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 like "What did T. rex taste like?"
Charles Darwin's theory of natural selection explains how creatures that are better equipped to adapt biologically to changing environments survive longer and those who do not become extinct. Science is about the process of biological evolutionary change.
What is Evolution?
The term "evolution" can have many nonscientific meanings. For instance "progress" or "descent with modification." Scientifically it refers to a changing the characteristics of living organisms (or species) over time. In terms of biology the change is caused by natural selection and genetic drift.
Evolution is a central tenet of modern biology. It is a theory that has been tested and verified by thousands of scientific tests. Evolution does not deal with God's presence or spiritual beliefs, unlike many other scientific theories such as the Copernican or germ theory of diseases.
Early evolutionists, such as Jean-Baptiste Lamarck and Erasmus Darwin (Charles's grandfather), believed that certain physical traits were predetermined to change, in a step-like manner, over time. 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 published his theory of evolution in his book On the Origin of Species, written in the early 1800s. It claims that different species of organisms share the same ancestry, which can be proven through fossils and other evidence. This is the modern view on evolution, and is supported in many disciplines that include molecular biology.
Although scientists aren't able to determine exactly how organisms evolved but they are certain that the evolution of life on earth is the result of natural selection and genetic drift. People with desirable traits are more likely to survive and reproduce, and 에볼루션 블랙잭 they pass their genes on to the next generation. Over time, the gene pool gradually changes and develops into new species.Some scientists employ the term"evolution" to refer to large-scale changes, like the evolution of an animal from an ancestral one. Other scientists, like population geneticists, define the term "evolution" more broadly by referring an overall change in allele frequencies over generations. Both definitions are acceptable and accurate however some scientists believe that the allele-frequency definition omits important features of the evolutionary process.
Origins of Life
A key step in evolution is the development of life. The beginning of life takes place when living systems start to develop at a microscopic scale, for instance within individual cells.
The origin of life is one of the major topics in various disciplines, including biology, chemistry and geology. The question of how living organisms began is a major topic in science because it is an enormous challenge to the theory of evolution. It is often referred to as "the mystery of life" or "abiogenesis."
The notion that life could emerge from non-living things was called "spontaneous generation" or "spontaneous evolutionary". This was a common belief prior to Louis Pasteur's tests showed that the creation of living organisms was not achievable through the natural process.
Many scientists still believe that it is possible to transition from nonliving substances to living. The conditions needed for the creation of life are difficult to reproduce in a lab. Researchers who are interested in the origins and development of life are also keen to understand 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 that are not predicted by the basic physical laws. These include the reading and the replication of complex molecules, such as DNA or RNA, to create proteins that perform a specific function. These chemical reactions can be compared with a chicken-and egg problem which is the development and emergence of DNA/RNA, the protein-based cell machinery, is necessary for the beginning of life. However without life, the chemistry that is required to make it possible appears to be working.
Research in the area of abiogenesis requires collaboration between scientists from many different disciplines. This includes prebiotic scientists, astrobiologists and planetary scientists.
Evolutionary Changes
The term "evolution" today is used to describe gradual changes in genetic traits over time. These changes could be the result of the adaptation to environmental pressures as discussed in Darwinism.
This is a process that increases the frequency of genes in a species that confer an advantage in survival over other species and causes a gradual change in the appearance of a particular population. These evolutionary changes are triggered 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 living things and the process by which beneficial mutations are more prevalent is known as natural selection. As noted above, individuals who possess the desirable characteristic have a higher reproduction rate than those who do not. Over the course of several generations, this difference in the number of offspring produced can result in an inclination towards a shift in the amount of desirable characteristics in a particular population.
One good example is the growing the size of the beaks on different species of finches on the Galapagos Islands, which have developed different beak shapes that allow them to easily access food in their new habitat. These changes in the shape and form of living organisms may also aid in the creation of new species.The majority of changes are caused by one mutation, although sometimes multiple occur at once. The majority of these changes are neutral or even detrimental to the organism, but a small percentage can have an advantageous impact on the longevity and reproduction of the species, thus increasing their frequency in the population over time. This is the process of natural selection and it is able to eventually result in the cumulative changes that eventually result in an entirely new species.
Some people confuse evolution with the idea of soft inheritance which is the notion that inherited traits can be changed by conscious choice or abuse. This is a misunderstanding of the biological processes that lead to evolution. It is more accurate to say that the process of 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, a group of mammals that also includes chimpanzees and gorillas and bonobos. The earliest human fossils indicate that our ancestors were bipeds, walking on two legs. Genetic and biological similarities suggest that we are closely related to chimpanzees. In fact we are the most closely related to the chimpanzees within the Pan genus which includes pygmy chimpanzees and bonobos. The last common human ancestor and chimpanzees lived between 8 and 6 million years ago.
As time has passed humans have developed a variety of characteristics, such as bipedalism and the use of fire. They also developed advanced tools. It is only in the last 100,000 years or so that most of the traits that distinguish us from other species have emerged. These include language, a large brain, the ability to create and utilize sophisticated tools, and a the diversity of our culture.
The process of evolution occurs when genetic changes allow individuals of a population to better adapt to their environment. This adaptation is triggered by natural selection, a process that determines certain traits are preferred over others. The ones with the best adaptations are more likely to pass their genes to the next generation. This is the way that all species evolve and is the foundation of the theory of evolution.
Scientists refer to this as the "law of natural selection." The law states that species that share a common ancestor tend to develop similar characteristics over time. This is because these traits make it easier for them to survive and reproduce in their environment.
Every organism has the DNA molecule, which contains the information necessary to direct their growth. The structure of DNA is composed of base pair which are arranged in a spiral, around sugar and phosphate molecules. The sequence of bases within each strand determines the phenotype which is the person's distinctive appearance and behavior. Variations in mutations and reshufflings of the genetic material (known as alleles) during reproduction causes variation in a group.
Fossils of the first human species, Homo erectus and Homo neanderthalensis, have been found 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 fossil evidence and genetic evidence suggest that early humans migrated out of Africa into Asia and then Europe.
