The Berkeley Evolution Site
The Berkeley site offers resources that can help students and educators to understand and teach about evolution. The resources are organized into optional learning paths, such as "What does T. rex look like?"
Charles Darwin's theory of natural selection explains that over time creatures that are better able to adapt biologically to changing environments do better than those that do not become extinct. Science is concerned with this process of evolution.
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." Scientifically it refers to a change in the characteristics of living organisms (or species) over time. In biological terms, this change is based on natural selection and genetic drift.
Evolution is an important principle in the field of biology today. It is a concept that has been tested and verified through thousands of scientific tests. In contrast to other theories in science such as the Copernican theory or the germ theory of disease, evolution is not a discussion of spiritual belief or God's existence.
Early evolutionists, such as Erasmus Darwin (Charles’s grandfather) and Jean-Baptiste Lamarck believed that certain physical characteristics were predetermined to evolve in a stepped-like manner over time. They called this 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, written in the early 1800s. It claims that different species of organisms share an ancestry that can be traced through fossils and other lines of evidence. This is the modern view on evolution, which is supported in a wide range of scientific fields that include molecular biology.
While scientists do not know exactly how organisms developed 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 live and reproduce. They pass on their genes on to the next generation. As time passes this leads to an accumulation of changes to the gene pool, which eventually lead to new species and forms.
Some scientists also use the term evolution to refer to large-scale changes in evolutionary processes like the creation of a new species from an ancestral species. Other scientists, like population geneticists, define evolution more broadly by referring the net change in allele frequencies over generations. Both definitions are correct and palatable, but some scientists argue that allele-frequency definitions omit important features of evolution.
Origins of Life
A key step in evolution is the emergence of life. The beginning of life takes place when living systems begin to develop at a micro level, such as within cells.
The origins of life are a topic in many disciplines, including geology, chemistry, biology and chemistry. The question of how living things got their start is of particular importance in science due to it being an enormous challenge to the theory of evolution. It is sometimes referred to as "the mystery" of life or "abiogenesis."
The notion that life could arise from non-living things was called "spontaneous generation" or "spontaneous evolutionary". This was a common belief prior to Louis Pasteur's experiments proved that the creation of living organisms was not achievable through the natural process.
Many scientists believe that it is possible to go from nonliving substances to life. However, the conditions that are required are extremely difficult to reproduce in the laboratory. Researchers investigating the nature of life are also keen to understand 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, that 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 issue of how life began in the first place. The development of DNA/RNA as well as proteins-based cell machinery is vital 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 cooperation among scientists from various disciplines. This includes prebiotic scientists, astrobiologists and planet scientists.
Evolutionary Changes
The term "evolution" today is used to describe the gradual changes in genetic traits over time. These changes could result from adaptation to environmental pressures, as described in the entry on Darwinism (see the entry on Charles Darwin for background), or from natural selection.
This is a method that increases the frequency of genes that confer an advantage in survival over others, resulting in an ongoing change in the appearance of a group. These evolutionary changes are triggered by mutations, reshuffling genes during sexual reproduction and gene flow.
While mutation and reshuffling of genes happen in all living things The process through which beneficial mutations are more prevalent is referred to as natural selection. As previously mentioned, those who have the advantageous trait have a higher reproduction rate than those who do not. Over the course of many generations, this differential in the number of offspring born could result in gradual changes in the number of advantageous traits within a group of.
A good example of this is the growth of 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 environment. These changes in form and shape can aid in the creation of new organisms.
Most of the changes that occur are the result of one mutation, but sometimes, several changes occur simultaneously. The majority of these changes are neither harmful nor even detrimental to the organism, however a small portion of them could have an advantageous impact on the longevity and reproduction of the species, thus increasing their frequency in the population over time. Natural selection is a process that can produce the accumulating change over time that leads to a new species.
Many people confuse the concept of evolution with the notion that traits inherited can be changed through conscious choice, or through use and abuse, which is known as soft inheritance. This is a misinterpretation of the nature of evolution and of the actual biological processes that trigger it. A more accurate description is that evolution is a two-step process which involves the separate, and often competing, forces of mutation and natural selection.
Origins of Humans
Humans of today (Homo sapiens) evolved from primates - a group of mammals that also includes gorillas, chimpanzees, and bonobos. The earliest human fossils show that our ancestors were bipeds. They were walkers with two legs. Genetic and biological similarities suggest that we are closely related to chimpanzees. In fact, our closest relatives are the chimpanzees belonging to the Pan genus. This includes pygmy as well as bonobos. The last common human ancestor as well as chimpanzees was born between 8 and 6 million years ago.
In the course of time, humans have developed a variety of traits, including bipedalism as well as the use of fire. They also created advanced tools. It's only in the last 100,000 years that we've developed the majority of our important traits. These include language, a large brain, the capacity to build and use complex tools, as well as the ability to adapt to cultural differences.
The process of evolution occurs when genetic changes allow individuals in a group to better adapt to their environment. This adaptation is triggered by natural selection, a process whereby certain traits are more desirable than other traits. People with better adaptations are more likely to pass on their genes to the next generation. This is the process that evolves all species and forms the basis of the theory of evolution.
Scientists refer to this as the "law of natural selection." 에볼루션 코리아 that species that share an ancestor will tend to develop similar traits over time. This is because these traits allow them to survive and reproduce in their natural environment.
All organisms possess a DNA molecule that contains the information needed to guide their growth. The DNA molecule is made up of base pairs that are spirally arranged around phosphate molecules and sugar molecules. The sequence of bases within each strand determines phenotype or the individual's unique appearance and behavior. Different changes and reshuffling of genetic material (known as alleles) during reproduction causes variation in a group.
Fossils from the first human species, Homo erectus, as well as Homo neanderthalensis have been discovered in Africa, Asia and Europe. These fossils, despite some differences in their appearance, all support the theory 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.