The Legacy of Developmental Biology
"The embryo shows remains of the development of an animal in former ages and former states; it recapitulates its former lives. The embryo of an Emperor may prove the missing link between birds and the reptiles from which birds have sprung."-Apsley Cherry-Garrard
I had an epiphany the other night.
In 1911 Edward Wilson set out with the Terra Nova Expedition to look for a bird that would serve as a "missing link" between modern birds and dinosaurs through embryology. This flawed idea of the developmental "missing link" originated in 1866 with Ernst Hæckel's famous "biogenic law" - a quickly disproven theory which was appealing in its simplicity but is untrue. (It nonetheless continues to be a part of the basic biology curriculum as an important historical idea just as the flat earth theory is part of the history of geography). Wilson was hopeful that the embryo of the "primitive" Emperor Penguin (ostrichs and their ilk are more ancestral birds) would hold a secret to evolution, part of the long association between the study of development and the study of evolution.
The three Emperor Penguin eggs collected during the Worst Journey in the World. Photographed by expedition photographer Herbert Ponting, now part of the Scott Polar Research Institute archives.
We as developmental physiologists are heirs to Wilson's ambitious legacy. While we do not study "evo-devo" in the strict sense, we are among only a few groups here focused on studying development, and we are learning about physiology and biochemical adaptation in extreme cold and stable pCO2 conditions--conditions that have inevitably played a role in the evolutionary history of the species.
We have not had to suffer the great hardships endured by Apsley Cherry-Garrard, Edward Wilson and Henry Robertson Bowers on the Worst Journey in the World to seek the answers to our questions. We seek mostly to keep our babies cold, our water chemistry measurements consistent and to get as many experiments done as we can in two and a half months. We have it easy. But we don't forget the Antarctic science legacy from which we scientists developed.
"But now I understand quite a lot more than I did then. Science is a big thing if you can travel a Winter Journey in her cause and not regret it. I am not sure she is not bigger still if you can have dealings with scientists and continue to follow in her path."-Apsley Cherry-Garrard
For a contemporary perspective on the development of feathers from scales and the molecular evolutionary link from reptiles to birds, I redirect you to the fascinating work of Prof. Cheng-Ming Chuong of the USC Keck School of Medicine. His laboratory has published extensive, elegant research on the molecular mechanisms of skin tissue differentiation, using feathers as a model tissue, and chickens as the model organism. Hardly much of a journey to obtain those eggs.
Cheng-Ming Chuong @ USC: