Hueyatlaco

What happened

1. 1967INAH prehistory director José L. Lorenzo alleges that laborers planted some Hueyatlaco artifacts, before digging is complete.
2. 1969Szabo, Malde and Irwin-Williams publish U-series dates on Valsequillo bones, ~245,000 yr for a Hueyatlaco camel pelvis, as a 'dilemma'.
3. 1969Outside scientists MacNeish, Petersen and Wormington are quoted in print attesting the in situ artifact-fauna associations.
4. 1973Beds traced during excavation in May 1973 place the artifact layers beneath ~10 m of water-laid Valsequillo gravels deposits.
5. 1981Steen-McIntyre, Fryxell and Malde publish the geology, with zircon FT ages on overlying tephra that they say agree with the U-series age.
6. 1981Irwin-Williams rejects the ages as inconsistent with tool typology (Quat. Res. 16(2)); Malde and Steen-McIntyre reply in 16(3).
7. 1997Pichardo, using Kiel University's 1973 biostratigraphy, puts the tool levels at ~10,000 and ~22,000-30,000 BP and invokes redeposited fossils.
8. 2000Pichardo, on biostratigraphic grounds, places the first Lerma/El Jobo points at Hueyatlaco at ~14,000-16,000 BP, before Clovis.
9. 2004VanLandingham's diatom study treats the artifacts as in situ and assigns their beds to the Sangamonian s.l. (80,000 to ca. 220,000 yr BP).
10. 2006Gonzalez, Huddart and Bennett add AMS 14C and ESR dates on the Valsequillo Gravels and place all artifact-bearing strata in the Late Pleistocene.
11. 2006VanLandingham's paper title widens the diatom-based age of the artifacts to Sangamonian-Illinoian (80,000-430,000 yr BP).
12. 2010VanLandingham's paper title gives a maximum Yarmouthian age (430,000-500,000 yr BP) for the artifacts; the paper was not read here.

Objections 0 of 8 proved wrong

• ?
  The ages are inconsistent with the typology of the tools, which include bifaces and a Lerma-style point.

  Contradicts the accepted model · Cynthia Irwin-Williams (1981) · 1981

  Unresolved — Malde and Steen-McIntyre replied (Quat. Res. 16(3): 418-421). Neither comment nor reply was read here; S8 gives the objection only in paraphrase.
• ?
  U-series ages on bone can be distorted by post-burial uranium uptake or contamination, so the camel-pelvis age may not date its burial.

  Dating or samples

  Unresolved — At nearby Caulapan the same method (21,500±1,500) matched 14C on shell (21,850±850), which weakens a blanket objection; no re-dating of M-B-3 appears in sources read.
• ?
  The two zircon fission-track ages (370,000±200,000 and 600,000±340,000 yr, 2σ) are in reverse stratigraphic order.

  Dating or samples

  Unresolved — Their 2σ ranges overlap (260,000-570,000 yr), so the order cannot be resolved at 2σ; the tephras have not been re-dated in sources read.
• ?
  Older, heavily mineralized fossils were redeposited into younger tool levels, explaining old U-series ages on bone found with young tools.

  Layers or association · Mario Pichardo (1997) · 1997

  Unresolved — Rests on Kiel University's 1973 biostratigraphy, which puts the bifacial level at ~10,000 and the unifacial level at ~22,000-30,000 BP; untested on the dated bones.
• ?
  Ages near 250,000 years would predate every widely accepted American site by over 200,000 years and clash with fossil and genetic evidence on human dispersal, as critics argued for Cerutti.

  Contradicts the accepted model

  Unresolved — Other Middle/Late Pleistocene claims exist, e.g. the Cerutti Mastodon (~130,000 yr; Holen et al. 2017), but none is widely accepted.
• ?
  The old ages rest on two dated bones: a camel pelvis from Hueyatlaco unit C and a mastodon molar (280,000 yr) from El Horno, a separate, stratigraphically lower site.

  Layers or association · Mario Pichardo (2000) · 2000

  Unresolved — Pichardo says the single-specimen criticism aimed at the younger Caulapan dates applies equally here; no added bone dates from the tool units appear in sources read.
• ?
  Some Hueyatlaco artifacts were planted by laborers working at the site.

  Fraud or provenance · José L. Lorenzo, INAH (1967) · 1967

  Unresolved — No source read reports the charge tested or withdrawn; in 1969 three outside scientists attested the in situ associations (S5).
• ?
  New AMS 14C (mollusc) and ESR (mammoth bone) dates on the Valsequillo Gravels support a Late Pleistocene age for all the artifact-bearing stratigraphy.

  Dating or samples · Gonzalez, Huddart & Bennett (2006) · 2006

  Unresolved — Dates are on the Gravels, which S2 places above Hueyatlaco's tool beds; how they constrain those beds is unclear from the abstract. S6 notes its Xalnene Ash dates proved controversial.

