Archaeology, or archeology, is the study of human activity in the past, primarily through the recovery and analysis of the material culture and environmental data that they have left behind, which includes artifacts, architecture, biofacts (also known as eco-facts) and cultural landscapes (the archaeological record). Because archaeology employs a wide range of different procedures, it can be considered to be both a social science and a humanity, and in the United States, it is thought of as a branch of anthropology, although in Europe, it is viewed as a separate discipline. Archaeology studies human prehistory and history from the development of the first stone tools in eastern Africa 4 million years ago up until recent decades. (Archaeology does not include the discipline of paleontology). It is of most importance for learning about prehistoric societies, when there are no written records for historians to study, making up over 99% of total human history, from the Paleolithic until the advent of literacy in any given society. Archaeology has various goals, which range from studying human evolution to cultural evolution and understanding culture history. The discipline involves surveying, excavation and eventually analysis of data collected to learn more about the past. In broad scope, archaeology relies on cross-disciplinary research. It draws upon anthropology, history, art history, classics, ethnology, geography, geology, linguistics, semiology, physics, information sciences, chemistry, statistics, paleoecology, paleontology, paleozoology, paleoethnobotany, and paleobotany. Archaeology developed out of antiquarianism in Europe during the 19th century, and has since become a discipline practiced across the world. Since its early development, various specific sub-disciplines of archaeology have developed, including maritime archaeology, feminist archaeology and archaeoastronomy, and numerous different scientific techniques have been developed to aid archaeological investigation. Nonetheless, today, archaeologists face many problems, such as dealing with pseudoarchaeology, the looting of artifacts, a lack of public interest, and opposition to the excavation of human remains.