A 'smoking gun' on the Ice Age megafauna extinctions

Feb 05, 2014
Pleistocene landscape, including mammoth, horse, reindeer, bison and musk ox. Credit: Mauricio Anton

It was climate that killed many of the large mammals after the latest Ice Age. But what more specifically was it with the climate that led to this mass extinction? The answer to this is hidden in a large number of sediment samples from around the Arctic and in the gut content from permafrozen woolly rhinos, mammoth and other extinct ice age mammals.

It is a bit of a shift in paradigme Willerslev and co-workers publish in this week's edition of the journal Nature. The common image of a light-brown grass-steppe dominating the northern hemisphere during the Ice Age does not hold any longer. The landscape was far more diverse and stable than today, and big animals like and mammoth fed on grasses and particularly on protein-rich forbs. But at the Last Glacial Maximum 25,000 – 15,000 years ago, at a time when the climate was at its coldest and driest, a major loss of plant diversity took place. The animals barely survived.

After the Ice Age ended about 10,000 years ago it became warmer again. After the large reduction of during the Last Glacial Maximum another kind of vegetation now appeared. One of the key food sources of the large mammals– the protein-rich forbs – did not fully recover to their former abundance. This likely proved fatal for species like woolly rhino, mammoth, and horse in Asia and North America. Even though it became warmer again after the end of the Ice Age the old landscapes did not return.

Professor Eske Willerslev, an ancient DNA researcher and director of the Centre for GeoGenetics at the Natural History Museum of Denmark, says: "We knew from our previous work that climate was driving fluctuations of the megafauna populations, but not how. Now we know that the loss of protein-rich forbs was likely a key player in the loss of the ice age megafauna. Interestingly one can also see our results in the perspective of the present climate changes. Maybe we get a hold on the greenhouse gases in the future. But don't expect the good old well-known vegetation to come back when it becomes cooler again after the global warming. It is not given that the 'old' ecosystems will re-establish themselves to the same extent as before the warming. It's not only climate that drives vegetation changes, but also the history of the vegetation itself and the mammals consuming it."

Mammoth tusk extracted from ice-complex deposits along the Logata River, Taimyr Peninsula. The ice-complex formed between 50-20 ka BP by deposition of sediment from overland flow and wind transport. Credit: Per Möller/Johanna Anjar

Footprints from past ecosystems

Professor Christian Brochmann, a botanist at the Natural History Museum at the University of Oslo in Norway, states:

We show that the permafrost contains a vast, frozen DNA archive left as footprints from past ecosystems, and that we can dechiffer this archive by exploring the collections of plants and animals stored in Natural History Museums. Using DNA from museum collections as reference, we could identify the different plant species that co-occurred with extinct ice age mammals.

Dr. Mari Moora and Professor Martin Zobel, vegetation ecologists from the University of Tartu, Estonia, say:

For the first time, ecologists have been able to piece together the characteristics of more complete plant communities occurring in the Arctic during the last 50,000 years. The new information shows clearly that the vegetation of the Late Pleistocene was rich in forbs but lost considerable diversity at the peak of the . Different plant communities, with graminoids and woody plants prevailing, then started to develop during the Holocene.

Permafrost core from Taimyr Siberia. Credit: Ross MacPhee

Dr. Pierre Taberlet, an ecologist at the CNRS in France, further states: "We should realise that the results presented in this paper would have never been obtained without a very broad collaboration (30 teams from 12 countries) involving the following scientific areas: ancient DNA, palaeo-ecology, taxonomy, molecular ecology, community ecology, zoology, bioinformatics, molecular genetics, and geology. Whereas competition among scientists often is believed to be the main stimulus promoting global scientific output, this study clearly demonstrates that extensive collaboration is a viable alternative."

'Smoking gun'

The article in Nature elaborates on the Willerslev group's results from 2011 where the researchers pointed at climate as the culprit for the of some of the large mammals'. But in 2011 the researchers lacked a 'smoking gun'. Now they got it! 242 permafrost and eight fossil samples from large mammals from around the Arctic have been dated and analysed for DNA. The data shows that the likely main reason for the mass extinction of the large mammals after the latest Ice Age is changes in the vegetation.

