17 July 2013

Misconceptions about evolution video has its own misconceptions

When you teach science, and biology, and evolution, you run into a lot of misconceptions. I can use all the help I can get. I should be grateful for “Myths and misconceptions about evolution” on the TED-Ed website.

It’s well-made and good-looking. Unfortunately, in setting a few of those perceptions right, it inadvertently fall into showing other misconceptions.

This is the serious one:

It’s the march of progress. The problem with this image is that it shows evolution as progressive and linear, while the scientific understanding of evolution is that it is undirected and branching. That so much of evolution occurs by branching is so important.

This video is hardly alone in using this. You see this left to right marching image all the time. Normally, I’d let it go, except that this video is supposed to address common misconceptions, not recycle them!

It’s weird, because the video explictly talks about “evolutionary purpose” as a metaphor. But the march of progress image is repeated twice, with it being one of the closing statements. Now, it is immediately followed by this image, which tries to show diversity of life:

But there’s no indication of the connection between organisms.

Compare what that march of progress image implies to this one (click to enlarge):

Branches and branches leading to diversity, with no preferred “direction,” and humans so hard to find as one of many species that they have to be marked with “You are here.”

This is the more trivial misconception. It introduces French biologist, Jean-Baptiste Lamarck:

Followed immediately by... giraffes!

Lamarck’s giraffes are a bad cliché. First, the idea of inheriting acquired characteristics was not abandoned with the publication of Darwin’s On the Origin of the Species. Darwin himself thought this happened and was a real mechanism of evolution. This is often forgotten, perhaps because he called it “use and disuse”, and thought that it only played a minor role in shaping species.

Second, it gives the impression that Lamarck put serious thought into his giraffe example, and that it appears in a lot of his work. Stephen Jay Gould, a formidable historian of science, checked Lamarck’s original texts (Gould 1996):

Lamarck did mention giraffes’ necks as a putative illustration of evolutionary enlargement by the inherited effects of lifetime effort. But his entire discussion runs for one paragraph in a chapter filled with much longer examples that he obviously regarded as far more important. Lamarck had this—and absolutely nothing more—to say about giraffes’ necks, a few lines of speculation never intended as the centerpiece of a theory:

It is interesting to observe the result of habit in the peculiar shape and size of the giraffe: this animal, the tallest of the mammals, is known to live in the interior of Africa in places where the soil is nearly always arid and barren, so that it is obliged to browse on the leaves of trees and to make constant efforts to reach them. From this habit, long maintained in all the individuals of the race, it has resulted that the animal’s forelegs have become longer than its hind legs and that its neck is lengthened to such a degree that the giraffe, without standing up on its hind legs, can raise its head to a height of six meters. (From Lamarck’s classic 1809 work, Philosophie zoologique, vol. 1, p. 122, my translation.)

That’s it. A person writes one paragraph about giraffes once, and that’s the only thing that he’s remembered for. It’s sad, because Lamarck made many substantial contributions to biology, like coining the word “invertebrate” and drawing the first phylogenetic tree.

Additional: See this article (PDF), “The Tree, the Spiral and the Web of Life: A Visual Exploration of Biological Evolution for Public Murals” by Joana Ricou and John Archie Pollock on how to represent the relationship of living organisms. Hat tip to Carl Zimmer.


Gould SJ. 1996. The Tallest Tale. Natural History 105: 18-23+. PDF

External links

Myths and misconceptions about evolution - Alex Gendler
Myths and misconceptions about evolution: A TED-Ed lesson about the subtleties
The march of progress has deep roots
Tree of life


Jeff Alexander said...

There is a good reminder around 2:11 that evolution produces survivable species, not survivable individuals, and that that can mean altruism and self-sacrifice get reinforced. In a Plate of Shrimp effect, I encountered this topic just last week on a Radiolab repeat. http://www.radiolab.org/2010/dec/14/equation-good/

John S. Wilkins said...

While I agree Lamarck is often misrepresented and dismissed unfairly, he did not draw the first phylogenetic tree. What he drew was a branching chain of being, along which independent lineages could evolve. The first phylogenetic tree is arguably that of Augustin Angier in 1801, and the notion of common descent was first proposed by Peter Simon Pallas in 1775.