Woolly mammoth movements tied to earliest Alaska hunting camps

Researchers have linked the travels of a 14,000-year-old woolly mammoth with the oldest known human settlements in Alaska, providing clues about the relationship between the iconic species and some of the earliest people to travel across the Bering Land Bridge.

Scientists made those connections by using isotope analysis to study the life of a female mammoth, named Élmayųujey'eh, by the Healy Lake Village Council.

A tusk from Elma was discovered at the Swan Point archaeological site in Interior Alaska.

Samples from the tusk revealed details about Elma and the roughly 1,000-kilometer journey she took through Alaska and northwestern Canada during her lifetime.

Isotopic data, along with DNA from other mammoths at the site and archaeological evidence, indicates that early Alaskans likely structured their settlements to overlap with areas where mammoths congregated.

Those findings, highlighted in the new issue of the journal Science Advances, provide evidence that mammoths and early hunter-gatherers shared habitat in the region.

The long-term predictable presence of woolly mammoths would have attracted humans to the area.

"She wandered around the densest region of archaeological sites in Alaska," said Audrey Rowe, a University of Alaska Fairbanks Ph.D. student and lead author of the paper.

"It looks like these early people were establishing hunting camps in areas that were frequented by mammoths."

The mammoth tusk was excavated and identified in 2009 by Charles Holmes, affiliate research professor of anthropology at UAF, and François Lanoë, research associate in archaeology at the University of Alaska Museum of the North.

They found Elma's tusk and the remains of two related juvenile mammoths, along with evidence of campfires, the use of stone tools, and butchered remains of other game.

All of this "indicates a pattern consistent with human hunting of mammoths," said Ben Potter, an archaeologist and professor of anthropology at UAF.

Researchers at UAF's Alaska Stable Isotope Facility then analyzed thousands of samples from Elma's tusk to recreate her life and travels.

Isotopes provide chemical markers of an animal's diet and location.

The markers are then recorded in the bones and tissues of animals and remain even after they die.

Mammoth tusks are well-suited to isotopic study because they grew throughout the ancient animals' lives, with clearly visible layers appearing when split lengthwise.

Those growth bands give researchers a way to collect a chronological record of a mammoth's life by studying isotopes in samples along the tusk.

Much of Elma's journey overlapped with that of a previously studied male mammoth who lived 3,000 years earlier, demonstrating long-term movement patterns by mammoths over several millennia.

In Elma's case, they also indicated she was a healthy 20-year-old female.

"She was a young adult in the prime of life. Her isotopes showed she was not malnourished and that she died in the same season as the seasonal hunting camp at Swan Point where her tusk was found," said senior author Matthew Wooller, who is director of the Alaska Stable Isotope Facility and a professor at UAF's College of Fisheries and Ocean Sciences.

The era in which Elma lived may have compounded the challenges posed by the relatively recent appearance of humans.

The grass- and shrub-dominated steppe landscape that had been common in Interior Alaska was beginning to shift toward more forested terrain.

"Climate change at the end of the ice age fragmented mammoths' preferred open habitat, potentially decreasing movement and making them more vulnerable to human predation," Potter said.

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New tusk-analysis techniques reveal surging testosterone in male woolly mammoths

Traces of sex hormones extracted from a woolly mammoth's tusk provide the first direct evidence that adult males experienced musth, a testosterone-driven episode of heightened aggression against rival males, according to a new University of Michigan-led study.

In male elephants, elevated testosterone during musth was previously recognized from blood and urine tests. Musth battles in extinct relatives of modern elephants have been inferred from skeletal injuries, broken tusk tips and other indirect lines of evidence.

But the new study, scheduled for online publication May 3 in the journal Nature, is the first to show that testosterone levels are recorded in the growth layers of mammoth and elephant tusks.

The U-M researchers and their international colleagues report annually recurring testosterone surges -- up to 10 times higher than baseline levels -- within a permafrost-preserved woolly mammoth tusk from Siberia. The adult male mammoth lived more than 33,000 years ago.

The testosterone surges seen in the mammoth tusk are consistent with musth-related testosterone peaks the researchers observed in an African bull elephant tusk, according to the study authors. The word "musth" comes from the Hindi and Urdu word for intoxicated.

