Two researchers at Albert Einstein College of Medicine of Yeshiva University have found that our 98.6° F (37° C) body temperature strikes a perfect balance: warm enough to ward off fungal infection but not so hot that we need to eat nonstop to maintain our metabolism.
"One of the mysteries about humans and other advanced mammals has been why they are so hot compared with other animals," said study co—author Arturo Casadevall, M.D., Ph.D., professor and chair of microbiology & immunology at Einstein. "This study helps to explain why mammalian temperatures are all around 37° C." Dr. Casadevall also holds the Leo and Julia Forchheimer Chair in Microbiology and Immunology.
The research builds upon earlier work by Dr. Casadevall showing that the number of fungal species that can thrive and therefore infect an animal declines by 6 percent for every 1° C rise in temperature. This means that tens of thousands of fungal species infect reptiles, amphibians and other cold—blooded animals, but only a few hundred harm mammals.
Such protection against fungal infection, Dr. Casadevall has speculated, could have been crucial for the triumph of mammals following the age of dinosaurs.
In this study, Dr. Casadevall and his Einstein coauthor, Aviv Bergman, Ph.D., professor and founding chair of systems & computational biology, devised a mathematical model that analyzed the benefits gained by body temperatures that protect against fungi versus the costs (in terms of extra food consumption) required to maintain body temperatures between 30° and 40° C. The optimal temperature for maximizing benefits while minimizing costs was found to be 36.7° C, which closely approximates normal body temperature.
"This study is a good example of how mammalian evolution has been driven by both external biological factors and internal physiological constraints," said Dr. Bergman.
The paper, "Mammalian Endothermy Optimally Restricts Fungi and Metabolic Costs," appeared in the November 9 edition of mBio.
About Albert Einstein College of Medicine of Yeshiva UniversityAlbert Einstein College of Medicine of Yeshiva University is one of the nation's premier centers for research, medical education and clinical investigation. During the 2009-2010 academic year, Einstein is home to 722M.D. students, 243 Ph.D. students, 128 students in the combined M.D./Ph.D. program, and approximately 350 postdoctoral research fellows. The College of Medicine has 2,775 fulltime faculty members located on the main campus and at its clinical affiliates. In 2009, Einstein received more than $155 million in support from the NIH. This includes the funding of major research centers at Einstein in diabetes, cancer, liver disease, and AIDS.
Other areas where the College of Medicine is concentrating its efforts include developmental brain research, neuroscience, cardiac disease, and initiatives to reduce and eliminate ethnic and racial health disparities. Through its extensive affiliation network involving five medical centers in the Bronx, Manhattan and Long Island - which includes Montefiore Medical Center, The University Hospital and Academic Medical Center for Einstein - the College of Medicine runs one of the largest post-graduate medical training programs in the United States, offering approximately 150 residency programs to more than 2,500 physicians in training. For more information, please visit www.einstein.yu.edu
Source: Albert Einstein College of Medicine of Yeshiva University