Inora Newsletter #44
SEXUAL DETERMINATION OF HAND STENCILS ON THE MAIN PANEL OF THE GUA MASRI II CAVE (EAST-KALIMANTAN/BORNEO INDONESIA)
Questions concerning age, gender of fingers or even of hand marks and stencils began to be studied some time ago with promising results by some scholars, including Sharpe and Van Gelder (Sharpe & Van Gelder, 2004) in particular at the IFRAO/RASI Agra Conference (last December 2004), or Snow. In fact, it was only after our program conception and tests were completed and our article finished (29 November 2005), that we incidentally learned by an e-draft called: “Sexual Dimorphism in Upper Paleolithic Hand Stencils”, that Snow had engaged a similar application of the Manning's ratios but not yet with any specific program. Our treks thus appear to be fortuitously converging and probably complementary.
The fact is that in a recent study by John T. Manning (Manning 2002; Manning et al. 1998), the ratio between two fingers of a hand (ring-finger and forefinger) is presented as expressing sexual identity. This is valid for everybody. According to this author, in the first months of a foetus’ life, the contributions of some hormones would influence the development of the fingers. Thus, oestrogens would mainly play a part in the growth of the forefinger whereas testosterone would do the same for the ringfinger. As a result, the ratio between forefinger and ringfinger sizes (called ratio 2-Digit/4-Digit or 2D/4D) will vary according to gender.
Moreover, Manning's statistical studies show that these ratios also vary according to human groups. Thus, in present day Europe, a man would have an average ratio of 0.96 and a woman an average ratio of 1.
Groups living closer to the Equator, however, seem to have smaller ratios, but the same mean difference exists between men and women.
If those observations are right, they may be applied to other disciplines, among which archaeological prehistory with its numerous handprints found in many caves and shelters all over the world. They provide clear examples of possible sexual differentiation. We thus decided to try and apply the formula and test it in order to get an overview of the possibilities opened by that unexpected correlation.
Although crucial questions remain unanswered -like: did the prehistoric ratios evolve in time? were they similar in any place in the world or were they smaller or higher in previous times?- our first results already provide an insight about preliminary interpretations for prehistoric East Borneo.
Application to prehistoric hand stencils
The possibility of determining a person’s sexual identity from measurements taken from his/her hand (or from its picture) allows us to try and determine the sexual identity of people having left hand stencils in prehistoric decorated caves.
If the sexual difference between men and women could be expressed or reproduced by their hand prints and stencils, it should be possible as a consequence to detect evidence of some social organization.
Based upon the probability that Manning's formula is valid, a specific program was then elaborated (Kalimain ©Noury 2005). It is able to check the size and morphology of hand stencils and hand prints, then, by using both one of the numerous remarkable hand stencil panels from Borneo and Manning's ratios, to test the efficiency of its application into Rock Art interpretation (see http://www.kalimanthrope.com for images and http://www.pacific-credo.net/staff (chazine) for a more complete bibliography).
The test sample selected is the large panel at Gua Masri II (Fig. 1) located in Indonesian East Borneo. It was discovered and studied by L.-H. Fage, J.-M. Chazine and P. Setiawan (Chazine 1999; Chazine & Fage 1999a & b). As the decoration of the cave is only made up of 140 or so hand stencils, that panel only consists of handprints, 34 of which could be identified and recorded by our team.
Applying Manning's 2D/4D ratio after visual analysis of each hand was managed by the program. After some calculation, it allowed us to determine the sexual identity of their authors (Fig. 2).
Right now, 16 hands are allotted to men and 15 to women; 3 gave litigious results, whereas one hand remains indeterminate because of its incomplete fingers. Calculation of ratios permitted us to determine that, for the 34 hands at Masri II, 15 are women’s hands and 16 are men’s hands. Two “litigious” hands, whose ratios are 0.998 and 0.985 (being close to 1) and the hand with a ratio of 0.977 would also correspond to a man (although the latter remains somehow hypothetical).
