Ice Age Cave Signs May Record Lunar Months and Animal Births, Study Suggests

A possible calendar beside the animals

A 2023 study proposes that dots, short lines and Y signs beside Ice Age animal pictures recorded lunar months and the timing of animal births. Its researchers compiled 606 animal depictions accompanied by dots or lines and another 256 with a Y added to the sequence. None of the sequences exceeded 13 marks.

Ben Bacon, an independent researcher based in London, developed the interpretation with academic collaborators. Their proposed system starts counting months in spring, when snow and ice receded and rivers thawed. Each dot or line represents a lunar month, while the position of the Y identifies the month of birth.

The suggestion gives a practical purpose to marks found beside bison, horses, deer, salmon and mammoths: they may have helped people anticipate mating, births and seasonal movements. Those events could determine when hunters found animals gathered together, when vulnerable newborns appeared and when fish moved upstream.

For generations, accounts of writing's origins have begun in Mesopotamia around 3400 to 3200 BC, with clay tablets bearing signs that developed into cuneiform, the script associated with wedge shaped impressions. The cave interpretation proposes a much earlier chapter in recording information, moving the beginnings of proto writing back by at least ten millennia.

Researchers disagree over both the proposed meanings and the label. Bacon's team describes a system at least 20,000 years old that stored particular facts rather than speech. Other specialists prefer terms such as notation or graphic communication. Their debate concerns what the marks meant, how consistently people used them and where information storage ends and writing begins.

A small repertoire across a vast landscape

Paleoanthropologist Genevieve von Petzinger's research provides a broader setting for the calendar proposal. A decade of fieldwork, including visits to 52 sites in France, Spain, Italy and Portugal, identified 32 recurring geometric symbols across a period of at least 30,000 years.

Her catalog includes dots, lines, triangles, zigzags, grids, ladders and negative hands, the outlines left when pigment surrounds a hand. It also includes penniforms, which resemble feathers, and tectiforms, which look like a post supporting a roof. The repeated use of a limited repertoire suggests deliberate choices and a shared tradition that may have roots outside Europe.

At Lascaux and Chauvet in France, Altamira in Spain and many less familiar caves, simple signs accompany animal scenes. Artists changed the size and style of their work while continuing to draw from a relatively small set of shapes. In many caves, geometric signs outnumber animal figures by at least two to one.

The marks occupy entrances, connecting passages and deep chambers. Some stand alone; others form clusters or appear closely associated with particular species. Their makers painted, engraved or pecked them into stone. Such repetition across regions and long periods supports the view that the signs carried meanings understood within the communities using them.

Portable objects extend the story beyond cave walls. Similar motifs appear on deer teeth strung into necklaces around 16,000 years ago. Objects carried by people could move information across landscapes and outside spaces used for ritual. Surveys and archives also record similar shapes in Africa, India, Southeast Asia, Australia and North America. One interpretation is that early modern humans carried parts of a symbolic repertoire as they dispersed, then added signs and combined them in new ways.

How the lunar interpretation works

Bacon began by counting marks in published images and site surveys. His team's model treats each sequence as a count of lunar months after a yearly spring reset. Three marks beside a horse, for example, would indicate mating beginning three months after spring. Five beside a mammoth would indicate a later start.

The Y adds another proposed layer of information. Its position within a sequence would identify when gestation ended and birth occurred. Together, the animal image, the count and the Y could work like a compact almanac, linking a species to events in its annual cycle.

Researchers compared the Ice Age sequences with the mating and birthing cycles of modern relatives, including horses, bison, red deer, reindeer and salmon. Durham University psychologist Robert Kentridge evaluated the data and reported strong correlations between mark counts, Y positions and the expected months for mating and birth.

Mathematician Tony Freeth, known for work on the ancient Greek Antikythera mechanism, contributed to the model that treats each mark as a lunar month rather than a day. The proposed unit matters: a short sequence could then record a substantial part of an animal's yearly cycle.

The team's interpretation would give hunters and foragers a portable, teachable way to remember recurring events. Knowledge about when herds gathered, calves appeared or salmon surged upriver could guide seasonal journeys and help people decide where to concentrate their efforts.

Ethnographic examples make that use of lunar counting plausible. The Yurok of northern California timed the construction of fish weirs for migrating steelhead with a lunar count. The Yami of Taiwan still follow a lunar calendar when targeting flying fish. These practices show how counting moon cycles can serve the practical needs of communities dependent on seasonal animal behavior.

