DNA testing is giving scientists a unique view of the diet of large mammals that roamed the northern hemisphere in the last ice age.
Researchers sequenced DNA taken from samples of frozen soils and the stomachs of creatures preserved in the permafrost of Siberia and Alaska-Yukon.
The results show that around 25,000 years ago vegetation in this area was rich in “forbs”—herbaceous flowering plants usually found in grasslands, meadows, and tundra.
“Permafrost is frozen soil and sediment which acts like a giant freezer, preserving countless plant and animal remains from ancient ecosystems,” says Mary Edwards, professor in physical geography at the University of Southampton. “It is ideal for this kind of study because the DNA isn’t lost to the normal processes of decay.
“By analyzing this preserved DNA, we have found that flowering plants, known as forbs, were far more prevalent than previously thought.
“In fact, forbs have been overlooked in many past studies of ice age ecosystems, but this study shows they may have been a critical source of nutrition in the diet of mammalian megafauna—huge animals such as mammoth, woolly rhino, bison, and horse.”
Until now, analyses of vegetation over the past 50,000 years has been based mainly on studying fossil pollen, showing that vegetation in cold environments, supporting large herbivores, was mainly made up of graminoids, plants such as grasses and sedges.
However, the latest study suggests instead a dominance of forbs, until at least around 10,000 years ago when woody plants and graminoids then become more prevalent.
For the study, published in the journal Nature, researchers interpreted millions of DNA sequences in terms of the ice age flora and developed an understanding of the composition of the forage and diets of megafaunal mammals.
“Analyzing plant DNA has provided us with a unique perspective on this now extinct northern ecosystem and given new insights into how such large animals could survive extreme cold and harsh ice-age conditions,” Edwards says.
Researchers from the University of Copenhagen, CRNS Grenoble, and the University of Oslo contributed to the study.
Source: University of Southampton