Extinction and Speciation

Extinction and Speciation Natural selection, Darwin argued, drives the interaction between rates of extinction and speciation.

Extinction, the complete loss of a species with no remaining members alive on Earth, is driven by natural selection. As Charles Darwin explains in The Origin of Species –

“We shall then see how Natural Selection almost inevitably causes much Extinction of the less improved forms of life, and leads to what I have called Divergence of Character.”

“Thus, extinction and natural selection go hand in hand,” Darwin argued. Extinction is a crucial driver of natural selection –

“The extinction of species and of whole groups of species, which has played so conspicuous a part in the history of the organic world, almost inevitably follows from the principle of natural selection

Balance

Darwin envisioned the rate of extinction to balance the emergence of “new forms,” arguing –

“The extinction of old forms is the almost inevitable consequence of the production of new forms [speciation].”

The “production of new,” Darwin argued, is connected with the forms now extinct –

“On the theory of natural selection, the extinction of old forms and the production of new and improved forms are intimately connected together.”

The new and old connecting forms Darwin called intermediate and transitional links. Connectedness, as demonstrated through “slight successive changes,” is a hallmark of Darwin’s theory of natural selection.

If Darwin’s theory is true, the evidence must demonstrate that “such [transitional links] have lived upon the Earth.”  Therefore, finding evidence of transitional links is his theory’s falsification test.

Extinction Versus Speciation Rates

The speciation rate must exceed the extinction rate to populate Earth’s vast biosphere; therefore, Darwin logically concluded –

“Therefore, the utter extinction of a group is generally, as we have seen, a slower process than its production [speciation].”

Darwin applied reasoning to determine these comparative rates, noting –

“There is reason to believe that the extinction of a whole group of species is generally a slower process than their production.”

While Darwin’s argument is necessary and logical since more than 99% of all species thought to inhabit Earth are now extinct, the evidence seems to contradict his “reason to believe.”

Scientific Validation

As a subcategory of Evolution and Science, evidence from origin of life research is essential for validating the theory of evolution scientifically.

Testing Extinction and Speciation Evidence

To understand how evidence from extinction and speciation challenges the theory of evolution, click to read the following –

Each article describes the evidence found and why it scientifically draws into question the validity of the theory of evolution, using the authors own words.

Darwin Then and Now is an educational resource on the intersection of evolution and science and the challenges facing the theory of evolution.

Refer to the Glossary for the definition of terms.

 

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