Evolution Explained
The most basic concept is that living things change over time. These changes help the organism to live and reproduce, or better adapt to its environment.
Scientists have employed the latest science of genetics to describe how evolution functions. They have also used the science of physics to determine how much energy is required to trigger these changes.
Natural Selection
In order for evolution to take place in a healthy way, organisms must be able to reproduce and pass on their genetic traits to future generations. This is the process of natural selection, which is sometimes referred to as "survival of the fittest." However, the term "fittest" is often misleading because it implies that only the strongest or fastest organisms survive and reproduce. In reality, the most adapted organisms are those that are able to best adapt to the conditions in which they live. Environmental conditions can change rapidly, and if the population isn't properly adapted, it will be unable survive, resulting in an increasing population or disappearing.
Natural selection is the most important factor in evolution. This occurs when desirable phenotypic traits become more prevalent in a particular population over time, which leads to the evolution of new species. This process is triggered by heritable genetic variations of organisms, which are the result of mutation and sexual reproduction.
Any element in the environment that favors or hinders certain characteristics can be a selective agent. These forces can be biological, such as predators or physical, for instance, temperature. Over time, populations that are exposed to different selective agents can change so that they no longer breed with each other and are regarded as separate species.
Natural selection is a straightforward concept however it can be difficult to comprehend. The misconceptions about the process are common, even among scientists and educators. Surveys have revealed that there is a small relationship between students' knowledge of evolution and their acceptance of the theory.
For example, Brandon's focused definition of selection is limited to differential reproduction, and does not include replication or inheritance. Havstad (2011) is one of many authors who have argued for a more expansive notion of selection, which encompasses Darwin's entire process. This could explain the evolution of species and adaptation.
There are instances where the proportion of a trait increases within the population, but not at the rate of reproduction. These situations may not be classified as a narrow definition of natural selection, but they may still meet Lewontin’s conditions for a mechanism similar to this to function. For instance parents with a particular trait may produce more offspring than parents without it.
Genetic Variation
Genetic variation is the difference between the sequences of genes of members of a particular species. It is the variation that enables natural selection, one of the main forces driving evolution. Mutations or the normal process of DNA restructuring during cell division may cause variation. Different gene variants could result in different traits, such as the color of eyes, fur type or the ability to adapt to changing environmental conditions. If a trait is beneficial it is more likely to be passed on to the next generation. This is known as a selective advantage.
A specific kind of heritable variation is phenotypic, which allows individuals to alter their appearance and behavior in response to the environment or stress. These changes can help them survive in a different habitat or seize an opportunity. For instance they might grow longer fur to shield themselves from cold, or change color to blend into a certain surface. These phenotypic changes do not alter the genotype, and therefore cannot be considered to be a factor in evolution.
Heritable variation enables adaptation to changing environments. Natural selection can also be triggered through heritable variations, since it increases the chance that those with traits that favor a particular environment will replace those who do not. However, in some instances the rate at which a genetic variant can be transferred to the next generation isn't sufficient for natural selection to keep up.
Many harmful traits, such as genetic diseases, remain in populations despite being damaging. This is due to a phenomenon referred to as reduced penetrance. It is the reason why some people with the disease-associated variant of the gene don't 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 necessary to have a better understanding of how genetic variation affects the evolution. Recent studies have demonstrated that genome-wide associations focusing on common variants do not capture the full picture of susceptibility to disease, and that a significant portion of heritability can be explained by rare variants. It is imperative to conduct additional studies based on sequencing to document the rare variations that exist across populations around the world and to determine their effects, including gene-by environment interaction.
Environmental Changes
While natural selection influences evolution, the environment affects species by changing the conditions in which they live. The famous story of peppered moths illustrates this concept: the moths with white bodies, which were abundant in urban areas where coal smoke blackened tree bark and made them easy targets for predators, while their darker-bodied counterparts thrived under these new conditions. The opposite is also the case that environmental changes can affect species' capacity to adapt to the changes they face.
Human activities are causing environmental changes on a global scale, and the impacts of these changes are irreversible. These changes affect biodiversity and ecosystem functions. In addition they pose significant health hazards to humanity, especially in low income countries, because of polluted water, air soil and food.
For instance, the growing use of coal in developing nations, such as India, is contributing to climate change and increasing levels of air pollution that threaten human life expectancy. The world's finite natural resources are being used up in a growing rate by the population of humans. This increases the likelihood that a lot of people will suffer from nutritional deficiencies and lack access to safe drinking water.
The impacts of human-driven changes to the environment on evolutionary outcomes is a complex. Microevolutionary responses will likely reshape an organism's fitness landscape. These changes can also alter the relationship between a particular characteristic and its environment. Nomoto et. al. showed, for example that environmental factors like climate, and competition can alter the phenotype of a plant and shift its selection away from its previous optimal match.
It is therefore essential to understand how these changes are influencing contemporary microevolutionary responses and how this information can be used to determine the future of natural populations during the Anthropocene period. This is vital, since the environmental changes caused by humans have direct implications for conservation efforts as well as our individual health and survival. It is therefore vital to continue the research on the relationship between human-driven environmental changes and evolutionary processes on global scale.
The Big Bang
There are several theories about the origin and expansion of the Universe. None of them is as widely accepted as the Big Bang theory. It is now a common topic in science classes. The theory explains a wide variety of observed phenomena, including the number of light elements, cosmic microwave background radiation, and the vast-scale structure of the Universe.
The Big Bang Theory is a simple explanation of how the universe began, 13.8 billions years ago, as a dense and extremely hot cauldron. Since then, it has grown. The expansion led to the creation of everything that exists today, such as the Earth and its inhabitants.
The Big Bang theory is supported by a mix of evidence, which includes the fact that the universe appears flat to us and the kinetic energy as well as thermal energy of the particles that compose it; the variations in temperature in the cosmic microwave background radiation; and the abundance of heavy and light elements 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 early 20th century, scientists held an unpopular view of the Big Bang. Fred Hoyle publicly criticized it in 1949. After World War II, observations began to arrive that tipped scales in favor the Big Bang. Arno Pennzias, Robert Wilson, and others discovered the cosmic background radiation in 1964. This omnidirectional microwave signal is the result of a time-dependent expansion of the Universe. The discovery of the ionized radioactivity with a spectrum that is consistent with a blackbody, at approximately 2.725 K was a major turning-point for the Big Bang Theory and tipped it in the direction of the prevailing Steady state model.
The Big Bang is a major element of the popular TV show, "The Big Bang Theory." Sheldon, Leonard, and the rest of the team use this theory in "The Big Bang Theory" to explain a variety of phenomena and observations. online is their experiment that explains how peanut butter and jam get mixed together.