VI. NEW RADIOCARBON DATES BASED ON BONE COLLAGEN OF CALIFORNIA PALEOINDIANS 1 2 3 Rainer Berger , Reine4 Protsch , Richard Reygolds , Charles Rozaire , and James R. Sackett Until recently it has been difficult to date directly and accurately human bones found in archeological explorations. With the development of radiocarbon measurements based on bone collagen (Berger, Horney and Libby, 1964) a method was introduced which allowed a new assessment of the antiquity of Homo sapiens fossils that cannot be dated by morphological criteria. Dur- ing the course of many years a number of human remains were found in Cali- fornia whose exact age had remained uncertain. It was therefore decided to apply this newly developed analytical technique in dating these specimens. However, first some check measurements were carried out involving a well- preserved mummy discovered in 1955 in Chimney Cave, Lake Winnemucca, Nevada. Skin tissue, bone collagen and vegetal clothing were dated by radiocarbon yielding dates of 2510 + 80 (UCLA-690), 2500 + .80 (UCLA-689) and 2590 + 80 (UCLA-692) respectively (orr and Berger, 1965). These analyses proved the equivalence of bone collagen dates with others derived from different organic materials. The first California skull dated was discovered in 1933 by M. H. Wilson and E. H. Marriner, then teen-agers, at 255 St. Ann's Drive, Laguna Beach. It was removed with a pick-axe at a depth of approximately 1.75 m from the top of a steep embankment which road grading operations had shortly before cut along the entire front of this property. The skull apparently lay alongside the long bone fragments discussed below; it was the protrusion of one of these from the face of the embankment that had originally prompted the discoverers' search. No other faunal materials nor any artifacts were found in the vicinity of the human remains. After a series of inconclusive consultations at both American and European museums the skull and some bone fragments were shown to L. S. B. Leakey who referred them for analysis to UCLA. Since the skull fragment had travelled to a number of different institutions it was first found necessary to establish if the specimen at hand was indeed the original. Fortunately a Departments of Anthropology and History, Inst. of Geophysics, UCLA. 2 Department of Anthropology and Inst. of Geophysics, UCLA. Los Angeles County Museum of Natural History and Inst. of Geophysics, UCLA. Los Angeles County Museum of Natural History. Department of Anthropology,UCLA. -43- 44 picture of the find had appeared in the Friday, January 15, 1937 issue of the Laguna Beach newspaper before it had left California. Comparison of the pres- ent skull with its marked scars with the original photograph appears to rule out substitution. Portions of the skull, parietal and temporal bones, were dated as follows: 78.5 g of bones were extracted continuously with ether for several days to remove any organic substances introduced by handling the skull. Then the mineral matrix of the bones was destroyed by dilute cold hydrochloric acid treatment. Finally humic acids of different specific activity were extracted with dilute, cold sodium hydroxide. The remaining organic portion was dated and found to correspond to an age of 17,150 + 1470 years (UCLA-1233A). Later the long bone fragments associated with the skull were dated in an analogous manner. 23.0 g of bones yielded insufficient CO2 for a finite date (UCLA-1233B). The age was calculated to be greater than 14,800 years confirming the late Pleistocene age of the skull bone fragments. The long bone fragments were identified as human by M. R. Urist of the UCLA Bone Re- search Laboratory. Casts of the fragments were made by the Department of Palaeontology of the Los Angeles County Museum of Natural History using a method avoiding organic carbon compounds. The nitrogen content of the skull and long bone fragments was calcu- lated based on the amino acid content. Furthermore, the fluorine content was determined by a colorimetric method and the uranium content by calculation from the radon present in the counting gas immediately after preparation or after a known elapsed time. Results obtained are listed below: N F U Skull 0.26% 0.30% 60 ppm as U308 Long Bones 0.23% 0.34% 63 ppm as U 308 Inspection of these data reveals that both types of bones are in all likeli- hood associated with each other. One of the long bone fragments