"Temporal patterns of testosterone preserved in fossil tusks show that, like modern elephants, mature bull mammoths experienced musth," said study lead author Michael Cherney, a research affiliate at the U-M Museum of Paleontology and a research fellow at the U-M Medical School.

The study demonstrates that both modern and ancient tusks hold traces of testosterone and other steroid hormones. These chemical compounds are incorporated into dentin, the mineralized tissue that makes up the interior portion of all teeth (tusks are elongated upper incisor teeth).

"This study establishes dentin as a useful repository for some hormones and sets the stage for further advances in the developing field of paleoendocrinology," Cherney said. "In addition to broad applications in zoology and paleontology, tooth-hormone records could support medical, forensic and archaeological studies."

Hormones are signaling molecules that help regulate physiology and behavior. Testosterone is the main sex hormone in male vertebrates and is part of the steroid group of hormones. It circulates in the bloodstream and accumulates in various tissues.

Scientists have previously analyzed steroid hormones present in human and animal hair, nails, bones and teeth, in both modern and ancient contexts. But the significance and value of such hormone records have been the subject of ongoing scrutiny and debate.

The authors of the new Nature study say their findings should help change that by demonstrating that steroid records in teeth can provide meaningful biological information that sometimes persists for thousands of years.

"Tusks hold particular promise for reconstructing aspects of mammoth life history because they preserve a record of growth in layers of dentin that form throughout an individual's life," said study co-author Daniel Fisher, a curator at the U-M Museum of Paleontology and professor in the Department of Earth and Environmental Sciences.

"Because musth is associated with dramatically elevated testosterone in modern elephants, it provides a starting point for assessing the feasibility of using hormones preserved in tusk growth records to investigate temporal changes in endocrine physiology," said Fisher, who is also a professor in the U-M Department of Ecology and Evolutionary Biology.

For the study, researchers sampled tusks from one adult African bull elephant and two adult woolly mammoths -- a male and a female -- from Siberia. The samples were obtained in accordance with relevant laws and with appropriate permits.

The researchers used CT scans to identify annual growth increments within the tusks. A tiny drill bit, operated under a microscope and moved across a block of dentin using computer-actuated stepper motors, was used to grind contiguous half-millimeter-wide samples representing approximately monthly intervals of dentin growth.

The powder produced during this milling process was collected and chemically analyzed.

The study required new methods, developed in the laboratory of U-M endocrinologist and study co-author Rich Auchus, to extract steroids from tusk dentin for measurement with a mass spectrometer, an instrument that identifies chemical substances by sorting ions according to their mass and charge.

"We had developed steroid mass spectrometry methods for human blood and saliva samples, and we have used them extensively for clinical research studies. But never in a million years did I imagine that we would be using these techniques to explore 'paleoendocrinology,'" said Auchus, professor of internal medicine and pharmacology at the U-M Medical School.

"We did have to modify the method some, because those tusk powders were the dirtiest samples we ever analyzed. When Mike (Cherney) showed me the data from the elephant tusks, I was flabbergasted. Then we saw the same patterns in the mammoth -- wow!"

The African bull elephant is believed to have been 30 to 40 years old when it was killed by a hunter in Botswana in 1963. According to estimates based on growth layers in its tusk, the male woolly mammoth lived to be about 55 years old. Its right tusk was discovered by a diamond-mining company in Siberia in 2007. Radiocarbon dating revealed that the animal lived 33,291 to 38,866 years ago.

The tusk from the female woolly mammoth was discovered on Wrangel Island, which was connected to northeast Siberia in glacial periods of lower sea level but is now separated from it by the Arctic Ocean. Carbon-dating showed an age of 5,597 to 5,885 years before present. (Wrangel Island is the last known place where woolly mammoths survived, until around 4,000 years ago.)

In contrast to the male tusks, testosterone levels from the female woolly mammoth tusk showed little variation over time -- as expected -- and the average testosterone level was lower than the lowest values in the male mammoth's tusk records.

"With reliable results for some steroids from samples as small as 5 mg of dentin, these methods could be used to investigate records of organisms with smaller teeth, including humans and other hominids," the authors wrote. "Endocrine records in modern and ancient dentin provide a new approach to investigating reproductive ecology, life history, population dynamics, disease, and behavior in modern and prehistoric contexts."

