Haeckel's Dream - Anthropogenie (2009.2.2[Mon])

 

It's time for me to write about Ernst Haeckel, almost a duty. Although he is a difficult figure to evaluate, one thing I can say is that, although he has nearly been forgotten in most advanced countries, Japan should be proud that his name still appears in high school textbooks (although that may only be a matter of time), and we can read translations of his works in Japanese. The writings of Lamarck, Darwin and Huxley are also available in translation here, an embarrassment of riches I believe no other country can boast.

    My recent enthusiasm for Haeckel was triggered by reading "The Tragic Sense of Life" by Robert J. Richards. Although the book is not an easy read, it follows Haeckel's career, the context in which his achievements took place and the responses to them, up to the present day. Richards provides a penetrating look into the reappraisal of his legacy by critics and scholars in postwar England and America. I felt particularly impressed and moved by the influence of Haeckel's first wife, Anna Sethe, who died young, on his scientific development. It seems to mirror the effect of the death of Darwin's daughter on "The Origin of Species"(her name was Anne as well). Despite the initial similarities in these events that took place in the latter half of the 19th century, a crucible of change in the history of biology and man's understanding of the natural world, they diverged and met very different fates. For me as an evolutionary developmental biologist, Darwin and Haeckel are the two pillars that undergird evolutionary thought, an inseparable and essential pairing. A second inspiration for me was given by a friend who said, "I think of Haeckel, like Darwin, as belonging to modern science, not as some relic of natural philosophy." I suppose I only half-agree with that, but it gave me a good opportunity to rethink how Haeckel's thought matured in light of the biological awareness of the day, beginning with Darwin's Origins.

    Haeckel is a magnet for criticism these days, the object of various scorn. He did not limit himself to the origins of man, but speculated on the origins of race as well, which was seized upon for ideological and political purposes, and lashed his name to the Nazi mast in World War II. Since the late 19th century, his penchant for hyperbole and the details of his images has drawn the ire of his fellow biologists as well. That said, he counted among his advocates such British luminaries as Darwin and Huxley. The English of the day learned about evolution not from the challenging Origin of Species, but from Haeckel's writings. Although Darwin was famously dejected when he saw the reception given to the anonymously published Vestiges of the Natural History of Creation by Robert Chambers (a sensationalist, cosmic interpretation of evolution), he greeted Haeckel's work with praise - "Everything you have written is true." But I don't intend to tease out the errors and issues that led to Haeckel's misfortune. I'm only interested in his science. He left us many books, but perhaps the three most important are General Morphology, Natürliche Schöpfungsgeschichte(The History of Creation) and Anthropogenie. They are all still available over the internet, and the latter two have been translated into English.

    Darwin's theory of evolution was an effort to create a logical approach to the process of changes in a genetic developmental system through natural selection. Populations constantly give rise to a surfeit of individuals, of which only those in possession of certain characteristics survive natural competition to pass their genomes on to the next generation. As we who are aware of the existence of genes know today, the developmental program changes with each generation through spontaneous mutations and new combinations of alleles. Haeckel relied entirely on natural selection and speculated on how it and genetic adaptation might alter and diversify the morphogenetic programs of animals and plants. Like Darwin, he discarded all theological and teleological principles, and followed a purely monistic philosophy. For him religious belief was no more than a manifestation of neural activity, and the soul was a figment. His was a highly mechanistic worldview.

    This shows in the following example. In Haeckel's view of development, ontogeny encapsulates and recapitulates the process of phylogeny. In essence, the heredity was transmission of the developmental program. Exactly right. As an embryologist who had already graduated from preformationist thinking, he rejected ideas such as Darwin's of gemmules circulating in the body, and settled rather on the concept that heritable factors must be in the nucleus or cytoplasm of the cell. Right again! Fertilization triggered the start of the developmental, and thus the encapsulated phylogenetic, process.

    Haeckel's student Oscar Hertwig (whom I wrote about previously) discovered that fertilization involves the fusion of the nuclei of sperm and egg, but Haeckel felt that both nuclei must disappear before a new nucleus could be fashioned from an amalgam of cytoplasm and the dissolved parental nuclei. For in his view of recapitulation, the appearance of the nucleus should reflect the evolutionary progress from protist to eukaryote. I see this as the baleful influence of his natural philosophy on his science, but even so, the level of observation was remarkable considering the era in which it was made. He represents a new breed of scientists, utterly distinct from the anatomists of the day who had barely even heard of cells. Although Haeckel had never heard of genes or DNA, his image of the cell and observations on the relationships between genes and development were wonderfully close to our own. He reconstructed a Darwinian history of the world that encompassed embryology, anatomy, geology, paleontology, anthropology and ecology and linked everything from the first prokaryote to the present day through modifications to the developmental program. His mechanistic view (excluding the principle of biological development) was nothing if not commonsensical and all-encompassing, and it is no exaggeration to say that his vision of the history of life is the template for our own. You could add that Darwin alone could never have led us here.

    I hope I've convinced you why I see Darwin and Haeckel as a single set. Both were prophets of an age that began to forge the bonds between science and natural philosophy, and authors of a compelling theory of how science could inform our understanding of the world which led to the break from religion (which continues even today). This is yet another reason for the calumny Haeckel now suffers. One contemporary eminent German scientist leveled the critique that development plays out following the logic programmed into the egg, eliminating the need to bring evolution into the argument. Since Dobzhansky's famous axiom we now see that view to be false, but this is an example of the kinds of attacks and diatribes and envy that Haeckel had to endure in promulgating his views, which have yet to abate even now. If we admit such a thing as a tragic scholar, I can think of no more fitting case than Haeckel's. And for that reason, I recommend reading his Anthropogenie, if only to have a glimpse of what true worth in a book is, unlike the pitiful offerings we see in bookshops today...



Reference : "The evolution of man : a popular exposition of the principal points of human ontogeny and phylogeny Vol.1 & 2 "