Local holes dating reviews

• Daniella E. Bar-Yosef Mayer ,

  Contributed equally to this work with: Daniella E. Bar-Yosef Mayer, Iris Groman-Yaroslavski

  Roles Conceptualization, Data curation, Formal analysis, Funding acquisition, Investigation, Methodology, Project administration, Writing – original draft, Writing – review & editing

  * E-mail:baryosef@tauex.tau.ac.il

  Affiliations The Steinhardt Museum of Natural History and Institute of Archaeology, Tel Aviv University, Tel Aviv, Israel, Peabody Museum of Archaeology and Ethnology, Harvard University, Cambridge, Massachusetts, United States of America

  ⨯
• Iris Groman-Yaroslavski ,
• Ofer Bar-Yosef †,
• Israel Hershkovitz,
• Astrid Kampen-Hasday,
• Bernard Vandermeersch,
• Yossi Zaidner,
• Mina Weinstein-Evron

Abstract

Glycymeris shell beads found in Middle Palaeolithic sites are understood to be artifacts collected by modern humans for symbolic use. In Misliya Cave, Israel, dated to 240–160 ka BP, Glycymeris shells were found that were neither perforated nor manipulated; nevertheless, transportation to the cave is regarded as symbolic. In about 120 ka BP at Qafzeh Cave, Israel, modern humans collected naturally perforated Glycymeris shells also for symbolic use. Use-wear analyses backed by experiments demonstrate that the Qafzeh shells were suspended on string, thus suggesting that the collection of perforated shells was intentional. The older Misliya shells join a similar finding from South Africa, while the later-dated perforated shells from Qafzeh resemble other assemblages from North Africa and the Levant, also dated to about 120 ka BP. We conclude that between 160 ka BP and 120 ka BP there was a shift from collecting complete valves to perforated ones, which reflects both the desire and the technological ability to suspend shell beads on string to be displayed on the human body.

Citation: Bar-Yosef Mayer DE, Groman-Yaroslavski I, Bar-Yosef O, Hershkovitz I, Kampen-Hasday A, Vandermeersch B, et al. (2020) On holes and strings: Earliest displays of human adornment in the Middle Palaeolithic. PLoS ONE 15(7): e0234924. https://doi.org/10.1371/journal.pone.0234924

Editor: Michael D. Petraglia, Max Planck Institute for the Science of Human History, GERMANY

Received: January 27, 2020; Accepted: June 4, 2020; Published: July 8, 2020

Copyright: © 2020 Bar-Yosef Mayer et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Data Availability: All relevant data are within the manuscript and its Supporting Information files.

Funding: Financial support came from the American School of Prehistoric Research, Harvard University and The Israel Science Foundation grant 1973/16 to DEBYM. The Qafzeh excavations (1965-1979) received support from the CNRS and the Ministère Français des Affaires Étrangères, the Centre de Recherche Français de Jérusalem, The Hebrew University of Jerusalem, Tel-Aviv University and The University of Bordeaux to BV and OBY (no grant numbers available). The Misliya Cave project was supported by the Dan David Foundation, Leakey Foundation, Irene Levi-Sala CARE archaeological foundation, Faculty of Humanities of the University of Haifa (no grant numbers available) and the Israel Science Foundation (grant no. 1104/12) to MWE.

Competing interests: The authors have declared that no competing interests exist.

Introduction

Homo sapiens evolved in Africa beginning at least about 200,000 years ago [1,2] and recent evidence suggests an even earlier appearance with specimens from Jebel Irhoud dated to about 300 ka BP [3]. These findings are backed by genetic evidence [4]. Early modern humans migrated out of Africa as early as 194–177 ka BP, as evident from their presence at Misliya Cave, Israel [5,6] and Apidima Cave, Greece [7]. The next physical evidence for the presence of modern humans outside of Africa is known from Skhul Cave [8–10] and Qafzeh Cave, Israel [11–13], as well as Fuyan Cave, Daoxian, China [14].

