Saturday 7 January 2023

Understanding the message behind Europe's Upper Palaeolithic cave art.

Prior to about 37 000 years ago, cave art in Europe consisted largely of patterns of hand-prints, rectangles, and dots. After this time, a wealth of engraved and painted images swept across the continent, depicting the Animals of the Late Pleistocene with a realism that still impresses modern artists. Almost all of these artworks depict large herbivorous Animals, thought to have been important food sources for hunters on the Eurasian Steppes. In most cases it is easily possible to tell what species is being depicted, and even what time of year the image was portraying. The paintings on the walls of the Lascaux Cave in southwest France show a sequence of rutting Animals which can be interpreted as an ethological calendar (calendar of Animal behaviour), and at other sites the presence of Cervids (Deer) with antlers, and the aggressive postures of these Animals, have been interpreted as depiction of a particular season.

However, this cave art does not just depict Animals, alongside these images are frequent abstract marks, mostly dots and lines, but including other shapes such as 'Y's. These marks are usually either directly adjacent to the Animal images, or actually overlie them, suggesting a strong connection between the two. Similar marks have been found carved onto bones, dating from the onset of the European Upper Palaeolithic (roughly equivalent to the African Middle Stone Age) onwards, and are generally thought to have had a recording function. It has been generally assumed that such marks are numeric, and probably recording periods of time, but their exact message has remained unclear. 

Previous studies have found that 66% of the Animal depictions in Upper Palaeolithic European cave art are associated with other symbols, although these vary in form, and probably convey a variety of messages. It is also likely, given the long chronological range and wide geographical area over which these symbols are found, that more than one form of symbolic recording is present. 

In a paper published in the Cambridge Archaeological Journal on 5 January 2023, independent researchers Bennett Bacon, Azadeh Khatiri, and James Palmer, together with Tony Freeth of the Department of Mechanical Engineering at University College LondonPaul Pettitt of the Department of Archaeology at the University of Durham, and Robert Kentridge of the Department of Psychology at the University of Durham and the Canadian Institute for Advanced Research programme in Brain, Mind and Consciousness, focus on two clear and simple patterns found in many of these depictions: Animals found associated with rows of dots and/or lines (which are presumed to be functionally the same) and branching 'Y' symbols. 

These symbols are found throughout the European Upper Palaeolithic, although most common from the later portion of this period, possibly implying that they became more common over time. Bennet et al. consider the meaning of the Animal depictions to be unambiguous, but consider the lines, dots, and 'Y' symbols to be potentially interpretable, and related to the ethology of the Animals they are found close to. The basis for this assumption is that the dots and lines in these sequences represent numbers, and that the combination of numbers and recognisable Animals gives the basis for deciphering messages tens of thousands of years ago.

Examples of animal depictions associated with sequences of dots/lines. (a) Aurochs: Lascaux, late period; (b) Aurochs: La Pasiega, late; (c) Horse: Chauvet, late (we differ in opinion with the Chauvet team, for whom it would be early); (d) Horse: Mayenne-Sciences, early; (e) Red Deer: Lascaux, late; (f) Salmon: Abri du Poisson, early; (g) Salmon (?): Pindal, late; (h) Mammoth: Pindal, early. Bacon et al. (2022).

It is now generally accepted that the regular marks left by Upper Palaeolithic peoples represent a form of counting, and therefore the storage of information outside of the brain. The processing of numbers can be done in several ways; by subitisation, or simply recognising small groups of objects at a glance (e.g. six tins in a box), by cardinality, or counting objects (twenty sheep in a field), or by ordinality, being able to place objects within a sequence (the third house in a row). Experimentally these have been shown to be distinct skills, carried out in different parts of the brain, and children have been shown to develop these skills in order as they develop, starting with subitisation and progressing to ordinality. 

