Species Endangered (MS-Blog Series from) – V / 09

Mammoth

“When aiming to depict a world, that once existed, 30 000 years in the prehistoric past, and from where not any concise written word can't reach our times, one has to rely on: 1. Known facts 2. Conclusions based on those facts 3. Imagination “

(Björn Kúrten, 1984, Mammutens Rådare)^{Transl; W-G.}

• Class: Mammal
• Order: Proboscidea
• Latin name: Mammuthus (Primigenius /Columbi)
• Range: From Mid-Europe to Northern parts of Asia (Siberia) ; North American continent
• Population Status: EX (Extinct), the time varying regionally, about 14000-8000 B.C. on continents [~1700 B.C., on Wrangel island])

(a 2008 situation)

It may feel a bit inconsistent and obscure, that we are including an extinct species in our series. However, there's innumerable animals which have disappeared from the evolutionary continutation in the prehistoric pasts, during millions of years. This renown species particularly we've selected to represent a larger phenomenon, extinctions timed for the end of last ice age (or in wider sense usually described as the Quaternary extinction event). (Our selection) also has reasons from the fact that mammoths are among the better/best known species from that time.

If we now allow ourselves this exception, and it's selected from mammals it has to be the mammoth. At least from the terrestrial animals, from among sea mammals there could possibly be alternative choices. (In fact we might also consider some examples from disappeared insect and reptile species, but on this logic the latter would then have to be a dinosaur and that doesn't really much fit for the ecological or evolutionary limits we're trying to keep...and as well I notice my knowledge from dinosaur consisting from the three earliest parts of Jurassic park...) It seems also we've quite slipped for to present solely mammals since there's now already 4 of the total 6 so far in our series. Nevertheless, not the least because human family tree derives from mammals by origin, I'd still like later to include an example from some sea mammal (likely the whales), one from the carnivorous species and perhaps still yet another one from primates, our closest relatives according the evolutionary theory.



What makes most arguments on behalf selecting mammoth as species in this series is their long common path with humans in prehistory, reaching culturally even the present. In during couple decades mammoths have become a popular subject of many famous novels, most forcefully since the 1980s. The mentioned dinosaur films pushed them little away from spotlight in 1990s, but more recently there's afresh found popularity in films and books, fx such as Stephen Baxter's Silverhair (1999) and the followed novels in the serie (Icebones, Longtusk), which combined the recent knowledge and the mythical status of these animals.



But, not less important, the mammoths strong relationship to humans in (pre)history is found from the cave-paintings and sculpted art (see picture above), also there's many prehistoric tools and objects which are carved from mammoth ivory (as well the vast bone founds, mostly from Siberia, that still make a feasible industry for the specialized handicraft), and – not to forget - of course the archaeological founds, plenty of them made even before the 19^th century. If there had to be one animal species in connected to the humans in the ice-ages, most people would by first impression probably think about mammoths (although, fx deers, horses and as well as perhaps the cave-bears probably may have had equal place in the mythical and spiritual world of those distant ancestors).


Like goes the phrase, mammoths were the 'shaggy beasts' and the mammoth image mostly is settled for the best known/most common species, Mammuthus Primigenius(the wool mammoth). But in fact, they weren't beasts at all, not carnivores but large herbivores¹ that tramped on North-American and Eurasian continents during the recent glaciation periods. Contrary to sometimes misleading belief, mammoths did not inhabit the glaciers which at the time reached from North-pole to middle of those continents, but instead lived on plains that were limiting to the edges of glaciers (areas usually called as the mammoth steppe). In general that steppe is known to have been more rich from plants and animal species than similar areas today, although it was also very harsh from climatic conditions. Its vegetation probably was various enough to offer diet for several large grass-eating herbivores. At least on the southern parts also occasional trees would grow in the middle of grasslands. From preserved mammoths stomachs fx trenches of willows and birch have been found. Various animals lived on steppe, a lot more than are found on todays northern tundras, including deers, reindeers, wolves, and as well carnivorous lion-sized cats. Various smaller species too, fx marmots and lemmings were just a few examples. The mixture of elements from tundra and more temperates grasslands was characteristic for this steppe. Mammoths which were gigantic in proportions, about the same as elephants, are not believed to have had much predators. Possibly few carnivours that could occasionally threaten them were the sabretooth cats (Homotherium ; Smilodon). Injured or young smaller individuals may have gotten for their prey (ao animals), sometimes. Also, mammoth was among the most common species (from that the name, 'mammoth steppe'), only more abundant were horses and prehistoric bisons – the latter also larger in size than the surviving ones today. As is also quite renown, mammoth bones, tooths and skeletons, and even frozen individuals have been found from the Siberian permafrost in numbers (best preserved example being the Dima).


