Many of the objects left behind by past human societies are not present in the archaeological record because they have disintegrated over time.The material remains that still exist after hundreds, thousands, or millions of years have survived because of favorable preservation conditions in the soil or atmosphere.For the most part, the only things that survive are durable items such as potsherds (small fragments of pottery), tools or buildings of stone, bones, and teeth (which survive because they are covered with hard enamel).
Archaeological research spans the entire development of phenomena that are unique to humans.
For instance, archaeology tells the story of when people learned to bury their dead and developed beliefs in an afterlife.
These remains include the fossils (preserved bones) of humans, food remains, the ruins of buildings, and human artifactsitems such as tools, pottery, and jewelry.
From their studies, archaeologists attempt to reconstruct past ways of life.
The archeological record encompasses every area of the world that has ever been occupied by humans, as well as all of the material remains contained in those areas.
Archaeologists study the archaeological record through field surveys and excavations and through the laboratory study of collected materials.
The earliest subjects of archaeological study date from the origins of humanity.
These include fossil remains believed to be of human ancestors who lived 3.5 million to 4.5 million years ago.
Archaeologists have also recorded how primitive forms of humans spread out of Africa into Asia about 1.8 million years ago, then into Europe about 900,000 years ago.
The first physically modern humans, Homo sapiens sapiens, appeared in tropical Africa between 200,000 and 150,000 years agodates determined by molecular biologists and archaeologists working together.
Archaeology plays a major role in the study of early civilizations, such as those of the Sumerians of Mesopotamia, who built the city of Ur, and the ancient Egyptians, who are famous for the pyramids near the city of Giza and the royal sepulchers (tombs) of the Valley of the Kings at Thebes.