A Critical Review

Happy Hyperdisease!

I may seem a little excited posting so soon after my last blog, but since it’s Halloween I felt that this would be the perfect time to talk about hyperdisease. So today we will have a brief critical review of the subject!

Beginning at around 50,000 years ago, until quite recently, most large land animals began to significantly decrease in numbers before becoming extinct (Koch and Barnosky, 2006; Stuart, 1999). One rather controversial explanation of this is the hyperdisease hypothesis. 

Extinct species of late-Pleistocene (white), alive in 20th Century (grey).

(Stuart,1999 p.258)

What is Hyperdisease?

Effectively, the idea is that hyperdisease was brought into North America by humans. That it could be passed widely and between species, and caused mass loss of megafauna. The implication being that this would spread around the globe and cause a mass extinction (MacPhee and Sues, 1999).

Evidence?

There is some support for this in the area of North America. Tuberculosis was found present in large quantities of Mastodon (Mammut americanum). Almost one quarter of 113 examined individuals showed signs of the disease (Rothschild and Laub, 2006). So, in North America it may have played a part in extinction.

Problems (e.g. many)

There are several problems with this:

1. There is really no solid evidence of this in Europe.
2. The Mammoths were not affected (Rothschild and Laub, 2006).
3. This hypothesis would not fit with the pattern of megafauna extinction in Europe (MacPhee and Sues, 1999).

This has been a rather brief summary of hyperdisease, which I believe (with the current evidence) can be put to rest for the area of Europe. In North America this may well have contributed to megafauna decline, but in Europe there is really no tangible evidence (at least that i can find)! Soon we will have a more detailed discussion on the migration of animals in and out of Europe over earlier glacial cycles, specifically hippos!

P.S..

If you have not followed the hyperdisease link then i suggest you check it out. This is the blog it takes you to, nice summary if you are interested in what was happening in North America.

LINK

Worth a read!

Beginning at the End

STARTING OFF BIG

Today we will attempt to address some of the larger issues in this blog series, beginning the story with a review of the most supported theories of how fauna came to disappear during the Quaternary. We will do this in the context of three species. It is really important to understand some of the main theories for faunal disappearance, in order to answer our questions. So, we will start by concentrating on two of these. Climate and people. To do this, we will assess these ideas in the context of some larger mammals of the late-Quaternary. The woolly mammoth, the straight-tusked elephant, and the European cave lion.

 

Today’s Contenders

As the sort of ‘logo’ of the Ice Ages, mammoth species are both well-known and well studied (Stuart, 2005). Towards the end of the Pleistocene woolly mammoths (Mammuthus primigenius) were still present in Europe, and are good indicators of megafaunal disappearance. As well as mammoths we will discuss the European Cave Lion (Pantheraleo spelaea), and the straight-tusked elephant (Palaeoloxodon (Elephas) antiquus), both are fairly well documented during the late-Quaternary. All three species were residing in Europe during the Pleistocene and offer us an insight into the reason so many large animals disappeared during a geologically short period of time. The largest and most recent transition in climate occurred during the switch from the last cold phase to the present warm phase (Lister and Stuart, 2008). At around 45-50,000 years ago modern humans entered Europe (Hoffecker, 2009; Müller et al., 2011). For this reason, it is important to understand the interaction between these animals and the factors that may have caused their demise. 

  (left) Woolly mammoth calf (Maschenko et al., 2006 p.154). (centre) Straight-tusked Elephant (Diedrich, 2014 p. 274). (right) Cave Lion (Diedrich, 2011 p.210).

    

The woolly mammoth: Mammuthus primigenius

The woolly mammoth was both widespread and in recent decades has been rigorously studied by scientists. As a cold adapted species, they thrived in cool episodes when open grassland environments covered the landscape. When the climate deteriorated it is thought that this species survived in Siberia, whilst in Europe its presence continued up until the late-glacial (below) (Stuart, 2005). During the most recent glacial-interglacial cycle this animal became extinct in Europe. The difference between this cycle, and those previous, was the presence of humans as predators (Stuart et al., 2004). It is likely that they played a role in mammoth disappearance. For example, during a stadial (cool interval) that lasted between around 34 and 24 thousand years ago the woolly mammoth occupied large areas of Europe, but this extent reduced before the Last Glacial Maximum (coldest point in stadial) (Markova et al., 2013). As a cold adapted species it would be expected that this animal would not begin to decrease its population size during a favorable climate. Humans were not around during previous cycles, and mammoths survived these (Stuart, 2005). This could suggest an interplay between humans and climate, contributing to mammoth decline.

Woolly mammoth distribution until disappearance from fossil record.

