The Berkeley Evolution Site
The Berkeley site contains resources that can assist students and teachers learn about and teach evolution. The materials are arranged in various learning paths that can be used in a variety of ways, such as "What does T. rex look like?"
Charles Darwin's theory of natural selection explains how in time, creatures more adaptable to changing environments survive and those that don't become extinct. This process of evolution is what science is all about.
What is Evolution?
The word evolution can have a variety of meanings that are not scientific. For example, it can mean "progress" and "descent with modifications." It is an academic term that refers to the process of changing characteristics over time in organisms or species. This change is based in biological terms on natural drift and selection.
Evolution is an important tenet in modern biology. It is a concept that has been tested and proven through thousands 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 like Erasmus Darwin (Charles’s grandfather) and Jean-Baptiste Lamarck believed that certain physical traits were predetermined to change in a gradual manner over time. This was called the "Ladder of Nature", or 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 asserts that all species of organisms share common ancestors that can be traced by fossils and other evidence. This is the modern view of evolution, which is supported by a variety of scientific fields, including molecular biology.
Scientists do not know how organisms evolved but they are sure that natural selection and genetic drift are responsible for the evolution of life. People with desirable traits are more likely to survive and reproduce. These individuals transmit their genes on to the next generation. As time passes this leads to a gradual accumulation of changes in the gene pool, which eventually result in new species and forms.
Some scientists use the term"evolution" in reference to large-scale change, such as the evolution of a species from an ancestral one. Certain scientists, such as population geneticists, define the term "evolution" in a broader sense by referring to the net change in the frequency of alleles across generations. Both definitions are valid and acceptable, but some scientists believe that allele-frequency definitions do not include important aspects of evolutionary process.
Origins of Life
The most important step in evolution is the appearance of life. The emergence of life happens when living systems start to develop at a microscopic level, such as within individual cells.
The origins of life are an important issue in many disciplines, including biology and the field of chemistry. The origin of life is a subject 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 idea that life could emerge from non-living objects was referred to as "spontaneous generation" or "spontaneous evolutionary". This was a popular belief prior to Louis Pasteur's experiments proved that the creation of living organisms was not possible through the natural process.
Many scientists still 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. Researchers studying the beginnings of life are also interested in determining the physical properties of early Earth and other planets.
The life-cycle of a living organism is also dependent on a series of complex chemical reactions which are not predicted by simple physical laws. These include the transformation 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 sequences of RNA. These chemical reactions are often compared to the chicken-and-egg dilemma of how life first appeared in the first place. The emergence of DNA/RNA and protein-based cell machinery is essential for the onset of life, but without the appearance of life the chemical process that allows it does not appear to work.
Research in the area of abiogenesis requires collaboration among scientists from many different fields. This includes prebiotic scientists, astrobiologists, and planet scientists.
Evolutionary Changes
The word evolution is usually used today to describe the accumulated changes in the genetic characteristics of a population over time. These changes could be the result of adaptation to environmental pressures as explained in Darwinism.
This is a method that increases the frequency of those genes that offer an advantage in survival over other species and causes an ongoing change in the overall appearance of a particular population. These evolutionary changes are caused by mutations, reshuffling genes during sexual reproduction and gene flow.
Natural selection is the process that allows beneficial mutations to become more common. All organisms undergo changes and reshuffles in their genes. As mentioned above, those with the beneficial characteristic have a higher reproduction rate than those that do not. This differential in the number of offspring produced over many generations can result in a gradual change in the average number advantageous characteristics in the group.
One good example is the growing the size of the beaks on different species of finches on the Galapagos Islands, which have evolved different shaped beaks to enable them to more easily access food in their new habitat. These changes in shape and form could also help create new organisms.
The majority of changes are caused by one mutation, although sometimes multiple occur simultaneously. The majority of these changes could be negative or even harmful however, a few may have a positive effect on survival and reproduce, increasing their frequency as time passes. Natural selection is a mechanism that causes the accumulating change over time that eventually leads to a new species.
Many people confuse the concept of evolution with the idea that traits inherited can be changed through conscious choice or use and abuse, a concept known as soft inheritance. This is a misunderstood understanding of the nature of evolution, and of the actual biological processes that trigger it. A more precise description is that evolution is a two-step procedure which involves the separate and often conflicting 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 show that our ancestors were bipeds - walkers with two legs. Genetic and biological similarities show that we share a close relationship with the chimpanzees. In fact we are the most closely connected to chimpanzees belonging to the Pan Genus, which includes pygmy chimpanzees and bonobos. The last common ancestor of modern humans and chimpanzees was born between 8 and 6 million years ago.
Humans have evolved a variety of traits over time, including bipedalism, the use of fire and advanced tools. It is only within the last 100,000 years that we've developed the majority of our important characteristics. They include language, a large brain, the capacity to create and utilize complex tools, and the diversity of our culture.
The process of evolution occurs when genetic changes allow members of an organization to better adapt to the environment. This adaptation is triggered by natural selection, a process that determines certain traits are more desirable than others. Those with the better adaptations are more likely to pass their genes to the next generation. This is the way all species evolve and is the foundation for the theory of evolution.
Scientists refer to it as the "law of Natural Selection." 에볼루션 룰렛 that species which have a common ancestor, tend to develop similar characteristics over time. This is because those traits allow them to survive and reproduce in their environment.
Every organism has a DNA molecule, which provides the information necessary to direct their growth and development. The DNA molecule is composed of base pairs that are arranged in a spiral around sugar molecules and phosphate molecules. The sequence of bases within each strand determines 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 of the earliest 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 idea of the origins of modern humans in Africa. The genetic and fossil evidence suggests that the first humans left Africa and moved to Asia and Europe.