The faces of human ancestors evolved to minimise injury from punches, according to new research.
Scientists have managed to extract human DNA from bone fragments that has been found to be 400,000 years old, confusing what we thought we knew about our historical ancestors.
Viruses make their living by breaking into cells and using the machinery and energy in the cell to reproduce. Once inside, some viruses immediately hijack the cell and make copies of themselves which burst out into the world to infect new cells. Other viruses take a staid approach, though. Instead of taking over the cell, they quietly slip a copy of their genes into its DNA. When the cell divides, it copies the newly acquired viral genes along with the rest of its genome.