What changed over time?

Von Petzinger's records suggest that the sign repertoire changed even while many shapes persisted. Some symbols became popular and later faded, potentially reflecting fashion, identity or changing uses.

Penniforms appear to have begun in northern France around 26,000 years ago before spreading south. Hand stencils were common early in the record and often appeared with dots. Thumb stencils and finger fluting, parallel trails made by dragging fingers through soft deposits, became more frequent later.

A short timeline places those developments beside other evidence discussed in the debate:

• About 500,000 years ago: a freshwater shell on Java was etched with a zigzag by Homo erectus.
• About 70,000 years ago: a piece of ochre at South Africa's Blombos Cave received a deliberate crosshatched design.
• About 26,000 years ago: penniform signs appear to have emerged in northern France before spreading south.
• About 16,000 years ago: recurring geometric motifs appeared on deer teeth used in necklaces.
• Around 3400 to 3200 BC: Mesopotamia enters the conventional account of writing's beginnings.
• 2023: Bacon and his collaborators proposed a lunar interpretation of Ice Age dots, lines and Y signs.

Von Petzinger sees the appearance, spread and decline of particular signs as possible traces of social networks and movement. Groups may have shared symbols as they met or merged, while preferences changed across generations.

Why specialists disagree

Paleoanthropologist Melanie Chang accepts that people of the Upper Paleolithic had the mental capacity to write and track time. She nevertheless calls for more exhaustive testing of the lunar model, arguing that other interpretations remain possible. Similar marks may have served different purposes at sites separated by centuries and cultures.

Paleolithic archaeologist April Nowell regards the approach as creative but points to its limited scope. The team analyzed three recurring signs from a European repertoire containing at least 32. Most documented symbol types therefore remain outside the proposed reading.

Nowell argues that examining the wider repertoire, both on cave walls and portable objects, would help test whether the lunar interpretation works beyond the most common marks. Bacon's team says further papers are in progress to extend the analysis.

Von Petzinger supports the idea that many dots and lines were counting notation, but stops short of calling them writing. In her view, writing, including proto writing in a narrow sense, involves representing spoken language through signs that can stand for sounds or words. She describes the cave signs instead as graphic communication: symbols carrying information without needing to be translated into speech.

French prehistorian Jean Clottes is skeptical that the signs point toward writing. He stresses their close connection with animal figures, which he considers the principal subject of the compositions.

MIT linguist Cora Lesure and her coauthors approach the issue differently. They argue that drawing and language share basic cognitive mechanisms. Under that interpretation, cave and rock art could constitute a form of linguistic expression, with abstract symbols developing from the same mental capacities. Ancient, fragmentary evidence and limited context leave considerable room for disagreement.

What Mesopotamian tablets recorded

Mesopotamia offers a useful comparison because its early marks developed within an administrative setting. In the Uruk world of the fourth millennium BC, people used clay tokens, bullae and cylinder seals to count flocks, textiles, grain and jars. Bullae were clay enclosures associated with accounting, while cylinder seals could roll images into wet clay.

From about 3350 to 3000 BC, proto cuneiform appears as a large collection of pictorial and abstract signs impressed or incised into tablets. Those signs identified quantities, goods and officials. Full cuneiform followed soon afterward and could record names, actions and eventually complex texts in Sumerian and Akkadian.

Research comparing cylinder seal imagery with early tablet signs suggests that some accounting symbols grew from familiar pictures. Motifs such as fringed cloth or vessels held in a net resemble signs in both form and meaning. A sign known as ZATU639 resembles a bull motif on seals and appears in similar accounting contexts.

Those matches suggest a process involving many clerks, craftspeople and traders across a region, rather than a single inventor. Images used in daily transactions may gradually have become a shared, formal script.

Ice Age sequences, under the lunar interpretation, served a different task tens of millennia earlier. They resemble field notes for foragers rather than records for administrators. Bacon's collaborators say the marks encode neither grammar nor speech, while the earliest Mesopotamian tablets primarily record inventories and accounts rather than myths or narratives.

Both systems would allow knowledge to survive beyond an individual's memory. One would preserve expectations about animals and seasons; the other would preserve information about goods, quantities and responsibilities. Their different purposes help explain why researchers disagree about applying the same term to both.

Older marks and the making of cave art

Abstract marking extends further into the past than Europe's painted caves. At Blombos Cave in South Africa, a piece of ochre dating to about 70,000 years ago bears a deliberate crosshatched design, often described as the earliest known drawing.

