Natural Selection vs. Evolution

A crucial distinction to grasp is that evolution and natural selection are not synonymous, a nuance that is frequently misunderstood.

Charles Darwin demonstrated that, absent other influences, natural selection is a driving force behind the evolution of living organisms. Humans, too, are a product of this process. Meanwhile, Gregor Mendel’s research revealed that genetic inheritance is not merely a blending of traits; rather, traits often manifest in distinct forms, as seen in eye color—either blue or brown, not a mix.

Later, Watson and Crick identified DNA as the medium of genetic information. Genes, composed of segments of DNA, encode for specific proteins and other functions. Richard Dawkins emphasized that we should concentrate on gene evolution rather than organism evolution, as genes can persist for millions of years, with some tracing back hundreds of millions of years.

However, natural selection is not the sole mechanism driving DNA-based evolution. Other forces, such as genetic drift—which can be more influential than selection when traits have no survival advantage—play roles too. For instance, while all domestic dogs descended from wolves, their evolution was significantly shaped by human intervention rather than natural selection. Humans selectively bred wolves to create dogs, which raises questions about the scope of “natural selection” when human actions are involved.

Dawkins also introduced the concept of “memes,” akin to genes, to explore how ideas evolve. Memes replicate and spread through human minds similarly to how viruses do. This concept transcends the realm of digital memes, delving into cultural evolution driven by the transmission of ideas.

Consider the classic game of “telephone,” where a simple statement transforms as it passes from person to person—akin to mutations in evolution. By the time the statement reaches the last person, it often bears little resemblance to its original form, exemplifying evolutionary processes. Digital memes also evolve in this way, with their spread across social media reflecting a form of cultural evolution.

While some might argue that internet memes undergo a sort of natural selection, their dependence on modern technology makes this claim more complex. Therefore, it seems prudent to view memetic evolution as distinct from traditional natural selection.

Defining an Evolutionary Process

Having established that evolutionary processes can manifest in various ways, let’s define what constitutes such a process.

The fundamental elements of an evolutionary process can be summarized as: - Variation - Selection - Inheritance

Variation refers to differences among individuals that selection can act upon. In DNA-based evolution, variations arise from genetic mutations and recombination, primarily through sexual reproduction. While mutations occur randomly and can lead to beneficial traits, sexual reproduction typically recombines existing traits.

Selection involves processes that favor certain variations. When a mutation confers a survival advantage, individuals with that trait are more likely to survive and reproduce, passing on the advantageous trait to subsequent generations.

Inheritance ensures that selected traits persist across generations. In DNA-based evolution, this occurs through the transmission of genetic material during reproduction.

The concept of the individual is crucial here. In DNA-based evolution, individuals are easily identifiable as organisms, but in other contexts, this can be more abstract.

Tinbergen’s Four Questions

Niko Tinbergen, a pioneering biologist and Nobel Laureate, developed four key questions to guide the study of evolutionary products. David Sloan Wilson has adapted these questions in his work, notably in This View of Life. These questions serve as vital tools in evolutionary analysis.

Tinbergen’s four questions can be summarized as follows: - Function - Mechanism - History - Development

Let’s apply these questions to the example of the human hand.

Function: What role does it serve? The human hand’s primary function is to grasp and manipulate objects.

Mechanism: What is its physical structure? This involves the anatomy and physiology of the hand, including the arrangement of bones, tendons, and muscles.

History: What is its evolutionary background? The human hand has evolved over millions of years from our ancient ancestors, reflecting the evolutionary history of vertebrates.

Development: How does it grow during an individual’s life? Hand development begins in the embryo and continues throughout childhood, with skills improving through practice.

Evolution in Action

Now, let’s examine several concrete examples of evolution in practice, drawing from both This View of Life and the mathematics text Evolutionary Dynamics.