Thursday, July 23, 2015

Gleaning: an ancient custom that may return in the future

Gleaning women in Italy in 1930 (image source). The ancient peasant society had found in gleaning an elegant and efficient way to optimize the management of low-yield resources.

Gleaning is an ancient tradition, deeply embedded in the agricultural world. In the past, it was common practice that the poor were given access to the grain fields after the harvest, so that they could collect the spikelets left on the ground by the harvesters. It wasn't done just with grain, but with all kinds of agricultural products: fruit, olives, chestnuts, and more. Whatever was left after the first pass was for the poor and for the destitute to collect.

Gleaning was so important in the past rural societies that it was even sacred. We read in the Bible that God explicitly ordered to owners to give to the poor a chance to glean in their fields. And the origin of David's lineage in the biblical tradition is related to gleaning, as described in the story of Ruth, a poor Moabite girl who married the owner of the fields where she gleaned. Other religions do not have such explicit references to gleaning, but most of them convey the idea that the rich should partake with the poor what they don't need. For instance, a similar sharing command from God can be found in the Islamic tradition, but directed to water.

Gleaning remained a fundamental feature of rural societies until recent times; it is still done, occasionally (as you can see in this movie), but it has lost importance with the onrushing growth of the industrial society. It is not considered sacred anymore; on the contrary, the suspension of the property rights associated with gleaning is often seen as subversive in a world that emphasizes fenced private property and strictly regulated activities. In some cases, gleaning was specifically prohibited by law, as in the Soviet Union in the 1930s. That was a terrible mistake that aggravated the famine known as the "holodomor" in Ukraine.

But why gleaning was so common? Why even sacred? And can we learn something useful for us from this ancient tradition? It turns out that, yes, we can. Far from being a primitive tradition, gleaning is a sophisticated and efficient technology designed for managing low yield resources. It is a technology that we could still use and that, probably, we'll have to re-learn as the gradual depletion of high-yield mineral resources forces us to abandon the wasteful and expensive industrial technologies we have been using so far. But it is a story that needs to be told from the beginning.

Gleaning to optimize the agricultural yield

Few of us have direct experience with the sickle (or the scythe, its long handled version, used specifically for reaping). We can only imagine how hard it must have been to use it to harvest crops during the Summer, under the sun; going on day after day, swinging it over and over, for as long as there was enough light. It took not just physical strength, it took endurance and skill. But it was the task of the peasant to do that and it has been done for thousands of years.

Now, imagine a line of reapers advancing in a grain field. Obviously, they had to stay at a certain distance from each other while swinging their sickles. So, it was unavoidable that some grain stalks would be left standing and that some spikelets would fall on the ground. Could you avoid this loss? Maybe you could try to get the reapers closer to each other; but that could even be dangerous. Or maybe you could force the reapers to be more careful, or to stop and collect what falls on the ground; but that would slow down the whole process. In short, we have here a classic problem, well known in economics: efficiency shows decreasing marginal benefits. The optimal yield of harvesting is surely obtained collecting less than 100% of the grains.

Now, there comes gleaning; and it is an extremely smart idea simply because it is so inexpensive. First of all, gleaners didn't need tools, nor needed special skills. They would simply walk in the fields, equipped with nothing more than their hands and a bag, collecting what they found on the ground. Gleaners didn't need to be trained in harvesting, nor to be in perfect physical shape. Women could do it, just as older people and youngsters could. Then, it was a totally informal operation, without the costs of bosses, of hierarchies, of organizations. (Image on the left "La Glaneuse", by Jules Breton, 1827-1906. Note how this woman has no tools, no equipment, not even shoes!)

But gleaning was not just a question of efficiency, it was way deeper than that. It provided a "social buffer" that allowed flexibility (or, if you prefer, "resilience") to the agricultural society. The vagaries of the weather, of insects, pestilences and other calamities always made the yield of the harvest uncertain. So, a peasant family that faced hard times could always fall back on gleaning to survive. Then, when the good times came back, the same family could provide the human resources for the regular harvesting. So, gleaning played the role that today we call "Social Security" or "welfare", reducing conflicts and frictions within society.