(Stuart, 2005 p.172) 

The straight-tusked elephant: Palaeoloxodon antiquus

The straight-tusked elephant had a very different ecology to the mammoth. Their greatest range was during warmer episodes. They preferred forested areas, temperate regions, and are well recorded in the Mediterranean (Stuart, 2005). Their extinction in Europe was earlier than the Woolly mammoth, and the difference between these species, ecologically, makes this a great comparison! There is much suggestion that this animal disappeared from Europe at the onset of the most recent cold period with the move towards grassland environments (Stuart, 2005). Very recently a study in Italy has provided evidence that humans scavenged the remains of this species, in this case where the animal had become trapped, and the carcass was then exploited by the local population (Santucci et al., 2016). Though there is evidence for scavenging, and some evidence for hunting. Whether this was sufficient enough to drive this species to extinction is questionable. 

The Cave Lion: Panthera spelaea

The European cave lion became extinct during the late-Pleistocene. This disappearance is thought to have occurred at around 14,000 years ago. There are suggestions that this was due to a move towards warmer temperatures, which resulted in a reduction in open habitat (Stuart and Lister, 2011). Though, there has been proof that humans exploited these animals for their furs, as well as evidence of the hunting of these animals. It is difficult to know to what extent this affected their survival, though, large hunting events have been recorded (Cueto et al., 2016). There are alternatives to this. For instance, the loss of prey. Data gathered on cave lion diet may suggest that they had a preference for preying on reindeer whose extinction is suggested to be at a similar time to that of the cave lion (Bocherens et al., 2011). Meaning that their disappearance could be the product of prey decline, or more likely multiple factors.

In all...

Stuart (2005) makes an important point, and in fact I like this paper a lot (which you may notice if you look at the citations!). Many species survived glacial-interglacial cycles in Europe, but not the last one. So why? Today has been a brief and broad summary and discussion of the disappearance of just three of the large mammals still around in the late-Quaternary, but there are many many more!

In Summary,

?

There are still a lot of questions... & we will look at these in the coming weeks!

In the following days we will be addressing two topics! Firstly, with one of the more controversial theories of species extinction in the Quaternary, as well as beginning to look at how animals moved in and out of Europe with climate change, and if that was the only reason for dispersal (likely not)...

This has been compiled by articles i have researched. Any add-ons, article links, and suggestions for future topics would be really appreciated (especially if there is any current evidence/news)!

Cya soon!

Welcome to the past!

A Very Mammoth Task

When you glance at the landscape around you today it is most likely that you don’t picture what it looked like thousands of years ago. Nor the animals that lived there. In fact, you probably haven’t thought about it much, possibly ever. Perhaps you have heard of these creatures? Can you tell me when they appeared? Can you say why they aren’t there now? Maybe it was climate change, a hyperdisease, environmental factors and lack of adaptability, or perhaps it was humans that caused them to disappear... 

This leads us to some very basic questions: 

What was here?

How, and when...
 

& Why isn’t it here now...?

That is the purpose of this blog. To identify, describe and discuss the animals that walked through Europe in the hundreds and thousands of years before we were born, in the context of where they came from and how they began to disappear. 

A bit of context

During the most recent geological period, the Quaternary (2.6 Million ago until present) there were warm stages (interglacial phases) and cold stages (glacial phases). When there is a switch between these two states, there is a change in the fauna that live in that area. Sometimes warming would permit the spread of species, but for more cold adapted animals, this could cause a reduction in their species range. Yet, other factors may also have contributed to their growth and decline. For example, Markova et al (2013) suggest that the expansion of the Woolly Rhinoceros in Europe was reduced during warm phases, but is this the case? Did Mesolithic hunters also play a part? Quite possibly. The Woolly Rhinoceros is part of a group known as megafauna, some of the largest animals that existed in this time frame (yes, this includes the mammoths). Megafauna are often some of the most well studied of the Quaternary animals, with complex histories and large geographical ranges. You will certainly get to know them in this blog. 

Mammoth (top) and Cave Lion (bottom) Skeletons

Why should we care about any of this?

Understanding how the creatures that once lived in our home came to exist, and how they disappeared helps us to understand what will happen to the animals we now share the Earth with in a warming world. What happened to Quaternary fauna under climate change? Did they adapt? Was it the cause of their demise, and if not, what was? Each species possesses its own story. 

If that isn't enough they are also pretty cool.

These are a few of my favourites:  

 Irish Elk: Megaloceros giganteus 
(Lange, 2002)

 Woolly Rhinocerous: Coelodonta antiquitatis

This blog will begin to explore the emergence, and disappearance, of interglacial fauna that walked through Europe during the Quaternary Ice Ages. Each week we will begin to unpick, critique, and discuss these animals, as well as the events that may have ultimately led to their disappearance. 

See you soon!