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Humans hastened the extinction of the woolly mammoth

New research shows that humans had a significant role in the extinction of woolly mammoths in Eurasia, occurring thousands of years later than previously thought.

An international team of scientists led by researchers from the University of Adelaide and University of Copenhagen, has revealed a 20,000-year pathway to extinction for the woolly mammoth.

"Our research shows that humans were a crucial and chronic driver of population declines of woolly mammoths, having an essential role in the timing and location of their extinction," said lead author Associate Professor Damien Fordham from the University of Adelaide's Environment Institute.

"Using computer models, fossils and ancient DNA we have identified the very mechanisms and threats that were integral in the initial decline and later extinction of the woolly mammoth."

Signatures of past changes in the distribution and demography of woolly mammoths identified from fossils and ancient DNA show that people hastened the extinction of woolly mammoths by up to 4,000 years in some regions.

"We know that humans exploited woolly mammoths for meat, skins, bones and ivory. However, until now it has been difficult to disentangle the exact roles that climate warming and human hunting had on its extinction," said Associate Professor Fordham.

The study also shows that woolly mammoths are likely to have survived in the Arctic for thousands of years longer than previously thought, existing in small areas of habitat with suitable climatic conditions and low densities of humans.

"Our finding of long-term persistence in Eurasia independently confirms recently published environmental DNA evidence that shows that woolly mammoths were roaming around Siberia 5,000 years ago," said Associate Professor Jeremey Austin from the University of Adelaide's Australian Centre for Ancient DNA.

Associate Professor David Nogues-Bravo from the University of Copenhagen was a co-author of the study which is published in the journal Ecology Letters.

"Our analyses strengthens and better resolves the case for human impacts as a driver of population declines and range collapses of megafauna in Eurasia during the late Pleistocene," he said.

"It also refutes a prevalent theory that climate change alone decimated woolly mammoth populations and that the role of humans was limited to hunters delivering the coup de grâce".

"And shows that species extinctions are usually the result of complex interactions between threatening processes."

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Did woolly mammoths overlap with first humans in what is now New England?

 Woolly mammoths may have walked the landscape at the same time as the earliest humans in what is now New England, according to a Dartmouth study published in Boreas. Through the radiocarbon dating of a rib fragment from the Mount Holly mammoth from Mount Holly, Vt., the researchers learned that this mammoth existed approximately 12,800 years ago. This date may overlap with the arrival of the first humans in the Northeast, who are thought to have arrived around the same time.

"It has long been thought that megafauna and humans in New England did not overlap in time and space and that it was probably ultimately environmental change that led to the extinction of these animals in the region but our research provides some of the first evidence that they may have actually co-existed," explains co-author Nathaniel R. Kitchel, the Robert A. 1925 and Catherine L. McKennan Postdoctoral Fellow in anthropology at Dartmouth.

The Mount Holly mammoth, Vermont's state terrestrial fossil, was discovered in the summer of 1848 in the Green Mountains during the construction of the Burlington and Rutland railroad lines. One molar, two tusks, and an unknown number of bones were excavated from a hilltop bog near Mount Holly. Over time, the specimens became scattered across several repositories, as they transferred from one collection to the next. A rib fragment from the Mount Holly mammoth became part of the Hood Museum of Art's collection and some of the other skeletal materials are now housed at the Museum of Comparative Zoology at Harvard University and the Mount Holly Historical Museum.

Kitchel stumbled across the Mount Holly mammoth rib fragment last December at the Hood Museum's offsite storage facility, as curators had invited him to take a look at some of their artifacts from New Hampshire and Vermont. He came across a large bone (approximately 30 cm. in length) that was stained brown in color from age. He had a hunch that this was the remains of a mammoth and when he looked down at the tag, it read, "Rib of fossil elephant. Mt. Holly R.R. cut. Presented by Wm. A. Bacon Esq. Ludlow VT." This was rather serendipitous for Kitchel, as he had recently delivered a talk at Mount Holly's Historical Museum for which he had read up on the Mount Holly mammoth.