Explore further: 'Severe reduction' in killer whale numbers during last Ice Age

More information: Paper: dx.doi.org/10.1038/nature12921

Related Stories

Rapid climate change ruled out ice age trees

May 17, 2013

Short, sharp fluctuations in the Earth's climate throughout the last ice age may have stopped trees from getting a foothold in Europe and northern Asia, scientists say.

Researchers discover important woolly rhino fossil

Sep 01, 2011

A paper to be published on September 2, 2011 in the authoritative magazine Science reveals the discovery of a primitive woolly rhino fossil in the Himalayas, which suggests some giant mammals first evolve ...

Recommended for you

NASA sees remnants of Nilofar go to cyclone graveyard

4 hours ago

Wind shear has caused the demise of former Tropical Cyclone Nilofar in the northern Arabian Sea. NASA's Aqua satellite passed over Nilofar on Oct. 31 and captured an image that shows strong wind shear has ...

User comments : 19

Adjust slider to filter visible comments by rank

Display comments: newest first

tadchem
3 / 5 (2) Feb 05, 2014
Does 'dechiffer' = 'decifer'? It isn't in any dictionary I can access.
tadchem
3 / 5 (6) Feb 05, 2014
Climate change was simply the trigger. It was the consequences of the change in terms of ecological realignments that doomed the megafauna.
Human beings are hereby found "Not guilty as charged."
Maggnus
3.7 / 5 (6) Feb 05, 2014
It was the consequences of the change in terms of ecological realignments that doomed the megafauna.
Ok.
Human beings are hereby found "Not guilty as charged."
This is not a logical conclusion. While the loss of the fauna would most assuredly have impacted the number of individuals, and may even account for the complete loss of some species, nothing in that article leads one to the conclusion that humans didn't arrive to finish them off. Or vice-versa.

The article clearly states that:
data shows that the likely main reason for the mass extinction of the large mammals after the latest Ice Age is changes in the vegetation
not that this is the only reason.
ryggesogn2
2 / 5 (12) Feb 05, 2014
How did climate change without humans burning oil and coal?

Maggnus
3.6 / 5 (8) Feb 05, 2014
How did climate change without humans burning oil and coal?


It likely went into an ice age as a result of the Milankovitch cycle taking the planet into a more extreme elliptical, resulting in less solar radiance especially in the Northern Hemisphere. It likely came out of the ice age when the Milankovitch cycle took the planet into a less extreme elliptical, resulting in higher solar radiance, especially in the Northern Hemisphere.

We are likely headed into another Milankovitch cycle wherein the Earth's ellipse will again be more extreme, which should lead to a new ice age. As a result of human derived CO2 changes in the atmosphere, it is probable that an ice age will not occur this time around, or at least be much less severe.

How did you get past your mom again? Have you looked into that condition I told you about?

Shakescene21
2.8 / 5 (4) Feb 05, 2014
This evidence is hardly a "smoking gun" that proves that climate change was the cause of the megafauna extinctions. There is plenty of evidence that humans hunted the megafauna-- is that a "smoking gun" proving that humans caused the extinction of megafauna?

Prof. Willerslev and others have a pre-determined opinion that climate change was the cause of megafauna extinction, and are letting their opinions bias their research. These guys deserve an A for data collection but a D for analysis.
runrig
3.9 / 5 (7) Feb 05, 2014
This article makes no mention of the asteroid event of circa 13000 years bp. There is multiple evidence of bolide collision in the NH around that time with elliptical craters still evident in Eastern USA in particular and of tsunami debris around Atlantic coasts.

http://www.atlant...oid.html
Maggnus
4 / 5 (8) Feb 05, 2014
Runrig, there are far more credible sites than that one! Here are a couple to look at:

http://phys.org/n...ory.html
http://www.scient...ars-ago/
http://www.sci-ne...384.html

There is a lot of controversy regarding the end of the Younger Dyas period. The best evidence I have seen suggests an impact of a comet or cometary like object that blew up over North America roughly 12,000 years ago, but there are very credible lines of evidence suggesting this is coincidental or even untenable with the mega-fauna die off at the end of that period.

