Lamarckian Inheritance and Epigenetics Evolution | 19 Jun 2025

Source: TH 

The recent discovery of heritable cold tolerance in rice plants through epigenetic changes marks a historic validation of Jean-Baptiste Lamarck’s theory that environmental influences can affect heredity — a concept once dismissed but now supported by modern science. 

• Epigenetics refers to heritable changes in gene expression caused by external factors that switch genes on or off without altering the DNA sequence. 
• Lamarck’s Theory (1809): It proposed that traits acquired during an organism’s lifetime through use, disuse, or environment could be inherited. 
  • It was dominant until Darwin’s natural selection (1859) and Mendel’s laws of inheritance disproved it. 
  • A study showed that exposing rice plants to cold triggered epigenetic changes in the gene, which conferred cold tolerance and was heritable for five generations. 
• Scientific Challenges to Lamarck: 
  • Darwin’s Natural Selection (1859): It argued genetic variations (not acquired traits) drive evolution via "survival of the fittest." 
  • Weismann’s Experiment (1890s): Tailless mice produced normal-tailed offspring, disproving inheritance of acquired traits. 
  • Gregor-Johann Mendel: It showed genes (DNA) are the stable units of heredity, not environmental adaptations. 
• Epigenetics Emerges: 
  • Royal Brink’s Maize Study (1956): It revealed that gene expression, not just DNA sequence, could be heritable, demonstrating non-DNA-based inheritance. 
  • Arthur Riggs’ Hypothesis (1975): It proposed epigenetic marks (chemical tags on DNA) could pass traits across generations without changing their DNA sequence. It is easier to change epigenetic marks than to mutate DNA.