contained in its hollow small pieces of Mytilus californianus Conrad as determined by the conchologist of the UCLA Department of Geology, Mrs. L. Saul. This particular species of mussel shell differs from European varieties by a special rib structure. Since the long bones appear to be Californian and the chemical composition is similar to the parietal and temporal bone fragments a case can be made for the skull also being Californian. The skull itself was analyzed by D. Stewart, Smithsonian Institution, whose preliminary analysis points out similarity of the Laguna skull with others found in the Santa Barbara region. Unfortunately the Laguna specimen 45 is not complete which rules out an exhaustive analysis. Yet an examination of the character of the supraorbital ridges and the orbital portion suggests a female cranium. The unexpected date of the Laguna skull prompted formal excavation aimed at securing additional in situ material. During several weekends in the late Winter and Spring of 1968, a crew composed of 6 to 10 UCLA students working under the direction of J. R. Sackett conducted test excavations in all accessible areas of the St. Ann's Drive property. This included exten- sive excavation of the embankment which fronts the property, with particular attention being devoted to the area surrounding the original find spot as best this could be determined in consultation with W. H. Wilson. The work was subsequently continued periodically until January 1969 by digging crews working under the di-rection of Dr. Tomchak of Fullerton State College. A detailed report of all these excavations is now in preparation, but their largely negative results can briefly be summarized here. The deposit is part of an alluvial fan that extends down one of the shallow estuary canyons which emanate from Hidden Valley Canyon above La- guna Beach. At least to the 5 m depth attained by excavation, the soil is composed of typical western coastal alkaline fine-grained sandy loam or outright yellow sand, in both of which turbulent lamellae may often be ob- served. Relatively homogeneous and free of concentrations of pebbles and rocks, the deposit exhibits little consistent bedding save for horizontal zones in which California mussel shells are concentrated. Assuming that the original find spot has been at least approximately located and that its soil was an integral part of the deposit seen today, the human remains would have occupied a stratigraphic position somewhere intermediate between two of these shell-bearing zones lying respectively 0.60 m and 2.0 m below the pre- sent surface of the embankment. A shell sample from the upper zone has given an age of 8950 + 80 years (UCLA-1349), while one from the lower has yielded a date of 8300 + 80 years (UCLA-1364). For a skull some 17,000 years old to have been located between these very much younger shell layers would obviously entail a marked strati- graphic anomaly. This possibility cannot be ruled out given the geomorpho- logical context of the deposit inasmuch as only erosion coupled with natural redeposition during mud flows or slides could have produced the inverted strati- graphy encountered with the insertion of much older bones between more recent depositions. But it must be stressed that the excavations have failed to yield any archeological or paleontological information that might be considered relevant to an explanation of the presence of the human skull and long bones. Indeed, throughout the excavations there was not obtained any substantial physical evidence to support the view that they were ever directly incorpor- ated within the deposit. The likelihood is great that the origin of the Laguna Beach remains and their subsequent depositional history on St. Ann's Drive may never be known. 