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Black Death Predated 'Small World' Effect, Say Network Theorists 168

Posted by Soulskill
from the good-thing-kevin-bacon-wasn't-around-back-then dept.
KentuckyFC writes "Epidemiologists know that modern diseases can spread almost simultaneously in different parts of the planet because an individual who becomes infected in Hong Kong, for example, can infect friends in New York the following day. This is known as the small world effect. It is the same property that allows any individual to link to another individual anywhere in the world in just a few steps. But in the 14th century, the Black Death spread in a very different way, moving slowly across Europe at a rate of about 2 kilometers a day. Now network theorists have simulated this spread and say it is only possible if the number of long distances travelers in those days was vanishingly small. In other words, people in medieval society were linked almost exclusively to others nearby and so did not form a small world network. That raises an interesting question. If society in 14th century Europe was not a small world but today's society is, when did the change occur? The researchers say the finger of blame points to the invention of railways and steamships which allowed large numbers of people, and the diseases they carried, to travel long distances for the first time."
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Black Death Predated 'Small World' Effect, Say Network Theorists

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  • The study assumes people did not have long distance links. Alternatively, they had long distance links, but did not travel when they were infected with the bubonic plague.

    • by Ultra64 (318705)

      >Alternatively, they had long distance links

      Do you know of some secret mode of transportation that has been lost to historians?

      • You mean like horses?

        • by Sarten-X (1102295) on Friday October 18, 2013 @03:28PM (#45168461) Homepage

          Horses are expensive to maintain, and have a rough daily limit of about 30 miles. In comparison, a human walking at 3 mph can go the same distance in only 10 hours. The difference, of course, is that horses can carry more and get there faster, before taking more time to rest.

          For the peasants who made up the majority of the population during the 14th century, a horse was a good tool for farmers or messengers, but regular travel would best be done on foot with a light pack and a steady pace.

          • Re: (Score:3, Informative)

            by Optali (809880)

            Very good point.
            And sum to it that people had a very good reason to do that as many laborers mved from place to place for the harvests.

            Here in Central Europe young men used to travel long distances during their time of apprenticeship in the different guilds, this tradition is still held in Germany (Wanderschaft). Guilds like the stonemasons travelled from Spain to Cenral Europe and you can find their guild emblems in Romanic and Gothic buildings across the whole continent. Some may even have been in Africa

          • by Shinobi (19308)

            Even up until WW2, the horses were what limited the rate of advance for armies, including the german invasion of Belgium and France, since horses were what pulled the majority of the logistics train.

            Also, in regions where roads were not common, or in VERY bad shape, you usually had no horse depots, meaning that humans were much faster, especially over broken terrain

          • by khallow (566160) on Friday October 18, 2013 @04:09PM (#45169093)

            Horses are expensive to maintain, and have a rough daily limit of about 30 miles. In comparison, a human walking at 3 mph can go the same distance in only 10 hours.

            That's not comparable. The horse could do that forever (for example, see this US cavalry manual [ibiblio.org] which stipulates cavalry can go 35 miles a day, six days a week indefinitely - page 152) while the person would not be able to maintain that sort of pace for more than a few hours to a day unless they were in really good shape.

            In comparison, typical indefinite marching rates for an army were about 10 miles a day [0catch.com] (both for roman legionaires and US soldiers).

            • by Wycliffe (116160) on Friday October 18, 2013 @07:07PM (#45170707) Homepage

              Horses are expensive to maintain, and have a rough daily limit of about 30 miles. In comparison, a human walking at 3 mph can go the same distance in only 10 hours.

              That's not comparable. The horse could do that forever (for example, see this US cavalry manual [ibiblio.org] which stipulates cavalry can go 35 miles a day, six days a week indefinitely - page 152) while the person would not be able to maintain that sort of pace for more than a few hours to a day unless they were in really good shape.

              In comparison, typical indefinite marching rates for an army were about 10 miles a day [0catch.com] (both for roman legionaires and US soldiers).

