Margaret Mead did this once, when she suggested that the first sign of ‘civilization’ in human history was not tool use but a 15,000-year-old skeleton that showed signs of having healed from a broken femur. It takes six weeks, she noted, to recover from such an injury; most animals with broken femurs simply die because their companions abandon them; one of the things that makes humans so unusual is precisely that we take care of one another in such situations.
