Mexican mammoth
For centuries, mammoths have fascinated scientists and the public alike. Two species roamed the Americas: the woolly mammoth, which thrived in the northern latitudes, and the Columbian mammoth, which spread from Canada all the way down to Costa Rica. Until recently, most evolutionary studies of the Columbian mammoth relied heavily on genetic data from fossil remains in the United States and Canada.
That perspective is now changing thanks to ground-breaking research conducted in Mexico. A team led by Federico Sánchez Quinto from the International Laboratory for Human Genome Research (LIIGH) at UNAM has incorporated samples from the tropical latitudes of central Mexico. Their work reveals surprising genetic differences in mammoths found in the Basin of Mexico, suggesting a much more complex evolutionary history than previously thought.
A breakthrough in Mexican paleogenomics
According to Sánchez Quinto and his colleagues, this is the first time Mexican mammoth fossils have been examined using advanced genetic techniques. “We found that mammoths from the Basin of Mexico possess mitochondrial lineages very different from those reported in the United States and Canada,” he explained.
This achievement also marks a milestone for Mexican science. As María del Carmen Ávila Arcos, also from LIIGH, noted: “It is the first genetic study of megafauna in the country. Building the technical capacity, human resources, and infrastructure here allows us to uncover more about our natural history.”
The findings were published in the prestigious journal Science under the title “Columbian mammoth mitogenomes from Mexico uncover the species’ complex evolutionary history.” The project was a collaborative effort between UNAM, the National Institute of Anthropology and History (INAH), and the National School of Anthropology and History (ENAH).
Origins of the Columbian mammoth
Mammoths first appeared in Africa around six million years ago before migrating to Eurasia, where they diversified into several species. One of these, the steppe mammoth, crossed into the Americas about 1.5 million years ago. Through hybridization with woolly mammoths, the Columbian mammoth eventually emerged.
This species was a true giant: it could reach more than four meters in height, weigh up to ten tons, and carry tusks stretching as long as five meters. Columbian mammoths thrived across North America until their extinction at the end of the Pleistocene, roughly 12,000 years ago.
Fossils unearthed at Santa Lucía
One of the most important fossil discoveries in recent decades took place during the construction of Felipe Ángeles International Airport between 2019 and 2022, on the site of a former military air base in Santa Lucía, State of Mexico. Archaeologists and paleontologists uncovered over 70,000 fossils of extinct megafauna, including horses, camels, bison, giant sloths, and more than 20,000 bones from mammoths.
According to Rubén Manzanilla, archaeologist at INAH and coordinator of the rescue effort: “From December 2019 onward, there were between one and five paleontological finds every single day. It is now the most important paleofauna collection in Latin America.”
This rich trove of remains provided the perfect opportunity for genetic sampling. Researchers extracted DNA from molars, which preserve genetic material particularly well thanks to their dense structure.
Surprising genetic diversity
What the team found was unexpected. Instead of resembling Columbian mammoths from Canada and the U.S., the Mexican mammoths displayed highly distinct mitochondrial DNA. The researchers named this new lineage Clade 1G, which is further divided into three sublineages: 1G.1, 1G.2, and 1G.3.
The divergence between these groups is so pronounced that it could reflect the process by which the Columbian mammoth species itself emerged. One hypothesis suggests that hybridization involved female woolly mammoths carrying unusually diverse mitochondrial DNA. Over time, a wave of this genetic diversity may have reached the Basin of Mexico, creating distinct evolutionary lineages.
Radiocarbon dating places these remains between 12,000 and 20,000 years old, confirming that mammoths roamed central Mexico until the end of the Pleistocene.
Population history and survival pressures
The study also sheds light on the population dynamics of these animals. In higher latitudes, woolly mammoth genetic diversity declined sharply as the Earth warmed after the last Ice Age. By contrast, mammoths in central Mexico appear to have maintained small but stable populations during their final 40,000 years.
This stability is consistent with fossil evidence showing congenital malformations in some Mexican mammoths, a possible sign of inbreeding within reduced populations. While further evidence is needed, the results hint at unique survival pressures faced by mammoths in this region.
Innovation in fieldwork and analysis
Conducting this research required significant ingenuity. Because the molars were too large to transport safely, researchers set up a temporary ancient DNA laboratory near the excavation site. There, wearing protective suits and working within sterile acrylic chambers, they drilled into molars to collect dentin powder.
Back at the Paleogenomics Laboratory in Juriquilla, they extracted DNA and built sequencing libraries. Using a specialized technique called capture-enrichment, the team managed to recover 61 mitochondrial genomes, 28 of them with very high coverage. This depth of data allowed for robust evolutionary inferences that would not have been possible otherwise.
Rewriting the history of mammoths in the Americas
The results from Mexico not only enrich our understanding of the Columbian mammoth but also highlight the importance of including diverse geographic samples in paleogenomic research. As Ávila pointed out, the Mexican lineages diverged from their northern relatives more than 400,000 years ago, long before the separation between the Columbian and woolly mammoths.
This discovery positions Mexico as a crucial region for understanding the deep evolutionary history of these Ice Age giants. It also underscores the growing role of Mexican science in global paleogenomics.
✨ The study of mammoths in the Basin of Mexico shows that even in well-known species, there are still secrets waiting to be uncovered. Each fossil and each strand of DNA brings us closer to understanding the long-lost worlds these majestic creatures once inhabited.