That modern humans exhibited symbolic behavior is by now well established [15–18] and the use of mollusc shell beads is an expression of this behavior is also well documented [19–21]. Shell beads from the Middle Palaeolithic or Middle Stone Age, dating to 120,000–70,000 years ago are known from three geographic regions: the Levant, North Africa and South Africa [22]. In the Levant, the shell beads found at Skhul Cave dated to between 135 and 100 ka BP, making them among the earliest ever found [23,24]. Though naturally perforated, the shells from Qafzeh Cave were suspended [25,26].

The best examples for early shell assemblages from North Africa are the caves of Contrebandiers [22] and Taforalt [27] both within Marine Isotope Stage (MIS) 5, with a date of 115±3 ka BP for the former, and 82 ka BP or earlier for the latter. Like Skhul and Qafzeh, these sites were occupied by modern humans. They were the ones responsible for the collection and use of the shells in both North Africa and South Africa, where a number of slightly later sites contained shell beads—in particular, Blombos, Sibudu and Border Caves [21, 28, 29] dating to around 80–70 ka BP.

Two other sites stand out in the list of locales containing marine mollusc shells of considerably older age: Pinnacle Point in South Africa, dated to about 160,000 years ago [30] and Misliya Cave on Mount Carmel, dated to between ca. 240,000 and 160,000 years ago [5,6,31]. At neither site were any of the symbolic shells perforated: At Pinnacle Point non-perforated Glycymeris connollyi shells were present and at Misliya Cave [32] Glycymeris nummaria (details in S1 Text in S1 File) were found.

The aims of the current research are: First, to describe the shell assemblage from Misliya Cave. Second, to apply use-wear analysis of the Glycymeris shells from Qafzeh Cave and Misliya Cave, coupled with a detailed experimental program to detect and catalogue microwear traces on bivalves, to test an earlier (but contested) claim that the Qafzeh shells were suspended. Third, to examine the possibility that early Middle Palaeolithic humans collected naturally perforated shells in order to display them as body ornaments, as a means of communication. This behavior was facilitated by the development of string, probably related to change in the style of clothing, apparently between 160 and 120 ka BP, thus the move from non-perforated shells to perforated ones was apparently a two-stage process.

Materials and methods

Mollusc shells were identified to the species level based on comparative material of the mollusc collection of The Steinhardt Museum of Natural History, Tel Aviv University and the WoRMS online database [33].

The analytical protocol used in this research applies the methodological framework of use-wear analysis, comprising a unique program that was formulated to address two main issues in the study of shells: a. To formulate a data set of attributes, borrowed from protocols employed in use-wear analysis of flint [34] and ground stone [35, 36] tools in order to define wear traces on shells; b. To examine whether shells can produce diagnostic traces that may be used to make inferences about the material that had been in contact with the shells or the function of the shell.

In the first set of experiments shells were systematically abraded against various types of materials (fibers, sand, leather, reed, wood, clay, stone, etc.) to produce a catalogue of wear patterns. Wear patterns were defined by their characteristics, looking specifically at polish, striations and pitting. Polish was defined by its topography, distribution, reflectivity and texture; striations were defined by their length, width and depth; and pits were defined by their size, shape, depth and distribution. In the final stage, wear patterns were documented using light microscope cameras and a scanning electron microscope (SEM).

A second set of experiments was aimed specifically at studying traces produced through the use of perforated shells as strung items. We produced strings from wild flax, tied them through the natural holes in Glycymeris by various methods, and put them in simulative settings where they hung loosely or were strung with knots, to create wear patterns produced through different binding modes. The patterns created by the strings and by shells rubbing against each other were then observed and documented (details in S1 Methods in S1 File).

Shells used in the experiments were obtained from The Steinhardt Museum of Natural History, Tel Aviv University, Tel Aviv, Israel. The shells from Qafzeh Cave are on loan from the Israel Museum, Jerusalem, Israel. The shells from Misliya Cave are under study at the Zinman Institute of Archaeology, University of Haifa, Haifa, Israel. No permits were required for the described study, which complied with all relevant regulations.

