Saying that evolution
…is an attempt to convince the audience that evolution is only a guess that's open to debate. This is definitely not the case. The word “theory” means something special to scientists.
In everyday usage, “theory” often refers to a hunch or a speculation. When people say, “I have a theory about why that happened,” they are often drawing a conclusion based on partial or inconclusive evidence. Scientists have hunches, too, but they call them hypotheses, which are the starting point of all good science.
A scientific definition of theory is quite different from the everyday meaning of the word. A scientific theory refers to a comprehensive explanation of some aspect of nature that unifies a vast body of reliable knowledge. In other words, a theory is born when a substantial number of hypotheses point to the same conclusion.
A simple example of a scientific theory is the Heliocentric Theory which states that the sun is the center of our solar system. Another example would be Cell Theory which states that all living things are composed of cells. Few people would refer to either of these theories as “hunches.” More likely, in everyday language, these theories would be called scientific facts.
In science, a Theory:
What are some notable scientific theories?
Reliance on theory is critical to every branch of science. Many scientific theories are so well established that no new evidence is likely to alter them substantially. We all accept that…
Each theory has been barraged with scientific tests and still stands intact.
This is true of the Theory of Evolution, too, which is why scientists do not find it controversial. Any perceived controversy comes from people who do not understand the scientific process.
By contrast, all of the following scientific theories were developed more recently than the Theory of Evolution. None are considered controversial.
Atomic Theory. Atomic theory states that all matter is composed of units called atoms. Atoms are discrete and cannot be divided further without destroying the substance. For instance, an oxygen atom divided is no longer oxygen.
Germ Theory of Disease. This theory states that most diseases are caused by germs, which are microscopic organisms that infect other living things. Modern medicine would be lost without this crucial understanding of many diseases.
Plate Tectonics. This theory describes how the Earth's outermost surface, called the crust, changes over time. It states that the continents rest on plates that form the Earth’s crust. These plates shift and change over time. Much like a conveyor belt, new crust is constantly being formed—at a snail’s pace!—at deepsea ridges; and old crust is being drawn under the edges of other plates at equally-slow rates.
Theory of Relativity. Einstein's theories of general and special relativity revolutionized how physicists understand the world. These theories describe how spacetime and gravity interact and how objects behave at speeds near the speed of light.
Contrary to common understanding, scientific theories do not “graduate” to laws…
Scientific laws are typically short, mathematical expressions representing how nature will behave under certain conditions. Most theories contain laws, and more importantly, they explain why laws work and what they mean.
Here Are Some examples of scientific laws
Evolution is the change in genetic characteristics of a group of organisms over time. No more, no less. Because evolution is something we see, it is a fact that evolution has occurred. Drawing upon…
we see that life changes through time. Scientists’ job is to explain what causes those changes to happen.
An example of evolution observed on the grandest scale is the gradual changes we see in fossil organisms in layers of rock. A more notorious example would be the way bacteria become resistant to antibiotics, requiring the development of new antibiotics. For more details about these and other examples, click here.
“Evolution” is not the same as “the theory of evolution.” “Evolution” is the observation. “The Theory of Evolution” is an explanation for what we observe.
The Theory of Evolution is the scientific explanation for how evolution occurred, past and present. Since Darwin’s ground-breaking work was published in 1859 (that's 150 years ago!), biologists have amassed a tremendous body of reliable knowledge supporting the Theory of Evolution. In fact, the Theory of Evolution is so central to modern biology that the great biologist Theodosius Dobzhansky said “nothing in biology makes sense except in the light of evolution.”
The Theory of Evolution by Natural Selection
Although there is only one Theory of Evolution, there are many proposed mechanisms for how it works – mutation, gene flow, genetic drift, and sexual selection. In fact, evolution occurs via all of these mechanisms. The questions evolutionary biologists deal with center around the relative contributions each mechanism makes under various circumstances.
Of these, the most well-known is Darwin’s Theory of Evolution by Natural Selection, also known as “descent with modification.”
The Theory of Evolution by Natural Selection is fairly straightforward.