The Berkeley Evolution Site
Students and teachers who explore the Berkeley site will find a wealth of resources to aid in understanding and teaching evolution. The resources are organized into optional learning paths like "What does T. rex look like?"
Charles Darwin's theory on natural selection describes how species who are better able to adapt to changes in their environment survive over time and those who do not become extinct. Science is all 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 mean "progress" and "descent with modifications." Scientifically, it is a term used to describe a changing the characteristics of living things (or species) over time. This change is based in biological terms on natural selection and drift.
Evolution is a fundamental principle in modern biology. It is an established theory that has withstood the test of time and thousands of scientific studies. It does not address God's presence or spiritual beliefs like other theories in science, like the Copernican or germ theory of disease.
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 scala naturae. 에볼루션코리아 used the term to describe this concept 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 asserts that all species of organisms have a common ancestry which can be traced through fossils and other evidence. This is the current view of evolution that is supported by a variety of lines of scientific research which includes molecular genetics.
Although scientists aren't able to determine exactly how organisms evolved, they are confident that the evolution of life on earth is the result of natural selection and genetic drift. Individuals with advantageous traits are more likely to live and reproduce, and they transmit their genes to the next generation. Over time the gene pool slowly changes and evolves into new species.
Some scientists also use the term"evolution" to refer to large-scale changes in evolutionary processes such as the creation of an entirely new species from an ancestral species. Other scientists, like population geneticists, define it more broadly by referring to the net change in allele frequencies over generations. Both definitions are correct and palatable, but certain scientists argue that allele frequency definitions miss important aspects of the evolution.
Origins of Life
The birth of life is a crucial step in evolution. This happens when living systems begin to evolve at a micro-level - within cells, for instance.
The origin of life is an issue in a variety of disciplines, including biology, chemistry and geology. The origin of life is an area of great interest in science, as it is a challenge to the theory of evolution. It is often called "the mystery of life" or "abiogenesis."
Traditionally, the idea that life could emerge from nonliving objects is known as spontaneous generation, or "spontaneous evolution." This was a popular belief prior to Louis Pasteur's experiments proved that it was impossible for the development of life to happen through an entirely natural process.
Many scientists believe it is possible to transition from living to nonliving substances. The conditions necessary to create life are difficult to reproduce in a lab. This is why scientists studying the origins of life are also interested in understanding the physical properties of early Earth and other planets.
In addition, the development of life is dependent on the sequence of extremely complex chemical reactions that can't be predicted from the fundamental physical laws alone. These include the reading and the replication of complex molecules, like DNA or RNA, to produce proteins that serve a specific function. These chemical reactions can be compared to a chicken-and egg problem that is the emergence and growth of DNA/RNA, the protein-based cell machinery, is essential to begin the process of becoming a living organism. Although without life, the chemistry needed to make it possible is working.
Research in the area of abiogenesis requires collaboration among scientists from many different disciplines. This includes prebiotic chemists, the astrobiologists, the planet scientists, geologists and geophysicists.
Evolutionary Changes
The word evolution is usually used to describe the accumulated changes in genetic characteristics of an entire population over time. These changes can result from adaptation to environmental pressures as described in the entry on Darwinism (see the entry on Charles Darwin for background) or may result from natural selection.
This process increases the frequency of genes that offer the advantage of survival for the species, leading to an overall change in the appearance of a group. The specific mechanisms behind these changes in evolutionary process include mutation and reshuffling of genes in sexual reproduction, and gene flow between populations.
Natural selection is the process that allows beneficial mutations to become more common. All organisms undergo changes and reshuffles of their genes. As mentioned above, those with the beneficial trait have a higher reproductive rate than those who don't. This variation in the number of offspring that are produced over many generations can result in a gradual shift in the average number of beneficial traits in the group.
An excellent example is the growth of beak size on various species of finches in the Galapagos Islands, which have developed different beak shapes that allow them to easily access food in their new habitat. These changes in form and shape can 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 could be negative or even harmful, but a small number may have a positive effect on survival and reproduction, increasing their frequency over time. Natural selection is a process that could result in the accumulation of changes over time that lead to the creation of a new species.
Some people confuse the idea of evolution with the notion that the traits inherited from parents can be changed through conscious choice or use and abuse, which is called soft inheritance. This is a misinterpretation of the biological processes that lead up to the process of evolution. It is more accurate to say that evolution is a two-step, independent process that involves the forces of natural selection and mutation.
Origins of Humans
Humans of today (Homo sapiens) evolved from primates, a group of mammals that also includes chimpanzees and gorillas and bonobos. Our predecessors walked on two legs, as evidenced by the earliest fossils. Genetic and biological similarities suggest that we share the same ancestry with the chimpanzees. In fact we are the closest related to the chimpanzees within the Pan Genus, which includes bonobos and pygmy-chimpanzees. The last common ancestor of modern humans and chimpanzees was born between 8 and 6 million years ago.
Over time, humans have developed a range of characteristics, such as bipedalism as well as the use of fire. They also created advanced tools. It is only within the last 100,000 years that we have developed the majority of our key characteristics. They include a huge, complex brain and the capacity of humans to construct and use tools, and the diversity of our culture.
The process of evolution occurs when genetic changes enable members of an organization to better adapt to their environment. Natural selection is the mechanism that drives this change. Certain traits are preferred over others. The better adapted are more likely to pass their genes on to the next generation. This is how all species evolve, and the foundation for the theory of evolution.
Scientists refer to it as the "law of natural selection." The law states that species which have an ancestor in common will tend to develop similar characteristics in the course of time. 에볼루션코리아 is because these traits allow them to survive and reproduce within their environment.
Every living thing has a DNA molecule that is the source of information that helps direct their growth and development. 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. The variations in a population are caused by reshufflings and mutations of genetic material (known collectively as alleles).
Fossils from the first human species, Homo erectus, as well as Homo neanderthalensis have been found in Africa, Asia and Europe. Although there are Full Content support the notion that modern humans first appeared in Africa. The genetic and fossil evidence suggests that early humans left Africa and moved to Asia and Europe.