Theory of Evolution Through Natural Selection

The Theory of Evolution Through Natural Selection is an explanatory model that provides explanation and guidance for how the living world is arranged and (nominally) why. It is not a 'belief' as such. It is an explanatory model for which we have much empirical evidence. Most of us have seen the evidence with our own eyes during our lived experience. I find it to be a simple logical construction, but it seems many if not most people find it somehow hard to understand. It is, in essence, a tautology, something which cannot be untrue -- that which survives survives. 

Darwin's theory of evolution through natural selection can be summarized in a simple 5-step process:

1. Variation: Within a population, individuals have different traits and characteristics(Ref 1)(Ref 2).
2. Inheritance: Many of these traits are heritable, meaning they can be passed down from parents to offspring(Ref 1)(Ref 2).
3. Selection: Due to limited resources, not all individuals can survive and reproduce. Those with traits better suited to their environment have a higher chance of survival and reproduction(Ref 1)(Ref 3).
4. Time: Over generations, the advantageous traits become more common in the population(Ref 3).
5. Adaptation: The population becomes better adapted to its environment as beneficial traits accumulate(Ref 3).

This process can be remembered using the acronym VISTA: Variation, Inheritance, Selection, Time, and Adaptation(Ref 3).Key points to understand about natural selection:

• It's a simple mechanism that causes populations to change over time(Ref 3).
• It requires no conscious direction or intervention(Ref 4).
• It acts on existing variation within a population(Ref 1)(Ref 2).
• Beneficial traits are those that increase an organism's chances of survival and reproduction(Ref 1)(Ref 5).
• The environment plays a crucial role in determining which traits are advantageous(Ref 1)(Ref 4).

Darwin drew inspiration for this theory from artificial selection practiced by farmers and breeders(Ref 2)(Ref 4). He realized that nature could act as a selective force in a similar way, but without human intervention(Ref 4).It's important to note that Darwin developed this theory without knowledge of genetics or the mechanisms of inheritance(Ref 1). Later discoveries in genetics provided additional evidence and explanations for how traits are passed down and how new variations arise through mutations(Ref 1)(Ref 4).

References

Ref 1: https://www.livescience.com/474-controversy-evolution-works.html

Ref 2: https://en.wikipedia.org/wiki/Ecological_selection

Ref 3: https://www.amnh.org/exhibitions/darwin/evolution-today/natural-selection-vista

Ref 4: https://education.nationalgeographic.org/resource/natural-selection/

Ref 5: https://evolution.berkeley.edu/evolution-101/mechanisms-the-processes-of-evolution/natural-selection/