Study
Early evolution of the venom system in lizards and snakes
Fry, Bryan G.; Vidal, Nicolas; Norman, Janette A.; Vonk, Freek J.; Scheib, Holger
Nature, 2006
Venom-gland transcriptomes and oral gland secretions were sampled across snakes and lizards previously considered non-venomous, and the toxin gene families recovered were mapped onto a squamate phylogeny to test whether venom arose once or many times.
- Studied in
- Serpentes, Anguimorpha, Iguania, Pogona barbata, Varanus varius
- Sample size
- comparative transcriptomics and phylogenetics across squamates
Toxin genes of the same families were recovered from lineages not previously regarded as venomous, including iguanian and anguimorph lizards, supporting a single early origin of the venom system in a common ancestor of snakes and several lizard groups, with subsequent elaboration in some lineages and reduction in others.
What it means
The authors' reading, and ours. Where they differ, that difference is the point.
How the authors put it
Venom is ancestral to a large clade rather than a snake innovation, and the traditional venomous/non-venomous division does not track the biology.
How NatureHQ reads it
Two things follow, and they pull in opposite directions, which is why this paper is worth reading carefully. It makes "venom" a much broader and older thing than the fangs-and-antivenom picture. It emphatically does *not* make every snake dangerous: the presence of toxin-family genes in an oral secretion is a fact about ancestry, not about delivery, dose or medical significance. A great many snakes with such genes have no delivery apparatus and no capacity to harm a person. The paper has been over-read in exactly that direction, and the distinction between an evolutionary category and a clinical one is the whole of the difference.
- Transcript presence establishes expression, not function, potency or delivery.
- The single-origin conclusion has been contested on the grounds that some recovered sequences may be housekeeping genes shared by many secretory tissues.
- Clinical risk is not addressed and cannot be inferred from these data.
What this study is used for on NatureHQ
One study can inform several subjects. Here is everywhere this one is cited.
Published by: Nature PortfolioPublished in a Nature Portfolio journal.
This reference was resolved automatically against Crossref on 2026-08-11.
NatureHQ summarises research in its own words and does not reproduce published text. Reviewed 2026-08-11.