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Long before Charles Darwin came up with his theory of natural selection,(and in doing so providing the English language with numerous adjectives for his name), Frenchman and naturalist Jean Baptiste Lamarck (1744 – 1829) (Figure 1) attached his own name to the concept of the inheritance of acquired characteristics. ‘Lamarckian’ refers to this doctrine which is also known as “soft hereditary”, but it was merely an incidental feature of Lamarck’s philosophy on nature.

Figure 1. Portrait of Lamarck at the age of 80(Packard 1901).

Viewed as the father of invertebrate palaeontology, Lamarck revived the ideas of the early 18th century French naturalist George Louis Buffon regarding the earth’s antiquity. From his observations of changing fossil forms in successive rock layers, Lamarck put forward the notion of the evolution of life as a consequence of changing environmental factors and its influence on the physical characteristics and adaptations acquired by organisms that are eventually inherited by succeeding generations over time.

From the time of Hippocrates, naturalists assumed that characteristics acquired by parents could influence the fundamental nature of offspring. Yet, unlike his peers, Lamarck actually applied the notion of “acquired characteristics” or “soft hereditary” to his thoughts on evolutionary change. In a seminal monograph called the Philosophie Zoologique, published in 1809, he offered a grand vision of how the world had developed. He argued that animals possess a quality that he called “besoin” which can be variously translated as “need” or “want”.

His most famous example demonstrating this theory was that of the giraffe’s long neck, gradually created by this species’ need to browse on the leaves of tall trees – this being the result of multiple generations producing the characteristic form of the giraffe in order to fill a specific ecological niche (Figure 2):

 “As regards habits, it is curious to observe the results in the special form and height of the giraffe (camelopardalis); we know that this animal, the tallest of mammals, inhabits the interior of Africa, and that it lives in localities where the earth, almost always arid and destitute of herbage, obliges it to browse on the foliage of trees, and to make  continual efforts to reach it. It has resulted from this habit, maintained for a long period in all the individuals of its race, that its forelegs have become longer than the hinder ones, and that its neck is so elongated that the giraffe, without standing on its hind legs, raises its head and reaches six meters in height (almost twenty feet)” (in Philosophie Zoologique, translated by Packard 1901).

Figure 2. Giraffes roaming the Serengeti Plain at Olduvai, Tanzania (photo: Lloyd Rossouw)

Lamarck’s notion of biological change over time challenged naturalists until Charles Darwin offered another version with his revolutionary thesis,On the Origin of Species by means of Natural Selection, more than 40 years later. Although Darwin’s concept of natural selection offered a more compelling mechanism for evolutionary change that provides for a range of physical characteristics within any individual species to allow some variants to breed more successfully than others, even he drew on notions of “acquired characteristics” and therefore, was Lamarckian in that sense.

References

McCarthy, T. and Rubidge, B.S. 2005. The story of Earth and Life. A southern African perspective on a 4.6 billion-year-journey. Struik Publishers. Cape Town.

Packard, A.S. 1901. Lamarck. The founder of evolution. His life and work, with translations of his writings on organic evolution. Longmans, Green and Co. New York.

Lloyd Rossouw
Author

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