Lamarckism

Definition

Lamarckism is a theory of evolution proposed by Jean-Baptiste Lamarck, suggesting that organisms can pass on traits acquired during their lifetime to their offspring. This idea emphasizes the role of environmental influence and individual adaptation in evolution, proposing that species evolve through the inheritance of characteristics that are developed in response to their environment.

5 Must Know Facts For Your Next Test

1. Lamarckism was introduced in the early 19th century as an alternative explanation to evolution before Darwin's theory gained prominence.
2. One of the classic examples often cited in Lamarckism is the idea that giraffes developed longer necks because their ancestors stretched to reach higher leaves and passed this trait to their descendants.
3. Unlike Darwinian evolution, which focuses on genetic variations and natural selection, Lamarckism emphasizes the direct effects of the environment on individual organisms.
4. Lamarck's ideas were largely dismissed in favor of Darwin's theory due to lack of empirical evidence supporting the inheritance of acquired traits.
5. Despite its historical significance, Lamarckism has influenced some modern evolutionary biology discussions, particularly in epigenetics, where acquired characteristics may influence gene expression.

Review Questions

• How does Lamarckism differ from Darwinian evolution in terms of how traits are inherited?
  • Lamarckism proposes that traits acquired during an organism's lifetime can be passed on to offspring, emphasizing environmental influence and individual adaptation. In contrast, Darwinian evolution is based on natural selection, where genetic variations occur randomly, and those advantageous traits are inherited over generations. While Lamarckism focuses on individual changes responding to environmental challenges, Darwinian evolution highlights the gradual accumulation of inherited traits that enhance survival.
• Evaluate the impact of Lamarckism on the understanding of adaptations in various species.
  • Lamarckism has played a significant role in shaping early thoughts about how species adapt to their environments. By suggesting that organisms could directly modify their traits based on environmental pressures and pass those modifications down, it provided a framework for understanding adaptation as a dynamic interaction between organisms and their surroundings. However, as modern genetics and evolutionary biology have developed, this view has shifted toward recognizing that adaptations result from random genetic mutations that confer advantages over time rather than acquired characteristics.
• Critically assess the relevance of Lamarckism in contemporary discussions about evolution and adaptation, particularly in light of recent scientific discoveries.
  • While Lamarckism was largely dismissed with the rise of genetics and Darwin's natural selection theory, its relevance has been reexamined with advances in fields like epigenetics. Recent studies suggest that environmental factors can influence gene expression in ways that may be passed down to future generations, echoing some aspects of Lamarck's ideas. This has sparked debates on how much acquired characteristics might play a role in evolution, challenging the strict genetic determinism previously held. Thus, Lamarckism remains an intriguing topic for understanding the complexities of adaptation and evolution in light of new scientific evidence.

Related terms

Natural Selection: The process by which organisms better adapted to their environment tend to survive and produce more offspring, a key mechanism of evolution proposed by Charles Darwin.

Inheritance of Acquired Characteristics: The principle that traits acquired or modified during an organism's lifetime can be passed on to its offspring, central to Lamarck's theory of evolution.

Adaptation: A change or adjustment in structure or behavior of an organism that enhances its ability to survive and reproduce in a specific environment.