It s Time To Increase Your Evolution Site Options
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The Berkeley Evolution Site
The Berkeley site contains resources that can assist students and teachers understand and teach evolution. The materials are organized into a variety of learning paths such as "What did T. rex taste like?"
Charles Darwin's theory on natural selection explains how animals who are better equipped to adapt biologically to changing environments over time, and those that don't become extinct. Science is concerned with the process of biological evolutionary change.
What is Evolution?
The term "evolution" could have a variety of meanings that are not scientific. For example, it can mean "progress" and "descent with modifications." Scientifically, it refers to a changing the characteristics of living organisms (or species) over time. In biological terms this change is due to natural selection and genetic drift.
Evolution is a fundamental concept in the field of biology today. It is a theory that has been proven by thousands of scientific tests. In contrast to other theories in science such as the Copernican theory or the germ theory of disease, evolution does not address questions of religious belief or God's existence.
Early evolutionists, like Jean-Baptiste Lamarck and Erasmus Darwin (Charles's grandfather), believed that certain physical traits were predetermined to change, in a gradual manner, as time passes. They referred to this as the "Ladder of Nature" or 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 Evolutionkr.Kr published it in his book On the Origin of Species. It states that all species of organisms have a common ancestry which can be traced through fossils and other evidence. This is the modern view on evolution, and is supported in a wide range of disciplines, including molecular biology.
While scientists don't know exactly how organisms developed however they are sure that the evolution of life on earth is the result of natural selection and genetic drift. People with advantages are more likely to live and reproduce. These individuals pass on their genes to the next generation. As time passes the gene pool slowly changes and evolves into new species.
Certain scientists also use the term evolution to refer to large-scale evolutionary changes such as the creation of an entirely new species from an ancestral species. Other scientists, like population geneticists, define the term "evolution" more broadly by referring the net variation in the frequency of alleles over generations. Both definitions are valid and acceptable, however some scientists believe that allele-frequency definitions omit important features of evolution.
Origins of Life
The most important step in evolution is the emergence of life. The emergence of life occurs when living systems start to develop at a microscopic level, like within cells.
The origin of life is an important issue in many areas such as biology and chemistry. The origin of life is an area of interest in science because it is a 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 matter was known as "spontaneous generation" or "spontaneous evolutionary". This was a popular belief prior to Louis Pasteur's tests showed that the creation of living organisms was not possible by the natural process.
Many scientists still believe that it is possible to go from nonliving substances to living. The conditions necessary to create life are difficult to reproduce in a lab. This is why researchers studying the nature of life are also interested in understanding the physical properties of early Earth and other planets.
Furthermore, the growth of life is a sequence of very complex chemical reactions that can't be predicted based on basic physical laws on their own. These include the reading and the replication of complex molecules, like DNA or RNA, in order to make proteins that perform a particular function. These chemical reactions can be compared with the chicken-and-egg problem that is the emergence and growth of DNA/RNA, the protein-based cell machinery, is necessary for the beginning of life. Although, without life, the chemistry required to enable it is working.
Research in the area of abiogenesis requires cooperation among scientists from many different disciplines. This includes prebiotic chemists, the astrobiologists, the planet scientists, geologists and geophysicists.
Evolutionary Changes
The term "evolution" today is used to describe the cumulative changes in genetic characteristics over time. These changes could result from the response to environmental pressures as described in the entry on Darwinism (see the entry on Charles Darwin for background) or natural selection.
This is a process that increases the frequency of those genes in a species which confer an advantage in survival over others which results in gradual changes in the overall appearance of a group. These evolutionary changes are caused by mutations, reshuffling of genes during sexual reproduction, and gene flow.
Natural selection is the process that allows beneficial mutations to become more common. All organisms undergo mutations and reshuffles of genes. As previously mentioned, those who have the advantageous trait have a higher reproduction rate than those that do not. This differential in the number of offspring produced over a long period of time can result in a gradual shift in the average number advantageous traits in the group.
This can be seen in the evolution of different beak designs on finches that are found in the Galapagos Islands. They have developed these beaks in order that they can access food more easily in their new environment. These changes in shape and form could aid in the creation of new organisms.
The majority of changes are caused by one mutation, but sometimes several occur simultaneously. Most of these changes can be harmful or neutral, but a small number can have a beneficial impact on survival and reproduction with increasing frequency as time passes. Natural selection is a mechanism that can produce the accumulating change over time that eventually leads to the creation of a new species.
Some people confuse evolution with the idea of soft inheritance that is the belief that traits inherited from parents can be altered by conscious choice or abuse. This is a misinterpretation of the biological processes that lead up to the process of evolution. A more accurate description of evolution is that it 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 mammal species which includes chimpanzees and gorillas. Our ancestral ancestors were walking on two legs, as demonstrated by the earliest fossils. Genetic and biological similarities suggest that we are closely related to chimpanzees. In reality our closest relatives are the chimpanzees from the Pan genus. This includes pygmy as well as bonobos. The last common ancestor between modern humans and chimpanzees dated 8 to 6 million years old.
Humans have developed a range of traits over time, including bipedalism, the use of fire and advanced tools. But it's only in the last 100,000 years or so that most of the essential traits that distinguish us from other species have emerged. They include language, a large brain, the ability to build and use complex tools, and the ability to adapt to cultural differences.
The process of evolution occurs when genetic changes allow members of a group to better adapt to the environment. Natural selection is the process that drives this change. Certain characteristics are more desirable than others. The ones with the best adaptations are more likely to pass on their genes to the next generation. This is how all species evolve and the foundation for the theory of evolution.
Scientists call this the "law of natural selection." The law states that species that have a common ancestor, tend to develop similar traits over time. This is because these traits allow them to live and reproduce in their environments.
All organisms have a DNA molecule that is the source of information that helps control their growth and development. The structure of DNA is composed of base pair that are arranged in a spiral around phosphate and sugar molecules. The sequence of bases within each strand determines phenotype, or the individual's characteristic appearance and behavior. Different mutations and reshuffling of the genetic material (known as alleles) during sexual reproduction cause variation in a group.
Fossils from the early 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 idea that modern humans' ancestors originated in Africa. The fossil evidence and genetic evidence suggest that early humans came out of Africa into Asia and then Europe.