But the idea of gleaning went beyond this utilitarian factor. It had to do with the very fact of being human and of helping each other. As such, it takes the name of solidarity (or, sometimes, of compassion). The reapers knew that the spikelets left on the ground would be collected by the gleaners following them. Would they leave some falling on purpose? We can't know for sure, but we can read in the story of Ruth in the Bible how the owner of the field himself ordered the harvesters to leave something on the ground for her to collect.

Biophysical economics of gleaning

Economics theories never considered gleaning. This is in part because gleaning does not involve money and prices and, therefore, it is invisible to economists. At most, economists might define the spikelets that fall on the ground as "diseconomies", goods of negative value. But why does the economic process generate goods of negative value? And how to get rid of them? (maybe it is this kind of reasoning that led the Soviet Government to enact a law that called for shooting gleaners)

So, if we want to understand the mechanisms of gleaning, we need to go to a different concept: "biophysical economics". It is the view that sees the human economy as an activity that mimics biology. So, each economic activity is like a biological species; it uses resources to live and reproduce, while producing waste.

Once we take this view, we immediately see what gleaning is. It is a "trophic cycle;" a manifestation of the fundamental idea in biology that one creature's waste is some other creature's food. Spikelets fallen on the ground are a low-yield resource not worth processing by traditional harvesting and therefore should be considered as waste from the point of view of the primary production process. But, from the viewpoint of gleaners, spikelets produce a sufficient yield to make them a resource worth processing. Gleaning is, therefore, a processing method specialized in low-yield resources. We can express this idea also using the concept of "energy return for energy invested" (EROI or EROEI). The energy yield of the spikelets fallen on the ground is not sufficient to generate a good EROEI if they were to be harvested by mechanized methods or by specialized personnel. But, if we reduce the energy investment by means of gleaning; then the process must have generated an acceptable (or even very good) EROEI if it was so commonly used in agriculture.

The low cost of gleaning derived from several factors, one was that it wasn't associated with the costs of private property; intended as claiming it, fencing it, defending it, and more. Indeed, gleaning can only function if the resource being gleaned is managed as a "commons;" that is, free for everyone to collect. Traditionally, it meant that private land ceased to be such for the period of gleaning (as in the case of grain fields). Other kinds of resources shared this characteristics, being so low yield that they can be gathered only informally and in a situation of commons; e.g. mushrooms, wood, grass, and others. That's true also for hunting as it was practiced in very ancient times. Overall, we can see gleaning as a "hunting and gathering plug-in" applied to the agricultural society.

On the subject of the commons, the analysis by Garrett Hardin is very well known under the name of the "Tragedy of the Commons". Hardin made the example of a pasture managed as a commons, noting that every shepherd can bring as many sheep as he wants to the pasture, and that the more sheep he brings the more the economic yield for him. However, if the total number of sheep exceeds the "carrying capacity" of the pasture, then the pasture is damaged. The cost of the damage, however, is spread over all shepherds, whereas each single shepherd still has an individual advantage in bringing one more sheep to pasture. The result is we call today "overexploitation" and it eventually generates the destruction of the resource being exploited.

However, if the commons have survived for millennia in agricultural societies, it means that the tragedy described by Hardin was not at all a common phenomenon. Hardin was not wrong, but he applied an industrial logic to an activity that was not industrial in the modern sense. For the "tragedy" to occur, there must be some kind of capital accumulation that you can re-invest in order to increase the rate of exploitation of the resource. Gleaning, instead, hardy generates capital accumulation. Think of gleaners collecting grain: how would they accumulate capital? Can't be; the most they can do is to is to collect enough to feed their families. The very concept of monetary capital is a burden that gleaning cannot afford.

Hence, we see how beautifully optimized gleaning is; a far cry from the brutal and inefficient method of "privatize and fence," often proposed as the solution to all problems of resource overexploitation. And we can also understand why gleaning has nearly disappeared from our world. With the energy supply that society obtains from fossil fuels, there was no need any more for such a radical optimization of the agricultural process as gleaning could provide. The industrial world was (and still is - so far) rich enough that it can think that it doesn't need to be efficient; it doesn't need gleaning. Indeed, the wealth generated by the industrial society can provide better services than those that gleaning produced, long ago: pensions, social security, food security and more. All that was the result of the high energy yield of fossil fuels. For how long that will be possible, however, is a completely different story; considering the fact that fossil fuel are not infinite.

