Archaeologists use artifacts and fossils to explore how environmental and historical conditions have produced a diversity of human cultures – the study of archaeology. Artifacts are objects made by human beings, such as tools or pottery. Fossils are the remains of organisms preserved in the environment. Archaeologists have developed careful methods of excavation, or removing fossils and artifacts from the ground, in order to learn as much as possible about how people lived in times before and after the development of writing. They are interested in how people met basic needs such as clothing and shelter, as well how they organized their societies in family groups, trade networks, and systems of leadership. Many archaeologists seek to understand how humans lived in relation to the natural world around them, altering the environment at the same time that the environment was shaping their evolution and social development. A group of archaeologists led by Tom Dillehay spent seven years excavating a set of sites in northern Peru, charting the development of human society in this area over a period of 14,000 years (2017). They traced the society from the early ways of life to the emergence of cities and early states, discovering how people there developed fishing, farming, and herding strategies that led to increased sociocultural complexity. The team collected data on the plants and animals of the area as well as the buildings, tools, cloth, and baskets made by the people. They concluded that the people who lived in this area placed a high value on cooperation and living in harmony with nature. Some archaeologists focus on more specific topics in more recent time periods. Archaeologist Eric Tourigny examined the graves at pet cemeteries in the United Kingdom from 1881 to 1981(2020). Looking at the epitaphs on the gravestones of the pets, Tourigny noted a change from earlier Victorian ways of thinking of pets as friends to later, more modern ways of conceptualizing pets as members of the family. He noted, too, that epitaphs expressed an increasingly common belief that pet owners would be reunited with their pets in the afterlife.