This image shows a single cell grown from a culture of lung epithelial cancer cells. The purple spheres are 'blebs': irregular bulges where the cell's internal scaffolding - its cytoskeleton - becomes unlinked from the surface membrane. This image received an award from the Wellcome Trust, as part of the annual Wellcome Image Awards, for its ability to communicate the wonder and fascination of science.

Is the common nature of cancer worldwide purely a man-made phenomenon? That is what some researchers now suggest.

Still, other specialists in cancer and in human fossils have strong doubts about this notion.

Cancer is a leading cause of death worldwide, accounting for roughly one in eight of all deaths in 2004, according to the World Health Organization. However, scientists have only found one case of the disease in investigations of hundreds of Egyptian mummies, researcher Rosalie David at the University of Manchester in England said in a statement. (The researchers did not reply to repeated queries made via phone and e-mail.)