The Berkeley Evolution Site
Students and teachers who explore the Berkeley site will find resources to aid in understanding and teaching evolution. 에볼루션 게이밍 are organized into optional learning paths, such as "What did T. rex taste like?"
Charles Darwin's theory of natural selection explains that over time, animals that are better able to adapt biologically to changing environments do better than those that don't become extinct. This process of evolution in biology is what science is all about.
What is Evolution?
The word evolution has many nonscientific meanings, such as "progress" or "descent with modification." It is scientifically based and is used to describe the process of changing characteristics in a species or species. In terms of biology this change is based on natural selection and genetic drift.
Evolution is an important tenet in modern biology. It is an established theory that has stood up to the tests of time and thousands of scientific experiments. In contrast to other theories in science such as the Copernican theory or the germ theory of disease, evolution does not address issues of religious belief or the existence of God.
Early evolutionists, including Jean-Baptiste Lamarck and Erasmus Darwin (Charles's grandfather) believed that certain physical traits were predetermined to change, in a gradual way, over time. They referred to this as the "Ladder of Nature" or the scala naturae. Charles Lyell first used this term in 1833 in his Principles of Geology.
In the early 1800s, Darwin formulated his theory of evolution and published it in his book On the Origin of Species. It states that all species of organisms have the same ancestry, which can be traced through fossils and other evidence. This is the current view of evolution, which is supported by a variety of disciplines that include molecular biology.
While scientists don't know the exact mechanism by which organisms evolved but they are certain that the evolution of life on earth is a result of natural selection and genetic drift. Individuals with advantageous traits are more likely to live and reproduce, and these individuals pass their genes on to the next generation. Over time, this results in gradual changes to the gene pool that gradually lead to new species and types.
Some scientists employ the term"evolution" to refer to large-scale change, such as the evolution of one species from an ancestral one. Some scientists, like population geneticists, define evolution in a more broad sense by referring to the net change in the frequency of alleles across generations. Both definitions are acceptable and accurate however, some scientists claim that the allele-frequency definition is missing essential aspects of the evolution process.
Origins of Life
One of the most crucial steps in evolution is the emergence of life. The emergence of life happens when living systems begin to evolve at a micro level, such as 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 that is of immense interest to scientists, as it challenges the theory of evolution. It is often referred to "the mystery" of life or "abiogenesis."
Traditionally, the belief that life could emerge from nonliving things is known as spontaneous generation or "spontaneous evolution." This was a common belief before Louis Pasteur's experiments proved that it was impossible for the emergence of life to be a result of the natural process.
Many scientists still think it is possible to go from nonliving substances to living ones. However, the conditions that are required are extremely difficult to replicate in the laboratory. This is why scientists studying the beginnings of life are also keen to understand the physical properties of the early Earth and other planets.
The life-cycle of a living organism is dependent on a variety of complex chemical reactions which cannot be predicted by basic physical laws. These include the reading and re-reading of complex molecules, like DNA or RNA, to create proteins that perform a particular function. These chemical reactions can be compared with the chicken-and-egg issue which is the development and emergence of DNA/RNA, protein-based cell machinery, is required to begin the process of becoming a living organism. However, without life, the chemistry that is required to enable it does appear to work.
Abiogenesis research requires collaboration among scientists from different disciplines. This includes prebiotic scientists, astrobiologists and planetary scientists.
Evolutionary Changes
The term "evolution" is commonly used to refer to the accumulated changes in genetic characteristics of populations over time. These changes may result from adaptation to environmental pressures as explained in the article on Darwinism (see the entry on Charles Darwin for background) or natural selection.
This mechanism also increases the frequency of genes that provide the advantage of survival for an animal, resulting in an overall change in the appearance of the group. These changes in evolutionary patterns are caused by mutations, reshuffling genes during sexual reproduction and the flow of genes.
Natural selection is the process that allows beneficial mutations to become more common. All organisms undergo mutations and reshuffles in their genes. This is because, as we've mentioned earlier those with the advantageous trait are likely to have a higher reproduction rate than those without it. This variation in the number of offspring born over many generations can result in a gradual change in the number of advantageous traits in the group.
A good example of this is the growth of beak size on various species of finches in the Galapagos Islands, which have developed different beak shapes to enable them to more easily access food in their new habitat. These changes in form and shape can aid in the creation of new organisms.
The majority of changes are caused by a single mutation, although sometimes multiple occur at the same time. Most of these changes can be negative or even harmful however, a small percentage could have a positive impact on survival and reproduction and increase their frequency as time passes. This is the process of natural selection, and it can be a time-consuming process that produces the gradual changes that eventually result in the creation of a new species.
Some people confuse evolution with the idea of soft inheritance which is the notion that inherited traits can be changed by conscious choice or by abuse. This is a misinterpretation of the nature of evolution and of the actual biological processes that cause it. A more accurate description is that evolution is a two-step procedure which involves the separate and often antagonistic forces of mutation and natural selection.
Origins of Humans
Humans today (Homo sapiens) evolved from primates, a group of mammals that includes gorillas, chimpanzees, and bonobos. Our predecessors walked on two legs, as evidenced by the first fossils. Genetic and biological similarities suggest that we are closely related to the chimpanzees. In reality our closest relatives are chimpanzees from the Pan genus. This includes pygmy as well as bonobos. The last common ancestor shared between modern humans and chimpanzees was 8 to 6 million years old.
Humans have developed a range of traits over time including bipedalism, the use of fire, and the development of advanced tools. However, it is only in the past 100,000 years or so that the majority of the essential characteristics that differentiate us from other species have emerged. They include a huge brain that is sophisticated and the capacity of humans to build and use tools, and the diversity of our culture.
Evolution happens when genetic changes allow individuals of a population to better adapt to their environment. Natural selection is the process that drives this change. Certain traits are preferred over others. The ones with the best adaptations are more likely to pass their genes to the next generation. This is the way all species evolve and is the basis for the theory of evolution.
Scientists refer to this as the "law of natural selection." The law states that species that share an ancestor will tend to develop similar characteristics over time. It is because these traits allow them to reproduce and survive within their environment.
Every living thing has an molecule called DNA that holds the information needed to guide their growth. The structure of DNA is composed of base pairs which are arranged in a spiral, around phosphate and sugar molecules. The sequence of bases within each strand determines phenotype, or the individual's characteristic appearance and behavior. Variations in a population are caused by mutations and reshufflings of genetic material (known collectively as alleles).
Fossils of the first human species, Homo erectus and Homo neanderthalensis, have been found in Africa, Asia, and Europe. Although there are some differences, these fossils all support the hypothesis that modern humans first came into existence in Africa. The evidence from fossils and genetics suggests that early humans left Africa and migrated to Asia and Europe.