              It's very comparable. A human can keep up a 3mph walk forever as well. A 3mph pace is not hard for a human at all and without
              a pack 30 miles a day would not be an issue for a human. 35 miles per day, six days a week indefinitely would not be a problem for
              the average person either. I don't think a march with camp setup, etc... is comparable to what the original poster was talking about.
              I think you underestimate what a human is capable of. When I was in college we went on a hike to the bottom of the grand canyon
              for a week. None of us were in great shape, did any training, or probably near as fit as a peasant who worked all day in the field
              every day yet we averaged about 20-25 miles a day for a week with heavy packs on rough terrain and making camp each night.
              We obviously could have done alot more with a light pack. And again, we were not in shape, didn't train, and most had never even
              been backpacking before. For endurance running a human is every bit as good as a single horse. The pony express used multiple
              horses because horses are faster over short distances but over multiple days a human is actually faster. A good runner can do alot
              more than 35 miles per day. This guy averaged over 50 miles a day for 40 days:
              http://www.outsideonline.com/blog/outdoor-adventure/the-human-express-interview-with-karl-meltzer.html [outsideonline.com]
              Here is one of many articles that states that humans can outrun every animal on the planet:
              http://discovermagazine.com/2006/may/tramps-like-us [discovermagazine.com]

              • by Wycliffe (116160)

                Oh, and reading over that article about Karl Meltzer, it says on the 40th day he ran over 100 miles.
                I'm not sure a horse is even capable of 100 miles in a single day where here is a person who
                did this after running over 2000 miles in the previous 39 days.

              • by khallow (566160)

                A human can keep up a 3mph walk forever as well.

                Not in reality. I notice that typical thru travel times for the Appalachian trail (2100 miles) are between 150 and 210 days which is again close to 10 miles a day.

                When I was in college we went on a hike to the bottom of the grand canyon for a week. None of us were in great shape, did any training, or probably near as fit as a peasant who worked all day in the field every day yet we averaged about 20-25 miles a day for a week with heavy packs on rough terrain and making camp each night.

                Healthy college students - for only a week. A peasant who works all day in a field is not going to be that fit because they aren't doing that sort of exercise and they just wouldn't be that healthy either due to nutrition, disease, and poorly treated injury.

                For endurance running a human is every bit as good as a single horse. The pony express used multiple horses because horses are faster over short distances but over multiple days a human is actually faster. A good runner can do alot more than 35 miles per day.

                And a good horse rider with multiple horses can do a lot better than that. For example, Com [blogspot.com]

                • by Wycliffe (116160)

                  And a good horse rider with multiple horses can do a lot better than that. For example, Commanche [blogspot.com] and Mongol [timcopejourneys.com] riders could easily do 75 to 100 miles a day by this means.

                  Again, you've changed the criteria to multiple horses. A peasant would be unlikely to have access to a single horse let alone have access to
                  multiple horses along a route. Most likely during this time though period people would rarely travel further than the closest village and only
                  traders would travel to the next village probably with a donkey or two. Even today most people rarely travel further than the closest town to
                  do business except on special occasions.

                  • by khallow (566160)

                    Again, you've changed the criteria to multiple horses.

                    Which is an obvious thing to do since it both was used in history at the time of the Black Death and demonstrates a counterexample to the somewhat off-topic claim I was arguing against.

              • It's very comparable. A human can keep up a 3mph walk forever as well. A 3mph pace is not hard for a human at all and without a pack 30 miles a day would not be an issue for a human. 35 miles per day, six days a week indefinitely would not be a problem for the average person either.

                Define "average person". I walk a lot compared to an average western person. I try to knock over a couple of kilometres a day, which might not sound like much, but compared to your average lazy westerner whose only walking is from the bedroom to the garage, it is above average. I can walk about 5kms at about 5km/h without thinking about it, but more than that and I feel it. And I do this almost every day. If I do a 10km walk I need a rest and don't feel much like repeating it the next day. 35miles (60km) i

                • by Wycliffe (116160)

                  Define "average person". I walk a lot compared to an average western person. I try to knock over a couple of kilometres a day, which might not sound like much, but compared to your average lazy westerner whose only walking is from the bedroom to the garage, it is above average.
                  I can walk about 5kms at about 5km/h without thinking about it, but more than that and I feel it. And I do this almost every day. If I do a 10km walk I need a rest and don't feel much like repeating it the next day. 35miles (60km) in one day would kill me.
                  I work in a company of 2000 people and looking around I would bet my house that at least half of them couldn't walk 5km a day for one week. 60 km a day would pose a huge problem for most western people.