3. Gleaning in the modern world.

One of the problems of the modern industrial economy is waste. We are possibly at the height of a historical cycle of energy production and, as a consequence, we probably never generated so much waste as we do today (there are indications that a decline in waste production may already have started in the rich regions of the world, see this article of mine). But, as mentioned before, we don't know very well what to do with this stuff that we call "negative value goods."

Normally, we tend to try to get rid of waste by using expensive industrial processes, for instance incineration plants which - miracle! - are said to produce energy (and, hence, they are renamed "waste-to-energy plants"). And our concept of recycling involves expensive methods that almost never repay their cost. But, as Einstein is reported to have said, we cannot solve our problems with the same thinking we used when we created them.

However, if we look at the hidden side of waste processing, we can see that gleaning, although nearly completely disappeared from agriculture, is still there; alive and well. An early example of modern waste gleaning can be found in the novel by Franck McCourt "Angela's ashes," where the author tells us of how his family could survive in the winters of the 1930s in Ireland, literally gleaning coal; that is collecting coal lumps fallen from coal carrying carts. Today, you could call "gleaning" the activity of "binners," "cartoneros," and "cataderos" who recover what they can from the trash bins of the rich Western society. (more data at this link).

These activities go under the general name of "informal participatory waste management" - a fancy term for what is simply gleaning applied to industrial waste. These modern gleaners use no expensive equipment, mainly bags and old carts. They move on foot or, occasionally, use supermarket carts as skateboards. They separate the mixed waste into (modestly) valuable objects by hand. In the picture, you see Professor Jutta Gutberlet of the University of Victoria, Canada, discussing with a Brazilian "catador."

We don't have precise data on the world trends of this kind of activities, but it seems clear that the increasing number of people who live in poverty in rich countries has generated a return to ways of living that seemed to have disappeared with the booming economy of the second half of the 20th century. Then, in poor countries, the poor have always been "gleaning" landfills, even though the poorer the country, the poorer also must be the landfills. It is a job that doesn't pay well (obviously) and that carries considerable danger: you never know what you can find in a waste bin. It can be something sharp, poisonous, contaminated, or dangerous for all sorts of reasons.

The gleaning of household waste is seen in different ways in different parts of the world. Some European and North-American countries have implemented "container deposit legislation." That is, the consumer who buys a bottle or some other kind of container, pays an extra as deposit, which can then be recovered by bringing back the container to the seller. This kind of legislation, obviously, generates a considerable gleaning-like activity on the part of poor people who actively search and collect thrown away containers.

The gleaning of industrial waste would seem to be a good idea under many respects; and it even seems to work where it has been implemented. However, there are big problems with making it a widespread and commonplace technology for waste management. On the basis of my personal experience, I can tell you that trying to fight the vested interests of the companies that make money out of traditional waste management is hard; think of taking away a fish from the crocodile's mouth. In some cases, disturbing the crocodile can even be dangerous, considering the widespread network of illegal activities related to waste management.

Then, in proposing participatory waste management, you risk being considered as an "enemy of the people" and accused of planning to prevent the poor from their legitimate right of becoming 9 to 5 office employees. You may also be seen as an enemy of science and technology, as you are intentioned to block the development of new and wonderful technologies that will bypass thermodynamics and transform waste into a high yield resource. Finally, often you face a stumbling block in the form of the "zero waste" idea, often intended as meaning that no waste should be produced at all. The fact that perfect efficiency implies zero resilience seems to be completely alien to the way of thinking of those who propose this idea.

So far, no one seems intentioned to propose shooting the informal waste collectors, as it was supposed to be done during Stalin's times, but it is easy to get discouraged facing the complete lack of understanding of the situation at all the levels of the decision making process. Most people simply don't want to hear about this subject, and the idea of having the poor scavenging their household waste horrifies them. They want it burned or removed from their view, and that's it. Hence, we are stuck with the traditional, industrial techniques of waste processing for as long as we will be able to afford them (not forever, for sure)

Conclusion: the future of gleaning. 

How can we see gleaning in our society? Can we see its return in one of its many possible forms? And, if so, will it be useful for something, for instance to solve the waste problem?

Personally, I would avoid seeing gleaning as a solution for any problem. Gleaning is simply something that happens, it is part of the way our world works and the way human beings adapt to change. Gleaning really never disappeared from human society and it will never disappear as long as human beings exist. The future will bring us the gradual winding down of the industrial society as cheap fossil fuels are burned and disappear. As a consequence, it will become more and more common to return to gleaning-like technologies that can optimize the return of low-yield resources, such as those left by the industrial binge of the past few centuries.

