The Berkeley Evolution Site
Teachers and students who browse the Berkeley site will find a wealth of resources to help them understand and teach evolution. The materials are arranged into different learning paths, such as "What did T. rex taste like?"
Charles Darwin's theory of natural selection explains how over time creatures that are more able to adapt to changing environments do better than those that do not become extinct. Science is about the process of biological evolutionary change.
What is Evolution?
The term "evolution" has a variety of nonscientific meanings, such as "progress" or "descent with modification." Scientifically, it refers to a process of changes in the traits of organisms (or species) over time. In biological terms, this change is based on natural selection and genetic drift.
Evolution is an important principle in the field of biology today. It is an accepted theory that has stood the test of time and thousands of scientific tests. Contrary to other theories of science such as the Copernican theory or the germ theory of disease, evolution does not address issues of religious belief or God's existence.
Early evolutionists, including Jean-Baptiste Lamarck and Erasmus Darwin (Charles's grandfather), believed that certain physical traits were predetermined to change, in a step-like manner, as time passes. This was referred to 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.
Darwin published his theory of evolution in his book On the Origin of Species published in the early 1800s. It states that all species of organisms share an ancestry that can be traced through fossils and other evidence. This is the current perspective on evolution, and is supported in many areas of science 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 the result of natural selection and genetic drift. People with advantages are more likely to live and reproduce. These individuals then pass their genes on to the next generation. In time, this results in gradual changes in the gene pool that gradually lead to new species and types.
Certain scientists use the term evolution in reference to large-scale changes, such the formation of an animal from an ancestral one. Others, like population geneticists, define evolution more broadly by referring a net change in allele frequencies over generations. Both definitions are valid and acceptable, but some scientists argue that allele-frequency definitions do not include important aspects of evolutionary process.
Origins of Life
A key step in evolution is the emergence of life. The emergence of life happens when living systems start to develop at a microscopic level, like within individual cells.
The origins of life are an issue in a variety of disciplines that include biology, chemistry and geology. The question of how living things started is of particular importance in science since it poses an important challenge to the theory of evolution. It is sometimes referred to as "the mystery" of life or "abiogenesis."
The idea that life could arise from non-living things was called "spontaneous generation" or "spontaneous evolutionary". It was a common belief prior to Louis Pasteur's tests showed that the development of living organisms was not achievable through the natural process.
Many scientists still believe it is possible to go from nonliving materials to living. The conditions needed 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 growth of life is dependent on a number of complex chemical reactions, which cannot be predicted by simple physical laws. These include the reading of long, information-rich molecules (DNA or RNA) into proteins that perform some function as well as the replication of these complex molecules to produce new DNA or sequences of RNA. These chemical reactions are comparable to the chicken-and-egg issue that is the emergence and growth of DNA/RNA, a protein-based cell machinery, is essential for the onset life. Although, without life, the chemistry required to enable it appears to be working.
Abiogenesis research requires collaboration with scientists from different disciplines. This includes prebiotic scientists, astrobiologists and planetary scientists.
Evolutionary Changes
The term "evolution" today is used to describe the general changes in genetic traits over time. These changes may result from the response to environmental pressures as described in the entry on Darwinism (see the entry on Charles Darwin for background), or from natural selection.
This process increases the number of genes that confer the advantage of survival for an animal, resulting in an overall change in the appearance of a group. The specific mechanisms responsible for these evolutionary changes include mutation or reshuffling genes during sexual reproduction, and gene flow between populations.
While mutation and reshuffling of genes happen in all living things, the process by which beneficial mutations are more frequent is called natural selection. This happens because, as noted above, those individuals with the beneficial trait tend to have a higher reproductive rate than those with it. Over many generations, this variation in the numbers of offspring produced can result in a gradual shift in the average number of beneficial traits within a group of.
A good example of this is the growth of the size of the beaks on different species of finches on the Galapagos Islands, which have developed beaks with different shapes that allow them to easily access food in their new habitat. These changes in shape and form can also aid in the creation of new species.
The majority of the changes that take place are the result of one mutation, however occasionally, multiple mutations occur simultaneously. Most of these changes are neutral or even harmful to the organism however, a small proportion of them can have a positive impact on the longevity and reproduction of the species, thus increasing their frequency in the population over time. Natural selection is a process that can produce the accumulating changes over time that lead to the creation of a new species.
Many people mistakenly associate evolution with the concept of soft inheritance which is the notion that traits inherited from parents can be altered by deliberate choice or misuse. This is a misunderstanding of the biological processes that lead up to evolution. A more precise description is that evolution is a two-step procedure involving the independent and often antagonistic forces of mutation and natural selection.
Origins of Humans
Modern humans (Homo sapiens) evolved from primates - a species of mammals that includes chimpanzees and gorillas and bonobos. Our predecessors walked on two legs, as shown by the first fossils. Genetic and biological similarities show that we have a close relationship with chimpanzees. In actual fact, our closest relatives are the chimpanzees from the Pan genus. This includes pygmy and bonobos. The last common human ancestor and chimpanzees was born between 8 and 6 million years ago.
As time has passed, humans have developed a range of characteristics, such as bipedalism as well as the use of fire. They also created 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 been developed. These include language, large brain, the ability to build and use complex tools, as well as the ability to adapt to cultural differences.
Evolution happens when genetic changes allow individuals in a group to better adapt to their environment. Natural selection is the mechanism that drives this change. Certain traits are preferred over others. The more adjusted are more likely to pass on their genes to the next generation. This is the way all species evolve and the basis for the theory of evolution.
Scientists refer to this as the "law of natural selection." The law states species that have an ancestor in common will tend to acquire similar traits over time. This is because those traits allow them to survive and reproduce in their natural environment.
Every organism has the DNA molecule, which contains the information necessary to direct their growth. The DNA molecule is composed of base pairs arranged spirally around sugar molecules and phosphate molecules. The sequence of bases found in each string determines the phenotype or the characteristic appearance and behavior of a person. 에볼루션사이트 and reshuffling of genetic material (known as alleles) during reproduction causes variations in a population.
Fossils of the earliest human species, Homo erectus and Homo neanderthalensis have been discovered in Africa, Asia, and Europe. While there are some differences between them, these fossils all support the notion that modern humans first appeared in Africa. Evidence from fossils and genetics suggest that early humans came out of Africa into Asia and then Europe.