Charles Darwin, an English scientist, introduced the theory of evolution through natural selection in his groundbreaking book, “On the Origin of Species,” published in 1859. This sparked heated debates among scientists of the 19th century. However, overwhelming evidence from various scientific disciplines established evolution as an undeniable truth by the 20th century. Surprisingly, more than 150 years later, some people still refer to evolution as “just a theory,” implying it’s unproven.
But is evolution really just a theory? And do theories only become facts when proven?
Scientific Hypotheses
A hypothesis is a proposed explanation for an unexplained phenomenon that doesn’t fit into the current accepted scientific framework. For a hypothesis to be scientific, it must be testable and falsifiable. Importantly, scientists test hypotheses without a predetermined outcome.
Here are some examples of scientific hypotheses:
- Moisture levels in the air may affect bacterial growth.
- 80% of the U.S. population gets a divorce because of irreconcilable differences.
- Women taking vitamin E grow hair faster than those taking vitamin K.
- The Moon formed from the debris of a collision between the proto-Earth and a Mars-sized planetesimal around 4.5 billion years ago.
Scientific Theories and Facts
The term theory entered the English language in the late 16th century, originally meaning conception, mental scheme, or speculation. However, in the 17th century, its use in arts and sciences took on a different meaning.
Contrary to popular belief, in science, a theory is not just an educated guess. A scientific theory is a well-substantiated explanation of some aspect of the natural world, based on a body of evidence and consistent with scientific methods. It not only addresses existing scientific data but also makes predictions that can be tested and confirmed through experiments or observation.
Examples of scientific theories include:
- Cell Theory
- Theory of Gravity
- General Relativity
Examples of scientific facts include:
- The Eiffel Tower can be 15 cm taller during the summer.
- Polar bears are nearly undetectable by infrared cameras.
- The Earth is a giant magnet.
The key difference between theories and facts is that theories can evolve as our understanding improves, but facts remain constant.
Scientific Laws
A scientific law describes what always happens under specific conditions and can often be expressed mathematically.
Examples include:
- Newton’s Laws of Motion
- Archimedes’ Principle
- Laws of Thermodynamics
It’s important to note that scientific theories do not become laws; they serve different purposes in science.
Why Evolution Is Not Just a Theory
Evolution refers to the change in the heritable traits of biological populations over successive generations.
We know evolution is a fact due to extensive evidence from paleontology, genetics, zoology, and molecular biology. The theory of evolution explains the mechanisms of how evolution works. Like other scientific theories, it is a dynamic framework that evolves with our growing scientific knowledge.
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