Once We All Had Gills: Growing Up Evolutionist in an Evolving World

13. Life with Sea Urchins

169 Life with Sea Urchins Seaside Science My former postdoctoral advisor,PaulGross,likedtosaythat“yourgraduatestudentsareyourfriends ,butyourpostdocsareyourenemies.”This was because graduate students would go off to do postdoctoral work in new areas of research but departing postdocs would want to kick-start theirindependentcareersbycontinuingtheresearchtheyhaddeveloped during their postdoctoral years. Thus they were virtually destined to becomecompetitorswiththeirownformermentors .Nonetheless,Paulwas generous about allowing postdocs to take their projects with them. For several years at Indiana, I continued the study of how protein synthesis was stimulated at fertilization of sea urchin eggs. By 1978, we had published our main findings on the “masking” of mRNAs of eggs and on the regulationofproteinsynthesisfromthesemRNAsinembryosfollowing fertilization, and I began to get restless. I was ready to start a new direction of research. I thought it was time to return to my early interest in evolution, but now with a better understanding and better methods, and a view toward thinking about evolution and development. Developmental and evolutionary biologists had diverged in their research objectives to the point where neither thought much about the role of the other. My firstapproachtotheexperimentalstudyoftheevolutionofdevelopment would be based in Indiana but was boosted by priceless summers in Woods Hole, Massachusetts, where I learned about marine embryos as creatures with life histories and their own evolutionary careers. Those evolving larvae have occupied my scientific life for three decades. thirteen 170 Finding Evolution, Founding Evo-Devo By 1979 Paul had become director of the Marine Biological Laboratory at Woods Hole. This was his dream job, and he took to it passionately .HeinvitedmetobecometheinstructorinchiefoftheWoodsHole summer embryology course starting in 1980. I was thrilled to take on this venerable course, which had been offered continuously since 1893. The great founders of American embryology taught the first years of the course. These scientists, notably Charles O. Whitman, Edmund B. Wilson, Frank R. Lillie, Edwin G. Conklin, Thomas Hunt Morgan, put into play the idea of German embryologist Wilhelm Roux that the workings of the embryo should be central to the study of development–not phylogeny, which had dominated the study of embryos from the 1860s to the end of the century. Thus the MBL became an indispensable center for the new science of experimental embryology, and the severing of development from evolution. With all the excitement of probing the cellular mechanisms by which development proceeds, evolution was easily put into the attic, like a gift painting of dogs playing poker, an irrelevantandtime -wastingdistraction.FollowingRoux’slead,theWoods Hole embryologists shifted their studies to understanding how development worked as a process. Understanding the machinery of development became the goal. The impressive compound German name that Rouxcoinedforthisnewsciencetellsitall:Entwicklungsmechanik,which translates in English as “developmental mechanics.” The Woods Hole embryologists made the tracing of the lineages of cells in embryos their organizing principle for achieving this new mechanistic understanding, with cells as the gear wheels of the embryo. They invented methods that allowed the destinations of each cell of an embryo to be traced. The results were spectacular, revealing that the egg wasorganizedintoregionsthatinfluenceddevelopment.Thesedifferent fates were mapped and then studied by experimental manipulations of cells with distinct fates to learn how they got their differences. Developmentalbiologyhadbecomeavigorousdisciplinedevotedtomechanistic questions about the function of developing organisms continuing the scientific vision of the Woods Hole pioneers. By the 1890s, with the idea of development as a handmaiden for tracking evolutionary history discredited , the focus on embryos for phylogeny building was over and the evolution of developmental features was relegated to only a peripheral curiosity. This dichotomy between evolutionary biology and functional Life with Sea Urchins 171 biology continues to have a disconcerting grip into our times. The present -day bias of developmental biology leans heavily on the functional side of biology, finding a place in the hearts, souls, and pocket books of funding agencies for obvious biotech and medical reasons. Thelate1880ssawthecreationofseasidemarinebiologicallaboratories around the world–the MBL in 1888 was the third. The first of these indispensable windows on the sea was the Stazione Zoologica, founded in Naples in 1872; the second such laboratory was founded at Misaki, Japan, in 1887. I was fortunate to be invited to take part in a symposium in Japan held in 1987 to celebrate the centenary of the founding of the Misaki Marine Station. I don’t mean “celebrate” lightly–the saki and wonderful seafood flowed freely, and Crown Prince Akihito, now the emperorofJapan,tookpartandmingledwiththespeakersatareception. The Japanese postalservice even issued a Misakicommemorative stamp. There is a beautiful link between Misaki and the MBL. On the...