Summary of Lamarckism and Darwinism

Goals

1. Understand the theories of Lamarck and Darwin.

2. Differentiate between Darwinism and Lamarckism.

3. Grasp the concept of natural selection and the law of use and disuse.

Contextualization

Throughout history, several theories have emerged to explain how living beings evolve and adapt to their surroundings. Among these, the theories of Lamarck and Darwin stand out as particularly influential. Lamarck was one of the pioneers suggesting that characteristics developed during an organism's lifetime could be inherited by subsequent generations. In contrast, Darwin introduced the concept of natural selection, reshaping our understanding of evolution by demonstrating that individuals possessing beneficial traits for survival are more likely to reproduce. This understanding is vital not only for the study of biology but also for grasping how species transform over time, which is critical in fields like medicine, agriculture, and environmental conservation, where evolution and adaptation yield significant real-world implications.

Subject Relevance

To Remember!

Lamarck's Theory: Law of Use and Disuse

Lamarck's theory proposes that traits acquired or lost throughout an organism's life—due to the use or disuse of certain structures—can be inherited by their offspring. This means that if organisms modify their physical characteristics during their lifetime to adapt to their environments, these changes can be passed on to future generations.

• Lamarck suggested that shifts in the environment create new needs for organisms.

• These new needs can cause changes in the behaviour and structures of organisms.

• The traits gained or lost during an organism's lifetime are inherited by their descendants, driving the evolution of species.

Darwin's Theory: Natural Selection

Darwin's theory of natural selection explains that individuals in a population show variations in their characteristics. Those with traits that provide better chances of survival and reproduction in a particular environment are more likely to pass these traits to the next generation, leading to gradual evolution.

• Variations are naturally found within any population.

• Certain variations offer survival and reproductive advantages.

• Individuals with advantageous characteristics are more likely to survive and have offspring.

• Over time, these beneficial traits become prevalent in the population.

Differences and Similarities between Lamarckism and Darwinism

Despite both theories addressing evolution, they differ in explaining how changes occur and accumulate in populations. Lamarck emphasised the inheritance of acquired traits, while Darwin focussed on natural selection as the primary mechanism driving evolution.

• Lamarckism highlights the transfer of traits acquired during an organism's lifetime.

• Darwinism emphasises the natural selection of existing variations present in the population.

• Both theories affirm that species evolve over time, but they diverge concerning the mechanisms driving these changes.

• In contemporary biology, Lamarckism is largely dismissed, whereas Darwinism remains a foundational pillar of evolutionary theory.

Practical Applications

• In agriculture, artificial selection is employed to cultivate crops with beneficial traits, such as increased yield or pest resistance, which is rooted in Darwin's principles of natural selection.

• In medicine, a solid grasp of evolution and natural selection is key to devising new antibiotics and defenses against swiftly evolving diseases, such as antibiotic-resistant bacteria.

• Environmental conservation also leverages natural selection concepts to understand how species can adjust to climate change and other environmental challenges, which aids in formulating effective conservation strategies.

Key Terms

• Lamarckism: A theory proposing that traits developed during an organism's life can be inherited by their descendants.

• Darwinism: A theory that identifies natural selection as the key mechanism of species evolution.

• Natural Selection: The process whereby individuals with advantageous traits are more likely to survive and reproduce.

• Law of Use and Disuse: Proposed by Lamarck, denoting that frequently used structures flourish, while those that are not used diminish.

Questions for Reflections

• How do the theories of Lamarck and Darwin shape our current understanding of evolution and species adaptation?

• In what ways can we observe natural selection in modern agriculture?

• Why is it important to understand evolution for the formulation of new drugs and treatments in healthcare?

Natural Selection Simulation

This mini-challenge allows participants to simulate natural selection, observing how various characteristics can influence survival under specific conditions.

Instructions

• Collect three types of coloured rice grains (white, brown, and black) and scatter them across a surface that has areas matching the colours of the grains.

• Use tweezers to represent predators and attempt to 'hunt' the grains for 2 minutes.

• After the 'hunt,' tally how many grains of each colour were 'caught' and how many are left.

• Discuss which coloured grains were easier or difficult to 'catch,' relating this to the principle of natural selection.

• Document your observations and reflect on how these traits might enhance survival probabilities in particular environments.