A Hike in the Jungle
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Current Step: Natural Selection
   
 

Now let's consider Darwin's second hypothesis:

Theory of Evolution

Current Scientific Status

Darwin Hypothesis2
The processes of natural selection accounts for why new characteristics appear and why some old characteristics disappear.

Somewhat controversial in the scientific community—but by far the majority view today.

There are questions about why living beings evolved in the way they did.

The process of natural selection comes in two stages:

  1. A mutation occurs that creates a novel variation.

  2. Natural selection occurs in a population of organisms when there is an inherited variation in fitness.

Without the introduction of a novel characteristic into a population, natural selection cannot operate.  

Darwin could not adequately explain how novel traits arise. But based on Gregor Mendel’s work, we now understand that genetic mutations are a primary source of variation in populations of species.

Ok. So how does a change within a species help explain the development or emergence of a new species?