46 The second California skeleton which was analyzed is that of a woman found on 5 February, 1941 by L. E. Wyman during excavations in Pit 10 at Rancho La Brea (Merriam, 1914). Sometimes the escape of petroleum and natural gas over long periods of time can create enlarged chimneys in the soil along lines of least resistance with a diameter on the order of a meter. In fact, Pit 10 had two such chimneys topped by a common asphaltic cap which stood 1 m above the adjacent ground surface. At a depth of about 1.50 m the vents opened into a large dome-shaped asphaltic mass extending downward to unknown depth. One of the chimneys led to the surface directly while the other, which con- tained the hum-an remains, extended 2 m horizontally and then abruptly sloped to the surface. Apparently the chimney containing human bones passed through an older asphalt deposit containing remnants of extinct late Pleistocene ani- mals. Merriam recognized this circumstance and felt that the human bones were of Recent age. Since the development of bone collagen dating,it became clear that a refinement was necessary to cope with the problem of petroleum-impregnated bones from the La Brea tar pits. Such a method was worked out in 1968 uti- lizing chromatographic separation of native amino acids in bones of extinct animals of the late Pleistocene (Ho, Marcus and Berger, 1969). For preliminary analysis the left ulna had been submitted by C. Rozaire. However, for final analysis 55 g of bone representing the proximal two-thirds of the left femur were used. After grinding this bone to pass 60 mesh, the powder was pre-cleaned with acetone and treated in 1.0 N HCI at room tempera- ture to dissolve the inorganic matrix. Subsequently alkali-soluble contamin- ants such as humic acids were removed by treatment with 0.1 N NaOH, also at room temperature. Then the sample was refluxed for 24 hours in 6.0 N HCl to complete hydrolysis of collagen into its component amino acids. The hydro- lyzed sample was purified using an ion-exchange column charged with Dowex 50W - X8. After final elution with 5.0 N NHyOH the amino acids obtained were dried, burnt and dated to be 9000 + 80 years old (UCLA-1292BB). From a morphological point of view the La Brea skeleton belongs to racial type not unlike the later Indians inhabiting Southern California (Kroeber, 1962). It belongs to a frail woman in her mid-twenties and con- sists of the following bones: skull, mandible, 4 vertebrae, a rib, left scap- ula, left pelvis and fragments of 6 limb bones. All the exterior surfaces of the bones have been polished by a process called "pit wear" which is thought to involve the abrasive effects of mineral grains suspended in moving asphalt (Stock, 1929). What makes the La Brea skull interesting is a radiating pattern of fractures around a large irregular hole above the glabella suggestive of a depressed skull fracture. Today it is almost impossible to decide whether this damage caused death or is post mortem. Yet a complete mano capable of inflicting such a wound was recovered from a location 10 cm above the skull. 47 A third California skull fragment dated at UCLA is the so-called Los Angeles Man. It was discovered on 23 January 1936 during excavation work of WPA Project C-642 in a location north of the Baldwin Hills (Lopatin, 1940). Originally a skull consisting mainly of the occipital and two adja- cent sections of the parietals,as well as several other human bones in- cluding a broken humerus were found in gray sandy clay some 4 m below the surface in the course of an ancient river bed. Despite excavation efforts to secure additional material only very small bone fragments but no tools were recovered. On 13 March, 1936 workers found the remains of a mammoth at the same depth but 370 m distant from the human find. Unfortunately the whereabouts of the faunal material cannot be ascertained today. It was our plan to date these remains if possible in order to obtain a corroborating age determin- ation. The fact that man and mammoth were found in late Pleistocene deposits suggested their very considerable age (Clements, 1938). In the course of time only the skull has remained accessible as of this writing. It was brought to UCLA for dating by C. Rozaire. Since the skull is heavily encrusted with secondary carbonate cementation and appears to be more darkly mineralized, its age was presumed to be considerable. There- fore great care was exercised to obtain a reliable radiocarbon date from a portion of the skull bones. For analysis ca. 100 g of bone were precleaned by scraping off extra- neous material. Then the amino acids in collagen were recovered in a pro- cedure similar to that used for the dating of the La Brea skeleton. Since the amount of bone used only yielded a partial filling of the UCLA propor- tional counter, no finite date could be calculated. This explains the final date of >23,600 years (UCLA-1430). Perhaps a finite date could have been obtained had most of the skull been used for amino acid isolation. However, this would have left little of the skull itself. Since