Ice Age paleontologist Prof. Dr. Ralf-Dietrich Kahlke of the Senckenberg Research Station for Quaternary Paleontology in Weimar recorded the maximum geographic distribution of the woolly mammoth during the last Ice Age and published the most accurate global map in this regard. The ice-age pachyderms populated a total area of 33,301,000 square kilometers and may thus be called the most successful large mammals of this era. The study, recently published online in the scientific journal Quaternary International, determined that the distribution was limited by a number of climate-driven as well as climate-independent factors.
The mammoth is the quintessential symbol of the Ice Age -- and the status of these shaggy pachyderms has now been confirmed scientifically. "The recent research findings show that during the last Ice Age, mammoths were the most widely distributed large mammals, thus rightfully serving as a flagship species of the glacial era," according to Prof. Dr. Ralf-Dietrich Kahlke, an Ice Age researcher at the Senckenberg Research Station for Quaternary Paleontology in Weimar.
Kahlke has summarized the mammoth's distribution during the most recent Ice Age, i.e., the period between approx. 110,000 and 12,000 years ago, on a worldwide map. All in all, the Weimar paleontologist determined a total distribution area of 33,301,000 square kilometers for these large mammals -- almost 100 times the area of Germany today. From Portugal in the southwest across Central and Eastern Europe, Mongolia, Northern China, South Korea and Japan up to Northeastern Siberia, and thence to the American Midwest and Eastern Canada, from the shelf regions of the Arctic Ocean and Northwestern Europe to the bottom of the Adriatic Sea and to the mountains of Crimea: the fossil remains of woolly mammoths have been found everywhere.
"We related the computed distribution area to the real land surface at that time, thus generating the most precise map to date regarding the global habitats of the woolly mammoth," explains Kahlke, and he adds, "Such detailed knowledge regarding the distribution area is not even available for many species of animals alive today."
The generated map is based on decades of surveys of thousands of excavation sites on three continents. "Even sites under water, off the North American Atlantic shore and the North Sea, were taken into account. Due to the lower sea levels during the Ice Age -- a large volume of water was bound in glaciers -- these areas had fallen dry and were also inhabited by Mammuthus primigenius," according to Kahlke.
Only the ice-age bison (Bison priscus) had a widespread distribution similar to that of the mammoths. Kahlke explains, "The bison were clearly more variable than the woolly mammoths. Obviously, the mammoths had a higher tolerance toward various environmental factors and they were able to successfully settle in a variety of rather different open landscapes."
But there were certain factors that limited the distribution of the hirsute pachyderms: glaciers, mountain chains, semi-deserts and deserts, as well as changes in sea level and shifts in vegetation placed restrictions on the mammoths' distribution area. "The analysis of these limiting factors is useful in understanding the distribution of fossil species and their extinction -- as with the mammoths toward the end of the last Ice Age. In addition, the data aid in comprehending current changes in the distribution areas of recent animal species," offers Kahlke in summary.
Men and persons age 65 and older who have access to natural surroundings, whether it's the green space of a nearby park or a sandy beach and an ocean view, report sleeping better, according to a new University of Illinois study published in Preventive Medicine.
"It's hard to overestimate the importance of high-quality sleep," said Diana Grigsby-Toussaint, a U of I professor of kinesiology and community health and a faculty member in the U of I's Division of Nutritional Sciences. "Studies show that inadequate sleep is associated with declines in mental and physical health, reduced cognitive function, and increased obesity. This new study shows that exposure to a natural environment may help people get the sleep they need."
In the study, Grigsby-Toussaint worked with both U of I researchers and scientists from the New York University School of Medicine. The team used data from the CDC's Behavioral Risk Factor Surveillance System, which surveyed 255,171 representative U.S. adults, to learn whether there was an association between self-reported days of insufficient sleep and access to green space. The team also used a USDA index that scores the country's geographical areas for their natural amenities, using hours of sunlight, which is important in regulating a person's circadian rhythm, and temperature.
In response to the survey question about sleep quality in the last month, the researchers found that the most common answer was that respondents had slept poorly for less than one week.
"Interestingly, though, across the entire sample, individuals reporting 21 to 29 days of insufficient sleep consistently had lower odds of access to green space and natural amenities compared to those reporting less than one week," she said.
For men, the relationship between sleep and exposure to green space was much stronger than for women. And males and females 65 and over found nature to be a potent sleep aid, she added.
Grigsby-Toussaint noted that living near green landscapes is associated with higher levels of physical activity and that exercise in turn predicts beneficial sleep patterns.
But men appeared to benefit much more from their natural surroundings. The researcher speculated that women may take less advantage of nearby natural settings out of concern for their safety, but she added that more research is needed.
The finding should be a boon for people who are having trouble sleeping as they age. "If there is a way for persons over 65 to spend time in nature, it would improve the quality of their sleep--and their quality of life--if they did so," Grigsby-Toussaint said.
The study points to the importance of conserving nature in general, she added.
"And, specifically, our results provide an incentive for nursing homes and communities with many retired residents to design buildings with more lighting, create nature trails and dedicated garden spaces, and provide safe outdoor areas that encourage outdoor activity for men and women," she said.