He didn't conclude that planetary changes/evolution had led to those specific sharks moving on to Australia and Fiji, his first thought was that it was all the fault of man...
They are the sort of weapons that could be worth hundreds to your average tooth fairy. But a cache of weapons made from shark teeth is also valuable to scientists because they have revealed the localised extinction of two species of shark. The swords, with a certain resemblance to ceremonial Klingon cleavers, were made by the …
The weapons are from the 19th century. Planetary changes and evolution generally do not cause such changes so quickly. But don't take my word for it -- go and actually read the article yourself rather than just assuming that the authors' conclusion was simply the first thing that came to their mind. You'll find some real food for thought there.
Or you could consider a simpler explanation, TRADE
If the two species of shark were ever common to those isles there would likely be some other evidence of this, like old piles of butchered shark bits? And as we have seen in other locales, there was inter island trade many places where shark tooth weaponry was common. A question that since it involves sharks, tropical islands (some of which are volcanoes!) and the topic of localized extinction events the Mad Scientist community should be all over this one.
Re: Or you could consider a simpler explanation, TRADE
Didn't read the article, did you.
"First, there are no records among the historical, archaeological, or linguistic literature of exchange among the Gilbert Islands and people in the Solomon Islands (the nearest location for C. sorrah) or Fiji (for C. obscurus). Second, the Gilbertese had a well-developed shark fishery using a variety of techniques and exploiting a variety of habitats , reducing the need to import a locally obtainable resource."
Re: Or you could consider a simpler explanation, TRADE
I also didn't see much analysis of the option that the well-developed shark-fishing techniques in the 1800's may have caught the odd rare dusky which had strayed well outside its normal habitat.
Considering the complete lack of evidence for the quantity of "extinct" sharks in the sea around the islands and the complete lack of evidence of fishing technique for/impact on different species, the leap to "we killed them all with industrial activities" seems a little premature. Trendy, perhaps even likely, but premature. I note that overfishing in the 1800's by the islanders doesn't appear to be considered as an option.
While the original article was more circumspect than el reg's version, there was still far too much certainty of interpretation given the very large holes in what is known.
Unfortunately, this appears to be a common problem in what is often labelled "science." It is certainly research, but it would be generous to even call it "forensic science." It is a survey with some educated-guesswork.
Don't get me wrong, I'm no fan of industrial-scale fish-harvesting, but I don't think the conservation cause is helped by shouting about overly-simplistic and thinly-evidenced studies.
"It ain't what you don't know what gets you into trouble, its what you know for sure that ain't so."
"In 1950 alone, fishermen took 7,716 pounds of shark fins from the Gilbert Island's waters."
"In 1950 alone, Chinese fishermen took 7,716 pounds of shark fins from the Gilbert Island's waters."
Given the extensive trading networks and 'gift sharing as a means of peace offering' culture in that part of the world, how do the researchers in this instance know that the source location of the swords is the same as the source of the teeth?
No laser beams?
work in historical museum collections
Work in historical museum collections lives and dies by the quality of the accession records and unfortunately the paper referenced here doesn't provide much information on their use of museum records for the sharktooth swords, just for the shark specimens themselves. These objects would have been tourist pieces from at least the 1920s on and that opens a host of problems for using them as records of species. On the other hand, it isn't impossible to control for the most obvious problems...by using only well provenanced pieces with indications of local use before collection, or at least by factoring in a history of local tourism. Regrettably, the authors don't provide much if any info on the circumstances of collection for the pieces analyzed, just the results of their physical observations. Regardless, it's a clever piece of scholarship that shows there is often good data sitting in plain sight if you're clever enough to spot the potential. It reminds me of the study of changing fish size using snapshots of the trophies of Caribbean sport fishermen.
Not just sharks
It is very difficult for a low-level technology community to cause species extinction if that species wasn't already under threat. To cause a species to disappear you need technology.
At the risk of stating the bleeding obvious, until certain North Eastern Asian nations stop not only harvesting sharks for their fins, but also hoovering up massive quantities of fishy products from nominally international waters in the Pacific, we will have more more extinctions across the food chain.
The indiscriminate by-catch (= a quaint name for sheer waste) in these operations is appalling and seems to currently be an 'out of sight, out of mind' problem. Fish stocks in the Pacific (and elsewhere?) are seriously in danger of overfishing.
No, I'm not a rampant greeny. I'd just like a bit of sustainability. I will now get off my soap box. Thank you...
Re: Not just sharks
To quote The Science of Discworld
"It may not be politically correct to say so, but most primitive humans did as much environmental damage as their puny technology would allow. When humans came to the Americas from Siberia, by way of Alaska, they slaughtered their way right down to the tip of South America in a few tens of thousands of years, wiping out dozens of species – giant tree sloths and mastodons (ancient elephants, like mammoths but different), for example. The Anasazi Indians in the southern part of today’s USA cut down forests to build their cliff dwellings, creating some of the most arid areas of the United States. The Maoris killed off the moas. Modern humans may be even more destructive, but there are more of us and technology can amplify our actions. Nevertheless, by the time humans were able to articulate the term ‘natural environment’, there wasn’t one. We had changed the face of continents, in ways big and small."
'The Shark Callers of Kontu', suggested reading 'The Iliad' by Homer.
Kiribat = Gilbert
Gilbert = Kiribat. So that would be "residents of Tungaru in the Republic of Kiribati" ???
(Which is to say, the Republic of Gilbert Islands" )
or, past tense "residents of the Gilbert Islands" (English/American name)
or, past tense "residents of Tungaru" (local name)
Not saying, just asking. Just looked very odd to me.
...from Gilberts disease. I assume the cause of this is tied up to these islands in some way?
Gilberts disease is pretty handy, as it is symptomless (for me anyway) and can be used as an excuse for all sorts of things: "Sorry dear, I can't come shopping, my Gilberts is giving me terrible gypp"
"I have to keep horizontal here on the sofa for a couple of hours, my Gilberts is acting up something fierce again"