Comments on: Australia on fire

By: Sandgroper

Sandgroper — Mon, 17 Oct 2011 17:20:47 +0000

But while you mention it, and it’s a bit of a trivial point, it’s worth noting not all Australian megafauna went extinct. The red kangaroo is a prime example of megafauna that is still with us today, and doing very well, thank you.

By: Sandgroper

Sandgroper — Mon, 17 Oct 2011 16:14:09 +0000

It’s probably too low in fat for barbecuing, it would come out too dry. It’s best fried or stewed. Or thrown whole on the fire until the fur is singed off

By: Justin Giancola

Justin Giancola — Mon, 17 Oct 2011 11:41:46 +0000

13. gotta love parallel evolution!

and I’ve had kangaroo before and it was good; I don’t think you guys would be amiss to try your hand at bbqing it.

By: Sandgroper

Sandgroper — Mon, 17 Oct 2011 09:20:18 +0000

#16 – Yes. From memory, Greg Laden expanded on that by discussing the types of foods that required heat treatment to make them digestible – roots, tubers etc. Greg is good on that stuff, if only he would do more of it and less of the other.

#17 – It doesn’t sound like a bad idea now. An ambush hunter that’s 20 feet long and possibly venomous? Yeesh.

By: Razib Khan

Razib Khan — Sun, 16 Oct 2011 21:52:51 +0000

#17, barbecue?

By: ackbark

ackbark — Sun, 16 Oct 2011 21:36:46 +0000

Setting fires to wipe out groups of megalania might have seemed highly practical 40,000 years ago.

By: TGGP

TGGP — Sun, 16 Oct 2011 20:20:55 +0000

“even the tropical rains were effected by human migration”
Shouldn’t that be “affected”?

Sandgroper, that sounds like Wrangham’s theory in “Catching Fire”.

By: Sandgroper

Sandgroper — Sun, 16 Oct 2011 15:05:19 +0000

#3 – Well, I’ll give you an answer. I would put it close to 1 because I read a lengthy paper Greg Laden had written on the use of roots and tubers as food sources which needed to be cooked to be digestible, plus the energy requirements for increasing brain size.

The earliest estimate I have seen is 1.5 billion years from archaeological sources, but that’s a tricky business of course.

By: Eurasian Sensation

Eurasian Sensation — Sat, 15 Oct 2011 12:33:12 +0000

@ Justin:

There are three realistic candidates for “apex predator” in Pleistocene Australia.

- The thylacine or Tasmanian Tiger
- Thylacoleo, the “Marsupial Lion”
- Megalania, a 6 metre long monitor lizard.

By: Sandgroper

Sandgroper — Sat, 15 Oct 2011 05:00:35 +0000

#9 – If you think Thylacine was cool, check out this furry pet: http://en.wikipedia.org/wiki/Thylacoleo_carnifex

No big cats and wolves, but parallel evolution provided some apex marsupial predators that bore some remarkable similarities to the placental mammal equivalents.

And if you think Komodo Dragons are neat, have a look at this: http://en.wikipedia.org/wiki/Megalania

#11 – Fine. So, being not totally convinced, what conclusion have you not jumped to about extinctions in Tasmania? Or does your lack of total conviction prevent you from joining dots and constructing hypotheses that fit the data?

By: clark

clark — Sat, 15 Oct 2011 03:29:07 +0000

Completely ignorant of all this stuff. Thanks for the post Razib. I wonder about the adaptivity of humans to these new environments versus the previous environments as humans move into an area. That is does the destruction by humans (planned or not) help or hinder humans or do the humans simply becomes what works in that environment. It certainly seems some environments are more conducive to reasonable populations of humans than others. (To take an extreme examples compare densities in tundra areas verses more moderate zones)

If there is such a link then that would provide yet an other “economic incentive” for humans with such capabilities to spread out successfully.

