© Universidad de Chile
At left, the controversial scientist Paul Kammerer. Upper right: An image of the fingers of an experimental male midwife toad, showing a rugose nuptial pad (red arrow). Lower right: A schematic illustration from a paper by Kammerer of an experimental water-breeding male midwife toad.
Paul Kammerer committed suicide in 1926 after being accused of fraud in his famous experiments of "inheritance of acquired traits" with the midwife toad. A new study shows how recent advances in molecular epigenetics and re-examination of his descriptions suggest the experiments were actually authentic.
The alleged scientific fraud by Paul Kammerer is perhaps one of the most controversial mysteries in the history of biology. In the early 20th century, he was a famous evolutionary scientist, hailed as a "new Darwin" in the pages of the
New York Times. His experiments
provided impressive evidence that environmental life experiences could have a direct, inheritable effect on progeny, as maintained by his intellectual predecessor Lamarck, and by Darwin himself. In one of his most famous experiments, Kammerer had shown how a normally terrestrial species, the midwife toad, could be made to live and mate in water when kept in an artificially heated environment. These modified "water" toads laid eggs that grew into toads with an innate preference to live and mate in water, even when raised in normal, unheated environments. In successive generations of water toads, Kammerer reported that male toads developed nuptial pads on their fingers. These are rough, dark-colored thickenings of skin that are usually absent in midwife toads, but present in other water-loving species, which use them to grasp females during copulation. Additionally, Kammerer crossed one of his modified "water" males with a normal, untreated land female, obtaining 100% water toads in the first generation, and about three-quarters water toads in the second generation. Thus,
modified traits were being inherited according to Mendel's rules of genetics, the same that most of us were taught in high school.
Comment: Bionic eye lets blind man see again