An essential objective of paleoanthropology is placing sites and fossils into a time frame. (Pg. 242) This is important because it provides us with an approximation of how old fossils are. By observing and testing fossils, it also presents us with information of the surrounding environments during the approximated time frames as well. Thus giving paleoanthropologists a scope of the larger and broader picture of all the factors contributing to the era, laying a foundation for an outline or timeline to be constructed.
It is extremely important to have accurate dates for paleoanthropological localities because one minor error could misconstrue an entire timeline of events and order of when species lived. As a consequence, possibly misunderstanding how Homo sapiens and other primates evolved in the first place. Especially since the origin of the species Homo sapien is one of the main points of investigation in the field of anthropology.
Scientists use two different kinds of dating known as relative dating and absolute dating (aka: chronometric dating). Relative dating arranges a sequence of sites, events, or artifacts in chronological order, from older to younger, without assigning dates. An example of relative dating is Stratigraphy, which is one of the first techniques used by scientists working with the vast period of geological time and is the main method that relative dating is based on. (Pg. 242) Absolute dating assigns an age to a specimen that includes a margin of error. Two examples of absolute dating is Radiometric dating and Radiocarbon dating. The absolute dating method provides an actual age in years for a defined piece of material or event, and accordingly, scientists are then able to construct an actual time line and/or time frame. Where as with relative dating, chronological order does not provide any help with dates or time frames but rather with sequences and orders for the material and/or the events. Having an alternative method to compare to certainly helps when dealing with common margins of error. Furthermore, the purpose of using more than one kind of dating technique is necessary and important to ensure the most accurate date(s) possible.
Reference: Jurmain, Robert; Kilgore, Lynn; Trevathan, Wenda; Ciochon, Russell. 2008. Introduction to Physical Anthropology, Eleventh Edition. Thomson Wadsworth, a part of The Thomson Corporation.