On Java, Homo erectus used a sharp tool to etch a zigzag into a freshwater shell about 500,000 years ago. Possible Neanderthal contributions include crosshatching at Gibraltar and red hand stencils in Spain that may predate the arrival of Homo sapiens. These objects and surfaces preserve experiments with pattern and symbol long before the European Ice Age masterpieces.

European cave artists also used techniques requiring preparation and control. Red ochre was a favored pigment and was sometimes heated to improve its color. To make hand stencils, artists blew pigment over a hand pressed against the wall, leaving a negative impression when the hand was removed.

The frequent pairing of hands with dots, followed later by thumb stencils or finger fluting, may reflect changing practices or several layers of meaning. Researchers can trace changes in form and placement even where the intended messages remain unread.

Calendars, identity or ritual?

Most signs still have no agreed meaning. Proposed readings include hunting magic, ritual, clan identity, hunting success and control of a particular site. Several purposes could have existed at different places and times.

Other interpretations assign gender associations to shapes, connecting hooks, lines and angles with male symbols and ovals or circles with female concepts. Cognitive scholars have also compared some geometric forms with visual effects experienced in altered states, offering another possible explanation for recurring patterns.

The practical interpretation treats the signs as a code for planning that adolescents and adults learned and passed between generations. Within that possibility, combinations could change the meaning of individual signs, rather as an adjective changes the meaning of a noun.

A hand stencil beside dots might identify someone's participation in a count. A penniform beside a deer might identify a location or a group connected with it. These are suggested readings rather than settled translations, and the exact meanings of most combinations remain uncertain.

Portable signs could have served as reminders in everyday life. Engraved teeth or decorated stones might have helped leaders coordinate a group's seasonal movement, carrying information away from the wall where a similar sign appeared.

Why storing information matters

A reliable way to record seasonal facts would reduce the amount each person had to remember. If other members of a group could understand the marks, knowledge could be shared, checked and taught to younger people.

A compact calendar could help a band coordinate movement and pass on news about recurring opportunities. Such advantages could accumulate across generations. The same basic need to preserve information later found different forms in clay tablets, tally sticks, quipu, alphabets and digital code.

Ice Age communities also appear to have made choices familiar in later systems of communication: reusing signs, drawing from a limited repertoire and maintaining conventions across groups or regions. The debate presents writing's origins as part of a longer history of marking and remembering, rather than an invention disconnected from earlier practices.

The practical consequences would have been concrete. Shared seasonal knowledge could help people arrive where herds were gathering, prepare for a fish migration or teach children when particular resources became available. Whether the cave sequences performed those tasks is the question researchers are now trying to test more thoroughly.

How researchers plan to test the proposal

Bacon and his collaborators plan to examine more signs, widen their geographical and chronological comparisons and test sequences against additional species. They also want to determine whether the order of marks conveys information beyond counts and proposed birth indicators.

Other teams are developing larger databases of cave and rock art, including portable objects. Those collections should make it easier to compare recurring combinations with regional differences and assess whether similar shapes followed common rules.

Technology may expand the evidence. Many coastal caves used during the Ice Age are now underwater, and marine archaeologists are deploying robots and advanced imaging to search submerged entrances and chambers.

High resolution scans in three dimensions, better dating methods and pigment analysis could refine timelines and help researchers identify who made particular marks more securely. Even where a precise translation remains beyond reach, those tools can clarify when signs appeared, how they were made and how their use changed.

The next stage is therefore broader than finding a single meaning for a Y. Researchers are testing whether a proposed calendar fits more of the evidence while building a fuller account of graphic communication before formal writing.

Highlights

• A 2023 study proposes that Ice Age dots and lines counted lunar months and that Y signs identified the timing of animal births.
• Bacon's team examined 606 animal depictions with dots or lines and another 256 with a Y; no sequence exceeded 13 marks.
• Von Petzinger documented 32 recurring geometric signs across at least 30,000 years, drawing on fieldwork at 52 European sites.
• Specialists disagree about the lunar interpretation and whether the signs should be called proto writing, notation or graphic communication.
• Mesopotamian proto cuneiform appeared around 3350 to 3000 BC and served accounting and administration.
• Older marks at Blombos Cave, on Java and possibly at Neanderthal sites place the debate within a much longer history of symbolic activity.
• Further work will examine more signs, species, regions and periods, alongside larger databases and searches of submerged caves.