Brian (10), oddly while I’ve not read about this and humans (other than in modern times) I have read about this with respect to wildlife. For example I know of several areas fenced in now to exclude deer with massive increases of bio-diversity. So the phenomena certainly isn’t limited to humans in the least.

It’s an interesting question since it suggests that a subtle change can lead to significant changes in both diversity but also relative success of various species. (OK, something I guess everyone already knew – but it’s kind of like in mathematics where you find Pi or e popping up over and over again – it’s always interesting in each context)

By: blindboy

blindboy — Sat, 15 Oct 2011 02:31:54 +0000

Sandgroper the piece clearly links the ecological change to the increase in fire frequency which they infer is a direct result of human arrival. My point is that this is only an inference. The drying out of Australia had been in process over a long period of time. We know from the palaeoclimatic record that changes can happen rapidly. Human arrival may have caused a tipping point but the tipping point may have happened anyway so the data is at best only weak evidence of (a) human arrival time and even weaker evidence for (b) humans causing the change.
The fact that they cannot identify a natural cause means only that, it does not mean there was no natural cause.

This is not say that the hypothesis is wrong there is plenty of other evidence for the vegetation changes at that time but being a bit of a skeptic I won’t be jumping to any conclusions about it’s cause.

By: Brian Too

Brian Too — Fri, 14 Oct 2011 23:29:12 +0000

Tangentially, I seem to remember some experiments involving elephants in Africa. They found that if you excluded elephants from an area of veldt, grassland species declined and trees increased sharply.

Mankind is not the only shaper of the land. Also relevant in relation to the extirpation of Australian megafauna.

By: Justin Giancola

Justin Giancola — Fri, 14 Oct 2011 21:42:06 +0000

Oh I really was asking – while repeating something I had heard like no big cats and wolves and what not past the Wallace Line – but that is very cool!

By: pconroy

pconroy — Fri, 14 Oct 2011 21:26:26 +0000

Justin,

What about the Thylacine, the so called “Marsupial Wolf”, wouldn’t that have been an apex predator?

http://en.wikipedia.org/wiki/Thylacine

By: Justin Giancola

Justin Giancola — Fri, 14 Oct 2011 21:20:42 +0000

In my environmental science class we recently watched a video in which a scientist quartered off a small bit of land in some desert and removed all the Kangaroo Rats. The desert rather quickly converted into grassland and other animals stopped showing up and new animals started coming in. They deemed the Kangaroo Rat a “keystone species” or something to that effect.

Being that Australia never had hominids at all – or seemingly top predators? – and had a very delicate balance with regards to animals that had already gone extinct elsewhere and their unique descendants, humans showing up may not have even had to do anything drastic themselves like set fires or over kill animals. They may have just tipped a scale that set a very delicate ecosystem out of wack and this had an affect on the wildfire cycle.

Even if this is rudimentary for some of you I think it’s an important point to make – some people may take on this Mr. Mackey-esque: h-humans are bad mmkay.

By: Blackbird

Blackbird — Fri, 14 Oct 2011 20:33:48 +0000

Guns, germs, steel and fire then?

By: Sandgroper

Sandgroper — Fri, 14 Oct 2011 18:05:11 +0000

“they may only have hastened the inevitable”

So what? I think you have missed the point, which is about pegging the time of human arrival, which turns out to be very important. No one cares about whether extincting megafauna was naughty or not – it’s an idiotic point.

By: blindboy

blindboy — Fri, 14 Oct 2011 11:52:35 +0000

Aboriginal fire may have caused the ecosystems involved to reach some kind of tipping point but given the nature of the soils, the climate trends and the type of fire prone vegetation that by that time dominated the forests, they may only have hastened the inevitable. The data presented here is less than totally convincing.

By: Razib Khan

Razib Khan — Fri, 14 Oct 2011 07:56:32 +0000

#2, well, there’s a touch of debate about that. i’d put the h. erectus use of fire at 0.75 probability. u?