In 1991, Alexander Marshack suggested that the dots and lines seen in Upper Palaeolithic art were numbers, most likely representing periods of time. In his view, each dot or line was likely to represent a day, with the sequences of pictures they were associated with being lunar calendars. The lunar calendar theory failed to win many supporters within the academic community, but the concept of the representations as a simple way of recording events outside the mind did gain wider acceptance. 

The grouping of engraved marks on bones and antlers from the Upper Palaeolithic has led to the conclusion that these marks were being used to store information, and that this information was most likely numeric. This has in turn led to the suggestion by cognitive archaeologist Karenleigh Overmann  that once Humans had begun to collect numerical data, it was almost inevitable that they would apply this to time, and in particular the seasons, important phenomena in the lives of people so closely dependent on nature.

The sequences of dots and lines found adjacent to Palaeolithic Animal images fit the same criteria for representing numbers as the carvings on bones and antlers, and are consistently arranged in lines horizontal to the orientation of the Animal images (which are often on ceilings). These sequences vary in length, but appear to have been recording numbers using the additive principle, where an extra mark represents an increase by one (as in the Roman numerals, I, II, III; or the Chinese 一, 二, 三).

In the 1990s archaeologist Carole Fritz assembled a database of 90 symbols used on portable objects associated with the Late Palaeolithic Magdalenian Culture, collected from the Dordogne and Pyranees, and including linear marks, dashes, angular signs, arc shapes, broken lines, dots, various impact marks and combinations and repetitions thereof. These symbols were used consistently at sites associated with the Magdalenian Culture, with no discernible variations over space and time. Based upon this, Fritz concluded that these marks represented a method of storing information recognised across the Magdalenian Culture, although the exact meaning implied remained obscure.

Hunting appears to have been an important source of nutrition to Upper Palaeolithic peoples, with the most important prey species being Horses, Bovids, Cervids, Caprids, Proboscideans, Birds, and aquatic Animals. Modern populations of these Animals show strong seasonal patterns of behaviour, with cycles of mating and birthing, and seasonal migrations in the spring and autumn. During this seasonal cycle, many of these Animals shift between large and small groups, and are present on different parts of the landscape.

Zooarchaeological studies have revealed a similar seasonality in the behaviour of these Animals during the Pleistocene, and it seems likely that a knowledge of migration patterns and breeding cycles would have been key information to Upper Palaeolithic hunters dependent on these Animals for survival. As such, it is unsurprising that these Animals were a central preoccupation for these people, and that images of them dominate their art. Furthermore, at sites such as Lascaux Cave depict these Animals in such detail that their pelage, hair, antler growth, gregarious and aggressive behaviour and other indications of rutting can be used to show that their breeding behaviour was also of great interest. Many of the Animal images at Lascaux are associated with symbols; for example a row of swimming Stags, generally interpreted as an autumn migration scene, is accompanied by a row of seven red dots, while a mating scene with male and female Aurochs in their summer coat is marked with four black dots. At a scene from the slightly later Font de Gaume Cave two Reindeer stags are depicted with locked antlers, and marked with a set of eight dots.

Bacon et al. accept the premise that the sequences of dots and lines associated with the Upper Palaeolithic Animal images are saying something about the Animals in the images with which they are associated. Furthermore, they accept that these are abstract representations, rather than parts of the images, noting that several different taxa are consistently annotated with the same number of dots, but on different parts of their anatomies. Given this consistency, they also accept that the message conveyed by the dots is numerical in nature, being either cardinal or ordinal.

Working from this, they assume that the objective was to convey some form of useful numeric information about specific prey Animals to future readers. Given this, it seems unlikely that they were recording the number of Animals sighted, the time at which they were sighted, or even the number of Animals killed. It is likely, however, that they would have wanted to record information about migrations, times when Animals could be relied upon to form aggregations, and times when Animals were most vulnerable to attacks by hunters (i.e. mating and birthing). Working from these assumptions, Bacon et al. propose that the timing of such events is the most logical numerical information to have been juxtaposed with the Animal images.

