The Berkeley Evolution Site
Students and teachers who explore the Berkeley site will find a wealth of resources to aid in understanding and teaching evolution. The materials are organized into optional learning paths such as "What did T. rex taste like?"
Charles Darwin's theory of natural selection explains how creatures who are better able to adapt to changes in their environment survive over time and those that do not end up becoming extinct. Science is about the process of biological evolutionary change.
What is Evolution?
The term "evolution" could have many nonscientific meanings. For example it could mean "progress" and "descent with modifications." Scientifically it refers to a change in the characteristics of organisms (or species) over time. This change is based in biological terms on natural selection and drift.
Evolution is the central tenet of modern biology. It is a concept that has been tested and verified by thousands of scientific tests. It does not address God's presence or spiritual beliefs, unlike many other theories in science, like the Copernican or germ theory of diseases.
에볼루션 사이트 , such as Erasmus Darwin (Charles’s grandfather) and Jean-Baptiste Lamarck believed that certain physical characteristics were predetermined to evolve in a gradual manner over time. This was called 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 have an ancestry that can be proven through fossils and other lines of evidence. This is the current understanding of evolution, and is supported by a variety of lines of scientific research, including molecular genetics.
Although scientists aren't able to determine exactly how organisms developed however they are sure that the evolution of life on earth is the result of natural selection and genetic drift. Individuals with advantageous traits are more likely to survive and reproduce, and they pass their genes on to the next generation. As time passes this leads to gradual changes to the gene pool, which eventually lead to new species and forms.
Certain scientists use the term"evolution" to refer to large-scale changes, such the evolution of an animal from an ancestral one. Certain scientists, such as population geneticists, define the term "evolution" in a broad sense, referring to the net change in the frequency of alleles across generations. Both definitions are acceptable and precise however, some scientists claim that the definition of allele frequency is lacking essential aspects of the evolution process.
Origins of Life
The emergence of life is a key step in evolution. The emergence of life occurs when living systems start to evolve at a micro level, like within cells.
The origin of life is an issue in a variety of disciplines such as geology, chemistry, biology and chemistry. The nature of life is an area of great interest in science, as it challenges the theory of evolution. It is often called "the mystery of life" or "abiogenesis."
Traditionally, the idea that life can arise from nonliving things is called spontaneous generation, or "spontaneous evolution." This was a common belief before Louis Pasteur's experiments proved that it was impossible for the creation of life to happen through a purely natural process.
Many scientists still think it is possible to move from nonliving substances to living ones. However, the conditions required are extremely difficult to reproduce in labs. Researchers studying the beginnings of life are also keen to understand the physical properties of early Earth and other planets.
Furthermore, the growth of life is the sequence of extremely complex chemical reactions that cannot be predicted from the fundamental physical laws on their own. These include the reading and the replication of complex molecules, like DNA or RNA, in order to make proteins that perform a specific function. These chemical reactions can be compared to the chicken-and-egg issue that is the emergence and growth of DNA/RNA, protein-based cell machinery, is necessary to begin the process of becoming a living organism. But without life, the chemistry required to make it possible appears to be working.
Abiogenesis research requires collaboration with researchers from different fields. This includes prebiotic scientists, astrobiologists, and planet scientists.
Evolutionary Changes
Today, the word evolution is used to describe the gradual changes in genetic traits 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 may result from natural selection.
This mechanism also increases the number of genes that provide a survival advantage in an animal, resulting in an overall change in the appearance of an entire group. The specific mechanisms responsible for these evolutionary changes include mutation and reshuffling of genes in sexual reproduction, as well as gene flow between populations.
Natural selection is the process that makes beneficial mutations more common. All organisms undergo mutations and reshuffles of genes. As noted above, individuals with the beneficial trait have a higher reproduction rate than those who don't. Over the course of several generations, this differential in the number of offspring born could result in a gradual shift in the number of beneficial traits in a population.
This is evident in the evolution of different beak designs on finches that are found in the Galapagos Islands. They have developed these beaks so that they can eat more easily in their new habitat. These changes in shape and form can aid in the creation of new organisms.
The majority of changes are caused by one mutation, although sometimes multiple occur at the same time. Most of these changes are neither harmful nor even detrimental to the organism, but a small percentage can have a positive impact on the longevity and reproduction of the species, thus increasing the frequency of these changes 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 the idea of evolution with the notion that inherited characteristics can be altered through conscious choice or use and abuse, a notion called soft inheritance. This is a misunderstood understanding of the nature of evolution, and of the actual biological processes that trigger it. A more accurate description of evolution is that it is a two-step process which involves the separate, and often competing, forces of mutation and natural selection.
Origins of Humans
Modern humans (Homo Sapiens) evolved from primates, which is a group of mammal species that includes chimpanzees as well as gorillas. Our ancestral ancestors were walking on two legs, as demonstrated by the oldest fossils. Genetic and biological similarities suggest that we are closely related to the chimpanzees. In actual fact we are the closest with chimpanzees in the Pan Genus that includes pygmy and pygmy chimpanzees and bonobos. The last common human ancestor and chimpanzees lived between 8 and 6 million years ago.
In the course of time, humans have developed a range of characteristics, including bipedalism as well as the use of fire. They also developed advanced tools. It's only in the last 100,000 years that we have developed the majority of our important characteristics. These include language, a large brain, the capacity to build and use complex tools, and the diversity of our culture.
Evolution occurs when genetic changes allow individuals of a population to better adapt to their surroundings. This adaptation is driven by natural selection, which is a process by which certain traits are preferred over others. People with better adaptations are more likely to pass on their genes to the next generation. This is how all species evolve and the basis of the theory of evolution.
Scientists call this the "law of natural selection." The law states that species which share an ancestor will tend to develop similar traits over time. This is because those traits allow them to live and reproduce in their environment.
Every organism has a DNA molecule that is the source of information that helps direct their growth and development. The structure of DNA is made of base pairs that are arranged in a spiral around sugar and phosphate molecules. The sequence of bases within each strand determines phenotype or the individual's unique appearance and behavior. Variations in a population are caused by mutations and reshufflings in genetic material (known collectively as alleles).
Fossils from the earliest human species Homo erectus, and Homo neanderthalensis have been discovered in Africa, Asia and Europe. Although there are some differences the fossils all support the notion that modern humans first appeared in Africa. Evidence from fossils and genetics suggest that early humans moved from Africa into Asia and then Europe.