Results

Misliya Cave

The site and its shell assemblage

Misliya Cave, Mount Carmel (Fig 1), is located at the top of a steep slope 90 m above msl (70 m above its surrounding surface), its entrance facing westward, overlooking the Mediterranean Sea (Fig 2). With a “Tabun D-type” lithic industry (early Mousterian) [32] and thermoluminenscence (TL) dates of 240–160 ka BP [5,6,31] it yielded eleven human-transported shells. The molluscan assemblage (S1 Table in S1 File) consists of Glycymeris nummaria and Cerastoderma glaucum of ornamental or symbolic value. In addition, a few edible species or ecofacts were present (Fig 3; details in S1 Text and S1 Table in S1 File). The four valves of G. nummaria exhibit wear resulting from having been washed ashore as empty shells after the death of the molluscs [37]. The shells found at the cave are slightly damaged and abraded, and one was broken and then abraded, but none were perforated. One was found in the uppermost archeological layer close to the surface, another was discovered in Unit 4 and two more came from Unit 6 of the excavation, both units attributed to the Early Middle Palaeolithic (EMP) based on both lithics and absolute dates (See S1 Text in S1 File). A burnt fragment of a C. glaucum shell was found in Unit 6 as well, while another was embedded in breccia and only a part of the valve could be seen (Fig 3a and 3e), but the brecciated context confirms its association with EMP levels.

Fig 3. Shells from Misliya Cave.

A: Shells of symbolic function: a-c, f: Glycymeris nummaria; d-e: Cerastoderma glaucum. B: Other mollusc shells that were transported into the cave: a-b: Patella caerulea; c: Potamides conicus; d: Melanopsis lampra; e: Donax trunculus. (Photos: Oz Rittner).

https://doi.org/10.1371/journal.pone.0234924.g003

Qafzeh Cave

Microwear analysis

Five shells were selected for microscopic examination due to their good state of preservation. These shells showed traces that were produced by contact with a string, coloring treatment with ochre and traces of shell-to-shell contact, all of which indicate that the valves had been arranged on a string (Table 1).

All shells exhibited fine striations (visible at magnifications of 100-200x) near the hole between the umbo and the center of the hinge (Fig 5a; S1b Fig in S1 File). The orientation of the striations was parallel to the long axis of the shell, corresponding to the pattern observed on the experimental shell.

Fig 5. Use wear on shells from Qafzeh.

a: fine striations near the hole between the umbo and the center of the hinge. b: Polish patches produced by valve-to-valve contact. c: Traces associated with colorant. (Photos: Use-wear Laboratory, Zinman Institute of Archaeology, Iris Groman-Yaroslavski).

https://doi.org/10.1371/journal.pone.0234924.g005

Polish patches produced by valve-to-valve contact were observed on four of the five shells (Table 1; Fig 5b). These isolated patches were distributed along the margins of the shells. The tiny striations appearing on their surfaces were probably produced by grains originating from a red substance, previously identified as ochre [38], which was used to color the shells (clearly visible on two of them, nos. 112 and 107). Based on the distribution pattern of the patches we were able to reconstruct the arrangement of the valves that had rubbed against each other concave side to convex side. A similar rubbing pattern was produced in our experiment. Considering that no such traces were observed on the center of the concave face of the shells, it is reasonable to assume that the shells had touched each other only at their margins.

Traces associated with colorant were observed on four shells (Fig 5c): A wide surface covered with striations indicates that the shell was rubbed against the colorant. The fifth shell had no residue of colorant.

To conclude, our analysis shows that the Misliya shells bore only use-wear consistent with natural abrasion, while the Qafzeh specimens manifested evidence of stringing near the holes, the use of ochre and contact between shells that were strung adjacent to each other.

