The Berkeley Evolution Site
The Berkeley site contains resources that can help students and teachers learn about and teach evolution. The resources are organized into different learning paths for example "What does T. rex look like?"
Charles Darwin's theory of natural selection explains how over time, animals that are more able to adapt to changing environments survive and those that do not become extinct. Science is about this process of evolutionary change.
What is Evolution?
The word evolution can have a variety of meanings that are not scientific. For example it could refer to "progress" and "descent with modifications." Scientifically, it refers to a process of changing the characteristics of living organisms (or species) over time. In biological terms the change is based on natural selection and genetic drift.
Evolution is a fundamental principle in modern biology. It is an accepted theory that has withstood the test of time and a multitude of scientific tests. Evolution does not deal with the existence of God or religious beliefs in the same way as other scientific theories such as the Copernican or germ theory of diseases.
Early evolutionists, such as Erasmus Darwin (Charles’s grandfather) and Jean-Baptiste Lamarck believed that certain physical traits were predetermined to change in a gradual manner over time. They called this the "Ladder of Nature" or the scala naturae. Charles Lyell used the term to describe this idea 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 claims that different species of organisms share an ancestry that can be proven through fossils and other evidence. This is the current perspective on evolution, and is supported by a variety of areas of science that include molecular biology.
Scientists don't know how organisms have evolved, but they are confident that natural selection and genetic drift are the primary reason for the development of life. People with advantages are more likely than others to survive and reproduce. They pass on their genes to the next generation. As time passes, the gene pool gradually changes and develops into new species.
Some scientists use the term evolution in reference to large-scale changes, like the evolution of one species from an ancestral one. Others, like 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 acceptable, but certain scientists argue that allele frequency definitions do not include important aspects of evolutionary process.
Origins of Life
One of the most crucial steps in evolution is the emergence of life. The emergence of life happens when living systems start to evolve at a micro level, such as within cells.
The origin of life is an issue in a variety of disciplines such as biology, chemistry and geology. The origin of life is a topic that is of immense interest to scientists, as it is a challenge to the theory of evolution. It is sometimes referred to "the mystery" of life or "abiogenesis."
The notion that life could arise from non-living objects was referred to as "spontaneous generation" or "spontaneous evolutionary". It was a common belief prior to Louis Pasteur's experiments proved that the development of living organisms was not achievable through the natural process.
Many scientists believe that it is possible to make the transition from nonliving substances to life. However, the conditions needed are extremely difficult to replicate in labs. This is why researchers investigating the origins of life are also interested in understanding the physical properties of early Earth and other planets.
Additionally, the evolution of life is dependent on the sequence of extremely complex chemical reactions that cannot be predicted based on basic physical laws alone. This includes the conversion 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 RNA sequences. These chemical reactions can be compared to a chicken-and egg problem: the emergence and development of DNA/RNA, the protein-based cell machinery, is essential for the onset life. However, without life, the chemistry that is required to create it does appear to work.
Research in the area of abiogenesis requires cooperation among scientists from many different fields. This includes prebiotic scientists, astrobiologists, and planet scientists.
Evolutionary Changes
The word evolution is usually used to describe the accumulated changes in the genetic characteristics of an entire population over time. These changes may result from adaptation to environmental pressures, as discussed in the entry on Darwinism (see the entry on Charles Darwin for background) or may result from natural selection.
This is a process that increases the frequency of those genes that confer a survival advantage over others which results in gradual changes in the overall appearance of a group. These evolutionary changes are triggered by mutations, reshuffling of genes during sexual reproduction and gene flow.
Natural selection is the process that allows beneficial mutations to become more common. All organisms undergo mutations and reshuffles in their genes. As noted above, individuals with the beneficial trait have a higher reproduction rate than those who don't. Over the course of many generations, this differential in the number of offspring produced can 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 evolved different shaped beaks that allow them to easily access food in their new home. These changes in the shape and form of living organisms may also be a catalyst for the creation of new species.
The majority of changes are caused by one mutation, however sometimes multiple occur at once. The majority of these changes could be neutral or even harmful however, a small percentage can have a beneficial impact on survival and reproduce, increasing their frequency as time passes. Natural selection is a process that causes the accumulating changes over time that lead to the creation of a new species.
Some people think that evolution is a form of soft inheritance, which is the idea that inherited traits can be changed by conscious choice or abuse. This is a misinterpretation of the biological processes that lead up to evolution. It is more precise to say that evolution is a two-step, separate process that involves the forces of natural selection as well as mutation.
Origins of Humans
Humans of today (Homo sapiens) evolved from primates, a group of mammals that includes chimpanzees and gorillas and bonobos. Our ancestors walked on two legs, as shown by the oldest fossils. Genetic and biological similarities suggest that we share an intimate relationship with Chimpanzees. In reality our closest relatives are chimpanzees of the Pan genus. This includes pygmy, as well as bonobos. The last common human ancestor as well as chimpanzees lived between 8 and 6 million years ago.
Humans have developed a range of traits over time, including bipedalism, the use of fire and advanced tools. However, it is only in the last 100,000 years or so that the majority of the traits that distinguish us from other species have emerged. These include language, a large brain, the capacity to build and use sophisticated tools, and a cultural diversity.
Evolution happens when genetic changes allow members of a population to better adapt to their surroundings. This adaptation is driven by natural selection, a process whereby certain traits are favored over other traits. The ones with the best 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 this as the "law of natural selection." The law states species that have an ancestor in common will tend to develop similar characteristics as time passes. This is because these traits make it easier to survive and reproduce within their environment.
All organisms possess the DNA molecule, which contains the information necessary to direct their growth. 에볼루션 바카라 체험 is composed of base pair arranged in a spiral around sugar and phosphate 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 reshufflings and mutations of genetic material (known collectively as alleles).
Fossils from the earliest human species Homo erectus and Homo neanderthalensis have been found in Africa, Asia and Europe. Although there are some differences the fossils all support the hypothesis that modern humans first came into existence in Africa. The fossil and genetic evidence suggests that early humans left Africa and migrated to Asia and Europe.