Could the Iberian slate plaques be bullroarers?
Over 2,000 engraved slate tablets, laid on the chests of the Copper Age dead, pierced at one end and read for a century as ancestor-records. Nobody has asked whether they could sing. So we asked.
Assessment
The surface resemblance to the Chahai case is real and worth taking seriously — but on the physics, the plaques fail where a bullroarer must succeed. One narrow door stays open.
Why it looked so promising
The same three-part signature as Chahai
End-pierced thin blades. Placed with the body in a tomb. Read as record or ornament for a century, with the acoustic question never once asked. That pattern is exactly what turned up a bullroarer at Chahai — so a family of 2,000+ slate blades wearing the same signature is worth a hard look.
The material coincidence sharpens it further. The only universally accepted prehistoric slate bullroarer — the Tuv specimen from arctic Norway, ~5,000 years old — is made of the very same stone. If the "swung blade misread as ornament" logic holds anywhere outside China, southwest Iberia is the obvious place to test it. The plaques are thin, drilled, and buried by the thousand. Everything about the framing invites the question.
So we ran it properly: pulled the physical corpus data, the bullroarer acoustics literature, and the use-wear studies, and asked whether these objects could actually work as swung aerofoils — not whether they vaguely resemble one.
The evidence, in hand
What a slate plaque actually looks like
Late Neolithic / Copper Age, ~3500–2500 BCE, southwest Iberia. Chalky lines incised into dark schist; a single biconical hole drilled through the narrow top. Note the form in every case: a broad trapezoid, widest at the base — a plate, not a blade.
Images: ESPRIT — Engraved Stone Plaque Registry and Inquiry Tool (Katina Lillios, Univ. of Iowa) and the Museu Nacional de Arqueologia, Lisbon.
The decisive mismatch
A bullroarer is a blade. A plaque is a plate.
This is the whole case in one picture. A bullroarer works by spinning on a cord so that air flows across a long, narrow aerofoil, generating the oscillating lift that makes the roar. That demands a high length-to-width ratio — ethnographic and archaeological examples run from roughly 5:1 to 13:1. The Iberian plaques sit near 1.5:1. Swing one on a cord and it does not knife through the air and sing; it flutters and tumbles like a thrown tile.
Everything else compounds it. At an average ~300 g the plaques are two to three times the mass of a working wooden bullroarer (~100–120 g), so far more of the load rides on a brittle stone plate at spin-up — schist under that centrifugal stress is a shattering risk, which is exactly why ethnographic bullroarers are almost always wood. And the mass is wide, not long: a plate this shape is aerodynamically "nervous," impossible to hold in a stable roar.
Side by side
The specification ledger
Red rows are the features that decide it — where the plaque falls outside the working range of a bullroarer rather than merely near its edge.
| Attribute | Iberian plaque | Working bullroarer | Verdict |
|---|---|---|---|
| Length : width | ≈ 1.5 : 1 | ≈ 5 : 1 – 13 : 1 | Out of range |
| Plan form | Broad trapezoid, widest at base | Symmetric elongated blade | Wrong geometry |
| Mass | ~300 g avg (to 234 g+) | ~100–120 g | Too heavy |
| Hole-wear signature | Static suspension wear | Rotational / string abrasion | Wrong wear |
| Thickness | ~10 mm | 5–10 mm | Compatible |
| Length | 100–200 mm | 150–400 mm | Overlaps (low end) |
| Perforation | One (often), at the top end | One, at the extreme end | Compatible |
| Material | Slate / schist | Wood; slate attested (Tuv) | Possible |
| Edge section | Flat, squared, engraved | Tapered / bevelled edges | Not aerodynamic |
Four of the mismatches are individually near-disqualifying. A candidate can survive being at the low end of the length range; it cannot survive being the wrong shape, the wrong mass distribution, and carrying the wrong wear all at once.
Weighing it honestly
What counts for, what counts against
For the idea
- The framing parallel is genuine. End-pierced, tomb-placed, acoustically un-asked — the same blind spot Chahai exposed.
- Slate is proven. The Tuv bullroarer shows the material can roar.
- Single-holed variants exist and are common, with the hole at the top end — the one geometry a bullroarer needs.
- No replica has ever been spun. The acoustic claim has been assumed false, not measured false.