Discussion

The presence of bivalve shells at sites containing early modern human remains comes as no surprise, as they are considered a hallmark of modern human behavior [17, 39]. Their social role is significant, possibly marking the wearer’s place in kinship networks, marital status and group affiliation. They may have served as a type of charm with apotropaic meanings. The choice of a smooth, round object as a social signal is probably not accidental, because primates’ brains respond favorably to curved forms, including concentric circles [40, 41]. Nonetheless, in order to function as a means of interpersonal communication and provide information about individual or group identity, the shells must not only have a symbolic meaning understood among different groups, they must also be displayed in a way that is clearly visible to others.

Two shell assemblages were chosen to study the notion of shell bead display by humans and its timing: Misliya Cave, dated to ca. 240–160 ka BP [5,6] and Qafzeh Cave, dated to 92±5 ka BP [42] or earlier, ca. 120 ka BP, based on other studies that correlate Qafzeh with MIS 5e [43, 44 and see 45, 46]. In both sites, empty and naturally abraded valves of Glycymeris nummaria had been collected from the Mediterranean shore by modern humans. The Misliya shells were not perforated. The Qafzeh shells included seven with the umbo intact, and all had naturally perforated holes ranging from ca. 3–6 mm in diameter [26].

The Misliya shells show no evidence of human manipulation, apart from having been collected and transported to the cave. The Glycymeris shells from Qafzeh Cave were naturally perforated, and had notches that were assumed to have resulted from their suspension [26]; however, a recent study demonstrated that these notches are part of the variability of naturally abraded holes of Glycymeris, i.e., not indicative of threading [47]. But in our current use-wear experimental analysis (see S1 Text in S1 File) testing various materials rubbing against such shells, the microwear pattern of strung shells corresponds to those observed on five of the best preserved Qafzeh shells, supporting our previous notion that the shells had been suspended.

Shells discovered to date in the Middle Palaeolithic/Middle Stone Age cave sites of Skhul, Qafzeh, Blombos, Border, Sibudu, Taforalt, Contrebandiers and others are dated to between 120 and 70 ka BP, and most are perforated. Ancient collectors relied mainly on naturally perforated and abraded shells and it would be reasonable to assume that much like the Qafzeh shells, those were also strung in order to be displayed [21]. Nonetheless, in two Middle Palaeolithic (or Middle Stone Age) sites, Pinnacle Point and Misliya Cave, dated to 164 ka BP (±12 ka) and 240–160 ka BP, respectively [5, 6, 30, 31] the shells were not perforated. Curiously, in both cases the shells that were collected belong to the genus Glycymeris, and in both sites the shells were rather small and abraded [31].

The desire of some of the earliest modern humans to collect shells may have triggered the search for a way to display them to others, and the already-invented string enabled such exhibition. Physical remains of fibers have been discovered at Dzudzuana (dated to ca. 30 ka BP) [48], where they were spun and dyed, and at Abri du Maras (dated to ca. 80 ka BP [49], where fiber fragments were twisted. At the latter site, a cord fragment adhering to a flake was recently discovered and dated to about 46–40 ka BP [50]. Circumstantial evidence for string use comes from Regourdou, where wear on a tooth suggests the manipulation of cord ca. 72 ka BP [51]. Bone needles, related to the use of string and considered to indicate the use of clothing, first appeared in about 45 ka BP, yet additional indications for the use of clothing date to at least 80 ka BP [52]. These examples are all dated to later than 100 ka BP; and additional evidence for the appearance of strings, cords or fibers indicates even younger occurrences [53, 54]. There are other claims for strung and perforated ornaments earlier than 100 ka BP [55, 56] but the chrono-stratigraphic context of the examples they provide have not been confirmed [57]. The only persuasive case is the recent reexamination of eagle talons from Krapina that revealed a fiber fragment attached to a talon, apparently dating to 130 ka BP [58]. To date, this find has no parallel. This discovery reinforces our notion of a connection between the emergence of string and the emergence of perforated shell beads.

