DNA testing has been used by a team of researchers to give a unique view of the diet of large mammals which roamed the northern hemisphere in the last ice-age.
The researchers, led by the University of Copenhagen, sequenced DNA taken from samples of frozen soils and the stomachs of creatures preserved in the permafrost of Siberia and Alaska-Yukon - an area many times the size of the UK.
Their 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. It is ideal for this kind of study because the DNA isn't lost to the normal processes of decay," Professor Mary Edwards at the University of Southampton, who is a physical geographer with expertise in permafrost deposits, said.
"By analysing 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," she said.
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, this latest study gives a new perspective on this, suggesting instead a dominance of forbs, until at least around 10,000 years ago when woody plants and graminoids then become more prevalent.