globe is reflected in chance and adaptation.
The Engine of Evolution
Selection is a process by which genes that produce functional adaptations become frequent over a period. For a species to be able t adapt to the environment quickly, it requires the right kind of traits. The required attribute makes adaptation to the environment for any species inevitable. In the natural selection component of Evolution, three things are critical for adaptation. The population must show variability, for example, variance in skin color. Secondly, the variation should come from a genetic mutation, also known as heritability. The third aspect is that the genetic variation ought to affect the individual probability of reproducing.
Evolution by the process of selection is a combination of two things; lawfulness and randomness. Randomness implies that genetic mutations occur regardless of whether the genes produced are good or bad. Lawlessness means that the right genes are bad ones and retained. Selection, therefore, means that natural selection does not happen by chance; the opposite is exact. Natural selection is a powerful force that accumulates genes which have a higher possibility of having offsprings that better adapt to their environment. Natural selection has puzzling questions to answer in biology. How does an adaptation evolve?
How Sex drives Evolution
The primary aim of selection is the successful reproduction of good traits. Naturally, in sexual selection, male species compete for female species. Females, by default, choose their mates while males woo. Sexual Evolution is viewed as an investment, and females bring eggs while males contribute the sperm. This investment, therefore, requires the female to nurture and nourish the pregnancy till maturity. Later, the female is basic in providing parental care. Females, therefore, have a choice in deterring the kind of offspring that they carry. Sexual selection thus allows the female the upper hand in determining the reproduction of good genes.
The Origin of Species
Species in the universe cannot be duplicated. Each is unique on its own. Darwin attempted to explain why species adapt to its environment by natural selection. What he failed to explain is how a species divides into two. This explanation is critical in describing the origin of new traits, hence new species. Speciation is what results in biodiversity. If that were not the case, only a single species would be available.
Species are defined as a group of mechanisms that have a close resemblance to one another. Some biologists consider this definition to be vague. The explanation would propose tigers and cats to belong to the same species. While there might exist close resemblance, striking differences are evident in those two animals. Cats are smaller in the body while tigers are large with patches all over. At what point do species need to be different enough for them to be termed as distinct? The definition of species is, therefore, subjective and should be reviewed to be standard.
Why then do species vary? Is it based on their inability to interbreed or rather their appearance? Species have barriers that prevent them from interbreeding. Species should, therefore, be looked at as a basic unit of Evolution. The origin of species is pegged on its ability to reproduce. What then causes species to separate into two distinct but closely related organisms? Some scientists argue that such distinctions happen due to geographical barriers. Natural selection is at play as the species adapt to the different environments that they find themselves in.
What About Us?
Since time immemorial, genetics have used fossils and DNA sequencing in establishing the place of human beings in Evolution. Evolution describes human beings as to apes, and apes are our ancestors. Chimpanzees are considered to be our closest cousins whose ancestors took a divergent path from the human ancestor some years ago. These are theories that have existed for a long time and proven to be facts. Scientists are hopeful of finding a species that will provide the missing link to explain the diversion of human beings and apes.
Scientists believe that the diversion of human beings from apes begun in East Africa several years ago. Why, then did human beings evolve? That is a pertinent question that scientists have tried to explain. Many scientists believe that the sweeping environmental changes may have propelled the change to happen. About 7 million years ago, climate change was witnessed in East and Central Africa. This climate change brought a drought that caused our ancestors to adapt. The human brain and the feet evolved first.
Human beings are different not only in the sequencing of their DNA but also in the absence and presence of some genes different from the other. Most biologists are, however, unable to explain how race came about. Anthropologists speculate that close to thirty races exist among human beings. The variation between the human race is insignificant since the sequencing is almost similar across the board. Sexual selection can be attributed to the existence of different kinds of races. Humans are easily adapted to the environment that they find themselves in. Overall, the genetic differences that exist in human beings because of their races are very insignificant.
Evolution Redux
Although the evidence of Evolution exists, some people still find it hard to believe. It is not because of the absence of evidence, but the new information that comes up daily. Enough evidence has been tabled regarding Evolution. The study of fossil records, biogeography, and transitional groups all points toward Evolution. Experiments are carried out daily regarding Evolution and the transitions found among significant groups. All these experiments that are carried by scientists all point to a common ancestor. Equal tests have been carried out to try and disapprove Evolution as untrue, but none has been tabled so far.
All biologists agree on the fact that Evolution occurred. The controversy is on how it happened. As it is with science, a debate is what propels science and research forward. Some biologist requires more than evidence for them to believe that Evolution happened. Such people view Evolution as a mystery that raises with it a lot of questions. Some people now question the purpose and meaning of life. What bothers such folks are not the fact that human beings evolved from apes; instead, it is the emotional repercussions of that fact. These concerns may look trivial, but they are very fundamental if we are to move forward in Evolution.
The proponents of creation theory are of the view that the evils that result from Evolution come from materialism and naturalism. Naturalism states that we can only understand our world through science and experiments. Materialism, on the other hand, says that the only reality of the universe comes from following the wills and emotions of all matters of the world. Evolution simply put a theory of all patterns of life, its diversification, and philosophy. The Evolution of human behavior should be subjected to research that is as thorough as those applied to the non-human.
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