Devoted to Charles Darwin, Ernst Haeckel was not above fabricating data to make his hero look better.
150 years ago, Phys.org reports, the German biologist Ernst Haeckel invented the word phylogeny and drew up Darwin’s ideas into a branching picture that replaced the Biblical tree of life (an actual, tangible tree as described in Genesis and Revelation) with an evolutionary metaphor. Darwin had sketched a branching diagram to show how speciation might occur, but it was Haeckel who drew all of the world’s organisms arising from a single trunk. Two German science historians from Jena, Haeckel’s hometown, tell how this happened.
Drawing on Darwin’s theory of evolution, Haeckel created the first Darwinian phylogenetic ‘tree of life’ of organisms exactly 150 years ago in Jena, and published it in his major work, the ‘General morphology of organisms’. In the current issue of the journal Nature, the historians of science and science education, Prof. Uwe Hoßfeld und Dr. habil. Georgy S. Levit of Friedrich Schiller University Jena in Germany, commemorate this anniversary.
“The idea of visually representing species and their development was already known at the time,” says Levit. “However, earlier ideas never took into account the principle of monophyly and natural selection in speciation.” This connection first emerged through the evolutionary theories of Charles Darwin. The British naturalist sketched in his diary an idea for a tree of life in 1837 and presented it in the form of a diagram in his ground-breaking work ‘On the origin of species’ in 1859. Haeckel took up Darwin’s theory of evolution in his 1866 book, ‘General morphology of organisms’, and drew the first phylogenetic ‘family tree of organisms’, or tree of life. “Phylogeny is the evolutionary history of organisms,” explains Hoßfeld. “Because Haeckel was the first actually to define this term, in that same work, he was also the only person capable of representing the first tree of life of this kind.” To be more precise, Haeckel designed the monophyletic tree of life, because it shows all three kingdoms – animals, plants and Protista (organisms that cannot be classified as a plant, animal or fungus) – arising from a common root (‘Moneren Radix’).
This metaphor has clouded observation for 150 years. Today, more biologists are describing a “web of life” or “network of life” (for instance, see Evolution News & Views about the data from hybridization that confuse the tree image). In addition, the data from paleontology (e.g., the Cambrian Explosion), show patterns of independent emergence and stasis, not a branching tree. But because of Haeckel’s propaganda that employed visualization in place of hard evidence, biologists ever since have been frustrated trying to force-fit the facts of nature into this mythical metaphor.
So do the German historians point this out? No. They have nothing but praise for Haeckel, who is also notorious for fudging his data in his famous drawings of “Haeckel’s embryos” that falsely depicted organisms replaying their evolutionary history during development. Old ideas die hard; Stephen Jay Gould lambasted Haeckel’s “recapitulation theory” (7/26/10, 3/08/05) but his embryo drawings still turn up in biology textbooks and science papers. The “tree of life” remains ubiquitous.
No better method has been devised to date for illustrating biodiversity. New techniques and methodologies may have come into use, and trees of life are now presented as cladograms, diagrams, etc., but the principle remains the same. “It is quite simply the best and clearest way of representing the results of biological research in this area,” notes Hoßfeld.
The journal Nature celebrated Haeckel’s tree of life, pleasing Hoßfeld no end.
For us it is always a success when our scientific fields attract the attention they deserve,” says Hoßfeld, who has seen six of his articles published in Nature. “It shows us that there continues to be great interest in the history of science and science education, and that they are repeatedly able to make a contribution to current debate,” adds Levit, who has had three publications in the British journal. For Friedrich Schiller University itself, such publications are evidence that Jena’s long academic tradition is consistently able to produce up-to-the-minute research.
Is it a “contribution” to current debate to cloud evidence with pictures? Like Phys.org, Nature mentions nothing about fraud. “As thousands of scientists and policymakers gather in Mexico this month for the COP13 summit on biodiversity … we should take a moment to celebrate the earliest ‘tree of life’ model of biodiversity.”
It doesn’t seem to matter to these evolutionists that the branches have been repeatedly cut down and grafted in all kinds of contradictory ways (see example on Phys.org about where to put placoderms, titled “Our ideas about vertebrate evolution challenged by a new tree of life”). Jonathan Keith’s “tree of life” posted on The Conversation looks vastly different from Haeckel’s. Keith seems to think we shouldn’t allow nasty facts to get in the way of a pretty picture. We don’t want to disturb the unwashed masses.
You’ve seen them in popular science news, biology textbooks, wall plaques in museums, perhaps even as tattoos. Evolutionary trees are among the most instantly recognisable, ubiquitous and iconic images of science.
At the end of his article, “How to grow an evolutionary tree,” he does ask, “Can you trust an evolutionary tree?” While giving room for skepticism, he concludes that we can trust these visualizations, at least the ones that try to tease out details of certain branches, like his favorite, the tree of mammals.
It is not possible to set aside all biases and preconceived ideas when inferring evolutionary trees, because even the methodology is based on assumptions about how evolution works.
But the better one understands the models and methods, the more one appreciates that trees are not mere guesses, nor even summaries of expert opinion.
They are products of careful and principled science informed by statistics.
Keith makes an incoherent argument. On the one hand, he admits to biases and preconceived ideas. On the other hand, he simply appeals to authority. Trust the experts, he says; they’re doing their best (cf. 12/05/16). And we all know that statistics never lie.
Would any of these Haeckel devotees ever take their “healthy skepticism” to the point of considering the possibility that the whole tree is a myth? Would they ever chop it down? Unlikely; it forms a key link in the materialist chain of molecules to man.
Recommended resource: See the chapter on “Tree of Life” in Icons of Evolution by Jonathan Wells. There’s a summary in this article on ARN.org. In another article on ARN, he responds to Eugenie Scott’s criticisms.
For fun, see our 2/01/07 article and commentary about Darwin’s sacred tree.