Its a really interesting subject, but a discussion of it this forum can't support. Do some checking though, I'm sure you'll find it a fascinating subject.
runrig
4 / 5 (4) Feb 06, 2014

Runrig, there are far more credible sites than that one! Here are a couple to look at:

Yes indeed Maggnus

I looked into this around 20 years ago now when I bought a book on it - can't find the damn thing now. I did find the evidence convincing and I know it surfaces occasionally - actually just a couple of days ago in the Daily "Wail" (they can/do print some descent science stuff)

http://www.dailym...nap.html
Sinister1812
5 / 5 (3) Feb 06, 2014
This is interesting, and it makes sense that large animals would've needed richer diets. If the herbivores died out due to lack of vegetation, it would've pushed the carnivores to disappear too. I had doubts about over hunting.
no fate
4.2 / 5 (5) Feb 06, 2014
This is interesting, and it makes sense that large animals would've needed richer diets. If the herbivores died out due to lack of vegetation, it would've pushed the carnivores to disappear too. I had doubts about over hunting.


Couple that with the practices of tribal societies, overhunting wasn't their way. They didn't hunt for sport because they were too busy hunting for food and they didn't kill what they didn't need so that it would still be around when they did need it.

They seem to have had an understanding we lack today.
no fate
5 / 5 (5) Feb 06, 2014
How did climate change without humans burning oil and coal?



This article is about good scientific collaboration and hard work that paid off. There are enough climate articles on this site that you don't have to troll for an opportunity to shovel your shit.
Sinister1812
4 / 5 (4) Feb 06, 2014
Couple that with the practices of tribal societies, overhunting wasn't their way. They didn't hunt for sport because they were too busy hunting for food and they didn't kill what they didn't need so that it would still be around when they did need it.

They seem to have had an understanding we lack today.


Exactly right! I couldn't agree more.
Maggnus
4 / 5 (3) Feb 06, 2014
I agree with you no-fate, a good observation! (Sense the but? :) ) However, I think that may simplify matters somewhat. If it was the case that the megafuana was already in decline, and it is accepted that they were not in contact with human hunters prior to the beginning of that decline, I can see it being possible that the actions of the new predators could have hastened their extinction, or even led to their extinction when they may not have gone extinct but for the actions of the new predators.

I guess I have trouble with the "either/or" arguments. In the situation I've outlined above, if the human hunters were hungry enough, they may have actually pursued the larger animals specifically because they were so few, in an effort to get their meat before they disappeared completely. There is some evidence this occurred with bison and Indians, as the bison were being slaughtered.

Admittedly a bit different, but I hope you catch my intent.
ryggesogn2
2 / 5 (4) Feb 06, 2014
How did climate change without humans burning oil and coal?



This article is about good scientific collaboration and hard work that paid off. There are enough climate articles on this site that you don't have to troll for an opportunity to shovel your shit.


CO2 is the ONLY cause of climate change today, but not 1000 + years ago?
But of course ALL influences on climate today are completely understood and well modeled?
This was the motivation of Mann's hokey schtick, make the MWP disappear.
ryggesogn2
2.3 / 5 (3) Feb 06, 2014
"Widespread evidence of cosmic impact documented – likely cause of the Younger Dryas cool climate episode
Posted on May 21, 2013 by Anthony Watts "
http://wattsupwit...episode/

When I saw a story about this on some science channel I was surprised at the hostility of many in the field regarding an extraterrestrial cause.

Planck was right:
"A scientific truth does not triumph by convincing its opponents and making them see the light, but rather because its opponents eventually die and a new generation grows up that is familiar with it.
Read more at http://www.brainy...ceOc1.99
vlaaing peerd
4.3 / 5 (6) Feb 07, 2014
CO2 is the ONLY cause of climate change today - no it isn't, it's the major man made contribution to climate change of today, that kinda thing you should want to avoid.

but not 1000 + years ago? - answering based on your false premise in the 1st statement, yes CO2 did contribute to climate change, but a lot less, because we weren't there pumping it in the air like madmen.

But of course ALL influences on climate today are completely understood and well modeled? no it isn't, any climate scientist will agree on that. What we do agree on is the amounts of CO2 that we produce is influencing it, in a bad way.
vlaaing peerd
5 / 5 (3) Feb 07, 2014
@roggebrood,

I wonder why I even bothered answering you, I know you are capable of understanding these things and I realize I just fed a troll.
ryggesogn2
1.8 / 5 (5) Feb 07, 2014
What we do agree on is the amounts of CO2 that we produce is influencing it, in a bad way.

Define 'bad'.
How much influence?
CO2 and temps are not positively correlated.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.