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Evolution Explained The most fundamental idea is that living things change as they age. These changes may aid the organism in its survival and reproduce or become more adapted to its environment. Scientists have used the new science of genetics to describe how evolution functions. They have also used physics to calculate the amount of energy needed to trigger these changes. Natural Selection To allow evolution to occur, organisms must be capable of reproducing and passing on their genetic traits to future generations. This is a process known as natural selection, which is sometimes referred to as "survival of the most fittest." However the term "fittest" can be misleading because it implies that only the strongest or fastest organisms survive and reproduce. In fact, the best species that are well-adapted are able to best adapt to the conditions in which they live. The environment can change rapidly, and if the population is not well adapted to the environment, it will not be able to survive, leading to an increasing population or disappearing. The most fundamental component of evolutionary change is natural selection. This occurs when advantageous traits are more common over time in a population and leads to the creation of new species. This process is driven by the genetic variation that is heritable of organisms that results from mutation and sexual reproduction as well as the competition for scarce resources. Selective agents can be any environmental force that favors or discourages certain characteristics. These forces can be physical, like temperature or biological, such as predators. Over time populations exposed to various selective agents can evolve so different that they no longer breed together and are considered to be distinct species. ???? is a simple concept, but it can be difficult to comprehend. Even among educators and scientists there are a lot of misconceptions about the process. Surveys have revealed that there is a small correlation between students' understanding of evolution and their acceptance of the theory. Brandon's definition of selection is restricted to differential reproduction and does not include inheritance. However, a number of authors, including Havstad (2011) has argued that a capacious notion of selection that encapsulates the entire Darwinian process is adequate to explain both adaptation and speciation. Additionally there are a variety of instances in which the presence of a trait increases in a population, but does not alter the rate at which people who have the trait reproduce. These cases may not be considered natural selection in the strict sense of the term but could still be in line with Lewontin's requirements for a mechanism like this to work, such as the case where parents with a specific trait produce more offspring than parents without it. Genetic Variation Genetic variation is the difference in the sequences of genes among members of a species. Natural selection is one of the main factors behind evolution. Variation can be caused by changes or the normal process through which DNA is rearranged during cell division (genetic Recombination). Different genetic variants can cause distinct traits, like the color of eyes, fur type or ability to adapt to adverse conditions in the environment. If a trait is characterized by an advantage it is more likely to be passed down to future generations. This is referred to as a selective advantage. Phenotypic plasticity is a special type of heritable variations that allows people to change their appearance and behavior in response to stress or the environment. These modifications can help them thrive in a different habitat or make the most of an opportunity. For example they might develop longer fur to protect their bodies from cold or change color to blend into a specific surface. These phenotypic variations do not alter the genotype and therefore, cannot be thought of as influencing the evolution. Heritable variation permits adaptation to changing environments. Natural selection can also be triggered through heritable variations, since it increases the likelihood that those with traits that are favourable to a particular environment will replace those who aren't. In some cases, however the rate of variation transmission to the next generation may not be enough for natural evolution to keep up with. Many negative traits, like genetic diseases, persist in populations, despite their being detrimental. This is due to a phenomenon known as reduced penetrance. It means that some people with the disease-associated variant of the gene do not show symptoms or signs of the condition. Other causes are interactions between genes and environments and other non-genetic factors like diet, lifestyle and exposure to chemicals. In order to understand the reasons why certain harmful traits do not get eliminated through natural selection, it is important to gain a better understanding of how genetic variation affects the process of evolution. Recent studies have revealed that genome-wide association studies focusing on common variations do not provide a complete picture of the susceptibility to disease and that a significant portion of heritability is attributed to rare variants. Additional sequencing-based studies are needed to identify rare variants in the globe and to determine their impact on health, including the role of gene-by-environment interactions. Environmental Changes The environment can influence species through changing their environment. This principle is illustrated by the infamous story of the peppered mops. The white-bodied mops which were common in urban areas where coal smoke was blackened tree barks, were easy prey for predators while their darker-bodied cousins thrived under these new circumstances. The opposite is also the case that environmental changes can affect species' ability to adapt to the changes they encounter. The human activities have caused global environmental changes and their impacts are largely irreversible. These changes affect biodiversity and ecosystem functions. They also pose health risks to the human population, particularly in low-income countries because of the contamination of water, air and soil. As an example the increasing use of coal by countries in the developing world such as India contributes to climate change and increases levels of air pollution, which threaten the human lifespan. Furthermore, human populations are using up the world's scarce resources at a rate that is increasing. This increases the chances that a lot of people will be suffering from nutritional deficiencies and lack of access to clean drinking water. The impact of human-driven environmental changes on evolutionary outcomes is a tangled mess microevolutionary responses to these changes likely to reshape the fitness environment of an organism. These changes may also change the relationship between a trait and its environmental context. For instance, a study by Nomoto et al. which involved transplant experiments along an altitude gradient demonstrated that changes in environmental cues (such as climate) and competition can alter a plant's phenotype and shift its directional selection away from its previous optimal suitability. It is important to understand how these changes are influencing microevolutionary patterns of our time and how we can utilize this information to predict the future of natural populations during the Anthropocene. This is crucial, as the environmental changes caused by humans will have a direct impact on conservation efforts as well as our own health and well-being. This is why it is essential to continue to study the interactions between human-driven environmental change and evolutionary processes at an international level. The Big Bang There are several theories about the origin and expansion of the Universe. None of is as well-known as the Big Bang theory. It has become a staple for science classrooms. The theory is able to explain a broad range of observed phenomena, including the abundance of light elements, cosmic microwave background radiation as well as the massive structure of the Universe. The Big Bang Theory is a simple explanation of how the universe started, 13.8 billions years ago as a huge and unimaginably hot cauldron. Since then, it has expanded. This expansion has created everything that is present today, including the Earth and all its inhabitants. This theory is the most supported by a mix of evidence. This includes the fact that the universe appears flat to us; the kinetic energy and thermal energy of the particles that compose it; the temperature variations in the cosmic microwave background radiation and the abundance of light and heavy elements found in the Universe. The Big Bang theory is also well-suited to the data gathered by particle accelerators, astronomical telescopes, and high-energy states. In the beginning of the 20th century the Big Bang was a minority opinion among physicists. Fred Hoyle publicly criticized it in 1949. After World War II, observations began to arrive that tipped scales in the direction of the Big Bang. In 1964, Arno Penzias and Robert Wilson serendipitously discovered the cosmic microwave background radiation, a omnidirectional signal in the microwave band that is the result of the expansion of the Universe over time. The discovery of the ionized radiation with an observable spectrum that is consistent with a blackbody, which is approximately 2.725 K was a major turning point for the Big Bang Theory and tipped it in the direction of the rival Steady state model. The Big Bang is a major element of the cult television show, "The Big Bang Theory." Sheldon, Leonard, and the rest of the team make use of this theory in "The Big Bang Theory" to explain a wide range of observations and phenomena. One example is their experiment which explains how jam and peanut butter get squished.
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