                  I would consider myself fairly "average" by your definition. I sit at a desk all day and work from home so I don't even have
                  to walk to the garage. I could probably afford to lose 15 pounds but I still have no problem on vacation going to the zoo,
                  six flags, disney world, etc... and walking for 8-10 hours straight at probably around 5km/h with no issues for an entire week.
                  So I'm guessing that I get close to the 35mi/60km per day where generally on a typical day I'm probably lucky to hit
                  3000steps/2km in a da

                  • You don't walk for 8 - 10 hours when you go to Six Flags or Disney World; you wait in lines at times, you stop to eat and drink, you stop to talk to whomever is with you about where you're going next. You may be on your feet but you aren't constantly walking, and that's quite a difference. (Ask any cashier that is on their feet 8 hours a day to walk for 8 hours a day instead.) I had no problem walking around "all day" for 3 days at a convention a few weeks ago, but if I am walking from one location to anoth
            • by Sarten-X (1102295)

              3 MPH is a typical hiking speed. Hiking 10 hours isn't terribly hard, even with a light pack. Armies, especially legionnaires and modern soldiers, do not carry light packs. They carry about 50 lbs or more.

              Horses are really beasts of burden, not suitable for speed. In 14th century Europe, they were most useful for trading caravans, whose profit was based on how much they could carry in one trip. They were also useful for nobles, who had to carry all of their regalia. It'd be pretty hard for anybody else to j

          • by dutchwhizzman (817898) on Friday October 18, 2013 @05:29PM (#45169957)

            Almost nobody had horses back then, compared to the 19th century. Working the land was done manually, or with the aid of oxen and such. Horses were more or less used as battle transportation and sometimes very important couriers. There was occasional other use for them, but horse ownership was usually reserved to the nobility and rich cities due to the cost of maintenance in the times that the black plague was hitting Europe.

            Keep in mind that the black plague was spread by fleas that favoured rats, cats, dogs and such as hosts. They would choose humans as hosts, but were repelled by horses and their smell. As such, people that lived in horse staples and worked with horses, or rode them to the next town, most often were spared. If a lone person travelling on horse back would come from an infested city and was not bitten by an infested flea by the time he left that city, he wouldn't be carrying any infested fleas or the bacteria by the time he arrived in the next town. The spread of the virus might have actually occurred without any human interaction whatsoever in a lot of cases where fleas just infected rodents living in the wild, or actually by people that travelled by foot and brought their dogs and such along.

      • by Ultra64 (318705)

        Yes. Thank you people, I know about ships and horses.

        Explain how a person with bubonic plague is going to survive traveling long distances on one of those.

        • by damienl451 (841528) on Friday October 18, 2013 @03:42PM (#45168709)

          There are other ways that the plague could spread. Yes, someone infected with the plague would die before reaching their destination. However, ships also carried cargo, which could be contaminated. Standard procedure was to quarantine ships and their cargo but, understandably, there could be pressures to rush things because people didn't like their precious fabrics to be kept on an isolated island for forty days, especially since they could easily get damaged in the process.

          This is how the Great Plague of Marseilles began: a ship laden with cargo belonging to important people was not quarantined according to procedure. Unfortunately, it had come from the Middle East where the plague was rampant and it starting spreading through the city.

          • Right. The authors have overlooked the fact, as shown by their own map, that, in 1347, the plague moved into Europe along a broad front: the Mediterranean coastline. I imagine that it spread along that front by ship, a good deal faster than the inland spread that the authors base their thesis on.

            Furthermore, the authors summarily dismiss the effect of the disease on its spread. It was very debilitating, and a traveller on land who fell sick would be unlikely to continue his journey. The authors exaggerate t

            • by cusco (717999)

              a traveller on land who fell sick would be unlikely to continue his journey.

              An adult traveler. Children in arms or carried in the cart/wagon/travios by parents fleeing the plague could travel quite a distance. If the parents were royalty or related to the gate guards they could probably the enter and infect the next community, if not they could camp outside the gates and infect the local rat population.

              Infected humans are not the only way the disease could travel, either. Fleas can live for months witho

              • a traveller on land who fell sick would be unlikely to continue his journey.

                An adult traveler. Children in arms or carried in the cart/wagon/travios by parents fleeing the plague could travel quite a distance.

                Good point - I had overlooked that possibility.

                Infected humans are not the only way the disease could travel, either.

                While I don't disagree with anything you say, I am not sure that animal vectors make a difference to this particular study. The question I have is, did the animals spread the disease across the continent independently, i.e. other than by being transported by humans, to any significant extent? If so, then we can only say that the data give an upper bound on the rate of spread by humans. While this would raise the possibility that this rate was lower than that ca

                • I am being serially dumb here. I see now that the animal vectors allow the disease to spread at the rate of asymptomatic travelers.

        • by H0p313ss (811249)

          Rats

        • by Optali (809880)

          Incubation period?

          And note that the fact that the Black Plague was actually the bubonic pest is not yet confirmed, we can't thus be sure if there may have been people infected with the plague while being asymptomatic.

