All-Inclusive Guide To Evolution Site
The Berkeley Evolution Site
Teachers and students who browse the Berkeley site will find resources to aid in understanding and teaching evolution. The resources are organized into optional learning paths, such as "What did T. rex taste like?"
Charles Darwin's theory of natural selection explains how over time creatures that are better able to adapt biologically to changing environments thrive, and those that are not extinct. This process of biological evolution is the basis of science.
What is Evolution?
The term "evolution" can have many nonscientific meanings, including "progress" or "descent with modification." Scientifically, it refers to a changes in the traits of living organisms (or species) over time. This change is based in biological terms on natural selection and drift.
Evolution is one of the fundamental tenets of modern biology. It is a theory that has been proven through thousands of scientific tests. Evolution doesn't deal with spiritual beliefs or God's presence, unlike many other theories of science, such as the Copernican or germ theory of diseases.
Early evolutionists, like Jean-Baptiste Lamarck and Erasmus Darwin (Charles's grandfather) believed that certain physical traits were predetermined to change, in a step-like way, over time. They called this the "Ladder of Nature" or the scala naturae. Charles Lyell used the term to describe this concept in his Principles of Geology, first published in 1833.
Darwin published his theory of evolution in his book On the Origin of Species published in the early 1800s. It claims that different species of organisms share a common ancestry, which can be traced through fossils and other lines of evidence. This is the current view of evolution, which is supported by many lines of research in science which includes molecular genetics.
While scientists do not know the exact mechanism by which organisms evolved, they are confident that the evolution of life on earth is the result of natural selection and genetic drift. People with traits that are advantageous are more likely to survive and reproduce, and these individuals pass their genes on to the next generation. As time passes this leads to gradual changes in the gene pool, which eventually lead to new species and types.
Some scientists also use the term"evolution" to refer to large-scale evolutionary changes, such as the formation of the new species from an ancestral species. Certain scientists, such as population geneticists, define evolution in a broad sense, referring to the net variation in the frequency of alleles over generations. Both definitions are acceptable and precise, 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 appearance of life. This happens when living systems begin to develop at the micro level, within individual cells, for example.
The origins of life are an important issue in many areas that include biology and chemical. The question of how living things started is of particular importance in science because it is an important challenge to the theory of evolution. It is often called "the mystery of life," or "abiogenesis."
The notion that life could emerge from non-living things was called "spontaneous generation" or "spontaneous evolutionary". It was a popular belief before Louis Pasteur's tests showed that the creation of living organisms was not achievable through a natural process.
Many scientists believe that it is possible to make the transition from nonliving materials to living. The conditions necessary to create life are difficult to reproduce in a lab. Researchers who are interested in the origins and evolution of life are also eager to know the physical properties of the early Earth as well as other planets.
The life-cycle of a living organism is also dependent on a series of complex chemical reactions which are not predicted by the basic physical laws. These include the reading and re-reading of complex molecules, like DNA or RNA, to produce proteins that perform a specific function. These chemical reactions are comparable to the chicken-and-egg issue that is the emergence and growth of DNA/RNA, the protein-based cell machinery, is essential to begin the process of becoming a living organism. However without life, the chemistry that is required to make it possible is working.
에볼루션바카라 in the area of abiogenesis requires collaboration among scientists from many different disciplines. This includes prebiotic chemists, planet scientists, astrobiologists, geologists and geophysicists.
Evolutionary Changes
The word evolution is usually used to describe the cumulative changes in the genetic traits of a population over time. These changes may be the result of the adaptation to environmental pressures as discussed in Darwinism.
This latter mechanism increases the number of genes that offer 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 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 through which beneficial mutations are more frequent is called natural selection. As noted above, individuals who have the advantageous characteristic have a higher reproduction rate than those who do not. This differential in the number of offspring that are produced over a number of generations could result in a gradual change in the number of advantageous characteristics in a group.
This can be seen in the evolution of different beak shapes for 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 the shape and appearance of living organisms may also be a catalyst for the creation of new species.
Most of the changes that occur are the result of one mutation, but occasionally, multiple mutations occur at once. The majority of these changes are neutral or even detrimental to the organism, however a small portion of them could have an advantageous impact on survival and reproduction, thus increasing their frequency in the population over time. Natural selection is a mechanism that causes the accumulating changes over time that lead to the creation of a new species.
Many people confuse the concept of evolution with the notion that traits inherited can be altered through conscious choice, or through use and abuse, a concept called soft inheritance. This is a misunderstood understanding of the nature of evolution and of the actual biological processes that lead to it. A more accurate description is that evolution is a two-step process involving the independent and often conflicting forces of natural selection and mutation.
Origins of Humans
Modern humans (Homo Sapiens) evolved from primates, a species of mammal species which includes chimpanzees and gorillas. The earliest human fossils indicate that our ancestors were bipeds. They were walkers on two legs. Genetic and biological similarities suggest that we share a close relationship with chimpanzees. In actual fact our closest relatives are the chimpanzees from the Pan genus. This includes pygmy, as well as bonobos. The last common ancestor of modern humans and chimpanzees was between 8 and 6 million years ago.
Humans have developed a range of traits throughout time, including bipedalism, the use of fire, and the development of advanced tools. However, it is only in the last 100,000 years or so that most of the essential characteristics that differentiate us from other species have developed. These include a large, complex brain, the ability of humans to build and use tools, and the diversity of our culture.
The process of evolution occurs when genetic changes enable members of the group to better adapt to their environment. This adaptation is driven by natural selection, which is a process by which certain traits are more desirable than other traits. Those with the better adaptations are more likely to pass on their genes to the next generation. This is how all species evolve, and the basis for the theory of evolution.
Scientists refer to it as the "law of natural selection." The law states species that have an ancestor in common will tend to acquire similar traits as time passes. This is because these traits make it easier for them to survive and reproduce in their environments.
All organisms possess the DNA molecule, which contains the information needed to guide their growth. The DNA molecule is composed of base pairs arranged spirally around phosphate molecules and sugar molecules. The sequence of bases within each strand determines the phenotype, or the individual's characteristic appearance and behavior. The 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 discovered in Africa, Asia, and Europe. These fossils, despite some differences in their appearance all support the hypothesis that modern humans' ancestors originated in Africa. The genetic and fossil evidence suggests that the first humans left Africa and moved to Asia and Europe.