It isn’t often that palaeopathology enters popular culture but then mammoths have long fascinated humanity. Perhaps it is because our ancestors actually lived alongside them, or maybe it is the existence of such beautifully preserved examples, often with intact hair and skin, that has given us such an intimate glimpse of these prehistoric mammals. A glimpse rarely possible with many older species. In fact it is this incredible preservation which lies at the heart of today’s post. If you saw the 2004 film the Day After Tomorrow you might have heard that some mammoths have been found ‘flash frozen’ with preserved food still in their mouths. The idea has also been taken up by several creationist groups as evidence for a recent, world-wide flood. One particular mammoth specimen often mentioned is the ‘Berezovka mammoth’ but why have they singled out this particular individual? And why is it so special?
First let’s set the scene. It’s 1901 and a team of scientists from St Petersburg has just been dispatched to retrieve a mammoth specimen recently discovered by local hunters in northern Siberia. The journey took them several months and when the expedition finally arrived they discovered the mammoth, still partially embedded in the banks of the Berezovka River (sometimes Beresovka) and beginning to decay as it defrosted. According to accounts from the time only the head and neck were exposed and they stank, as did the earth they were buried in. Wolves had already begun scavenging the remains, further damaging them. The team set about uncovering the rest of the specimen, slowly removing it from its the icy mud it was buried in and this allowed the expedition’s resident palaeontologist, Eugen Wilhelm Pfizenmayer, to examine it. The first thing that struck him was that the animal must have died very suddenly because there was still plant material caught in its back teeth suggesting whatever had overtaken the mammoth had literally taken place mid-bite. This one piece of information seems to have spawned many of the more unconventional theories about what killed the Berezovka mammoth since it seems to call for an unprecedentedly rapid death and preservation. However, Pfizenmayer himself actually came to a perfectly logical conclusion about what happened to this mammoth based on his autopsy of the body.
The Berezovka mammoth had suffered a fractured humerus and pelvis. There was no evidence that either injury had begun to heal and because of the angle of both fractures it seemed that they had been caused at the same time, by the same trauma. There was also a pronounced hematoma between the muscles and connective tissue. A hematoma is a localised blood clot outside of the blood vessel and is often caused by leakage from the vessel because of an injury. To Pfizenmayer this suggested that the mammoth was killed when it fell into a crevasse in the ice alongside the river and was smothered by the ensuring landslide of half-frozen mud. This would have killed the mammoth very quickly and the rapid burial in very cold conditions would also explain the excellent preservation of the specimen. In fact this theory is the one that Pfizenmayer wrote up in his 1939 book on the subject called Siberian Man and Mammoth. Since then many other frozen mammoths have been discovered in Siberia and Alaska, as have similarly preserved bison, some of which seem to have fallen its crevasses and been buried and others which seem to have become trapped in bogs. Some are so well preserved that scientists have been able to recover DNA from them. None show any evidence of having been ‘flash frozen’ and in fact in a 1961 paper in Science, William Farrand of Columbia University deconstructed many of the arguments in favour of this idea. This included histological data from the Berezovka mammoth which proved that it had begun to decay before it fully froze, which is what you would expect if it had been buried and slowly frozen.
Today you can still visit the Berezovka mammoth, which is preserved at the Zoological Museum in St Petersburg. The Smithsonian, USA, also have a piece of the mammoth; some pickled muscle tissues preserved in jars and not on public display. Carbon dating as placed the age of the Berezovka mammoth at around 35,000-39,000 years old and we think the individual was around 35-40 years old when it died. It is beautifully preserved but there is no need to invoke any exotic theory of world-wide, climatic disaster, to explain this.
Also see this article from the National Center for Science Education for more detailed arguments.