Investigations of mummified remains have grown increasingly sophisticated with advances in dating techniques and forensic science. Mummies provide clues to everyday life through such items as clothing, tools, and tattoos. Stomach contents may reveal data on subsistence and the local ecology. Trace-element analysis of hair can reveal exposure to toxic elements (e.g., mercury and lead). Causes of death and active or inactive disease processes can often be ascertained and sometimes point to murder or ritual sacrifice. Mummies can yield blood and DNA samples providing valuable medical and genetic information.