In this vision, a good case could be made that the gleaning of waste should be encouraged already today by laws and subsidies. Even if you don't agree with this idea, at least, we should avoid the mistake of forbidding gleaning, or to make it impossible under the burden of taxes and bureaucracy (to say nothing about the idea of shooting gleaners). It is not just a question of opportunity, but a wider one of solidarity. God Himself (or Herself) commanded us to let gleaning be and, as God is said to be compassionate and merciful, I think we should take that into account.

A stunningly beautiful movie on present day gleaning, "Les glaneurs et la glaneuse" by Agnes Varga (2000)

h/t Jutta Gutberlet and Charles Juhn


  1. Dumpster diving for food waste is the obvious example of a gleaning activity that is forbidden in most western countries (and other as well?). I am not sure why, but the only reason I can think of is that reduced waste would hamper demand - and profits.

    1. Yes... our youngest daughter at University participated in dumpster-diving where supermarkets dumped good usually packaged food according to its, often inappropriate, 'sell-by' date. The students could not eat that much of it, there was so much - so I think they mostly cooked it and offered it free on the street. It was before the days of USA-type 'Food Banks' in the UK and they had difficulty in getting people to accept 'free food'. Nevertheless they persevered as best they could, except where supermarkets took to trashing packaging and spraying the food with dye. Anyway dumpster diving was illegal. I have since met students who tell me they actually survived by dumpster diving.

      Back in 1997 I saw early morning Roma women in Skopje - the country still not recovered from economic free-fall - extracting food before the sun got hot. In later years it was more organised round recycling cardboard and any household discard that might be re-serviced or contained recyclable metals etc.


    2. Dumpster diving actually seems to be legal in most US states, although laws against trespassing might be applied and particular municipalities may have their own local prohibitions. California v. Greenwood (1988) is often cited to claim that once refuse is discarded it enters into the public domain. For example:

    3. Apparently there are very few prosecutions in the UK,
      Here is an interesting enough story in the Daily Mail.
      There is apparently a Gleaning Network.

  2. It's a laudable post and spirit Ugo, but I think Gleaning only works if there is substantial surplus, which I don't expect will be the case when fossil fuel fertilizers run out. What happens when there are more people wanting to Glean than there is room for Gleaners? They start fighting, that's what happens.

    We already have this situation occuring here in Alaska. Alaska Residents are permitted to "dip net" for Salmon during the annual run, and take up to 25 salmon and 10 flounder as their subsistence fishing right. A few years ago, this was relatively polite, and most people would help each other. In the last 2 years, this has become a battleground, as one dip netter tries to get in front of the other to capture the fish. Too many people fighting for the same resource, same old problem.


    1. Well, gleaning has been around much before fossil fuels appeared and I think it will outlast them for good.

    2. Yeah, gleaning was a tradition fortifying the solidarity of a community by way of which the rich gave a favor to the poor.

    3. We needed as many people as we could get to defend the harvests from outside forces

    4. Gleaning may outlast fossil fuels, but will it outlast drought and soil depletion?


  3. All nice and well, but personally I find REALLY upsetting that accepting gleaning ("spigolare"... yes, I'm Italian, and in my ears still resound the school "refrain" about "La spigolatrice di Sapri"... :-) as another form of "new normal" mean of survival for the destituded (instead that an occasional and time limited pratice) moves the focus from the REAL problem that generate the necessity of the gleaning itself in the first place: DISTIBUTION INEQUALITY.

    I mean: why the 99% of the total of the fruits of the work of the *real* working classes must end in the hands of the Robber Barons ("Padroni del Vapore"... do you remember, Ugo? :-) and others similar PARASITES only becuase the "own" the land/mill/factory/hedge fund/whatever?

    It is so sad to see how quickly we are loosing even the basic concepts of decency and solidarity and social justice... :-(

    1. As I say in the post, this is a rather typical criticism I receive when I discuss the idea of waste gleaning. I understand it perfectly, but I think that the situation has been collapsing so fast that we must abandon "plan A", the idea of a fair distribution of the available resources, and move fast to "plan B", try to insure the physical survival of as many people as possible.

      Then, there is Plan C, trying to at least avoid extinction......................

