Based on its primitiveness, Stringer says, most researchers guessed it was an early individual who lived around half a million years ago, some 200,000 years before the earliest Homo sapiens were starting to emerge. In the 1980s, however, museum paleoanthropologist Chris Stringer took another look at the skull and classified it as belonging to the species Homo heidelbergensis, an ancient hominin thought to be a human ancestor. But later that year, museum paleontologist Arthur Smith Woodward noticed what he interpreted as typically human features, such as the skullвЂ™s thin and relatively large braincase, that motivated him to designate the specimen as its own hominin species. It looked so primitive that the miner who had discovered it in 1921 at a lead mine in the Zambian town of Kabwe, then in the British territory of Rhodesia, first thought it had belonged to a gorilla. The bone fragment had come from a skull-still stored at the Natural History Museum in London-with a heavy brow ridge and a large face. In 2016, he carried with him a particularly precious piece of cargo: a tiny sliver of fossilized bone covered in bubble wrap inside a box. GrГјn specializes in developing methods to discern the age of such specimens. Jawbones from extinct hominins in Indonesia, Neanderthal teeth from Israel, and ancient human finger bones unearthed in Saudi Arabia have all at one point spent time in his lab at Australian National University before being returned home. ItвЂ™s not unusual for geochronologist Rainer GrГјn to bring human bones back with him when he returns home to Australia from excursions in Europe or Asia. ABOVE: MODIFIED FROM В© MARK GARLICK, SCIENCE PHOTO LIBRARY

Step on a crack origin