The reasons for shell collection in the EMP could have varied from deep symbols relevant to the protection of life [59] to identity representation. Specific focus on bivalves (Glycymeris and Cerastoderma in the case of Misliya) may have been due to mental templates inherent in all humans. They may represent cosmic powers, but also the mere notion of life itself as originating in the sea. Smooth and round bivalves with their subconscious connotations have a universal appeal.

While these suggestions are based on psychoanalytical research [59], an alternative explanation could be related to the abundance of the species (the Levantine coast’s malacofauna composition in the MIS5e is not known to us) or simply to the attraction of the color or pattern on the natural shells. From as early as the Lower Palaeolithic [60] humans collected shells and carried them to habitation sites, yet around 120 ka BP, they started collecting perforated shells. Because in current thanatocoenosis about 40% of Glycymeris shells are naturally perforated [37], the fact that almost all of the specimens found in the archaeological sites are perforated, albeit naturally, suggests their collection is intentional and is meant to enable their stringing and display. On the other hand, the fact that all shells from two earlier Middle Palaeolithic assemblages are not perforated, suggests that there was neither need, nor intention or possibility of their display, and they were collected for their “face value”, but without necessarily showing them to others.

The ability to display shell beads depended on their suspension on string, directly on the human body or by attachment (sewing) shells onto clothes. We thus come a step closer to finding out the date when the use of string was first introduced. Our data suggest that sometime within the time range of 160 and 120 ka BP the technology for making strings emerged, and that this technology boosted the collection of naturally perforated shells for display, a practice common to this day.

Acknowledgments

We are grateful to The Steinhardt Museum of Natural History, Tel Aviv University for their support. The use-wear analysis was performed at the Use-wear Analysis Laboratory, Zinman Institute of Archaeology, University of Haifa. Misliya Cave is located in the Mount Carmel Nature Reserve, managed by the Israel Nature and Parks Authority. Thanks are due to the Hof Hacarmel Regional Council and the Israel Nature and Parks Authority for their assistance. Special thanks go to the late Dan David and his son, Ariel David, for their inspiration and continuous support of the Misliya Cave excavation project. Israel Antiquities Authority permit numbers for the Misliya Cave excavations: G-16/2001, G-39/2002, G-14/2003, G-29/2004, G-12/2005, G-12/2006, G-4/2007, G-54/2008, G-52/2009, G-50/2010. We thank Marjolein D. Bosch (Cambridge University) for her advice. Jane Balme and an anonymous reviewer are thanked for their comments on a previous version of this paper. We thank Svetlana Matskevitch and Oz Rittner for photography and layout of maps and figures. Prof. Ofer Bar-Yosef passed away before the submission of the final version of this manuscript. Daniella Bar-Yosef Mayer accepts responsibility for the integrity and validity of the data collected and analyzed.