Against the idea
- Aspect ratio ~1.5:1. Too broad to sustain a roar — the single biggest problem.
- ~300 g of brittle schist at spin-up: a fracture risk, not a design.
- Suspension wear, not spin wear. Use-wear studies read the holes as hung, not whirled.
- Fragile engraved faces survive intact — spinning would abrade them.
- Paired-hole and bipartite forms point to hanging/representation, not a single spin axis.
The one door left open
The verdict above is about the corpus as a whole — the typical broad, heavy, chest-laid plaque. But "over 2,000 specimens" is a distribution, not a single object. If a small tail of them are unusually narrow, light, single-holed and thin-edged, those specific pieces would deserve the acoustic question on their own terms. And the honest gap remains: no one has ever spun a replica and put a microphone in front of it. The function has been dismissed by assumption, never by experiment.
That is a cheap, decisive test. A faithful slate replica of a narrow-variant plaque, swung and recorded, would settle it in an afternoon — either producing a tone (reopening the whole question) or tumbling silently (closing it for good).
Why this isn't another Chahai
Same signature, different physics
It matters to say clearly where this lands relative to the case that inspired it. Chahai stayed open because a single missing measurement — the blade's thickness — was all that stood between it and a verdict. Here the measurements largely exist, and they point away. The parallel is what made the question worth asking; the data is what answers it.
Chahai bi-object
Xinglongwa, NE China
End-pierced blade, right proportions for a swung aerofoil. The one datum that would confirm or kill it — thickness — was never published.
Status · genuinely open, awaiting a number
Iberian slate plaques
Alentejo, SW Iberia
The proportions, mass, and wear are known — and they fall outside a bullroarer's working envelope. A narrow-variant subset is the only live thread.
Status · probably not, pending a replica test
Bottom line
A real question, honestly answered
The Iberian engraved slate plaques are almost certainly not a lost family of bullroarers. The resemblance that made them exciting is a resemblance of context and framing — pierced blades buried with the dead — not of the physics that makes a bullroarer roar. On shape, mass, edge, and wear, the typical plaque fails the test a swung aerofoil has to pass.
That is not a wasted look. The plaques were worth interrogating precisely because they wore the Chahai signature so plainly, and the exercise sharpens the atlas's own criteria: it shows that "end-pierced blade in a tomb" is a prompt to measure, not a diagnosis. The century-old readings — genealogical record, lineage heraldry, protective image — remain the better fit. But the microphone test on a narrow-variant replica is cheap enough that the door should be left visibly ajar, not nailed shut.
Sources
- Lillios, K. T. (2008). Heraldry for the Dead: Memory, Identity, and the Engraved Stone Plaques of Neolithic Iberia. University of Texas Press.
- Lillios, K. T. (2004). "Lives of Stone, Lives of People: Re-Viewing the Engraved Plaques of Late Neolithic and Copper Age Iberia." European Journal of Archaeology 7(2): 125–158.
- ESPRIT — Engraved Stone Plaque Registry and Inquiry Tool. iberian.its.uiowa.edu.
- García Rivero, D. & O'Brien, M. J. (2014). "Phylogenetic Analysis Shows That Neolithic Slate Plaques … Are Not Genealogical Recording Systems." PLOS ONE 9(2): e88296.
- Woods, A. & Lillios, K. T. (2006). Experimental use-wear replication of engraved plaque perforations.
- Langley, M. C. et al. (2022). "Owl-like plaques of the Copper Age and the involvement of children." Scientific Reports 12: 23530.
- Roger, M. & Aubert, S. "Aeroacoustics of the Bullroarer." École Centrale de Lyon. acoustique.ec-lyon.fr.
- Fletcher, N. H. et al. "Rotational aerophones." J. Acoust. Soc. Am.
- Morley, I. (2013). The Prehistory of Music. Oxford University Press.
- Tuv, Saltstraumen (Bodø) slate bullroarer — Bjerck & Hauglid, exc. 1991. Bullroarer Atlas record lund1998-001.
Prepared for the Bullroarer Atlas as a candidate assessment — not a published record. Judgment: the plaque corpus is an unlikely bullroarer family; a narrow-variant replica spin-test is the outstanding experiment. Related atlas cases: Tuv (accepted slate bullroarer) · Chahai bi-object (open).