Biology, the study of life, encompasses investigations of all aspects of living organisms, including evolution, genetics, cellular structure and function, anatomy, physiology, ecology, behavior, diversity, conservation, host-pathogen interactions, biochemistry, and molecular biology. Biologists study basic aspects of organisms and how they function, how they are adapted to and interact with their environment (both internally and externally), and how they are related to each other through descent with modification from common ancestors. Fields of biology are intimately intertwined with all other areas of natural science as well as the social sciences, philosophy, art, and the humanities. Efforts of biologists have important contributions to an understanding of functioning and adaptations of living organisms as well as to the applied problems and issues facing all inhabitants on planet Earth, such as those involving medical advances, diseases, global changes, agriculture, biotechnology, bioinformatics, environmental management, conservation of species and genetic diversity, and many others.