References

1. 1. McDougall I, Brown FH, Fleagle JG. Stratigraphic placement and age of modern humans from Kibish, Ethiopia. Nature 2005;433: 733–736. pmid:15716951
2. 2. White TD, Asfaw B, DeGusta D, Gilbert H, Richards GD, Suwa G, et al. Pleistocene Homo sapiens from Middle Awash, Ethiopia. Nature 2003;423: 742–747. pmid:12802332
3. 3. Hublin J-J, Ben-Ncer A, Bailey SE, Freidline SE, Newbauer S, Skinner MW, et al. New fossils from Jebel Irhoud, Morocco and the pan-African origin of Homo sapiens. Nature 2017;546(7657): 289–292. pmid:28593953
4. 4. Schlebusch CM, Malmström H, Günther T, Sjödin P, Coutinho A, Edlund H, et al. Southern African ancient genomes estimate modern human divergence to 350,000 to 260,000 years ago. Science 2017;358(6363): 652–655. pmid:28971970
5. 5. Hershkovitz I, Weber GW, Quam R, Kinsley L, et al. The earliest modern humans outside Africa. Science 2018;359(6374): 456–459. pmid:29371468
6. 6. Hershkovitz I, Duval M, Grün R, Mercier N, Valladas H, Ayalon A, et al. Response to comment on “The earliest modern humans outside Africa”. Science 2018;362: eaat8964. pmid:30361343
7. 7. Harvati K, Röding C, Bosman AM, Karakostis FA, Grüb R, Stringer C, et al. Apidima cave fossils provide earliest evidence of Homo sapiens in Eurasia. Nature 2019;571(7766): 500–504. pmid:31292546
8. 8. Garrod DAE, Bate DMA. The Stone Age of Mount Carmel, Oxford: Clarendon Press; 1937.
9. 9. McCown T, Keith A. The Stone Age of Mount Carmel. Vol. 2: The Fossil Human Remains from the Levalloiso-Mousterian. Oxford: Clarendon Press; 1939.
10. 10. Grün R, Stringer C, McDermott F, Nathan R, Porat N, Robertson S, et al. U-series and ESR analyses of bones and teeth relating to the human burials from Skhul. Journal of Human Evolution 2005;49(3): 316–334. pmid:15970310
11. 11. Vandermeersch B. Les hommes fossiles de Qafzeh (Israël). Paris: CNRS; 1981.
12. 12. Vandermeersch B, Bar-Yosef O. The Paleolithic Burials at Qafzeh cave, Israel. Paléo 2019;30(1): 256–275.
13. 13. Valladas H, Mercier N, Hershkovitz Y, Zaidner Y, Tsatskin A, Yeshurun R, et al. Dating the Lower to Middle Paleolithic transition in the Levant: A view from Misliya cave, Mount Carmel, Israel. Journal of Human Evolution 2013;65: 585–593. pmid:24034982
14. 14. Liu W, Martinón-Torres M, Cai Y-J, Xing S, Tong H-W, Pei S-W, et al. The earliest unequivocally modern humans in southern China. Nature 2015;526(7575): 696–699. pmid:26466566
15. 15. McBrearty S, Brooks AS. The revolution that wasn’t: A new interpretation of the origin of modern human behavior. Journal of Human Evolution 2000;39(5): 453–563. pmid:11102266
16. 16. d’Errico F, Stringer CB. Evolution, revolution or saltation scenario for the emergence of modern cultures?. Philosophical Transactions of the Royal Society B: Biological Sciences 2011;366: 1060–1069.
17. 17. Kuhn SL. Signaling theory and technologies of communication in the Paleolithic. Biological Theory 2014;9: 42–50.
18. 18. Wadley L. What is cultural modernity? A general view and a South African perspective from Rose Cottage Cave. Cambridge Archaeological Journal 2001;11(2): 201–221.
19. 19. Stiner MC. Finding a common bandwidth: Causes of convergence and diversity in Paleolithic beads. Biological Theory 2014;9: 51–64.
20. 20. Malafouris L. Beads for a plastic mind: The ’blind man’s stick’ (BMS) hypothesis and the active nature of material culture. Cambridge Archaeological Journal 2008;18(3): 401–414.
21. 21. Vanhaeren M, d’Errico F, van Niekerk KL, Henshilwood CS, Erasmus RM (2013) Thinking strings: Additional evidence for personal ornament use in the Middle Stone Age at Blombos Cave, South Africa. Journal of Human Evolution 64: 500–517. pmid:23498114
