The curious case of the people who forgot how to fish

Indigenous Tasmanians colonised the island armed with a complex toolkit. But most of their fancy technology has since been lost. How could this happen and what does it mean for human evolution?


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Tasmania 14,000 years ago; when it was still connected to the Mainland. The dots are sites we know people lived in from this period

Tasmania 14,000 years ago; when it was still connected to the Mainland. The dots are sites we know people lived in from this period

Around 30,000 years ago a group of Australians migrated into an isthmus on the south coast of Australia1. As the last glacial period came to an end ice sheets around the world melted and sea levels rose almost 100 meters2. By ~12,000 years ago this isthmus had become an island, its inhabitants cut off from the rest of the world. These early islanders produced complex technology; on par with anything found on the mainland. They could make weapons, bone tools, composite technology, cold weather clothing and they were excellent at fishing. Archaeological evidence from this period indicates fish made up almost 1/5 of their diet1.

In the 18th century European ships begin to stop at the island; which eventually came to be called Tasmania. The seas around Tasmania were full of fish and were a great place to replenish food reserves after a long voyage. This fact surprised the original inhabitants of the island. Upon seeing these Europeans eat the fish they were disgusted and point blank refused all offers by the sailors to share in the bounty. It would seem that in the intervening 12,000 years the aboriginal Tasmanians had forgotten how to fish and become revolted at the very idea of eating it (and even if they sometimes accidentally caught them whilst gathering shellfish they would not eat them)1.

And that wasn’t the only thing. Their cold weather clothing, bone tools, spear throwers, and stone tipped spears and much more had all vanished from the Tasmanian repertoire; despite the fact their cousins on the Australian mainland were still making them. Some early observers even thought they had forgotten how to make fire, instead preferring to maintain existing fires (although this was later found to be false. They could still make fire, they just preferred to curate it)1.

Simple bone points, used to make clothes, stopped being manufactured by Tasmanians even though people on the mainland continued to create them

Simple bone points, used to make clothes, stopped being manufactured by Tasmanians even though people on the mainland continued to create them

Looking at the archaeological record things get even more fascinating. 8,000 years ago fish made up 21% of the Tasmanian diet, making them the second most valued food source (after seals) and three times greater than wallabies. Yet by 3,800 years ago they had completely disappeared from the record; replaced by wallabies, shellfish and seals. Bone tools follow a similar trajectory. 7,000 years ago they were being made 1/3 as often as stone tools. 4,000 years ago it was 1/15 as often and by 3,000 years ago they vanished entirely. In other words, although they’d been living on Tasmania for over 30,000 years, it was only after it became an island and they were cut off from the rest of Australia that their technology began to degenerate1.

Perhaps what’s most interesting isn’t that all of this technology disappeared; but that in the intervening 4,000 years it never re-appeared. That’s 4,000 years of people accidentally catching fish whilst gathering fish and at no point did anyone think “hmm, I wonder if I could eat it.” Instead these techniques remained gone from the record, and in the case of fish they even developed an active dislike for it1.

So what on earth happened?

There are dozens of possible explanations for this turn of events. Some doubt that they even had these technologies in the first place. The fish bones are just from the stomachs of the seals they always hunted; mainland Australians developed warm clothes after the split so the Tasmanians never had them to lose. So why did fish cease to appear in the archaeological record when they kept hunting seals? And why were they making the bone points used to create cold weather clothes if they never invented them? In most cases there is strong evidence that the Tasmanians once had this ability, but lost it1.

Another idea is that these complex tools just weren’t need to survive in Tasmania. It’s a pleasant place (well, as pleasant as anywhere in the deathtrap that is Australia can be) and one could survive just as well with a sharpened wood spear as they could with a stone-tipped one. So why bother making stone tipped ones? Some of the bone tools used to make cold weather clothes disappear as the temperature begins to rise. Could it be all these tools were simply unnecessary? This could explain some of the disappearances, but not all of them3. Again, they sometimes accidentally catch fish but don’t eat them. They’re doing a lot of the steps needed to fish, but aren’t actually fishing. This alternative doesn’t seem much easier than just getting some damn fish in the first place1.

The last four full-blooded native Tasmanians. Taken in the 1860s

Which brings us to the most controversial idea: demography. Cut off from the mainland the Tasmanian population was stuck at around 4,000 individuals3. This simply wasn’t enough people to sustain these technologies. With a smaller population there is less chance you’ll get people good at making these tools, forcing you to learn from more average teachers. But the learning process is imprefect, so your tools will be sub-par; and when the next generation learns from you it will be lower still. Over time they’ll disappear entirely and only the easy to make technologies will remain1.

