DNA Rewrites the American Cheetah: An Arctic, Salmon-Eating Relative of the Puma
The North American fossil record has long housed a "cheetah": *Miracinonyx trumani*, tall, slender, and long-limbed—a New World lookalike of the African cheetah that textbooks cast as the ecological equivalent, the grassland sprint specialist of the Americas. On September 4, a paper in *Current Biology* dismantled that story at the root: it has no close kinship with cheetahs. Its closest living relative, its genes say, is the puma.
The paper comes from UC Santa Cruz's ancient DNA lab, with corresponding author Beth Shapiro, first author Molly Cassatt-Johnstone, and nine authors in total—including Yukon paleontology veteran Grant Zazula.
A Two-City Archive Over 20,000 Years Old
The team obtained two nuclear genomes: a Wyoming individual of roughly 23,000 years ago, from a radius bone in Natural Trap Cave, and a Yukon individual of about 31,000 years ago—separated by eight thousand years and more than twenty degrees of latitude. The phylogenetic conclusion is emphatic: *M. trumani* is the sister species of the puma (*Puma concolor*), with the two lineages splitting around 2.6 million years ago, amid the dramatic climate swings of the late Pliocene and Pleistocene. The cheetah-like body has a different origin—convergent evolution. Long legs and narrow shoulders are a generic solution for runners, not evidence of a family tree.
What really caught attention was the diet section. The evidence is not DNA but stable isotopes—the carbon and nitrogen ratios stored in bone, a ledger of an animal's menu over its final decades. The Yukon population's trophic position is markedly higher, consistent with a diet dominated by anadromous fish; the Wyoming population was a generalist terrestrial predator. One cat, two diets.
The abstract also contains a sentence easy to skim past: the Yukon specimen extends the species' known range northward by more than 20 degrees of latitude, into the Arctic. One degree of latitude is about 111 km; twenty degrees is roughly 2,200 km—the species' actual territory was suddenly half the diagonal of a large country beyond the textbook's northern limit.
Fine Print in the Genome
The genome also turned up two inactivated genes. A set of circadian rhythm genes lost function—in the Arctic summer there is no night, in winter no day; a biological clock loses its warranty value in the far north. The abstract calls this "relaxed constraint." The other, according to the phys.org release, is the first documented loss of a sour taste perception gene in cats. Both are examples of evolution "coming clean": what is unused is allowed to break.
The extinction story gains texture too. Shapiro: "The decline was slow, not sudden, and that may be what left it unable to adapt when the climate shifted."
An old case gets a footnote: the popular explanation for the pronghorn's speed—that it evolved to escape the American cheetah in a predator-prey arms race—loses another piece of its foundation given this study's range and diet data. Cassatt-Johnstone's summary: "These cats were remarkably flexible, much like pumas are today."
Why It Matters
1. A standard textbook case of convergent evolution now has fresh evidence—morphology can lie, genes cannot. Names of kinship assigned by shape alone, like "American cheetah," deserve an extra question. 2. The detailed ledger of Pleistocene megafauna extinctions keeps being filled in: the slow-decline hypothesis gains another species' testimony. 3. The workflow itself: samples came from the traditional territories of the Tr'ondëk Hwëch'in and Vuntut Gwitchin, with community collaboration acknowledged in authorship and thanks—the ethical foundation of ancient DNA is being built up alongside its technical one.
The last American "cheetah" bowed out more than ten thousand years ago. The verdict it was waiting for took twenty thousand years to write—and was submitted this September weekend.
References: Paper DOI · UCSC press release · phys.org coverage