the facial portion of the skull is entirely missing, no defin- ite inferences as to racial origin or sex can be made. However, the brain capacity has been estimated and does not differ from the average of that of other more recent Indians. As of now, this skull is the oldest directly dated human fossil in the Americas. The most recent analysis of human remains from Tranquillity, California has shed more light on a complex archeological situation. A number of highly mineralized human skeletons were excavated under carefully controlled con- ditions by Hewes (1943, 1946) and by Satterthwaite (Angel, 1966). The site itself had been discovered in 1939 by the Hewes and Masseys in the Central San Joaquin Valley some 24 miles west of Fresno exposed as the result of ero- sion processes caused by changes in the drainage system between the Kings and San Joaquin rivers. At issue in the interpretation of the Tranquillity site 48 was the question if man was indeed associated with an extinct late Pleistocene fauna as observed. However some of the cultural material found appears to be- long to the California Middle Horizon of considerably more recent age. The enigma was further compounded by chemical analyses made by Heizer and Cook (1952) which suggested considerable antiquity for the human bones. Indeed, more recent microanalytical data for nitrogen and fluorine agree with this earlier investigation. N(%) F(%) UCLA analyses, this paper Human 6464A 0.04 0.11 6464B 0.06 0.12 Human 6073 0.03 0.12 Heizer and Cook, 1952 Human 6073 0.060 0.208 6071 0.092 0.185 6072 A 0.110 0.156 B 0.072 0.102 6075 0.053 0.136 Tranquillity site consisted of a number of burials which yielded a considerable amount of human remains. For radiocarbon dating 1220 g of human bones from burials 3 and 4 were obtained through R. F. Heizer and A.B. Elsasser of the Department of Anthropology, University of California, Berke- ley. First the bones were continously extracted with analytical grade sol- vents to remove any preservative or glue. Then they were treated in a simi- lar manner as the Laguna skull. Finally the radiocarbon age was determined to be 2550 + 60 years. As a result burials 3 and 4, as well as any bones with similar fluorine or nitrogen content, belong-in context to the artifacts of the California Middle Horizon. At this point it is not entirely clear if all the human material found at Tranquillity is of the same general age. More- over, we do not know the exact age of the faunal material either. However, on balance, a direct association between man and extinct fauna appears to be more a matter of geographical coincidence than a true tight association in space and time. We wish to thank R. F. Heizer, L. S. B. Leakey, W. F. Libby, P. C. Orr and W. H. Wilson for support and encouragement in these studies. Furthermore, we are indebted to the Hancock Foundation of the University of Southern Cal- ifornia, and the Isotope Foundation and National Science Foundation for grants. 49 Bibliography Angel, J. L. 1966 Early skeletons from Tranquillity, California. Contributions to Anthropology 2 (1). Smithsonian Berger, Rainer, A. G. Horney and W. F. Libby 1964 Radiocarbon Dating of Bone and Shell From Their Organic Compon- ents. Science 144:999-1001. Clements, T. 1938 Age of the Los Angeles Man Deposits. Am. J. Sci.36: 137-141. Heizer, Robert F. and S. F. Cook 1952 Fluorine and Other Chemical Tests of Some North American Human and Fossil Bones. J. Phys. Anthropol. 10:289-393. Hewes, Gordon W. 1943 Camel, Horse and Bison Associated with Human Burials and Arti- facts near Fresno, California. Science 97: 328-329. 1946 Early Man in California and the Tranquillity Site. Amer. Antiq. 11:209-215. Ho, T.-Y., L. F. Marcus and Rainer Berger 1969 Radiocarbon Dating of Petroleum-impregnated Bone from Tar Pits at Rancho La Brea, California. Science 164: 1051-1052. Kroeber, A. L. 1962 The Rancho La Brea Skull. Amer. Antiq. 27: 416-417. Lopatin, I. 1940 Merriam, J. 1914 A. Fossil Man in the Vicinity of Los Angeles, California. Proceed. Sixth Pacific Science Congress 4:177-181. C. Preliminary Report on the Discovery of Human Remains in an Asphalt Deposit at Rancho La Brea. Science 40: 198-203. Orr, Phil C., and Rainer Berger 1965 Radiocarbon Age of a Nevada Mummy. Science 148: 1466-1467. Stock, Chester 1929 Significance of Abraded and Weathered Mammalian Remains from Rancho La Brea. Bull. South. Calif. Acad. Sci. 28: 1-5.