But this all rests on the idea that learning from someone necessarily produces an inferior result; and that’s what a lot of the debate is about. Many argue that it is simply untrue and there are numerous studies showing that learning from someone can result in tools just as good as theirs’3,4. Besides, if this was the case why are the groups with a smaller population that still have complex technology? Some of the early inhabitants of Greenland became isolated and numbered just 600 individuals; yet their technology did not degenerate3.

However, it is becoming apparent that whilst small populations don’t halt teaching they do decrease the chance of innovation. In a smaller group there is less chance some technological genius will arise; capable of inventing new tools. As such, if some technology was lost on Tasmania for another reason (like life being easy, or it not being present in the first place) it would be unlikely to re-appear4.

This has some fascinating implications for human evolution. Around 150,000 years ago our ancestors were making tools just as advanced as any other species of human (like the Neanderthals). But over the next 100,000 years or so our technology took off and we invented dozens of new tools, hunting techniques and more. Armed with this new technology we colonised the whole planet and out-competed all the other species of human living alongside us (like the Neanderthals)5. For years people have debated what it was that kicked off this “revolution.” Perhaps there was a brain mutation that made our ancestors smarter? Maybe their environment drove them to be more innovative? Maybe their brain was just differently organised from all the other humans?

But this Tasmanian example suggests the explanation was much more mundane. Perhaps the secret to our success isn’t that we’re super smart or special; there’s just a lot of us, increasing the chance an innovator is born. Human success is based around the fact we multiply.

A lot.

References

  1. Henrich, J. (2004). Demography and cultural evolution: How adaptive cultural processes can produce maladaptive losses-The Tasmanian case. American Antiquity69(2), 197-214.
  2. Lambeck, K., & Chappell, J. (2001). Sea level change through the last glacial cycle. Science292(5517), 679-686.
  3. Read, D. W. (2011). The misuse of a mathematical model: the Tasmanian case (reply to Henrich’s response).
  4. Baldini, R. (2013). Revisiting the effect of population size on cumulative cultural evolution. bioRxiv.
  5. d’Errico, F., & Stringer, C. B. 2011. Evolution, revolution or saltation scenario for the emergence of modern cultures? Philosophical Transactions of the Royal Society B: Biological Sciences, 366(1567):1060-1069.

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19 thoughts on “The curious case of the people who forgot how to fish”

  1. Artem Kaznatcheev says:

    I like this sort of work because it is a useful counterpoint to people who like to go on about constant ‘progress’ or increases in ‘complexity’. This and cancer-dog.

    1. Adam Benton says:

      Are you sure you don’t just like it because the people who are looking into the demography do all sorts of fancy modelling? BECAUSE THAT IS YOUR ONLY INTEREST

      1. Artem Kaznatcheev says:

        I haven’t seen any of the papers, actually, so I didn’t know there was any fancy modelling going on. BECAUSE YOU NEVER TALK ABOUT THE MATH. Although from the title ref.3 sounds like it comes from a line of papers I might enjoy. Any specific recommendations?

        1. Adam Benton says:

          MATH IS HARD.

          The Henrich paper (ref 1) is what kicks off a lot of the modelling of demography and technology, and started a whole back and forth between him and Read (ref. 3); culminating in that third reference (which lays the smackdown). So those two I’d recommend. Ref 4 also goes into it a bit, trying to fix Henrich’s models to see what the actual relationship between demography and technology is.

  2. Marcel Williams says:

    Cultural isolation is almost never good for progress.

    Marcel

  3. Dwight Read says:

    The statement “barbed spears, spear throwers, boomerangs and stone tipped spears and much more had all vanished from the Tasmanian repertoire” is factually incorrect. They never had the items in this list. The only artifact they stopped making were simple bone points that they used during extremely cold conditions to make simple clothing. They stopped making bone points when the climate warmed up. They continued to innovate with stone artifacts. The Tasmanians had a carbohydrate poor, protein rich diet. The fish have 0 carbohydrates, but the shellfish they ate in quantities are about 15% carbohydrates. The simplest explanation for the Tasmanians is that they stopped making bone points when the climate improved and they focused on shellfish, rather than fish, because they needed carbohydrates, not protein. Also, in the population of 4,000 persons in Tasmania, there would be, on average 90 persons, hence 45 adults, of IQ at least 130, which is considered to be an intelligence level sufficient to do well at college and to be a successful professional. There were, then, no shortage of bright Tasmanians who could easily have re-invented simple bone points if they needed them.

