dinosaur fossil on rough stone formation
Changes in species1

In this article, we will try to summarize in a few lines what the postulates of the theories of Darwin and Lamarck are, in order to later, as an activity, see their similarities and differences.

Introduction

Let’s start with a little biographical history. Who are we talking about when we mention Darwin and Lamarck?

Darwin (1809 – 1882) was an English naturalist who started a trip around the world aboard the HMS Beagle when he was only 22 years old, which would give him the necessary basis to devise his evolutionary theory, the most influential that has ever existed, even to this day.

Lamarck (1744 – 1829), on the other hand, was a French naturalist who also contributed his own evolutionary idea; however, it turned out to be erroneous. But this does not take away the credit he deserves, since he introduced the idea that living beings evolve, something very contrary to the thoughts of his time.

The fundamental aspects of Lamarck’s and Darwin’s theories

Lamarck, in his evolutionary theory called transformism, postulated that species change over time, that species change is gradual and goes from simple to more complex forms, as there is a tendency towards perfection. These changes occur through various mechanisms. That is why Lamarckism proposes the existence of a vital impulse (a natural tendency that leads organisms towards perfection and complexity).

From generation to generation, there is an inheritance of acquired characteristics. And how can we explain it? Populations are, according to this theory, uniform; that is, if organisms are subjected to the same environmental conditions for long periods, small changes occur in body structures that become hereditary and can be passed on to offspring.

In other words, changing environmental conditions would generate the need for new habits. Finally, there is usually a greater or lesser use of certain organs, which leads to their development or atrophy (that is, they deteriorate or disappear over time).

Lamarck.
Jean-Baptiste Lamarck (1744 – 1829)

Darwin, on the other hand, proposed the existence of a common ancestor for all species and that they could become extinct.

He formulated the theory of natural selection, which is based on the idea that individuals of all species exhibit heritable variations (meaning that they exhibit variations that can be passed down from generation to generation and that these differences, although small, can mean an adaptive advantage), that species change (making those organisms that exhibit more “advantageous” characteristics in a given environment better suited to survive and leave a greater number of offspring, a factor called differential reproduction).

In other words, there is a natural selection of better adapted organisms, and there is a struggle for survival (all species tend to produce more offspring than necessary for their preservation, and thus, the offspring will have to compete for resources).

Darwin.
Charles Darwin (1809 – 1882).

Differences and similarities between Lamarck and Darwin.

Let’s take a look at the following table where some fundamental questions are answered about each naturalist:

QuestionLamarckDarwin
Do species evolve?Yes, through linear evolution.Yes, organisms share a common ancestor.
Do species go extinct?NoYes.
What was the driving force of evolution?The driving force of evolution was a natural tendency towards perfection of species.The driving force of evolution was natural selection.
Are changes gradual and continuous?Yes.Yes.
Is there variability within populations?No.Yes, there is variability within populations on which natural selection acts.
Is there inheritance of acquired characteristics?Yes.Yes.
Does the environment induce changes?Yes, the environment induced changes in the organism.No, the environment does not induce changes but only selects individuals carrying the most favorable traits.
Do they believe in the use and disuse of organs as a possible source of variability?YesYes

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Teaching resources

here are some sources where you can find simulations or apps about Darwin and Lamarck’s theories:

  1. “Evolution: The Game of Intelligent Life” – This is a simulation game that allows players to experience evolution and natural selection. It is available for purchase on Steam: https://store.steampowered.com/app/375810/Evolution_The_Game_of_Intelligent_Life/
  2. “Darwin’s finches” – This is an interactive app that allows users to explore the evolution of Darwin’s finches on the Galapagos Islands. It is available for free on the HHMI Biointeractive website: https://www.hhmi.org/biointeractive/darwins-finches
  3. “The Evolution Lab” – This is an online interactive activity that explores evolution and natural selection. It is available for free on the PBS website: https://www.pbs.org/wgbh/nova/labs/lab/evolution/
  4. “Lamarck’s Giraffe” – This is an interactive app that allows users to explore the concept of Lamarckian evolution through the example of the giraffe’s neck. It is available for free on the University of Utah Genetic Science Learning Center website: https://learn.genetics.utah.edu/content/variation/lamarck/

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