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The Calaveras skull, first reported in 1866, represents the earliest purported fossil human discovery in California and one of the earliest in the New World. The specimen is in the possession of the Peabody Museum, Harvard University. The validity of the original "Tertiary" age assignment was rejected by the first generation of professional American archaeologists early in the twentieth century. Radiocarbon analyses using both conventional decay counting and accelerator mass spectrometry indicate a late Holocene age for the Calaveras skull.

Osteocalcin, a non-collagen bone-matrix protein, has been examined as a possible source of autochthonous14C data in fossil bones where collagen has been seriously degraded. Extraction procedures for osteocalcin yield a well-characterized product that can be clearly distinguished from collagen. The Gla content indicates that osteocalcin is present in the fossil bones at levels similar to the range present in modern bone. However, it appears to be extracted primarily as proteolytic polypeptide fragments rather than as an intact protein. Concordant14C determinations are obtained on osteocalcin and gelatin extracts from the same bone when the collagen is relatively well preserved. However, increasing discordances in the14C values of the osteocalcin and gelatin fractions are associated with reduced concentrations of the gelatin extract in the bone.

The origin of five iron cannons recovered in 1981 from a beach near Goleta on the southern California coast has been investigated by evaluating stylistic, archival, historical, metallurgical, and radiocarbon (14C) data. Particular attention has been focused on these cannons due to the suggestion advanced by previous writers that they were brought ashore by Sir Francis Drake in 1579. This proposed origin for the cannons would add another locality as the proposed site of Drake’s Nova Albion. The authors conclude that the weight of the evidence assigns a post-16th-century age to the Goleta cannons although the current physical evidence including the 14C data does not indicate whether they are 17th-, 18th- or 19th-century artifacts.

Radiocarbon analyses by accelerator mass spectrometric (AMS) techniques on organic fractions of human bone from various North American localities previously assigned ages ranging from about 70,000 to 15,000 years B.P. now suggest that none of these skeletons is older than 11,000 C-14 years B.P.

Graphite in various forms has become the standard target for accelerator 14C dating. Graphite has been made by catalytic graphitization of charcoals (Lowe, 1984). Thin films of graphite have also been produced by thermal cracking (Beukens & Lee, 1981), electric discharge (Andrée et al, 1984; Wand, Gillespie & Hedges, 1984). Vogel et al (1984) pointed out the ease of graphite formation on iron from CO2 and H2 mixtures at ca 600°C. The deposition reactions of carbon from the CO, H2, and CO2 equilibria are well known (Wagman et al, 1945) and well studied. Formation of graphite from CO2 was discussed extensively by Boudouard (1902) and Schenck and Zimmerman (1903), and was known to chemists in France in 1851. We have used a related method, where graphite forms away from the iron, by using a higher temperature, and reduction of CO2 to CO over Zn in the presence of H2 (Jull et al, 1986) as an alternative to the use of Fe alone. The object of this paper is to point out an even simpler graphite preparation system, which eliminates hydrogen. The decomposition reaction of CO (Boudouard, 1902) takes place according to reaction (1).

The ability of AMS facilities to obtain direct 14C determinations on milligram amounts of organic extracts of bone has significantly advanced efforts to reexamine the validity of the dating evidence for a number of allegedly Pleistocene Homo sapiens skeletons from the Western Hemisphere previously assigned ages of from about 20000 to 70000 years. AMS 14C analysis has indicated that four of these skeletons are actually of Holocene age, i.e., less than 10000 years old. Holocene ages have previously been documented on the basis of conventional 14C analysis for six other purported Pleistocene human skeletons from the New World. These data point to the danger of accepting pre-Holocene age assignments for such skeletal materials in the absence of direct 14C evidence.

The radiocarbon (14C) method is a well-known isotopic dating technique by which age can be assigned to organic materials, including human bone. Natural and anthropogenic anomalies in 14C activity in the biosphere over the last few centuries, including the presence of artificial or “bomb” 14C after 1950, can be used as an isotopic tracer to assign human bone samples with high degrees of probability to one of three temporal periods within the recent past: a Non-modern period (before about A.D. 1650) of no forensic science interest, a Pre-modern period (A.D. 1650 to 1950) of possible or potential forensic science interest, and a Modern period (A.D. 1950 to the present) of definite forensic science interest. We illustrate the use of the 14C method to assign human bone in five forensic science cases to one of these time periods.