The Berkeley Evolution Site
The Berkeley site offers resources that can help students and teachers understand and teach evolution. The materials are arranged in various learning paths that can be used in a variety of ways for example "What does T. rex look like?"
Charles Darwin's theory of natural selection explains how animals who are better equipped to adapt to changes in their environment survive over time and those that don't end up becoming extinct. Science is concerned with the process of biological evolution.
What is Evolution?
The term "evolution" can have a variety of meanings that are not scientific. For instance it could refer to "progress" and "descent with modifications." Scientifically, it refers to a change in the characteristics of living things (or species) over time. In terms of biology, this change is due to natural selection and genetic drift.
Evolution is a central tenet of modern biology. It is an established theory that has withstood the tests of time and thousands of scientific experiments. Evolution does not deal with spiritual beliefs or God's presence, unlike many other theories in science, like the Copernican or germ theory of diseases.
Early evolutionists, like Jean-Baptiste Lamarck and Erasmus Darwin (Charles's grandfather), believed that certain physical characteristics were predetermined to change in a gradual 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.
In the early 1800s, Darwin formulated his theory of evolution and published it in his book On the Origin of Species. It claims that different species of organisms share a common ancestry, which can be determined through fossils and other lines of evidence. This is the modern view of evolution, which is supported by a variety of areas of science which include molecular biology.
Scientists aren't sure how organisms evolved however they are certain that natural selection and genetic drift is responsible for the development of life. People with desirable traits are more likely to live and reproduce, and these individuals transmit their genes to the next generation. As time passes the gene pool gradually 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 formation of a new species from an ancestral species. Other scientists, such as population geneticists, define evolution more broadly by referring an overall variation in the frequency of alleles over generations. Both definitions are acceptable and accurate, although some scientists argue that the allele-frequency definition is missing crucial aspects of the evolutionary process.
Origins of Life
The most important step in evolution is the emergence of life. The emergence of life occurs when living systems start to evolve at a micro level, like within cells.
The origins of life are an important subject in a variety of areas such as biology and chemical. The question of how living things started is of particular importance in science due to it being an important challenge to the theory of evolution. It is often referred to "the mystery" of life or "abiogenesis."
The idea that life could emerge from non-living matter was known as "spontaneous generation" or "spontaneous evolutionary". It was a common belief prior to Louis Pasteur's tests showed that the creation of living organisms was not possible through an organic process.
Many scientists believe it is possible to move from nonliving substances to living ones. However, the conditions required are extremely difficult to replicate in the laboratory. Researchers studying 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 dependent on a number of complex chemical reactions which are not predicted by simple physical laws. These include the reading and replication of complex molecules, such as DNA or RNA, to produce proteins that perform a specific function. These chemical reactions are often compared to the chicken-and-egg issue of how life came into existence with the emergence of DNA/RNA and proteins-based cell machinery is vital to the birth of life, but without the emergence of life the chemical reaction that is the basis for it does not appear to work.
Abiogenesis research requires collaboration among researchers from different fields. This includes prebiotic scientists, astrobiologists, and planetary scientists.
Evolutionary Changes
The term "evolution" today is used to describe general changes in genetic traits over time. These changes may result from adaptation to environmental pressures, as explained in the article on Darwinism (see the entry on Charles Darwin for background), or from natural selection.
This process increases the frequency of genes that confer a survival advantage in the species, leading to an overall change in the appearance of the group. The specific mechanisms that cause these evolutionary changes include mutation or reshuffling genes during sexual reproduction, and gene flow between populations.
Natural selection is the process that makes beneficial mutations more frequent. All organisms undergo changes and reshuffles of genes. As previously mentioned, those who possess the desirable trait have a higher reproductive rate than those who do not. Over the course of several generations, this differential in the numbers of offspring born can result in an inclination towards a shift in the number of beneficial characteristics in a particular population.
One good example is the increase in beak size on various species of finches found on the Galapagos Islands, which have developed different beak shapes to enable them to more easily access food in their new environment. These changes in the form and shape of organisms can also aid in the creation of new species.
The majority of changes are caused by a single mutation, however sometimes multiple occur at once. Most of these changes may be negative or even harmful, but a small number may have a positive effect on survival and reproduce and increase their frequency over time. Natural selection is a mechanism that can produce the accumulating changes over time that lead to the creation of a new species.
Some people think that evolution is a form of soft inheritance, which is the idea that inherited traits can be changed through conscious choice or by abuse. This is a misunderstanding of the nature of evolution and of the actual biological processes that cause it. A more accurate description is that evolution is a two-step procedure that involves the distinct and often antagonistic forces of natural selection and mutation.
Origins of Humans
Humans of today (Homo Sapiens) evolved from primates, which is a group of mammal species that includes chimpanzees as well as gorillas. Our predecessors walked on two legs, as demonstrated by the earliest fossils. Genetic and biological similarities suggest that we are closely related to the chimpanzees. In reality our closest relatives are chimpanzees of the Pan genus. This includes pygmy, as well as bonobos. The last common human ancestor and chimpanzees was between 8 and 6 million years ago.
Humans have evolved a wide range of traits over time, including bipedalism, the use of fire and advanced tools. It's only within the last 100,000 years that we have developed the majority of our essential characteristics. They include language, a large brain, the capacity to build and use sophisticated tools, and a the diversity of our culture.
에볼루션 룰렛 occurs when genetic changes allow members of a population to better adapt to their surroundings. Natural selection is the mechanism that drives this change. Certain characteristics are more desirable than others. Those with the better adaptations are more likely to pass on their genes to the next generation. This is the way all species evolve, and the basis of the theory of evolution.
Scientists call it the "law of Natural Selection." The law states that species which have a common ancestor are likely to develop similar traits over time. This is because those characteristics make it easier for them to survive and reproduce in their natural environment.
Every organism has a DNA molecule that contains the information needed to control their growth. The DNA structure is composed of base pair which are arranged in a spiral, around phosphate and sugar molecules. The sequence of bases within each strand determines phenotype which is the person's distinctive appearance and behavior. Variations in a population are caused by mutations and reshufflings of genetic material (known collectively as alleles).
Fossils from the earliest human species Homo erectus and Homo neanderthalensis have been found in Africa, Asia and Europe. These fossils, despite a few 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 moved from Africa into Asia and then Europe.