The wool mammoths evolutionary road goes back some 300 000 years when it evolved from the earlier mammoths (preceding species M. Meridionalis originated in warmer latitudes, and as it's successsor then about half million years ago evolved M. Trogontherii). From the latter further evolved the mentioned wool mammoths. On the North-American continent, since about 1.5 M years ago evolved slightly different comparable mammoth species, M.Colombi. It was (considerably) larger than M.Primigenius(wool mammoth was about 2.5 to 3.5 m tall and weighed about 4-6 tons). Also is supposed that M. Colombi might have lived on a bit warmer regions than wool mammoth, though not on the South-American region. With most probability species ranges not overlapped each other, although from some places remains from both have been found, and the wool mammoths skeletons (and frozen ones) have been found also from Alaska. In Any case these two presented the most abundant species before they both disappeared at the end of the latest ice-age, soon after the retreat of glaciers in the continents.


What has still remained somewhat unsolved (and as the most debated from mammoths for decades) is the question from their disappearance. Overally Pleistocene extinctions are known having followed supposed human arrival on various continents which makes a quite convincing argument on human participation on event (see the above Wikipedian link from that). In spite of that, on different continents this may have had more complex reasons too.


A well-known theory (among others) since the 1960s, is so called Overkill-theory, as such somewhat displaced nowadays. It focused largely on mammoths, since its main assumption was from the larger animals having been quickly annihilated by earliest arrivals on American continent, who (supposedly) were big game hunters (as the theory was concerned on N.A. and the first human settlement was earlier believed to date around 11200 B.C.). Originally, theory relied (largely) on founding of Clovis points(/Clovis spear points) first discovered at 1928, and since that from various places at mammoths skeletons and/or close their remains. More recent research has pushed the time of the first settlement further past(basically proves the theory inadequate). Also, Clovis people more likely were typical hunters and relied at least as much for various kinds of smaller prey, including fish, mussels, collecting grains and peanuts. They are known having inhabited large areas from the western part of continent, but little else from the culture is preserved until our times. The spear points have been found all around the Northern America, including Canada which also makes overkill-supposition more unlikely, as only about dozen mammoth kill sites at continent are known with certainty. (Fagan, 2005) So the theory becomes reasonable only if one thinks the arrivals having spread around continent surprisingly fast, and the spear points presenting a highly advanced paleolithic technology compared to preceding methods (of hunters). To certain level they perhaps might, but as the founds are such rare it only proves early humans having killed and eaten mammoths(as well as other herbivores), and as did also fx the Neanderthalians at least 100 000 years ago.


Since the mammoths disappeared only after the most recent glaciation, this also has given some argument on behalf the human causes. However, at the end of the Pleistocene climatic changes are known to have been more dramatic and varying by many ways, fx about 13000 years ago there might have been a sharp decline of several degrees in global temperatures in just couple decades (Lister-Bahn 1994) and 1000 years that followed were a period of cooler climates (in the middle of slow overall warming towards the end of glaciation)(Fagan 2005). That may have had many effects, but fx because the mammoths were large grass-eating animals it is reasonable to suppose that disappearance of ice-age tundra and spread of forests may have diminished their living area - It is also sometimes stated that mammoths might have become out-competed on those fewer remaining plains and grasslands by other herbivores, bisons mostly. The last mammoth populations might have evolved too specialized for the earlier conditions and therefore did not survive post glacial changes.

On the other hand it seems that these species were able to migrate in between regions, as one research notices that there may have been a 'return movement' of wool mammoth populations from the Beringia to Siberia. The likely cause for mammoths return via Beringia, could have been the climatic changes and in any case this seems to support a view from drastic changes in temperatures at the time(reason why the 'newcormers' replaced the earlier Siberian mammoths is not known, likely various possibilities exist). As other studies (DNA-researches) also seem to give an argument that also the populations of bisons in Beringia were affected by climate and declined in genetic diversity, it strenghtens the supposition that the dramatic changes (in climate) may have had serious effects on many species (and their ecological ranges). But even so, it is also often stated that no climate theory can adequately explain the total amount of the large species died out worldwide in about same period of time (the late Pleistocene).