           

        • IIRC the incubation period between exposure and first symptoms of bubonic plague is approximately six days, which would mean a determined walker could cover over 100 miles spreading his disease wherever he stopped to eat, converse, and sleep. Retarding that spread would be the fact that most travelers were not traveling any great distance. Serfs and peasants were tied to the land, seldom traveling further than the nearest market, but there were peddlers, pilgrims and couriers, as well as the upper class

      • by icebike (68054)

        Ships can deliver rats a long distance. As can wagon loads of produce.

    • by Richy_T (111409)

      Though it would seem likely that some of the spread was due to traveling to get away from the plague when one was (unwittingly) infected with it.

    • by Mobster75 (234793)

      I would suspect the major factor back then on why the plague didn't spread so far, so quickly was that while they had long-distane trade links, the time period during which the plague would incubate and ultimately kill someone was far shorter than the time it took to travel great distances. I'm sure that if someone in a travel party began exhibiting symptoms of the plague, they were rather quickly left to die on their own in some remote location to avoid infecting the rest of the party.

    • by icebike (68054)

      You have to evaluate the transit time required via any given mode of transportation, compared to the time it takes to incapacitate a person after initial infection.

      That limits the distance a lone carrier could spread the disease. People going to the next village to trade, or (once the danger becomes apparent) to request help or warn them would be the likely rural vectors, and that sounds like the two km / day limit. People could obviously walk farther in a day, but didn't need to. The next village or se

      • by swb (14022)

        I've read that most of the road network in Europe at this time was originally built by the Romans and Roman armies would basically build a fort at the end of every day's march; these forts would be the basis of towns along the road. This meant that the nearest village was basically a day's walk.

        I would argue that they didn't have much reason to travel even to the next village. At best they would trade for agricultural products or craft goods they didn't have or have enough of (pottery, animals, wood goods

        • by icebike (68054)

          That sounds reasonable. So how far apart did they build them?

          As north america was being settled, horses were in wide use, by every household. Walking was less of an influence.

          The average distances between towns averaged 18 miles, the distance you would want to travel on horseback per day. Someone did some research on the distances horses could cover in a day [cartographersguild.com], given the conditions of un-improved trails and found that pretty much agreed with historical records of the location of Roadhouses, which tended to

        • Actually, someone's now suggesting the "Roman" roads actually predated the Romans [telegraph.co.uk]. I'd be tempted to dismiss this as another wild theory in search of fame, but it fits with the general trend in history: after centuries of belief in the superiority of a few "great civilisations", we are increasingly realising that there were no true "dark ages", and that civilisation has always progressed. Hell, some of the greatest monumental engineering and architecture came out in the Middle Ages, and they dubbed it "Goth
      • by cusco (717999)

        Wagon freight and carriage travel didn't become common until the late-7th/early-18th century, as the Roman road system had collapsed from lack of maintenance and was never repaired outside of urban areas. It wasn't until later than that when horses became common, and really the late 19th century before riding horses became widely available to anyone beyond the aristocracy.

        • by icebike (68054)

          Yes, but much of Europe is served by river and canals, and has been for a long time before rail came into existance.

          Most of the canals began construction in the 16th century in some parts, and really took off in the 19th.
          But rivers were the highways, an Europe has many long rivers that cross borders, and goods transport on them was bound to include rats.
          Further it was easy, so even mildly sick people could use this means.

          • by cusco (717999)

            True enough, but by that time the Black Death had already swept through Europe several times. Travel has improved by orders of magnitude over the last few centuries.

    • by dpilot (134227)

      > but did not travel when they were infected with the bubonic plague.

      Or at least not far. Any idea what the incubation time of the plagues were, or how that time compared to how long a trader would spend in one market before moving to the next? In other words, were they in one spot long enough to get infected and start showing symptoms before they would have been scheduled to move on.

      Another thought... Someone once wrote about mapping plague outbreaks to elevation in London - really to river and sewer

    • by rasmusbr (2186518)

      People have traveled long distances for thousands of years and the way to do it has always been by boat. It turns out that rowing is typically more effective than walking and horseback riding even if the land route is shorter. This is especially true if you assume that the main purpose of the trip is to carry cargo (or loot...).

      If you were a young man born and raised near the coast in the bronze age odds are you would end up travelling hundreds of kilometers/miles from home at least once in your life, perha

  • by Anonymous Coward on Friday October 18, 2013 @03:17PM (#45168307)

    The Bubonic plague was carried by the rats. It can only be transmitted human to human in it's final stages and the fleas can't survive long on human body. Two km a day seems about right for rats.

