The Berkeley Evolution Site
Teachers and students who browse 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 in time, creatures more able to adapt to changing environments survive and those that don't become extinct. Science is about this process of evolutionary change.
What is Evolution?
The term "evolution" can have many nonscientific meanings. For example, it can mean "progress" and "descent with modifications." Scientifically, it refers to a process of changing the characteristics of organisms (or species) over time. In terms of biology this change is caused by natural selection and genetic drift.
Evolution is a fundamental tenet in the field of biology today. It is an accepted theory that has stood the test of time and a multitude of scientific experiments. Contrary to other theories of science like the Copernican theory or the germ theory of disease, evolution does not address issues of religion or the existence of God.
Early evolutionists, like Jean-Baptiste Lamarck and Erasmus Darwin (Charles's grandfather), believed that certain physical characteristics were predetermined to change in a step-like manner, as time passes. They referred to this as the "Ladder of Nature" or the scala naturae. Charles Lyell first used this term in 1833 in his Principles of Geology.
Darwin presented his theory of evolution in his book On the Origin of Species published in the early 1800s. It asserts that all species of organisms have common ancestors that can be traced by fossils and other evidence. This is the modern view on evolution, and is supported in a wide range of scientific fields which include molecular biology.
While scientists do not know the exact mechanism by which organisms evolved however they are sure that the evolution of life on earth is a result of natural selection and genetic drift. People with desirable traits are more likely than others to live and reproduce. These individuals transmit their genes on to the next generation. As time passes, this results in a gradual accumulation of changes to the gene pool which gradually lead to new species and forms.
Certain scientists also use the term evolution to refer to large-scale evolutionary changes like the creation of the new species from an ancestral species. Certain scientists, including population geneticists define evolution in a broad sense, using the term "net change" to refer to the change in allele frequency over generations. Both definitions are acceptable and precise however, some scientists claim that the allele-frequency definition omits essential aspects of the evolution process.
Origins of Life
The most important step in evolution is the appearance of life. This happens when living systems begin to develop at the micro level - within individual cells, for instance.
The origin of life is an issue in a variety of disciplines, including geology, chemistry, biology and chemistry. The question of how living things started has a special place in science since it poses an enormous challenge to the theory of evolution. 에볼루션 바카라사이트 is often referred to as "the mystery of life," or "abiogenesis."
Traditionally, the idea that life could emerge from nonliving things is called spontaneous generation, or "spontaneous evolution." This was a common belief before Louis Pasteur's experiments showed that it was impossible for the development of life to occur by a purely natural process.
에볼루션 블랙잭 believe it is possible to move from nonliving to living substances. The conditions necessary to make life are not easy to replicate in a laboratory. Researchers studying the origins of life are also keen to understand the physical properties of early Earth and other planets.
Additionally, the evolution of life is dependent on an intricate sequence of chemical reactions that can't be predicted from the fundamental physical laws on their own. This includes the conversion of long, information-rich molecules (DNA or RNA) into proteins that carry out functions and the replication of these intricate molecules to generate 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 required for the beginning of life. Although without life, the chemistry that is required to enable it does appear to work.
Abiogenesis research requires collaboration between scientists from various disciplines. This includes prebiotic chemists planet scientists, astrobiologists geophysicists and geologists.
Evolutionary Changes
The term "evolution" is commonly used to describe the cumulative changes in the genetic traits of a population over time. These changes could be the result of adapting to environmental pressures, as described in Darwinism.
The latter is a mechanism that increases the frequency of those genes that offer a survival advantage over others, resulting in an ongoing change in the appearance of a population. These changes in evolutionary patterns are caused by mutations, reshuffling genes during sexual reproduction, and the flow of genes.
Natural selection is the process that makes beneficial mutations more frequent. All organisms undergo changes and reshuffles of genes. This is because, as mentioned above those with the advantageous trait are likely to have a higher fertility rate than those without it. This difference in the number of offspring that are produced over a number of generations could cause a gradual change in the average number advantageous traits within a group.
An excellent example is the growing the size of the beaks on different species of finches in the Galapagos Islands, which have developed beaks with different shapes to enable them to more easily access food in their new environment. These changes in shape and form could also aid in the creation of new species.
The majority of changes are caused by a single mutation, although sometimes multiple occur at the same time. Most of these changes may be negative or even harmful, but a small number can have a beneficial impact on the survival of the species and reproduce, increasing their frequency as time passes. Natural selection is a process that causes the accumulating change over time that eventually leads to a new species.
Some people confuse the idea of evolution with the idea that inherited characteristics can be altered by conscious choice, or through use and abuse, a concept called soft inheritance. This is a misinterpretation of the biological processes that lead up to evolution. It is more accurate to say that evolution is a two-step independent process, that is influenced by the forces of natural selection and mutation.
Origins of Humans
Modern humans (Homo Sapiens) evolved from primates, which is a group of mammal species that includes gorillas and chimpanzees. Our ancestors walked on two legs, as demonstrated by the first fossils. Genetic and biological similarities suggest that we are closely related to chimpanzees. In fact we are the closest connected to chimpanzees belonging to the Pan genus which includes bonobos and pygmy-chimpanzees. The last common ancestor of modern humans and chimpanzees lived between 8 and 6 million years ago.
Over time humans have developed a number of characteristics, such as bipedalism and the use of fire. They also created advanced tools. It's only within the last 100,000 years that we've developed the majority of our essential traits. These include a large brain that is complex and the capacity of humans to create and use tools, and the diversity of our culture.
Evolution happens when genetic changes allow individuals in a group to better adapt to their surroundings. Natural selection is the process that drives this change. Certain traits are preferred over others. Those with the better adaptations are more likely to pass their genes to the next generation. This is the way that all species evolve and forms the basis of the theory of evolution.
Scientists call this the "law of natural selection." The law states species that have an ancestor in common will tend to develop similar traits as time passes. This is because these traits allow them to survive and reproduce within their environment.
All organisms possess an molecule called DNA that holds the information needed to guide their growth. The DNA molecule consists of base pairs that are arranged in a spiral around phosphate molecules and sugar molecules. The sequence of bases within each strand determines phenotype, or the individual's characteristic appearance and behavior. Variations in mutations and reshuffling of the genetic material (known as alleles) during sexual reproduction cause variation in a population.
Fossils from the first human species, Homo erectus, and Homo neanderthalensis have been discovered in Africa, Asia and Europe. These fossils, despite a few variations in their appearance, all support the theory of the origins of modern humans in Africa. Genetic and fossil evidence also suggest that early humans came out of Africa into Asia and then Europe.