22. 22. Steele TE, Álvarez-Fernández E, Hallett-Desguez E. A review of shells as personal ornamentation during the African Middle Stone Age. PaleoAnthropology 2019;2019: 24–51.
23. 23. Bar-Yosef Mayer DE. The exploitation of shells as beads in the Palaeolithic and Neolithic of the Levant. Paléorient 2005;31(1): 176–185.
24. 24. Vanhaeren M, d’Errico F, Stringer C, James SL, Todd JA, Mienis HK. Middle Paleolithic shell beads in Israel and Algeria. Science 2006;312: 1785–1788. pmid:16794076
25. 25. Taborin Y. La mer et les premiers hommes modernes. In: Vandermeersch B, editor. Échanges et diffusion dans la préhistroire Méditerranéenne. Paris: Editions du comité des travaux historiques et scientifiques; 2003. pp 113–122.
26. 26. Bar-Yosef Mayer DE, Vandermeersch B, Bar-Yosef O. Shells and ochre in Middle Paleolithic Qafzeh cave, Israel: Indications for modern behavior. Journal of Human Evolution 2009;56: 307–314. pmid:19285591
27. 27. d’Errico F, Vanhaeren M, Barton N, Bouzouggar A, Mienis HK, Richter D et al. Additional evidence on the use of personal ornaments in the Middle Paleolithic of North Africa. PNAS 2009;109(38): 16051–16056.
28. 28. d’Errico F, Backwell L. Earliest evidence of personal ornaments associated with burial: The Conus shells from Border Cave. Journal of Human Evolution 2016;93: 91–108. pmid:27086058
29. 29. Vanhaeren M, Wadley L, d’Errico F. Variability in Middle stone age symbolic traditions: The marine shell beads from Sibudu Cave, South Africa. Journal of Archaeological Science: Reports 2019;27: 101893.
30. 30. Marean CW, Bar-Mattews M, Benatchez J, Fisher E, Goldberg P, Herries AIR, et al. Early human use of marine resources and pigment in south Africa during the Middle Pleistocene. Nature 2007;449: 905–908. pmid:17943129
31. 31. Jerardino A, Marean CW Shellfish gathering, marine palaeoecology and modern human behavior: Perspectives from cave PP13b, Pinnacle Point, South Africa. Journal of Human Evolution 2010;59: 412–424. pmid:20934094
32. 32. Weinstein-Evron M, Zaidner Y. The Acheulo-Yabrudian—Early Middle Paleolithic Sequence of Misliya Cave, Mount Carmel, Israel. In: Marom A, Hovers E, editors. Human Paleontology and Prehistory: Contributions in Honor of Yoel Rak. Dordrecht: Springer; 2017. pp. 187–201.
33. 33. MolluscaBase (2019) Glycymeris nummaria (Linnaeus, 1758). accessed through: World Register of Marine Species 2019(-03-05)
34. 34. Van Gijn AL. The wear and tear of flint: principles of functional analysis applied to Dutch Neolithic assemblages. Leiden: University of Leiden; 1990.
35. 35. Adams JL, Deldado S, Dubreuil L, Hamon C, Plisson H, Risch R. Functional analysis of macro-lithic artefacts: A focus on working surfaces. In: Sternke F, Eigeland L, Costa LJ, editors. Non-Flint Raw Material Use in Prehistory Old Prejudices and New Directions Oxford: Bar International Series 1939; 2009. pp. 43–66.
36. 36. Dubreuil L, Savage D. Ground stones: A synthesis of the use-wear approach. Journal of Archaeological Science 2014;48: 139–153.
37. 37. Sivan D, Potasman M, Almogi-Labin A, Bar-Yosef Mayer DE, Spanier E, Boaretto E. The Glycymeris query along the coasts and shallow shelf of Israel, southeast Mediterranean. Palaeogeography, Palaeoclimatology, Palaeoecology 2006;233: 134–148.
38. 38. Walter P. Caractérisation des traces rouges et noires sur les coquillages perforés de Qafzeh. In: Vandermeersch B, editor. Échanges et diffusion dans la préhistoire méditerranéenne. Nice: CNRS. 2003; pp. 122.
39. 39. Godfrey-Smith P. Signs and symbolic behavior. Biological Theory 2014;9: 78–88.
40. 40. Hodgson D. Understanding the origins of paleoart: The neurovisual resonance theory and brain functioning. PaleoAnthropology 2006;2006: 54–67.