    1. Adam Benton says:

      Many of those tools were widespread in Australia prior to Tasmanian isolation, so I think it’s reasonable to infer their presence on Tasmania too. There is even some evidence (albeit inconclusive) of hafting being present on Tasmania itself. That being said, the evidence for some of these items being widespread (most notably boomerangs) during this time period is less solid than I thought, so have removed them from the list of lost technology.

      However, whilst I disagree over the specifics of the technology and behaviours which disappeared, I do agree with you that environmental factors are the best explanation for why they stopped being created. The relationship between temperature and clothing is just too juicy to ignore. Besides, Henrich’s model has been thoroughly eviscerated by subsequent research.

      But whilst demography doesn’t explain why this technology vanished I do think the research I cited (and a few other papers out there) make a rather compelling case that it was part of the reason it (or similar technologies) weren’t reinvented. Now, I’m no fan of silver-bullet explanations that claim to be the solution to everything (and a fair bit of the research into innovation and demography is theoretical, so there are still question marks over it). As such, I think environment was still an important contributing factor to this (perhaps the most important).

      My point was simply that there’s evidence demography was influenced innovation rates and that this has implications for other periods of innovation throughout prehistory.

      1. Dwight Read says:

        There is no credible archaeological evidence showing that Tasmanians ever had spear throwers, barbed points, etc. (see discussion of Tasmania in Peter Hiscock (2008) Archaeology of Ancient Australia).

        That demography relates to the absolute rate of innovation is clear; a hunter-gather group of 500 persons will have a much lower rate of innovation than an agricultural group of 500,000 persons, for example. That is not the issue — the claim Henrich made was that small hunter-gatherer groups would not be able to make complex implements, not that they would have a lower innovation rate than a much larger population. However, as you say, “Henrich’s model has been thoroughly eviscerated.”

        Most likely, Tasmania had a stable population size that was well below carrying capacity, hence there was no reason to make complex tools that were not needed. According to Richard Gould, a similar pattern of stasis for about 10,000 years characterizes the Western Desert of Australia, which was also a region that most likely had a stable population size well below carrying capacity.

        While small hunter-gatherer groups would have lower rates of innovation, this does not mean that complex tools would not be invented, just that it would require longer time periods than would be the case for larger populations. Of course, there are technologies that are not feasible without having a larger population to provide the range of support needed for the technology to be viable.

  4. Scott McGreal says:

    I found this quite a thought provoking post. I have read other articles that claimed that Tasmanians did not know how to make fire, so thanks for pointing out this is not correct, as I always found the idea very puzzling.
    I am not really convinced though of your closing statement that human success occurred because we multiplied better than our rivals, because then you would have to explain why this would be the case. That is, did we humans just happen to multiply faster due to some random factor (i.e. nothing special about us, we just got lucky), or did we have some selective advantage that improved our ability to reproduce? If it was the latter, then we may well be smart or special in some way, even if only slightly.

    @Dwight Read – your comments regarding IQ assume that Tasmanians had an IQ distribution in the same range and variance (i.e. with a mean of 100, SD of 15) as modern European peoples. This is problematic, because IQ averages have varied over time (e.g. consider the Flynn effect where IQ averages in each generation increased 3 points a decade during much of the 20th century) and also vary between ethnic groups. Why IQ varies in these ways is highly controversial, but the degree of variance that is known to exist suggests that we are not justified in making such assumptions about a particular ethnic group in another era.

    1. Dwight Read says:

      @Scott McGreal — You correctly point out that merely saying group A reproduced at higher rates than group B doesn’t explain why the higher rate in the first place. Two references relevant to this topic are: Read, D. 1987. Foraging Society Organization: A Simple Model of a Complex Transition. European Journal of Operational Research 30:320-326 and Read, D. and S. LeBlanc 2003. Population Growth, Carrying Capacity, and Conflict. Current Anthropology 44 (1) :59-85. The critical difference, though, is not the rate of reproduction, but whether one group, with its mode of organization, can sustain a higher population density than another group — the group that can sustain a higher population density will outcompete a group that can only sustain a lower population density Hunter-gatherers have been replaced by agriculturalists, horticulturalists and pastoralists (except in “refuge” areas”) because the latter can sustain higher population densities than hunter-gatherers in the same region due to a food production mode for obtaining food resources.