Evidence at the time within ~5 years of the claim

• Unambiguous evidenceYes — Contemporaries described 'man-made artifacts' (bifaces, retouched tools) with extinct fauna; later critics disputed their age and context, not their manufacture.
• Documented contextPartly — In 1969 three outside scientists attested the in situ associations (S5), but in 1967 Lorenzo alleged that laborers had planted some artifacts.
• Independent dating methodsNo — Before 1981 the only published dates were U-series on bone (230Th, plus a 231Pa minimum), one method family. Zircon FT ages on tephra were first published in 1981.
• More than one labNo — Within about five years all dates were Szabo's U-series set (S1); C.W. Naeser's fission-track dates on the tephra were published only in 1981.
• Professional recoveryYes — Dug from 1962 by a team led by archaeologist Cynthia Irwin-Williams, with archaeologist Juan Armenta Camacho, geologist H.E. Malde and tephrochronologist V. Steen-McIntyre.
• Peer-reviewed reportPartly — Within five years only a dating paper (EPSL 1969) and a short comment on the associations (Am. Antiq. 1969) appeared; the full geological report came in 1981.
• Open to criticsPartly — Three outside scientists examined the in situ associations in 1969; critics' access to the dated bones is undocumented. Most Valsequillo finds are now missing (S6).
• Independent teamsPartly — Outside scientists attested the field associations in 1969, but no independent group produced dates or analyses within about five years.
• Outside stakeNo — No commercial, religious or nationalist motive is documented in the sources read.

What would settle it for a field partner

1. Clean the Hueyatlaco section, log whether units C and E are primary beds or channel fill, and date them directly: AMS 14C on in situ shell or bone and post-IR IRSL on feldspar.Medium cost
   Would show: Finite ages under ~50,000 yr would falsify the ~250,000-yr claim; saturated or infinite ages in primary beds would keep it alive.
2. If camel pelvis M-B-3 is still curated (most Valsequillo finds are reported missing), re-date it by U-series at a second lab with ESR as a cross-check; otherwise date new in situ bone from unit C.Medium cost
   Would show: Whether ~245,000-yr bone ages replicate, or reflect uranium uptake or redeposited older fossils.
3. Re-date the two FT-dated tephras by single-crystal methods (e.g. 40Ar/39Ar or zircon U-Th/He) that give grain-by-grain ages, so older detrital crystals in water-laid ash can be spotted.Medium cost
   Would show: Whether the 370,000-600,000-yr FT ages reproduce, or were inflated by reworked older crystals.
4. Have a second diatomist, blind to earlier results, analyze splits of the same Hueyatlaco beds to test VanLandingham's single-author diatom ages.Low cost
   Would show: Whether the diatom-based Sangamonian (80,000-220,000 yr) assignment replicates independently.

What would change this record

Refuted if Hueyatlaco units C and E date directly to under ~50,000 yr, if re-dated bone shows uranium uptake or redeposited older fossils, or if grain-by-grain tephra dating shows older detrital crystals. Strengthened if independent labs replicate old ages on primary beds.

Notes

• Status. Prehistorians rejected the ages on typology, but they were never replicated or directly refuted. Gonzalez et al. (2006) place all artifact strata in the Late Pleistocene, using new dates on the Valsequillo Gravels, not on the tool beds.
• Accepted view then. Clovis-first: no secure human presence in the Americas before Clovis, ~11,500 14C yr BP (≈13,350 cal BP after calibration).
• Dating basis. 230Th 245,000±40,000 and 231Pa >180,000 yr on camel pelvis M-B-3 (Szabo et al. 1969). Zircon FT on overlying tephra: 370,000±200,000 and 600,000±340,000 yr (2σ), said to agree. Calendar yr.
• Correction. Brief: "Excavated in the 1960s by Cynthia Irwin-Williams". Digging began in 1962 (S13) but continued: beds were traced during excavation in May 1973 (S2).
• Distinct from the Xalnene Ash footprints, a separate dispute. Irwin-Williams, principal investigator, co-authored S1 and S5 but in 1981 rejected the ages on typology (S8); Webb & Clark say she acknowledged estimates of 11,000 to over 30,000 yr for people there. S2 reports the dated pelvis with bifacial tools; S8 puts it in unit C, while the Lerma point came from unit E, a unit of shifting channels. independent_methods_count counts U-series and FT; hydration and etching are qualitative. Most Valsequillo finds are now missing (S6). Reports that Steen-McIntyre met professional hostility rest on her personal communication in Webb & Clark 1999: UNVERIFIED.

People and evidence

• Proponents. Virginia Steen-McIntyre, Harold E. Malde, Roald Fryxell, Barney J. Szabo
• Critics. José L. Lorenzo, Cynthia Irwin-Williams, Mario Pichardo, S. Gonzalez, D. Huddart, M. Bennett
• Evidence types. u series, geology, stratigraphy, lithics, fauna · 2 independent lines
• Record confidence. medium — S2, S5-S9, S11, S13, S15 checked (S8, S13 via open full text); S1, S3, S4, S10, S12, S14 metadata only. Irwin-Williams's own reports and Lorenzo's 1967 text were not read.