The Rise and Fall of Darwinian Embryology

Everybody remembers, if he had a secular biology class, the famous claims made by evolution on the development of embryos. Earnst Haeckel developed his theory of embryological recapitulation, the idea that all embryo’s repeat their evolutionary history as they develop in the womb, in the late 19th century. He supported this idea by drawing pictures of the various embryos to highlight their similarity, superficially, at the early stages of growth.

Unfortunately, it seems the resemblance wasn’t great enough to suit him, so he decided to help matters along a little by altering his drawings to favor his theory. The fact that even at the superficial level the embryo’s don’t always conform to evolutionary expectations is supported by high school and jr.high textbooks which still insist on using Haeckel’s drawings or close facsimiles of them instead of readily available photographs of embryos at all levels of development. The fact that he falsified his drawings is well attested by the trial and condemnation he received by his own colleagues at his own university and others. For example, Prof.Rutimeyer of the University of Basle called Haeckels distorted drawings, “A sin against scientific truthfulness deeply compromising to the public credit of a scholar“. (1)

Haeckels’ idea that human embryos went through a fish stage exemplified by what observers thought were gills, and the later reptile stages and bird like stages hasn’t fared well outside of the textbooks and has been rejected by many evolutionists. Keith Thompson, of Yale and president of the Academy of Natural Sciences, said in The American Scientist, (vol.76, 1988);

“Surely the “biogenetic law” is as dead as a doornail. It was finally exorcised from biology textbooks in the fifties. As a topic of serious theoretical inquiry, it was extinct in the twenties.

Unfortunately, the idea that it has been exorcised from textbooks is far from true and a vague belief in Haeckel’s law still occasionally haunts modern biology as well.

The problem is that even though embryos and adult animals of different kinds can have very similar looking parts, the resemblance is extremely superficial and does not extend beyond the outward appearance. While the textbooks love to look at the similarity between the dolphin flipper and the human arm and bat wing, it has been known for decades that these structures are controlled by different genes.

And while embryos’ can go through stages of similar appearance, they reach those stages by radically different patterns. They all go through cell movement and division unique to each class; fish follow a different path than reptiles or amphibians or birds. The same is true of later development. The growth and development of limb structure and bone development is different for each major class of animal and does not follow Darwinian predictions. Cartilage development, cell division and branching is all quite different for each class.

So the similar appearance of some physical structures (homology) , does not turn out to be evidence for ancestral relationship. The belief that the human arm developed from slight modifications in the gene controlling arm development in dolphins, inherited by amphibians, and then passed on with more changes to reptiles, birds and finally humans has been falsified. And thanks to advances in embryological studies and the discovery of DNA, we know that a human embryo does not pass through reptile or chicken stages as it develops, but follows the unique DNA blueprint passed on to it from its human parents.

Now if we can only get the textbooks bring themselves up to date.

(1) “Haeckels Frauds and Forgeries”, authors Asmuth and Hull

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About notmanynoble

woodcutter from Washington State
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