      My comment about IQ was only intended to be illustrative of the fact that in a population of 4,000 persons (the size of the population in Tasmania) there is no shortage of bright persons, not a factual statement about IQ scores among the Tasmanians. Another way to phrase it is to say that persons with a z-score of 2 (computed using the mean and standard deviation of the group), which corresponds to the upper 2.275% of the population, are considered to be “bright.” Among the Tasmanians, there would be 90 such persons and surely they were smart enough to figure out how to make a simple bone point since they were smart enough to introduce innovations in their stone tool technology. The comment that very small groups may, by chance, not have a bright person who can be inventive refers to drift effects and drift effects are negligible with sample sizes of around 30 or larger.

      The fact is, the Tasmanians stopped making bone points when the climate warmed up substantially and they no longer needed the kind of clothing they had made under extremely cold conditions. It has nothing to do with population size.

    2. Adam Benton says:

      I was quite disappointed. “The people who forgot fire” is a much better title! As for why we were so great at reproducing; one explanation I quite like is that our bodies are quite efficient. We’re very gracile compared to many other hominins (especially Neanderthals) so the amount of energy we need to survive and flourish is much lower than other species (returning to the Neanderthals, we may have needed half the daily caloric intake they did). Of course, there were likely a multitude of other factors (many of which Dwight notes), but that was one he seems to have missed.

  5. ThQ says:

    Maybe they simply did not have a need for these technologies and so there was no point for them to maintain knowledge of them. I was thinking of a distant example somewhat reminiscent of this: in bronze age Britain, people knew the potter’s wheel. Then came the Romans, and the vast market that stretch the empire. During the late Roman times, all the potteries available in Britain had been imported from mainland Europe, probably in exchange for local products specific to Britain. Shortly after the fall of the Roman empire, with the vast commercial routes going to Britain gone, we find tombs of chiefs, with rich metallurgy but pottery that is Neolithic in quality: in particular no pottery from 6th century Britain was made on a potter’s wheel. They had forgotten it!

    1. Adam Benton says:

      I think that’s probably the best explanation for their original disappearance; there is a very neat correlation between when cold weather clothing (and the tools needed to make it) disappeared and the weather got warmer.

      1. ThQ says:

        Sure it makes sense, although it is quite different from fishing: it’s clear that cold weather clothing is useless in warm weather but what conditions are required to make fishing useless? What it is that made these people abandon fishing when it seems to be employed by virtually all ancient and modern societies near a sea-shore/river/lake. I can’t find a reason.

        1. Dwight Read says:

          Why is it illegal to sell horse meat for human consumption in the US (except in Oregon, though that may have changed since the 1960’s). It’s nutritious, doesn’t have the saturated fats of beef, and is inexpensive (in Oregon it was cheap in comparison to beef).

          As I mentioned before, the Tasmanians had a protein rich, carbohydrate poor diet. Their problem was getting carbohydrates, not protein. The Tasmanian fish have no carbohydrates; the shell fish they ate in large quantities were about 15% carbohydrates. One explanation is that they ate shell fish but not fish because they needed carbohydrates, not protein.

  6. simonhoyte says:

    Interesting stuff. Reminds me of the key arguments made by Jared Diamond in Guns, Germs and Steel. Particularly, that the major inventions such as tool making and writing only evolved independently very few times, and the vast majority of subsequent appearances arose through ‘idea diffusion’.

  7. hertfordshirechris says:

    Early humans will often have split into different groups, exploiting different environments in different ways, with changes sometimes triggered by climate change, and separations caused by sea level changes. It now seems that groups which had been assumed to be separate species, and which may have been separated over hundreds of thousands of years could still interbreed and undoubtedly exchanged elements of their cultures. In view of the comments I feel that there is a need for more research on the Tasmanian case, but clearly it is a reminder that we must keep our minds open to expect similar happenings on many occasions over the last few million years.

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  10. philipcoggan says:

    I honestly don’t understand why you all agree that Tasmania is a warm island – because it’s in the South Seas? Average night-timer temperatures in Hobart in June are around zero Centigrade, day-time around 14, and the rain never stops falling the wind never stops blowing – and you know where it’s coming from. The place is freezing!

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