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 resources are arranged into different learning paths like "What did T. rex taste like?"
Charles Darwin's theory of natural selection explains how animals that are better equipped to adapt biologically to changing environments survive longer and those that don't end up becoming extinct. Science is concerned with this process of biological evolution.
What is Evolution?
The word evolution can have many nonscientific meanings. For instance it could refer to "progress" and "descent with modifications." Scientifically, it refers to a process of change in the characteristics of living things (or species) over time. This change is based in biological terms on natural drift and selection.
Evolution is the central tenet of modern biology. It is a theory that has been proven through thousands of scientific tests. Unlike many other scientific theories, such as the Copernican theory or the germ theory of disease, the evolution theory 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 step-wise manner, over time. They referred to this as the "Ladder of Nature" or scala naturae. Charles Lyell used the term to describe this concept in his Principles of Geology, first published in 1833.
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 a common ancestry which can be traced through fossils and other evidence. This is the modern view of evolution, and is supported by numerous lines of research in science, including molecular genetics.
While scientists do not know exactly how organisms developed however they are sure 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 leads to a gradual accumulation of changes in the gene pool which gradually create new species and types.
Some scientists use the term"evolution" to refer to large-scale changes, such the development of an animal from an ancestral one. Other scientists, such as population geneticists, define evolution more broadly by referring to an overall change in the frequency of alleles across generations. Both definitions are valid and palatable, but certain scientists argue that allele frequency definitions miss important aspects of the evolution.
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 develop at a micro scale, for instance within individual cells.
무료 에볼루션 of life are one of the major topics in various disciplines that include biology, chemistry and geology. The question of how living organisms began has a special place in science due to it being an enormous challenge to the theory of evolution. It is often described as "the mystery of life" or "abiogenesis."
Traditionally, the belief that life can arise from nonliving things is called spontaneous generation or "spontaneous evolution." This was a common belief before Louis Pasteur's research showed that it was impossible for the emergence of life to happen through a purely natural process.
Many scientists still think it is possible to go from living to nonliving substances. The conditions required to create life are difficult to replicate in a laboratory. This is why scientists investigating the beginnings of life are also interested in determining the physical properties of early Earth and other planets.
In addition, the development of life is the sequence of extremely complex chemical reactions that can't be predicted based on basic physical laws alone. These include the reading of long information-rich molecules (DNA or RNA) into proteins that carry out functions, and the replication of these complex molecules to produce new DNA or RNA sequences. These chemical reactions can be compared to the 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 required to make it possible is working.
Abiogenesis research requires collaboration with scientists from various disciplines. This includes prebiotic scientists, astrobiologists and planetary scientists.
Evolutionary Changes
The term "evolution" is used to describe the general changes in genetic traits over time. These changes may be the result of adaptation to environmental pressures as discussed in Darwinism.
This mechanism also increases the frequency of genes that provide a survival advantage in the species, leading to an overall change in the appearance of the 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 mutation and reshuffling of genes happen in all organisms, the process by which beneficial mutations are more prevalent is called natural selection. As previously mentioned, those who have the advantageous characteristic have a higher reproduction rate than those that do not. Over many generations, this difference in the number of offspring born could result in an inclination towards a shift in the average number of beneficial traits within a group of.
One good example is the increase in beak size on different species of finches found on the Galapagos Islands, which have developed beaks with different shapes to enable them to more easily access food in their new habitat. These changes in the form and shape of organisms can also aid in the creation of new species.
The majority of changes are caused by a single mutation, however sometimes multiple occur at the same time. Most of these changes may be harmful or neutral however, a few can have a beneficial impact on survival and reproduce with increasing frequency over time. This is the process of natural selection, and it could, over time, produce the gradual changes that eventually lead to a new species.
Some people think that evolution is a form of soft inheritance which is the notion that traits inherited from parents can be altered by 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 accurate description of evolution is that it involves a two-step process, that involves the distinct, and often competing, forces of mutation and natural selection.
Origins of Humans
Humans of today (Homo Sapiens) evolved from primates, a species of mammal species which includes gorillas and chimpanzees. Our ancestral ancestors were walking on two legs, as demonstrated by the oldest fossils. Genetic and biological similarities suggest that we have an intimate relationship with the chimpanzees. In fact we are the most closely related to the chimpanzees within the Pan genus, which includes bonobos and pygmy-chimpanzees. The last common human ancestor as well as chimpanzees was born between 8 and 6 million years ago.
As time has passed, humans have developed a range of characteristics, such as bipedalism and the use fire. They also created advanced tools. It is only in the last 100,000 years or so that most of the important characteristics that differentiate us from other species have been developed. These include language, a large brain, the capacity to construct and use complex tools, as well as the ability to adapt to cultural differences.
The process of evolution occurs when genetic changes enable members of the group to better adapt to the environment. This adaptation is triggered by natural selection, a process that determines certain traits are preferred over others. 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 foundation for 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 acquire similar traits as time passes. This is because those traits allow them to survive and reproduce in their environment.
Every organism has the DNA molecule, which contains the information needed to guide their growth. The structure of DNA is composed of base pair arranged in a spiral around phosphate and sugar molecules. The sequence of bases within each strand determines the phenotype or the individual's unique appearance and behavior. A variety of mutations and reshuffling of the genetic material (known as alleles) during reproduction causes variation in a group.
Fossils from the early human species Homo erectus and Homo neanderthalensis have been discovered in Africa, Asia and Europe. These fossils, despite differences in their appearance, all support the theory of the origins of modern humans in Africa. The evidence from fossils and genetics suggests that early humans left Africa and moved to Asia and Europe.