  • by DerekLyons (302214) <fairwater@gmai l . c om> on Friday October 18, 2013 @03:20PM (#45168341) Homepage

    From TFS:

    In other words, people in medieval society were linked almost exclusively to others nearby and so did not form a small world network.

    Um, who exactly is this news to? Historians and sociologists have known this for decades.

  • The researchers say the finger of blame points to the invention of railways and steamships which allowed large numbers of people, and the diseases they carried, to travel long distances for the first time.

    Or sick people didn't travel. Or the long-distance traveler stopped traveling after they became ill. Or a horse drawn cart didn't hold as many rats as ships or trains.

    It would be neat to see a visualization of the spread of various diseases in our known history.

    • Or sick people didn't travel.

      True, but they could with steam ship or train. This effect was seen in WW1 and was in an article about the great flu epidemic and why it was so great. Usually, sick stay home and don't travel while well people do. In the war, the really sick were evacuated out of the trenches and back to cities and sometimes back home, while everybody else stayed.

      • by nullchar (446050)

        Exactly. It's quite difficult to walk or ride a horse while very ill. But lying on the floor on a steam ship or train car will spread the illness around.

  • by jovius (974690) on Friday October 18, 2013 @03:20PM (#45168353)

    So it's true that I could catch some disease if I go out then?

  • by Richy_T (111409) on Friday October 18, 2013 @03:20PM (#45168365) Homepage

    What if human beings were not, in some way, a vector?

  • I recommend they publish this in Duh: The Journal of the Insipidly Obvious. Does anyone really believe you need to be a medievalist to know that communication and travels was much slower in the middle ages than it is in the modern day? Simulations of how the disease spread are interesting from a historical point of view, but it's not even like we're talking about a time when humanity was on the cusp of "small world" connectiveness.
    • What they are talking about is the same phenomenon in medieval terms; they're arguing that even by our current understanding they had limited contact with the wider world. Look at it this way, at an average spread of 2km per day and an incubation period of days or weeks, all it would is a single traveler to blow that average out of the water. One guy riding a horse for 2 hours a day could plant incubation sites 50 or 100 km ahead of the larger wave of the outbreak before he even knew he was sick. So, eith

      • by starX (306011)
        Why would you find minimal long distance travel hard to believe? Also, since in the years following the black death, in England at least, laws were passed to tie workers to the land and punish masterless men and vagabonds: there were so few peasants to work the land that the lowest classes could demand higher wages and buy their way into the yeoman class, but the anti-vagabond laws were designed to put an end to that. This is well documented, but even before then few people would have left the immediate vic
  • the small world effect is possible by low cost and fast transportation. The same holds true for tourism. So the intrepid British explorers who started early in the 18th century to roam all across Europe are the first indicators of this change. Look how old Thomas Cook (the company) is (Link: http://www.thomascook.com/thomas-cook-history/ [thomascook.com])
  • ...or the ones that survived the smallpox.

  • \m/
    Srry mates, it's friday...

  • My hometown (Weymouth, Dorset) has the dubious distinction of being the port where the black death entered England. Cool huh?

  • ...is that we wouldn't have modern epidemiology and many advances in modern medicine had the issue not been pushed by the "small world" effect.

  • Worse Yet (Score:4, Interesting)

    by b4upoo (166390) on Friday October 18, 2013 @04:27PM (#45169309)

    Passenger airline traffic has the potential to disperse a world wide plague more deadly than all past wars combined. It is another issue which is shrouded by deliberate blindness as the cure would be very disruptive.

    • by evilviper (135110)

      Passenger airline traffic has the potential to disperse a world wide plague more deadly than all past wars combined. It is another issue which is shrouded by deliberate blindness as the cure would be very disruptive.

      Air travel only shrinks the oceans... Cars / trains / horses / bicycles are good enough to spread a plague entirely across two or three continents, even if air travel didn't exist at all.

      For the sake of destroying the world economy, you'd only be keeping 15% of the world population safe from th

  • Before the pathological evil of what we know as the industrial war machine, with broadcast technologies and deployment tactics that could harness fear and loathing to politics everywhere at once--- and the tireless drudges who worship them came to the fore---

    We were becoming increasingly cyclical, distracted by moment, swaying in tighter rhythms while not dancing -- a bad sign. Hypnotized by the leafspring, the mainspring, the ratchet, the pendulum and most obnoxious of all, an hour-bell that means somethin

What ever you want is going to cost a little more than it is worth. -- The Second Law Of Thermodynamics

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