AUnlike the rapid developments in genetics over the past few decades, modern medicine is by no means linked to a thoroughly deterministic understanding of genes. In particular, the influence of the environment – and maternal behavior – on the developing fetus in the womb is a paradigmatic example of how the environment can modulate the action of genes and how such environmental effects can remain effective over several generations.
The inheritance of acquired traits is not a heresy in medicine, but the basis of an enormously productive research program. The cross-generational consequences of the Dutch famine in the winter of 1944/45 or the transmission of the trauma from Holocaust survivors to their descendants are two paradigmatic examples of the findings of this research. However, the fact that mothers can have a special influence on their offspring during pregnancy is anything but a new idea.
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Science historian Sarah Richardson puts this research in its historical context and takes a critical look at its basic assumptions, methods and conclusions. In the first four chapters of her book, Richardson presents concise and vividly how medical and scientific thinking about the maternal and paternal contribution to the development of the offspring developed. The pivotal point of their presentation is August Weismann’s germ plasm theory (1882), which stated that only the genetic material in the egg or sperm cells is passed on, that father and mother make the same contribution to the offspring, that it does not matter whether a genetic factor is present comes from the maternal or paternal side, and that there can be no inheritance of acquired traits.
Sarah S. Richardson: „The Maternal Imprint“. The Contested Science of Maternal-Fetal Effects.
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Bild: The University of Chicago Press
Weismann’s theory – for which the term “neo-Darwinism” was coined – formed a radical break with earlier theories of reproduction and heredity and was an essential element in the development of modern evolutionary biology. From ancient times to the nineteenth century, the influence of the mother and father was judged to be different. Exceptionally significant was the idea that a pregnant woman’s emotions and experiences can imprint themselves on the fetus and lead to birthmarks, deformities, or personality traits. Other theories saw the female egg cell as nourishing and passive, while the sperm contributed all of the “life force”. A third class of theories acknowledged both egg and spermatozoa, but the contributions of the two cell types were considered complementary. Weismann’s theory and its experimental confirmation did away with these theories, but they survived for several decades in an area where progressive politics allied with positive eugenics to create a modern society with healthy citizens.
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