Genetic analysis of hair samples attributed to yeti, bigfoot and other anomalous primates

TL;DR

In the first systematic genetic survey of hair samples attributed to anomalous primates, 30 samples yielded DNA and most matched known extant mammals, but two Himalayan yeti-attributed samples matched a Palaeolithic polar bear, *Ursus maritimus*. The authors conclude these samples provide no evidence for anomalous primates, though the polar bear result is preliminary.

Key findings

• Of the 30 samples from which DNA was recovered, only one (no. 25072) yielded a human sequence, identified as *Homo sapiens* of likely European matrilineal descent; the rest matched known extant mammals, often domesticates.
• Two Himalayan samples—no. 25025 from Ladakh, India, and no. 25191 from Bhutan—had a 100% match with DNA from a Pleistocene fossil more than 40,000 BP of *U. maritimus* (polar bear), but not with modern examples of the species.
• Other matches included brown bear, horse, cow, American black bear, raccoon, sheep, North American porcupine, deer, wolf/coyote/dog, serow, and Malaysian tapir; sample nos. 25074 (*U. americanus*) and 25075 (*P. lotor*) were submitted from Russia even though they are native to North America.
• Seven samples failed to yield any DNA sequences despite multiple attempts.

Methods

• A total of 57 hair samples were received after solicitation from museum and individual collections; macroscopic, microscopic, and infrared fluorescence examination excluded one plant sample and one glass fibre sample, and 37 were selected for genetic analysis based on provenance or historic interest.
• Lengths (2–4 cm) of individual hair shafts were cleaned, ground in buffer, incubated with proteinase K, extracted with phenol/chloroform/isoamyl alcohol, and PCR-amplified for the mitochondrial 12S fragment corresponding to bps 1093–1196 of the human mitochondrial genome; recovered sequences were compared to GenBank accessions.
• Because mitochondrial 12S is identical in *H. sapiens* and *H. neanderthalensis*, sample no. 25072 was additionally sequenced for mitochondrial DNA hypervariable region 1 (bps 16,000–16,400), which matched the revised Cambridge Reference Sequence.

Limitations

• The paper states the polar bear match should be regarded as preliminary because it is based on a segment only 104 bp long, albeit in the conserved 12S RNA gene, and genomic sequence data are needed to decide whether the hairs are from a previously unrecognized bear species, colour variants of *U. maritimus*, or *U. arctos*/*U. maritimus* hybrids.
• The paper states the deliberately permissive primer combination allowed a wide range of mammalian DNA to be amplified but sometimes limited identification to genus, for example no. 25029 was identified as *Canis* without distinguishing wolf, coyote, and domestic dog.
• The paper states that absence of evidence is not evidence of absence and the survey cannot refute the existence of anomalous primates; evident from the text, 7 of the 37 selected samples failed to yield DNA, so conclusions rest on 30 recovered sequences.