Inhumation or cremation - the laying of a body in the ground, in a natural or artificial chamber, or in an urn after burning. In collective burial, a single chamber is used for more than one corpse. A primary burial is one for which a burial monument such as a barrow was erected. The term secondary burial is used for the practice of collecting the bones of a skeleton after the flesh has decayed, and placing them in some form of ossuary. In fractional burial, only some of the bones are so collected and interred. Archaeologists can learn a great deal about prehistoric societies by studying skeletons and the way they were buried. In some cultures, bodies were buried stretched out; in others they were placed in the ground in a fetal, or flexed position. In still other societies, the dead were exposed on platforms or in charnel houses, then when the flesh had decayed or been scavenged, the disarticulated bones were made into a bundle and buried. Sometimes bodies were cremated and the remains buried. Goods interred with a burial give many clues to the social position of the person and their culture and the study of bones can reveal sex, age, and information about nutrition and disease. The earliest deliberate burial of their dead was that of Neanderthal man of Palaeolithic times 100,000 years ago. They were buried in the cave in which the family continued to live. Food and tools were buried with them, proof of the belief in an afterlife. Neolithic man buried his dead in the long barrow, a communal tomb. Inhumation was followed by cremation in the Late Bronze Age.