Darwinism vs Neo-Darwinism

 

Darwinism vs Neo-Darwinism

Introduction

Evolution is the process by which species change over time due to variations in inherited traits. Charles Darwin's theory of natural selection laid the foundation for modern evolutionary studies. However, with advancements in genetics, Neo-Darwinism emerged, incorporating new scientific findings into Darwin’s original ideas.

Darwinism (Theory of Natural Selection)

Introduction

Darwinism refers to Charles Darwin's theory of evolution by natural selection, published in On the Origin of Species (1859). It proposes that organisms best adapted to their environment survive and reproduce passing beneficial traits to the next generation.

Key Principles of Darwinism

1. Variation – Individuals within a species show differences in traits.
2. Overproduction – More offspring are produced than can survive.
3. Struggle for Existence – Due to limited resources, individuals compete for survival.
4. Survival of the Fittest – Organisms with advantageous traits survive and reproduce.
5. Descent with Modification – Over generations, beneficial traits become more common.

Limitations of Darwinism

1. Did not explain the origin of variations – Darwin was unaware of genetics.
2. Lacked a mechanism for inheritance – He did not know how traits were passed from parents to offspring.

Neo-Darwinism (Modern Synthetic Theory of Evolution)

Introduction

Neo-Darwinism is the modern version of Darwin’s theory, incorporating findings from genetics, molecular biology, and population genetics. It emerged in the early 20th century with contributions from scientists like Hugo de Vries, Ronald Fisher, J.B.S. Haldane, and Theodosius Dobzhansky.

Key Features of Neo-Darwinism

1. Role of Mutations: Variations arise due to genetic mutations, not just environmental changes.
2. Mendelian Genetics: Genes, discovered by Gregor Mendel, determine traits and are inherited.
3. Recombination & Genetic Drift: Recombination during reproduction creates new genetic variations.Genetic drift can change allele frequencies in small populations.
4. Natural Selection Acts on Genes: Favorable genetic traits increase survival and reproduction.
5. Gene Flow & Migration: Movement of genes between populations affects evolution.
6. Gradual and Continuous Evolution: Evolution occurs slowly and cumulatively over generations.

Differences Between Darwinism and Neo-Darwinism

Feature	Darwinism	Neo-Darwinism
Basis	Natural selection	Natural selection + genetics
Source of Variations	Environmental influences	Genetic mutations & recombination
Mode of Inheritance	Unclear	Mendelian genetics
Mechanisms of Evolution	Survival of the fittest	Natural selection, mutation, genetic drift, gene flow
Modern Understanding	Lacks genetic basis	Explains evolution using DNA and population genetics

 

Darwinism laid the foundation for evolutionary biology but lacked a genetic explanation. Neo-Darwinism integrates modern genetics, explaining how variations originate and are inherited. Together, they form the Modern Synthesis of evolution, shaping our understanding of natural selection and adaptation.

 

References

1. Darwin, C. (1859). On the Origin of Species. John Murray.
2. Dobzhansky, T. (1937). Genetics and the Origin of Species. Columbia University Press.
3. Fisher, R. A. (1930). The Genetical Theory of Natural Selection. Clarendon Press.