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Evolution of Energy Metabolism

Lesser hedgehog tenrecs – higher mammals that do not have constant body temperature – allowed the scientists to conclude that fat burning is a physiological process that was developed early in mammalian evolution, possibly prior to sustained high body temperature.

Scientists of the Institute for Diabetes and Obesity, together with colleagues of the University of Marburg and the Medical Research Council, Cambridge, UK have found that thermogenesis in the brown adipose tissue of mammals is an ancient mechanism.
Brown adipose tissue serves mammals in the generation of heat by burning fat reserves. The ability to maintain high body temperatures without shivering – i.e. without the physical work of muscles – has played an important evolutionary role for the colonization of cold habitats but presumably also for reproduction.

The team led by Martin Jastroch and Carola Meyer of the Institute for Diabetes and Obesity was able to demonstrate that fully functional brown adipose tissue developed at an early stage in mammalian evolution. To this end, the researchers studied Madagascan Lesser hedgehog tenrecs (Echinops telfairi), a species that diverged from modern mammals long ago. Tenrecs display primitive thermoregulatory features as they do not maintain a constant high body temperature. However, they have brown adipose tissue and active uncoupling protein 1 (UCP1), the latter being essential for burning fats. The scientists conclude that fat burning is a physiological process that developed early in evolution, independent of sustained body temperatures.

The study allows a new view on energy metabolism with regard to evolution and the functionality of brown adipose tissue. The scientists intend to broaden technological advances of this study to characterize brown adipose tissue to identify novel activators of fat burning. Of particular interest are the uncoupling proteins such as UCP1, which are crucially involved in the balance of energy metabolism. Translating the fundamental findings on brown adipose tissue function, their studies will assist in developing new therapeutic concepts to increase fat burning , thus reducing excess fat reserves, e.g. in obesity.

Brown adipose tissue is a special form of fat tissue, whose cells are able to generate heat by oxidation of fatty acids (thermogenesis). This occurs in numerous mitochondria, which are also responsible for the yellow-brownish color of the tissue.