If Upper Palaeolithic people were able to record numbers using the additive principle, then it is quite likely that the rows of dots or lines seen on their art represent amounts of time. Furthermore, the number of dots or lines associated with an Animal image is never particularly high (and never higher than thirteen), so if each dot or line represents a single unit of time, then that unit is almost certainly a lunar month, since this is one of the few units which would have been obvious to pre-agricultural people. Based upon this, Bacon et al. believe that the dots and lines present in Upper Palaeolithic images represent lunar months, presenting information about the behaviour of Animals on a seasonal calendar. 

If this is correct, then the calendar being used by these people must have had an established beginning; a time of year against which the tallies could be counted, giving the people using it a point to count from. Most historical calendars have their roots in astronomical observations, counting from the solstices and equinoxes. These give accurate dating systems usable by agriculturalists, but are difficult to observe, and likely to have been of limited use to Palaeolithic hunters. Rather, these people lived in a world dominated by meteorological events, and seasonal cycles in temperature and the behaviour of Plants and Animals. One seasonal event which Bacon et al. believe would have been hard for Palaeolithic peoples to miss would have been the annual spring thaw. This is widely referred to using the French term bonne saison by zooarchaeologists, marking a period when rivers unfroze, snow melted, and the world began to turn green. This would not have occurred everywhere at the same time, with spring coming several weeks earlier in southern Europe than in the north, but would have provided a useful starting point for a yearly calendar used by people needing to track the migrations and mating habits of Animals, but not exchange accurate date information with distant communities. 

One of the problems for peoples wanting to record time in the ancient world was that the solar year cannot be divided into an exact number of lunar months (there are approximately 12.37 lunar months in one solar year). This led to the development of a variety of complex calendars, with periodic adjustments being made to bring the solar and lunar cycles into alignment. None of this is likely to have mattered much to Upper Palaeolithic peoples counting from the bonne saison, who could have just counted the lunar months from each spring thaw into the depths of winter, when it would have become irrelevant. 

Bacon et al. therefore theorise that the sequences of dots and lines in Upper Palaeolithic art represent lunar months after the bonne saison. Therefore, if an Animal is represented along with a sequence of three dots, then the intent was to imply some important feature of that Animal's life cycle happened three months after the spring thaw. This is technically an interval calendar, recording that events happened a certain period after the bon saison, rather than a true calendar recording accurate dates.

Furthermore, Bacon et al. note that many of the sequences contain a 'Y' symbol in the midst of a series of dots or lines, which they believe represents a significant event in the life cycle of these Animals, and reason must be one of four possible annual occurrences, spring migration, mating, birthing, or autumn migration. 

The 'Y' symbol is one of the most commonly depicted symbols in Upper Palaeolithic art, and therefore presumably has an important meaning. Bacon et al. note that the position of this symbol within sequences varies between Animal taxa, but remains constant for each taxon, implying that it is carrying species specific data, and that that data appears to be ordinal in nature, within an ordinal sequence. Thus the total number of symbols potentially records one piece of information, with the position of the 'Y' symbol conveying a second. Bacon et al. further propose that, given the known biology of the Animals involved, the 'Y' symbol is most likely to represent birthing.

In order to test this hypothesis Bacon et al. compiled a database of Animal symbols with associated symbol sequences, and compared these to known data on the reproduction and migration of their modern relatives, and information about Pleistocene Animals established by previous zooarchaeological studies. Having eliminated any dubious or ambivalent sequences from the record, Bacon et al. were left with 256 sequences containing a 'Y' symbol and 606 sequences which did not.  The majority of these sequences came from France and Spain, although some came from further east. Chronologically, the images span the whole of the Late Upper Palaeolithic, although the majority come from the end of this period. 

Bacon et al. initially divided their data into two chronological sections, the Early and Middle Upper Palaeolithic Aurignacian and Gravettian cultures, and the Late Upper Palaeolithic Solutrian and Magdalenian cultures, but surprisingly no difference could be found between these datasets, suggesting that, contrary to expectations, the same data-recording system seems to have persisted in Europe for over 20 000 years. 