From mammoths is also known that they may have survived somewhat longer on islands than on the continent. Best known example is from the Wrangel Island in Arctic sea, near East-Siberian coast, where the mammoths survived until about 3400 years before the present (most recent timing known they existed anywhere), but finally were – probably – wiped out by human, since human arrival on island has been timed close that (it's not known humans having hunted the mammoths there, though). As well, on St Paul Island near Alaskan coast, the mammoths survived until about 6000 B.C., extinction having followed from natural reasons, since humans are ruled out due that they first arrived on isolated island at 18^th century (Lister-Bahn [2007], p 163). Finally, from the examples of (dwarfed) isolated island mammoths, there is the Channel Islands 'pygmy mammoth' (subspecies M. Exilis), which had evolved to a lot smaller size in islands (during about 40000-20000 years period) after having swam to islands. Sea was then lower and the islands originally larger forming in the ice-age a 'super island', where mammoths would have grazed. It is believed that the disappearance closely correlates to (supposed) human arrival around 12900 years ago(Lister-Bahn [2007], p 160). Although, one feels likely the islands might well have been populated even earlier (how regularly is perhaps less clear). Whatever the most recent knowledge, I think any of preceding still gives only little explanation on behalf or against, since islands are isolated cases by any means. Yet, many believe the survival of several (prehistoric) animal species on islands long after the disappearance on mainland as strong argument (pro human caused event).


More recently (perhaps), as the most likely cause, has been raised the co-effect, where human hunters might have replenished last surviving populations. Seems logical to think so, largely because humans are known having extinct a number of animals, either remnants from earlier abundant populations declined from other reasons(like Steller's Sea Cow, Hydrodamalis gigas, Extinct at 1770s), and/or as well species which may have originally been numerous but vulnerable like Passenger pigeon, Ectopistes migratorius (last specimen died in captivity, 1914) - though concerning the latter mentioned, it has also been speculated the abundance of the bird having resulted from human caused changes in the ecological balance(Mann, 2005). In both cases, however, when species populations had weakened and become vulnerable the final period of annihilation(human caused) didn't take much longer than some 20-30 years. Even after loss of most of the suitable living habitat, mammoths disappearance would have taken a far longer period of time.


Last mammoths were disappearing from final parts of the Europe around 14000 years ago estimated, and the last founds, from Sweden and Denmark, are timed around 13000 years ago(Nogues-Bravo, 2008). Overally, mammoths vanished from across most of their known range in about 14000-10000 years ago. (But, in the southernmost places, South Europe and China they were gone already about 24000 years past). On the North-America the timing is closer to 11000 ago, supposedly M.Colombi having survived little later (about 500 years) than woolly mammoths.(Lister-Bahn [2007], 146).

Finally, a recent study seems to offer a combined explanation from the climatic and human caused influences, and it presents that major part of the most suitable climatic areas for (woolly) mammoths reduced continuously from 42000-6000 B.C., the species geographic range disappearing about 90 per cent during that time. Humans might have then finished the remaining pockets, where mammoths perhaps could have survived - like they did from earlier glaciation periods. According to that even limited hunting and low human population density might have been sufficient to cause final disappearance. The view is also supported with the last non islands mammoths founds located at northeastern Siberia, in the area classified by model as most suitable remaining living area 6000 B.C. The Wrangel island is believed to present an exception where vegetation and climate resembling ice-age tundra could have remained sometime longer (though according to model it wouldn't have been counted among those best suitable 'pockets' left in about that time, 4000 B.C. (Nogues-Bravo, 2008) Mammoths (species that come in the question here, M. Primigenius and mostly also M. Colombi), were from the evolutionary perspective species that roamed numerous and flourished during past the ice-ages, but it is supposable that whether there had been humans or not, might have after it either disappeared or been forced to adapt for somewhat more limited range/environments. And basically, it seems as most logical conclusion, so forth, case closed (at least for the wool mammoth); 'Increase of anthropogenic impacts in the Holocene are most likely to have been 'coup de grace' that set time and place for the extinction', like concluded in the research.

But since I feel some healthy suspicion - equally for statistics, quantitative analyses and lab-techs - I think it is worth the effort also consider all this from yet another perspective. At least because our series here mostly is focused on the endangered animals, not yet extinct.


As was noted, it is believed mammoths were not adapting for the spread of forests that increased in the end of last glacial, this being a (one) main cause for their disappearance. However, to the contrary it is sometimes assumed that their 'cousins', African savannah elephants (Loxodonta Africana) might have survived the recent (glaciation) periods because of the large forests that also existed in during ice-ages, though somewhat smaller in range. The glaciation(s) affected the African rain forests by reducing their geographic area, but they existed even during the so called glacial maximum (ie coldest period, when the sheets were at their largest). As consequence, todays savannah elephants therefore (supposedly) might have evolved from forest elephants for current species, only after ice-age(s) having populated the savannahs. The view is (was?) based on that from preceding times there is some 2 million year gap in the fossil remains of Loxodonta species (and rain forest conditions effectively prevent the formation of fossil remains). In during the same time Elephas-species were prevailing ones, their disappearance having happened in during those glaciation periods (Gamlin-Rohan, 1996). (The mentioned elephant species most probably include Elephas recki, abundant species in the past and E. antiquus which were found habitating even the European ranges still some 70 000 years ago - I guess there's plenty research about them too, though they seem less studied than mammoths) Be the elephants (recent) evolution and ecological ranges gone that way or not, the supposition doesn't completely hold because a study from current African elephant species DNA (forest and savannah), finds it more likely them being different species, that supposedly a result of the several millions years evolutionary divergence (Eggert-Rasner, 2002).