    2. Sorry Ugo, but if this mean to fight for the survival of a species that knowligly accept systemic & systematic inequality as the BASIC normal status quo of its social structure (notwitstanding being able to imagine better social systems), I cannot care less if said species survive, even if it is my species. I am ashamed of being part of it and welcome its extinction... :-(

    3. It is a difficult challenge. Literally, we emerged out of the woods yesterday and we don't know yet how to manage a society of billions of people, not even of millions. I think we'll learn, one day or another, but it will take time. A lot of time.

    4. I have my doubt about learning.
      The (un?)natural selection in acto in our species seems de facto to privilege the egomaniac/socio/psichopats as the fittest ones to survive and (after the Big General Diyng Off) reproduce (and, so doing, spreading the genetic component of their "moral diseases").
      Universal evolution in general, IMO, seems to prefer the "stronzi-est" (pardon my pun...) kind of forms of life & existence: less empathy & simpathy seems a better survival trait in this Universe (the "indifferent Demiurgo" of one of your post in the Italian version of your blog) than the contrary... :-(

    5. Reply to AnonymousJuly 24, 2015 at 3:31 PM

      I disagree that sociopathy is an insurmountable survival advantage, although it certainly does seem to overly reward some who fall into that category. Also a lot of people in that category end up in prison, which is the other side of it -- it is not always rewards they reap. But taking a step back, evolutionarily it can be regarded as a "cheating" strategy to which social strategies are susceptible. Becoming social is a difficult evolutionary leap that few species have accomplished, but once accomplished has enabled them to dominate the earth's landmasses with their biomass. I remember reading somewhere that something like 90% of land invertebrate biomass is composed of the social insects: ants, bees, termites, and some wasps. And a similarly huge proportion of land vertebrate biomass is composed of humans and their domesticated animals (especially cows, pigs, sheep, chickens). So social strategies are hugely successful at the macro level. However, as game theory tells us, most social strategies are at least somewhat susceptible to being invaded by "cheaters" -- that is, others playing a different game and taking advantage of the main game. But the proportion of such cheaters has to remain small, else it will upset the entire strategy and lead to failure and collapse of the species as a whole. Humans seem to have evolved defensive strategies against such cheaters (e.g. eventually the social members have had enough and begin applying madame guillotine to the sociopaths). The social insects' defense against cheating is largely because they have all achieved sociality by the entire colony having identical genetics. Humans were not so lucky and apparently evolved religion and religious awe as a glue to bind genetically different individuals into a single co-operative colony, but this is much more subject to cheats arising as we all have different genetics.

    6. "I disagree that sociopathy is an insurmountable survival advantage, although it certainly does seem to overly reward some who fall into that category. Also a lot of people in that category end up in prison, which is the other side of it -- it is not always rewards they reap. (...) Humans seem to have evolved defensive strategies against such cheaters (e.g. eventually the social members have had enough and begin applying madame guillotine to the sociopaths)."

      I wish this could really be. AAMOF at this historical moment they simply RUN THE GAME, they are at the top of every economical, political and social totem pole and organization. They play to have the POWER *ON* the structure to which they belong, not for what the structure is doing/could do. Thay are the lurid offspring of Gordon Gekko and the yuppie/alien for Carpenter's "They Live" (morally, I mean: no reptilian overlord memes here, OK? :-)
      And only the small psicho-fry goes to jail, ecc. The big ones, every time could be caught, today they simply CHANGE THE LAWS to be free to continue to steal. And with today technology (in the propaganda field but, not only) their powers are amplificated as never before.
      So, if this is the subset on humanity that will inherit the Earth (or what will be left of it...), SCREW THE SPECIES... :-(

  4. Dear Prof Bardi

    Yet another interesting and thoughtful post; renewed thanks!

    And you are surely quite right, fully equitable distribution is just a day-dream: good to bang one's fist about over wine or coffee, but quite hopeless as a practical ideal.

    Well, a salute to the peasants; their ghosts still haunt the now empty and mechanized fields and the ancient paths they once passed along.

  5. Ugo, as someone who actually does use a scythe (although, admittedly, not for long periods), I have also found myself doing a bit of gleaning recently here in the UK. The fields surrounding my path of land are mercilessly exploited, with four crops a year being the usual. In the spring I get to glean many bunches of daffodils (a useless but picturesque flower).

