Haeckel, embryos, and evolution.
[Letter]
A recent study (Richardson et al, 2007) coauthored by several of us and discussed by Elizabeth Pennisi (Research News, 5 Sept. 1997, p. 1435) examined inaccuracies in embryo drawings published last century by Ernst Haeckel. Our work has been used in a nationally televised debate to attack evolutionary theory, and to suggest that evolution cannot explain embryology (“Firing Line with William Buckley,” PBS 12/13/1997). We strongly disagree with this viewpoint. Data from embryology are fully consistent with Darwinian evolution. Haeckel's famous drawings are a Creationist cause célèbre (Rusch, 1969). Early versions show young embryos looking virtually identical in different vertebrate species. On a fundamental level, Haeckel was correct: All vertebrates develop a similar body plan (consisting of notochord, body segments, pharyngeal pouches, and so forth). This shared developmental program reflects shared evolutionary history. It also fits with overwhelming recent evidence that development in different animals is controlled by common genetic mechanisms (Slack, Holland, and Graham, 1993).