For the sake of convenience, Bacon et al. sorted some of the Animals depicted into groups, such as Cervids, Caprids, Birds, and Fish, while others were retained as separate species, i.e. Bison, Aurochs, Horses, Mammoths and Rhinos. Other species, such as Snakes and Wolverines, were present, but in very low numbers, and were excluded from the dataset, as were images of Humans.

In order to make the comparison, Bacon et al. converted the expected birthing season for the Animals into months relative to the Pleistocene bonne saison. Thus, assuming the bonne saison started around the start of May, the birthing season for European Bison, typically August, should be 3 or 4. Such a calendar is necessarily approximate, given that it is based upon seasonal events which might themselves vary from year to year, and will certainly vary regionally.

Bacon et al.'s prediction was that the 'Y' symbols related to each Animal group should be clustered, rather than randomly distributed throughout the sequences, and that these clusters should correspond to the predicted birthing seasons of the Animals, adjusted to an ordinal calendar rooted at the bonne saison. Since this should be different for the different groups, the position of the 'Y' symbol in the sequence should also vary between groups.

This prediction proved to be true for the majority of the groups, with the 'Y' symbol being both consistent and coinciding with the predicted birthing season for Aurochs, Bison, Horses, Fand Mammoths, and less clear but still matching the prediction for Cervids. Only Caprids failed to match the prediction, with no clear pattern observable in the data for this group. No correlation could be made between the position of the 'Y' symbols and the predicted times of mating or migration. However, the observed total number of marks correlated to the predicted mating season for Aurochs, Bison, Horses, Mammoths, and probably Cervids.

The two non-Mammalian groups, Birds and Fish, showed slightly different patterns, with the 'Y' correlating with mating and the end of the line with hatching for Birds, and the 'Y' correlating with the spring migration and the end of the line with hatching in Fish; in both cases the sequence relates to the appearance of a food source.

Bacon et al.'s data provides strong statistical evidence for a correlation between the position of a 'Y' symbol in a sequence associated with an image of an Animal, and the birthing season of that Animal, as calculated on an interval lunar calendar rooted in the Pleistocene bonne saison. It also provides weaker statistical support for the total number of marks representing the mating season of the same Animals. 

The idea of Upper Palaeolithic peoples in Europe using a form of numeric notation using notches, lines, and other marks has been accepted for some time, and is no longer really controversial. Based upon this, it has also been generally assumed that other marks used by these people were recording some form of information, although the exact nature of this information has, until now, remained unclear. 

Bacon et al. propose that the symbols associated with the (unambivalent) Animal images relates directly to the biology and behaviour of those Animals, providing a key to understanding the Upper Palaeolithic notation system. This is based on the assumption that the position of a particular mark, the 'Y' symbol, within a sequence of simpler marks (dots or lines), represents a key event in the life cycle of these organisms, in this instance the birthing season, something supported by a statistical analysis of the data.

This means that these Upper Palaeolithic people had a means of preserving information which could be read back after thousands of years, by people who might have quite different languages, but understood the common notation system (we know little of the languages spoken in the Upper Palaeolithic, but they are unlikely to have remained constant for tens of thousands of years). The widespread use of this system over long periods of time and a wide geographical area suggests that it was important to record this information in a way that went beyond oral traditions (although these are likely to have also been used).

The symbols represent more than a simple tally, and Bacon et al. propose that they represent the development of a simple calendar, based upon meteorological events and the biology of important prey Animals. This would predate by many thousands of years any previously known calendar or writing system.

It is far from clear how widely the interpretation of this data would have been understood in the communities which produced it. Objects, such as bones or antlers, with tallies on them are widely known from this period, and would presumably have been present in domestic environments, carried by members of the community. However, the cave art was typically placed in deep cave environments, where it was potentially not seen by the whole community, and may have been restricted to a small number of people.