    Later in the year it will be cabbages, cauliflower and potatoes. Only the perfect-looking cabbages and cauliflowers are selected by the 'farmer' (note: there is no 'farmer' just a corporation employing Romanian people to drive around in computer-controlled harvesting machines), leaving literally hundreds of 'imperfect' ones lying around. The same with the potatoes - all the green ones are rejected, although I've yet to figure out what to do with them all (perhaps I could ferment and distill them).

    I have friends that also make use of this excess, so it's by no means only me. Some people I met even put on a feast of cauliflower curry for about 16 of us, which was rather nice. Some may get hung up on the ethics of the system as a whole, but while there's still fat of the land one may as well eat it.

    1. Yes, I tried to use the scythe, once, at a harvest festival. It is called here "falce fienaia". Hmmm... excellent way to cut off one's feet. Some time ago, we had this festival every year, where old people would take up their old farming tools, including a prehistoric engine powered thresher and go on for a few hours harvesting the old way. I tried to help, and I still remember the back-ache I got from the experiment. So, harvesting required great strength and well developed skill.

      I don't know why these festivals are not done any more. Possibly because the old people got older, possibly because the climate changed. Once, swinging the scythe in late July was a terrible effort, but not impossible. This July in Italy, the heat would kill whoever were to try.

    2. There is festival of scything over here that is gaining in popularity. I had friends who went this year and really enjoyed it:

      But as for the heat in Italy in July - I will find out about that for myself next week when we go to Milan.

    3. Worst heat wave in history, here. Today is not so bad, but they say it will restart next week

    4. Yes, our youngest working near Trieste in the north has reported temperatures over 40 deg C for several days last week.

      Nice one Jason. I was given an Austrian pattern scythe a few years back and use it regularly. It is one of the best hand tools I have ever used and I try to live up to it, though I shall never be expertl. Doing it all day would be something else.

      Here in NE England, scythes and reaping hooks or sickles were still in use including ancient pattern serrated hooks, almost in living memory. This PhD thesis from Nottingham University talks in much the same terms used by Ugo about the economics of manual harvesting after 1851 when reaping machines became available. Quote: "The conclusion is that there is a phase of economic development in which [intermediate technology such as improved light-weight hand tools] renders a scythe economically and socially more useful than a reaping machine." E.J.T. Collins, Nottingham University.

  6. Ugo - fascinating topic; I'm interested in biophysical economics of farming, but know little about it. I'm working with an initiative ( to develop ways to help smallholder farmers adapt to climate change.

    A major doubt I have is that we may suggest new techniques (e.g. conservation agriculture) which improve yields, but cause farmers to expend too much extra time and energy and therefore make things worse.

    Do you know if there are standard ways to measure human energy expenditure that would be practical in the field? I'm thinking that heart rate monitors might be the best way to derive a proxy indicator, but not sure that even these would be practical or acceptable to some farmers. Do you know anyone studying this aspect, which I believe is a neglected subject - a lot of farm data is taken but I've never seen energy expenditure measured, because, I suspect, it's a tricky and invisible concept.

  7. With the arctic ice melting as quickly as it is, and the heat becoming a truly menacing problem for mankind, I doubt that there will be much to glean in the future. With global change, the avocado farmers have already suffered huge losses in their crops, and I can't tell you how many flowers and crops I've seen that are browner and crispier than they ever were in the 70s, 80s and 90s. Global warming will destroy the food supply no question. I've start growing perennial vegetable in my yard but I wonder if I'm not wasting my time. So far, they seem to be doing fine because I'm on them daily.

  8. Nice post, but two quibbles:

    (1) Gleaning is not about waste so much as market segmentation, eg, the big supermarket for most food, the corner store occasionally

    (2) The tragedy of the commons (of grazing land) was not prevented by lack of capital accumulation but community mgmt of the resource, just as gleaning was not about no property rights but allowing others in the community on your land.

  9. Very good article prof. Bardi!
    Do you think that used stuff market could be related to gleaning?
    At least it is a method to reduce waste.


  10. Gleaning in spanish: "respigadoras (recolectoras de espigas).
    They were very busy during and after our last civil war.



Ugo Bardi is a member of the Club of Rome and the author of "Extracted: how the quest for mineral resources is plundering the Planet" (Chelsea Green 2014)