These first results (supposing all the hand stencils should be contemporaneous) show that the distribution of men and women does not seem to be random (Fig. 2). Men’s and women's hands are located in three different visible areas. Moreover, the sexual differentiation of the hands precisely confirms our first impression of a deliberate organization. Their areas and forms of distribution are not the same from one place to the other. Circular dispersal and bipolar impositions appear to be more linked to women's practices.
This first level of interpretation, based upon a schematic computerised image of paintings, does not allow us to proceed further and to attribute a firm chronology to the different paintings. Closer observation is still needed to work out a definite succession order in the realisation of the paintings. When this is done, the importance of sexual differentiation will take up all the more importance, in particular if we can correlate it to the lateralization process, whose importance might be major.
Another important function is under study with Kalimain1.0. It concerns the locations of hands from one and the same person. Kalimain can also calculate the ratios for all fingers and compare them with those of other hands formerly discovered. A first test using a ±10% difference bracket for similarity was used. Its results are presented in Fig. 3.
They show that six different hands were identified as being multiple or reproduced. This is a complementary indication which may be used later, depending on the values of the factors selected in the program, for a more precise sexual identification, as well as to establish the chronology of the process. Different finger sizes and hand characteristics will complete the correct individual (and gendered) identifications.
This first summary study of the Gua Masri II panel, using Manning's ratios integrated into a specific program created for that purpose, is particularly rich concerning the lay-out of the paintings and the processes of their realisation:
The panel was made by both men and women, in differentiated places, but none of the two genders seems to have had a numerical prevalence on the other.
Each gender seems organized in a different manner: men rather chose a system based on “succession” or “hierarchy”, while women preferred to paint their hands in a “circuit” or a “path” recalling a spiral.
At least six different individuals took place in the process (a more precise account is under study).
Among the six “identified” people, at least two series of hand stencils were carried out at different places which had obviously been chosen intentionally. Each hand would thus be involved in the conception of each complete part forming the whole panel.
Other hand stencilled panels from East Borneo, found during our Kalimanthrope's surveys (and also some other well-known World Heritage List sites) are under study and have begun to reveal unexpected dispersals or concentrations from the point of view of gender.
Other applications of the Kalimain (©Noury 2005) program will soon be undertaken with some other contemporary and well-dated hand prints and stencils, after further checks that will complement our program.
The actual development of this program already provides numerous opportunities for studying any occurrences and correlations linking motifs, locations, quantities, similarities and all other statistical combinations happening in various Rock Art expressions. Its further extension will enlarge these capacities even more.
Jean-Michel CHAZINE1 & Arnaud NOURY2
1 Ethno-archéologue, CNRS/MAP-CREDO/Marseille
2 Analyste-programmeur et archéologue océaniste amateur
CHAZINE J.-M., 1999. Préhistoire : Découverte de grottes ornées à Bornéo. Archeologia, 352, janv. 1999, p. 2-19.
CHAZINE J.-M. & FAGE L.-H., 1999a. La Ligne de Wallace a-t-elle été franchie par les artistes des temps préhistoriques ? Deux nouvelles grottes ornées à Bornéo en sept. 1998. Karstologia, 32, fév. 1999, p. 39-46.
CHAZINE J.-M. & FAGE L.-H., 1999b. De Nouvelles grottes ornées à Bornéo. INORA, 23, p. 1-3.
MANNING J. T. , 2002. Digit Ratio: A Pointer to Fertility, Behavior and Health. Rutgers University Press.
MANNING J. T., SCUTT D., WILSON J. & LEWIS-JONES D. I., 1998. The Ratio of 2nd to 4th Digit Length: A Predictor of Sperm Numbers and Concentrations of Testosterone, Luteinizing Hormone and Oestrogen. Human Reproduction,13 :11, p. 3000-3004.
SHARPE K. & VAN GELDER L., 2004. A Method for Studying Finger Flutings, to be published in Exploring the Mind of Ancient Man: Festschrift to Robert G. Bednarik.
SNOW D. R, 2005. Sexual Dimorphism in Upper Paleolithic Hand Stencils. e-draft 15 p. (pers. comm. to L.-H. Fage, Sept. 2005).