Bacon et al. do not argue that their interpretation is exclusive of the artworks having had other purposes, aesthetic or ritual, nor do they claim to have unravelled all of the meaning behind the symbols (other symbols are present in the cave art, which they have not included in this study). Furthermore, they do not assert that this notation system was used by all peoples present in Europe throughout the Upper Palaeolithic, and acknowledge that there are plenty of instances of Upper Palaeolithic art in which Animals are depicted without the presence of additional symbols of any kind.

They do however, believe they have uncovered a method of storing data about the behaviour of important prey Animals, which was used in parts of western and central Europe for a period which lasted from about 37 000 years ago to about 13 000 years ago. In this interpretation, the individual images do not represent individual Animals, but are instead representative of entire species, and the behaviour of these species as experienced by the creators of the art. 

The rows of symbols and position of marks within them represent a simple syntax combining linear and ordinal numbers to record and communicate information, a form of intellectual abstraction, something which is considered to a key achievement of modern Humans (Upper Palaeolithic peoples are universally accepted as fully Modern Humans). This ability to record a combination of information derived the behaviour of Animals, number-based information, seasonal meteorology, and lunar months, therefore represents a significant intellectual achievement. This provided a system to preserve this information that went beyond oral tradition, and enabled the comparison of data from multiple years, presumably enabling the people who collected it to make estimations about variations in natural phenomena, something hard to do with purely oral records.

This raises the question of whether this system could genuinely be called writing. The system does seem to be able to deal with discrete quantities, i.e. using numbers to say something about the Animals they are associated with, rather than just counting the numbers. Furthermore, the use of placement to determine the value of the 'Y' symbol is a precursor of the use of place to show the value of a number (as in 1, 10, 100), something previously assumed to have been a Sumerian invention. It could even be considered that the 'Y' symbol represents a verb, 'to give birth', although this is less than clear, it could simply be a noun such as  'birth' or 'birthplace'.

The common modern use of the term language implies that it has a phonetic connection to a spoken language, generally that used by the writer. This is again thought to have originated in ancient Sumer, Mesopotamia, around 3300 BC, when a system comprising a mixture of pictograms and abstract numerical symbols first appeared. These system evolved into Cuneiform, which is considered to be a script rather than a language (in the sense that the modern English and French languages are written in Latin script). A form of record-keeping using small tokens is known to have been used in the Near East in the Neolithic, during the tenth millennium BC, with the system evolving over time and being widespread in the region by the sixth millennium BC. By the fourth millennium BC these tokens appeared to have taken other, non-numeric functions, something which evolved further into the Cuneiform script of Uruk-era Sumer. 

Bacon et al. postulate that the European Upper Palaeolithic system actually conveys more information than the first Mesopotamian scripts, in that in relates the behaviour of wild Animals to a meteorologically derived calendar, whereas the earliest Mesopotamian records appear to have just recorded quantities of items. Based upon this, they argue that this system can justifiably be called a script. However, they note that the system gives no indication as to how the people using it would have described the Animals depicted, the Moon or its phases, or the bonne saison, although they do assume that these people would have been able to describe all these things orally.

The European Upper Palaeolithic recording system appears to contain no grammatical syntax, which would justify its description as a true written language, but does seem to be recording data at least as well as the proto-Cuneiform script of ancient Sumer (although, unlike the Sumerian records, this system could not be described as 'administrative documents'). 

For this reason Bacon et al. do not press the claim that this system should be seen as a language (something they see as potentially controversial, and at best semantic), but a form of proto-writing forming a step between a simple tallying system and a true writing system. They are aware that this claim is likely to be contested, and that others in the field are likely to come up with other ideas about what this system should be called. 

For the time being they restrict themselves to describing the system as a form of proto-writing, conveying a phrenological/meteorological calendar, although they welcome debate on the subject. However this system should be described, it clearly represents a system of symbolic record-keeping dating from tens of thousands of years before the earliest Sumerian writing system, making it a highly significant discovery.

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