## Intestine Shape

Who says that mathematical surfaces can not be important? Here is the Nature article.From the Crimson of 16. September, 2011:

Harvard professors recently determined how vertebrate intestines grow into their characteristically coiled shape, through a combination of biological methods and mathematical modeling. Researchers began by considering the intestine of the chicken. For the last 15 years,Cliff Tabin, head of the Department of Genetics at Harvard Medical School, has been investigating the underlying biological causes for the orientation, or chirality, of intestinal looping. But, while trying to understand how a chicken's intestine grows, Tabin, a biologist, turned to friend and Harvard mathematicianLakshminarayanan Mahadevanfor help. Mahadevan realized that physics could be used to explain the looping: each loop does not have to be formed separately, but rather, if the conditions are right, all the loops will form naturally as a consequence of basic physics laws. It came down to a simple matter of stress and strain on parts of the chicken's intestine, producing its coiled shape. Mahadevan's mathematical model proved accurate when tested. Not only could it predict the thickness and shape of chicken intestines, but with the proper experimentally-determined inputs, it could also predict the precise coiling of quail, zebra finch, and mouse intestines as well.