To appreciate the significance of the Mount Holly mammoth remains, including the rib fragment, it is helpful to understand the paleontology of the Northeast. During the Last Glacial Maximum around 18,000 -- 19,000 years ago when glaciers were at their maximum extent, the ice began to retreat, gradually exposing what is now New England. During that period, it is likely that the glaciers probably sufficiently ripped up whatever soil might have been preserving fossils, reducing the likelihood for fossils to remain intact. These changes combined with the Northeast's naturally acidic soils have created inhospitable conditions for the preservation of fossils. While Kitchel had discussed the complicated paleontology of the Northeast in the past with colleague and co-author Jeremy DeSilva, an associate professor of anthropology at Dartmouth, he never thought that he would have much of an opportunity to work on it.

After seeing this mammoth material in the Hood's collection, he and DeSilva decided to obtain a radiocarbon date of the fragmentary rib bone. They took a 3D scan of the material prior to taking a small (1 gram) sample from the broken end of the rib bone. The sample was then sent out to the Center for Applied Isotope Studies at the University of Georgia for radiocarbon dating and a stable istotopic analysis.

Radiocarbon dating enables researchers to determine how long an organism has been dead based on its concentration of carbon-14, a radioactive isotope that decays over time. Stable isotopes however, are isotopes that do not decay over time, which provide a snapshot of what was absorbed into the animal's body when it was alive. Nitrogen isotopes can be used to analyze the protein composition of an animal's diet. The nitrogen isotopes of the Mount Holly mammoth revealed low values in comparison to that of other recorded mammoths globally while also reflecting the lowest value recorded in the Northeast for a mammoth. The low nitrogen values could have been the result of these mega-herbivores having to consume alder or lichens (nitrogen fixing species) during the last glacial period when the landscape was denser due to climate warming.

"The Mount Holly mammoth was one of the last known occurring mammoths in the Northeast," says DeSilva. "While our findings show that there was a temporal overlap between mammoths and humans, this doesn't necessarily mean that people saw these animals or had anything to do with their death but it raises the possibility now that maybe they did."

The radiocarbon date for the Mount Holly mammoth of 12,800 years old overlaps with the accepted age of when humans may have initially settled in the region, which is thought to have occurred during the start of the Younger Dryas, a final pulse of glacial cold before temperatures warmed dramatically, marking the end of the Pleistocene (Ice Age).

While other research on mammoths in the Midwest suggests that humans hunted and buried these animals in lakes and bogs to preserve the meat, there's little evidence that early humans in New England hunted or scavenged these animals.

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The last mammoths died on a remote island

Woolly mammoth illustration.

The last woolly mammoths lived on Wrangel Island in the Arctic Ocean; they died out 4,000 years ago within a very short time. An international research team from the Universities of Helsinki and Tübingen and the Russian Academy of Sciences has now reconstructed the scenario that could have led to the mammoths' extinction. The researchers believe a combination of isolated habitat and extreme weather events, and even the spread of prehistoric man may have sealed the ancient giants' fate. The study has been published in the latest edition of Quaternary Science Reviews.

During the last ice age -- some 100,000 to 15,000 years ago -- mammoths were widespread in the northern hemisphere from Spain to Alaska. Due to the global warming that began 15,000 years ago, their habitat in Northern Siberia and Alaska shrank. On Wrangel Island, some mammoths were cut off from the mainland by rising sea levels; that population survived another 7000 years.

The team of researchers from Finland, Germany and Russia examined the isotope compositions of carbon, nitrogen, sulfur and strontium from a large set of mammoth bones and teeth from Northern Siberia, Alaska, the Yukon, and Wrangel Island, ranging from 40,000 to 4,000 years in age. The aim was to document possible changes in the diet of the mammoths and their habitat and find evidence of a disturbance in their environment. The results showed that Wrangel Island mammoths' collagen carbon and nitrogen isotope compositions did not shift as the climate warmed up some 10,000 years ago. The values remained unchanged until the mammoths disappeared, seemingly from the midst of stable, favorable living conditions.

This result contrasts with the findings on woolly mammoths from the Ukrainian-Russian plains, which died out 15,000 years ago, and on the mammoths of St. Paul Island in Alaska, who disappeared 5,600 years ago. In both cases, the last representatives of these populations showed significant changes in their isotopic composition, indicating changes in their environment shortly before they became locally extinct.

