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Charles Darwin's theory of natural selection states that over time, animals that are more adaptable to changing environments survive and those that do not become extinct. Science is all about this process of biological evolution.
What is Evolution?
The term "evolution" has a variety of nonscientific meanings. For instance "progress" or "descent with modification." It is an academic term that is used to describe the process of changing characteristics over time in organisms or species. In terms of biology the change is based on natural selection and genetic drift.
Evolution is a central tenet of modern biology. It is a theory that has been tested and proven through thousands of scientific tests. Evolution does not deal with God's presence or spiritual beliefs, unlike many other theories in science, like the Copernican or germ theory of diseases.
Early evolutionists, like Jean-Baptiste Lamarck and Erasmus Darwin (Charles's grandfather), believed that certain physical characteristics were predetermined to change, in a step-wise manner, over time. They called this the "Ladder of Nature" or scala naturae. Charles Lyell used the term to describe this idea in his Principles of Geology, first published in 1833.
Darwin published his theory of evolution in his book On the Origin of Species which was written in the early 1800s. It states that all species of organisms share common ancestors that can be traced using fossils and other evidence. This is the modern view of evolution, which is supported by a variety of scientific fields, including molecular biology.
Scientists aren't sure the evolution of organisms, but they are confident that natural selection and genetic drift are the primary reason for the evolution of life. People with advantages are more likely to live and reproduce. They transmit their genes on to the next generation. Over time the gene pool slowly changes and develops into new species.
Certain scientists also use the term"evolution" to refer to large-scale changes in evolutionary processes, such as the formation of the new species from an ancestral species. Some scientists, like population geneticists define evolution in a more broad sense by talking about the net change in allele frequency over generations. Both definitions are valid and palatable, but certain scientists argue that allele frequency definitions omit important features of evolutionary process.
Origins of Life
The development of life is a crucial step in evolution. The emergence of life happens when living systems start to develop at a microscopic level, like within individual cells.
The origins of life is a topic in many disciplines, including biology, chemistry and geology. The nature of life is an area of great interest in science, as it is a challenge to the theory of evolution. It is sometimes referred to "the mystery" of life or "abiogenesis."
Traditionally, the notion that life can arise from nonliving things is called spontaneous generation, or "spontaneous evolution." This was a common belief before Louis Pasteur's experiments showed that it was impossible for the development of life to be a result of an entirely natural process.
Many scientists believe that it is possible to make the transition from nonliving materials to living. The conditions required to make life are not easy to reproduce in a lab. This is why researchers investigating the beginnings of life are also interested in understanding the physical properties of early Earth and other planets.
Additionally, the evolution of life is an intricate sequence of chemical reactions that cannot be predicted based on basic physical laws on their own. These include the reading and replication of complex molecules, such as DNA or RNA, in order to make proteins that serve a specific function. These chemical reactions are often compared to the chicken-and-egg problem of how life began: The development of DNA/RNA as well as protein-based cell machinery is essential for the beginning of life, however, without the development of life the chemical process that allows it is not working.
Abiogenesis research requires collaboration among researchers from different disciplines. This includes prebiotic scientists, astrobiologists and planetary scientists.
Evolutionary Changes
Today, the word evolution is used to describe gradual changes in genetic traits over time. These changes can be the result of the adaptation to environmental pressures as discussed in Darwinism.
This is a process that increases the frequency of genes in a species that offer an advantage in survival over other species which results in gradual changes in the overall appearance of a group. These changes in evolutionary patterns are caused by mutations, reshuffling of genes in the process of sexual reproduction, and also by the flow of genes.
While reshuffling and mutation of genes happen in all organisms, the process by which beneficial mutations are more frequent is referred to as natural selection. As noted above, individuals who possess the desirable characteristic have a higher reproduction rate than those who don't. Over the course of many generations, this differential in the numbers of offspring produced can result in gradual changes in the amount of desirable traits in a population.
This is evident in the evolution of various beak shapes on finches from the Galapagos Islands. They have developed these beaks in order that they can access food more quickly in their new home. These changes in form and shape can also aid in the creation of new species.
The majority of changes are caused by one mutation, although sometimes multiple occur at the same time. The majority of these changes are neutral or even harmful to the organism, but a small percentage can have an advantageous impact on the survival of the organism and its reproduction, thereby increasing their frequency in the population over time. Natural selection is a mechanism that can produce the accumulating change over time that leads to a new species.
Some people confuse evolution with the idea of soft inheritance, which is the idea that inherited traits can be altered by conscious choice or by abuse. This is a misunderstanding of the biological processes that lead up to evolution. It is more accurate to say that evolution is a two-step, independent process that involves the forces of natural selection as well as mutation.
Origins of Humans
Humans of today (Homo sapiens) evolved from primates - a group of mammals that also includes gorillas, chimpanzees, and bonobos. Our predecessors walked on two legs, as evidenced by the oldest fossils. Genetic and biological similarities suggest that we are closely related to the chimpanzees. In reality, we are most closely with chimpanzees in the Pan genus that includes pygmy and pygmy chimpanzees and bonobos. The last common human ancestor and chimpanzees was born between 8 and 6 million years ago.
As time has passed, humans have developed a variety of characteristics, such as bipedalism and the use of fire. They also created advanced tools. However, it is only in the last 100,000 years or so that the majority of the important characteristics that differentiate us from other species have been developed. They include language, a large brain, the capacity to construct and use complex tools, as well as the diversity of our culture.
The process of evolution occurs when genetic changes allow individuals in a group to better adapt to their surroundings. This adaptation is driven by natural selection, a process that determines certain traits are favored over others. People with better adaptations are more likely to pass their genes to the next generation. This is how all species evolve and is the foundation of the theory of evolution.
Scientists refer to it as the "law of Natural Selection." The law says that species that have a common ancestor, tend to develop similar characteristics over time. This is because the characteristics make it easier for them to survive and reproduce in their environment.
All organisms have a DNA molecule, which provides the information necessary to guide their growth and development. The DNA structure is composed of base pairs arranged in a spiral around sugar and phosphate molecules. The sequence of bases within each strand determines phenotype, or the individual's characteristic appearance and behavior. Variations in a population can be caused by reshufflings and mutations of genetic material (known collectively as alleles).
Fossils from the first human species, Homo erectus, and Homo neanderthalensis have been discovered in Africa, Asia and Europe. Despite some differences, these fossils all support the hypothesis that modern humans first appeared in Africa. The fossil evidence and genetic evidence suggest that early humans moved from Africa into Asia and then Europe.