The Berkeley Evolution Site
Students and teachers who explore the Berkeley site will find resources to assist them in understanding and teaching evolution. The materials are organized in optional learning paths, such as "What does T. rex look 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 are not extinct. Science is all about this process of biological evolutionary change.
What is Evolution?
The word evolution can have many nonscientific meanings. For example, it can mean "progress" and "descent with modifications." It is an academic term that refers to the process of change of traits over time in organisms or species. This change is based in biological terms on natural selection and drift.
Evolution is a fundamental concept in the field of biology today. It is a well-supported theory that has stood up to the test of time and a multitude of scientific studies. In contrast to other theories in science such as the Copernican theory or the germ theory of disease, the evolution theory is not a discussion of religious belief or the existence of God.
Early evolutionists such as Erasmus Darwin (Charles’s grandfather) and Jean-Baptiste Lamarck believed that certain physical characteristics were predetermined to change in a gradual manner over time. This was known as the "Ladder of Nature" or 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 share the same ancestry, which can be proven through fossils and other lines of evidence. This is the current understanding of evolution, which is supported by numerous lines of scientific research that include molecular genetics.
Although scientists aren't able to determine exactly how organisms evolved however they are sure that the evolution of life on earth is the result of natural selection and genetic drift. People with desirable traits are more likely than others to live and reproduce. These individuals pass on their genes on to the next generation. Over time, this results in an accumulation of changes to the gene pool that gradually result in new species and forms.
Some scientists also employ the term evolution to refer to large-scale changes in evolutionary processes, such as the formation of an entirely new species from an ancestral species. Other scientists, such as population geneticists, define the term "evolution" more broadly by referring a net change in the frequency of alleles across generations. Both definitions are valid and reliable, although some scientists argue that the allele-frequency definition omits essential aspects of the evolution process.
Origins of Life
A key step in evolution is the development of life. The emergence of life occurs when living systems start to develop at a microscopic scale, for instance within individual cells.
The origins of life are an important topic in many areas such as biology and chemical. The origin of life is a subject of interest in science, as it challenges the theory of evolution. It is often referred to "the mystery" of life or "abiogenesis."
Traditionally, the idea that life can emerge 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 creation of life to happen through an entirely natural process.
Many scientists believe it is possible to transition from living to nonliving substances. The conditions necessary for the creation of life are difficult to reproduce in a lab. Researchers studying the origins of life are also interested in understanding the physical properties of the early Earth and other planets.
In addition, the development of life is the sequence of extremely complex chemical reactions that can't be predicted from basic physical laws alone. These include the transformation of long, information-rich molecules (DNA or RNA) into proteins that carry out some function and the replication of these complex molecules to produce new DNA or sequences of RNA. These chemical reactions can be compared to a chicken-and egg problem that is the emergence and growth of DNA/RNA, protein-based cell machinery, is essential for the beginning of life. However, without life, the chemistry that is required to make it possible does appear to work.
Abiogenesis research requires collaboration between scientists from different fields. This includes prebiotic scientists, astrobiologists and planet scientists.
Evolutionary Changes
The term "evolution" is typically used today to describe the accumulated changes in the genetic characteristics of a population over time. These changes may result from adaptation to environmental pressures as described in the entry on Darwinism (see the entry on Charles Darwin for background), or from natural selection.
This latter mechanism increases the frequency of genes that confer an advantage for survival in the species, leading to an overall change in the appearance of a group. These evolutionary changes 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 changes and reshuffles of genes. As previously mentioned, those who possess the desirable trait have a higher reproduction rate than those who don't. Over many generations, this differential in the number of offspring born could result in a gradual shift in the amount of desirable characteristics in a particular population.
This can be seen in the evolution of various beak designs on finches that are found in the Galapagos Islands. They have developed these beaks so they can get food more easily in their new environment. These changes in the form and shape of organisms can also be a catalyst for the creation of new species.
The majority of changes are caused by a single mutation, although sometimes multiple occur at the same time. The majority of these changes could be harmful or neutral however, a small percentage could have a positive impact on survival and reproduce and increase their frequency over time. This is the process of natural selection and it could, over time, produce the gradual changes that eventually lead to the creation of a new species.
에볼루션 바카라 confuse evolution with the idea of soft inheritance that is the belief that inherited traits can be changed through conscious choice or by abuse. This is a misunderstanding of the nature of evolution and of the actual biological processes that trigger it. A more precise description is that evolution is a two-step procedure which involves the separate, and often competing, forces of natural selection and mutation.
Origins of Humans
Humans of today (Homo Sapiens) evolved from primates, a species of mammal species which includes chimpanzees and gorillas. Our ancestors walked on two legs, as evidenced by the first fossils. Biological and genetic similarities indicate that we have an intimate relationship with chimpanzees. In fact, our closest relatives are the chimpanzees of the Pan genus. This includes pygmy and bonobos. The last common human ancestor and chimpanzees was between 8 and 6 million years ago.
Humans have evolved a wide range of traits over time, including bipedalism, the use of fire and advanced tools. 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. These include language, large brain, the capacity to construct and use complex tools, and the ability to adapt to cultural differences.
Evolution occurs when genetic changes allow individuals in a group to better adapt to their environment. Natural selection is the process that triggers this adaptation. Certain characteristics are more desirable than others. The more adaptable are more likely to pass their genes on to the next generation. This is how all species evolve and is the foundation of the theory of evolution.
Scientists refer to this as the "law of natural selection." The law states species that share an ancestor will tend to develop similar traits as time passes. This is because the traits make it easier for them to live and reproduce in their natural environment.
Every living thing has a DNA molecule that contains the information needed to control their growth. The structure of DNA is composed of base pairs arranged in a spiral around phosphate and sugar molecules. The sequence of bases within each string determines the phenotype or the appearance and behavior of a person. Different mutations and reshufflings of the genetic material (known as alleles) during sexual reproduction cause variation in a population.
Fossils from the first human species, Homo erectus and Homo neanderthalensis have been discovered in Africa, Asia and Europe. These fossils, despite variations in their appearance, all support the hypothesis that modern humans' ancestors originated in Africa. Evidence from fossils and genetics suggest that early humans moved out of Africa into Asia and then Europe.