Earlier aDNA studies indicate that the Wrangel Island mammoths suffered mutations affecting their fat metabolism. In this study, the team found an intriguing difference between the Wrangel Island mammoths and their ice age Siberian predecessors: the carbonate carbon isotope values indicated a difference in the fats and carbohydrates in the populations' diets. "We think this reflects the tendency of Siberian mammoths to rely on their reserves of fat to survive through the extremely harsh ice age winters, while Wrangel mammoths, living in milder conditions, simply didn't need to," says Dr. Laura Arppe from the Finnish Museum of Natural History Luomus, University of Helsinki, who led the team of researchers. The bones also contained levels of sulfur and strontium that suggested the weathering of bedrock intensified toward the end of the mammoth population's existence. This may have affected the quality of the mammoths' drinking water.

Why then did the last woolly mammoths disappear so suddenly? The researchers suspect that they died out due to short-term events. Extreme weather such as a rain-on-snow, i.e. an icing event could have covered the ground in a thick layer of ice, preventing the animals from finding enough food. That could have led to a dramatic population decline and eventually to extinction. "It's easy to imagine that the population, perhaps already weakened by genetic deterioration and drinking water quality issues could have succumbed after something like an extreme weather event," says professor Hervé Bocherens from the Senckenberg Center for Human Evolution and Palaeoenvironment at the University of Tübingen, a co-author of the study.

Another possible factor could have been the spread of humans. The earliest archaeological evidence of humans on Wrangel Island dates to just a few hundred years after the most recent mammoth bone. The chance of finding evidence that humans hunted Wrangel Island mammoths is very small. Yet a human contribution to the extinction cannot be ruled out.

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Woolly mammoths and Neanderthals may have shared genetic traits

Mammoth rendering.

A new Tel Aviv University study suggests that the genetic profiles of two extinct mammals with African ancestry -- woolly mammoths, elephant-like animals that evolved in the arctic peninsula of Eurasia around 600,000 years ago, and Neanderthals, highly skilled early humans who evolved in Europe around 400,000 years ago -- shared molecular characteristics of adaptation to cold environments.

The research attributes the human-elephant relationship during the Pleistocene epoch to their mutual ecology and shared living environments, in addition to other possible interactions between the two species. The study was led by Prof. Ran Barkai and Meidad Kislev of TAU's Department of Archaeology and Ancient Near Eastern Cultures and published on April 8 in Human Biology.

"Neanderthals and mammoths lived together in Europe during the Ice Age. The evidence suggests that Neanderthals hunted and ate mammoths for tens of thousands of years and were actually physically dependent on calories extracted from mammoths for their successful adaptation," says Prof. Barkai. "Neanderthals depended on mammoths for their very existence.

"They say you are what you eat. This was especially true of Neanderthals; they ate mammoths but were apparently also genetically similar to mammoths."

To assess the degree of resemblance between mammoth and Neanderthal genetic components, the archaeologists reviewed three case studies of relevant gene variants and alleles -- alternative forms of a gene that arise by mutation and are found at the same place on a chromosome -- associated with cold-climate adaptation found in the genomes of both woolly mammoths and Neanderthals.

The first case study outlined the mutual appearance of the LEPR gene, related to thermogenesis and the regulation of adipose tissue and fat storage throughout the body. The second case study engaged genes related to keratin protein activity in both species. The third case study focused on skin and hair pigmentation variants in the genes MC1R and SLC7A11.

"Our observations present the likelihood of resemblance between numerous molecular variants that resulted in similar cold-adapted epigenetic traits of two species, both of which evolved in Eurasia from an African ancestor," Kislev explains. "These remarkable findings offer supporting evidence for the contention regarding the nature of convergent evolution through molecular resemblance, in which similarities in genetic variants between adapted species are present.

"We believe these types of connections can be valuable for future evolutionary research. They're especially interesting when they involve other large-brained mammals, with long life spans, complex social behavior and their interactions in shared habitats with early humans."

According to the study, both species likely hailed from ancestors that came to Europe from Africa and adapted to living conditions in Ice Age Europe. The species also both became extinct more or less at the same time.

"It is now possible to try to answer a question no one has asked before: Are there genetic similarities between evolutionary adaptation paths in Neanderthals and mammoths?" Prof. Barkai says. "The answer seems to be yes. This idea alone opens endless avenues for new research in evolution, archaeology and other disciplines.

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