In any case, it is somewhat interesting because much from what is known about mammoths behavior is assumed by known/observed from the elephants. Also, it seems that both may have been common species in their particular habitat, but the post ice-age period (conditions) shows completely opposite. Not comparable with each other, since the geographic regions much differ and so did the climatic effects, but as mammoths disappeared, the current African elephants populations probably increased (and became as well very successful species in their habitat, like can be read from the following).


According to DNA-researches mammoths were found more related to Indian elephant, (Elephas maximus), but differences in between the three are relatively small. Mammoths fx were similarly slowly reproducing species (for an African elephant, as much cousin for mammoths as Indian, gestation period takes about 2 years, fx), a thing likely to increase species vulnerability. Nowadays less threatened from the two surviving elephant species, African elephant had populations counted in tens of millions still in the beginning of 19^th century. Today, the numbers are around half million specimen (in the early 1970s there were still about 2 million, but as result of increased killing for ivory, the species was conserved in 1990). If one then thinks that about 500-1000 years on most geographic ranges would have been 'needed' for the final days of the mammoths (that a direct following from human caused pressure or not) the similarities in between the two start to seem almost too alarming. In fact, the elephants are actually more in process of rapid endangerment than our prehistoric example ever was. The process only seems somewhat backwards, earlier major hunt largely having reduced their populations already. There's conservation areas today but they can't cover the whole of species ranges and as well the illegal pouching still is mentioned an existing threat.


So, perhaps our effort here was a little too devoted for these most interesting prehistoric questions and distant pasts. But all the same, it of course also quite well reflects that mythical image humans have always felt connected to mammoths. As the species is among the most researched ice-age topics, one feels it also makes quite convenient selection to this series. Even though there are various other (more peculiar) surviving species in existence today (not to forget the colourful frogs, birds, etc). And probably a reader, thousand years from now, would much agree with this last paragraph (not that I would suppose anyone reading this that far, or that being likely even...)

Pic (from Lister-Bahn, 1994) ; Mammoth-engraving in the Rouffignac-cave.

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Notes:

1. (Actually, seems that, we must have stolen that last sentence from somewhere, though I don't quite recollect from where...) But, on the other hand it can be remembered: mammoths were close relatives to elephants, animals that are not just among the most intelligent, but also known as one of the most (potentially) dangerous of them. So, on that basis the image of 'beast' can be argumented although not proven as most correct definition. Also the species huge size and proportions give some grounds for the view from humans point-of-view (not any beast of burden, anyway...)
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Reference (literature):


Lister, A. and Bahn, P, 1994, [2007], Mammoths - the Giants of the Ice-Age.

- Much of this text actually is based on information from the book. It's the best general source, likely. The newer edition contains more up-to-date knowledge and can be viewed on Google's book search (though, I've mostly relied on the older edition, from the reason that it's equally informative). However, one interested from mammoths easily finds lots researches, (also) sometimes from different views / focused on other aspects than the ones presented in the preceding.


Eggert, L.S., Rasner, C.A., Woodruff, D.S., 2002, The evolution and phylogeography of the African elephant inferred from mitochondrial DNA sequence and nuclear microsatellite markers. doi: 10.1098/rspb.2002.2070 Proc. R. Soc. Lond. B 7 October 2002 vol. 269 no. 1504 1993-2006. (Pdf - here) ; From Royal Society Proceedings (Biology)


Fagan, Brian, 2005, The long summer ; how climate changed civilization. NY.

Gamlin, L. and Rohan, A., 1996, Mysteries of the Rain Forest.


Kurtén, Bjorn, 1984, Mammutens rådare. (Fictional)


Mann, Charles C., 2005, 1491. New revelations of the America's before Columbus. NY.


Nogués-Bravo D, Rodríguez J, Hortal J, Batra P, Araújo MB (2008) Climate Change, Humans, and the Extinction of the Woolly Mammoth. PLoS Biol 6(4): e79. doi:10.1371/journal.pbio.0060079



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