Lamarckism

Definition

Lamarckism is a theory of evolution proposed by Jean-Baptiste Lamarck that suggests organisms can pass on traits acquired during their lifetime to their offspring. This idea challenges the concept of fixed species, proposing that species change over time through the accumulation of these acquired characteristics. While this theory has been largely overshadowed by natural selection, it played a crucial role in early discussions about evolution and species change.

5 Must Know Facts For Your Next Test

1. Lamarck proposed that organisms could adapt to their environments through the use or disuse of certain body parts, leading to changes that could be inherited.
2. His most famous example involves the giraffe, suggesting that they developed longer necks as they stretched to reach higher leaves, and this trait was passed down.
3. Although Lamarck's ideas were influential in the early 19th century, they were eventually challenged and largely replaced by Darwin's theory of natural selection.
4. Lamarckism emphasizes the role of the environment in shaping organisms, suggesting a more active role for organisms in their own evolution compared to natural selection.
5. While Lamarckism is not widely accepted today, some aspects have found relevance in epigenetics, where changes in gene expression can occur due to environmental factors and potentially be passed on.

Review Questions

• How does Lamarckism differ from the modern understanding of evolution through natural selection?
  • Lamarckism differs from natural selection primarily in its mechanism of evolution. While Lamarck proposed that acquired traits during an organism's lifetime could be inherited by offspring, natural selection suggests that genetic variations already present in populations determine which individuals are more likely to survive and reproduce. In essence, Lamarckism focuses on direct adaptations influenced by an organism's experiences, whereas natural selection relies on pre-existing genetic diversity within populations.
• Evaluate the significance of Lamarck's theories on the development of evolutionary biology and their influence on later theories.
  • Lamarck's theories were significant in shaping early thoughts about evolution by introducing the idea that species could change over time. His focus on the role of environmental factors and adaptation highlighted important concepts that would later be refined by Darwin. Although his specific mechanisms were incorrect, Lamarck's work prompted further investigation into how species evolve and adapt, paving the way for modern evolutionary biology and discussions about inheritance and variation.
• Critically assess how contemporary science has revisited aspects of Lamarckism through studies in epigenetics and inheritance.
  • Contemporary science has seen a resurgence of interest in concepts reminiscent of Lamarckism through epigenetics, where environmental factors can influence gene expression without altering the underlying DNA sequence. This research indicates that some acquired traits might indeed be passed on to future generations, albeit through complex mechanisms not envisioned by Lamarck. This evolving understanding challenges traditional views of inheritance and suggests a more dynamic interaction between organisms and their environments, reflecting an intriguing blend of old ideas with new scientific findings.

Related terms

Acquired Characteristics: Traits that an organism develops during its lifetime due to environmental influences or use, which Lamarck believed could be inherited by future generations.

Natural Selection:

A mechanism of evolution proposed by Charles Darwin, where individuals with advantageous traits are more likely to survive and reproduce, leading to changes in species over time.

Evolution: The change in the heritable characteristics of biological populations over successive generations, encompassing various mechanisms including natural selection and genetic drift.