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This is one of a series of questions also discussing floating farms and city buiding.

There is an early Iron Age civilization spread out along the riverbanks of an enormous tropical river (think Amazon or Congo). There are small villages spread out along the banks and islands of the great river and its tributaries. Larger cities, floating or on high ground, of up to 100,000 people are built at critical river junctions and places where caravan routes cross the rivers.

Various infectious diseases are obviously a large problem for this civilization. A simple expedient that would be very effective to prevent many diseases would be mosquito netting. To develop an advanced civilization, I imagine that these people developed effective mosquito countermeasures from the Neolithic, early Farming period. As agriculture develops, this civilization is able to move from scattered bands to permanent villages to densely populated floodplains and cities. While making this transition, they must develop defenses against mosquito-born diseases to keep them from all dying of malaria by the time they live in densely populated cities.

What mosquito countermeasures would be developed alongside agriculture using products available in the rainforest? Eventually this civilization reached the Iron Age and was in trading contact with the nearby savanna and highlands (think the Peruvian Andes or African Rift mountains). Bonus points for discussing improvements would be possible with additional technology and trading resources.

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  • $\begingroup$ Only certain species of Mosquitos can carry certain diseases like malaria or dengue fever. So you only have to control those ones. Also, Mosquitos like standing stagnant water. So your civilisation has to learn from an early period to drain pools of water in the fields into a free flowing canal or river. This may be a little tricky in a rainforest. While it won't stop the disease spreading it will reduce the concentration of Mosquitos. $\endgroup$ – EveryBitHelps Jan 21 '17 at 15:59
  • $\begingroup$ @EveryBitHelps I doubt that kind of drainage is possible in a place that gets 20 cm of rain every month of the year. Also, I don't know how you would tell mosquito species apart in the Iron Age or earlier. $\endgroup$ – kingledion Jan 21 '17 at 16:07
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    $\begingroup$ Can you clarify what you mean by the phrase, "alongside agriculture?" I honestly don't know whether your intent is to exclude botanical mosquito repellants (see Citronella) or botanical treatments for mosquito-borne illnesses (see Quinine.) $\endgroup$ – Catalyst Jan 21 '17 at 16:10
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    $\begingroup$ If it is rampant the ones that are immune will be naturally selected LONG before they develop agriculture. Sickle cell, Thalassemia, and other changes might happen in your population, as it did in areas where the primitive population never figured things out. $\endgroup$ – Erin Thursby Jan 21 '17 at 18:04
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    $\begingroup$ @ErinThursby I agree that the answers are fine. Of course there's no way to tell if it was one person, but the downvotes appeared to happen at or close to the same time, and entire questions with their answers are seldom wholly downvoted - making me think one person was responsible. $\endgroup$ – Zxyrra Jan 22 '17 at 3:52
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Some possibilities:

  1. Body Paint: Being painted by vegetal dyes which have insect repellent effect is a working possibility. It can mean some degree of protection when far from home. (Just like @ThreeLifes suggested)

  2. Mosquito curtains. They can have pieces of fabric (possibly impregnated whit the same oil) in the windows and doors, to protect them at home, since it's probably uncomfortable to wear paint while sleeping.

  3. Natural immunity. Since they live in the rainforests for thousand of years, it's perfectly possible that they developed immunity against most of the local mosquito-borne diseases. For example the yellow fever only caused influenza-like nonlethal illness to native africans. https://en.wikipedia.org/wiki/Yellow_fever#History I think, that new viruses, changing from freshly domesticated animals to humans, would mean greater danger to this civilization.

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    $\begingroup$ +1 for acquired immunity, I had not considered that at all. Regarding mosquito curtains, most modern nets are made of fine nylon mesh. What materials could the ancients use instead? $\endgroup$ – kingledion Jan 21 '17 at 16:04
  • $\begingroup$ I think any durable, thick fabric would suffice, but won't be transparent, as modern day nets. $\endgroup$ – b.Lorenz Jan 21 '17 at 17:05
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    $\begingroup$ You'd want the net to be white, or close to. It's not as good for seeing through, but it's good for being able to see mosquitos against the light background, if they should get in. $\endgroup$ – Tim Kennedy Jan 22 '17 at 1:18
  • $\begingroup$ Could they have also developed a natural mosquito repellent as part of their physiology? $\endgroup$ – jpmc26 Jan 22 '17 at 2:21
  • $\begingroup$ This would be a significant change i human physiology, since our immune system woks that way, that it remembers the survived diseases, and protects against them, but insect repellent sweat will require evolution, and possibly larger timescale. $\endgroup$ – b.Lorenz Jan 22 '17 at 8:10
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The rainforest people probably noticed that that insects don't approach the leaves of a certain plant, so they would use it to make an oil that they use as repellent. Also, it may sound like a bit "Flinstone" but keeping chameleons or frogs in or around the hut so they eat the mosquitoes is not a far fetched idea. Cats were kept as pets because they hunted down the vermin.

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@b.Lorenz is absolutely correct with #3: Natural immunity gets the job done.

The Aztec civilization began to fall in the 16th century, in part due to massive epidemics. While some diseases may have been local, the popular belief is that most were introduced from overseas. The locals had been dealing with the native diseases (syphilis, lupus, tuberculosis) for thousands of years, and thus immunity was relatively widespread

While the diseases brought over by the Spanish (small pox, chicken pox, measles, mumps) may have proliferated, especially in near-tropical conditions, their effects were significantly worsened specifically because they were new.

The civilization will not be at risk if they don't develop technology to keep away disease - it really shouldn't be that bad. If worse comes to worst, nets should be fine.

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  • $\begingroup$ While that is applicable in the Americas, the premise of Africa by John Reader is that the disease burden in Tropical Africa was so high that it prevented development of the high populations densities that made agriculture relatively advantageous. Basically, he is saying that tropical African people were able to get to sub-tropical or temperate climates (Egypt, Mesopotamia, Indus, China) where diseases no longer affected them as much, and thus civilization began, but they couldn't thrive if they stayed in Africa. $\endgroup$ – kingledion Jan 21 '17 at 18:10
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    $\begingroup$ Whether this thesis is correct or not is debatable, but I'm postulating that acquired immunity is not sufficient by itself, and thus some technological developments are also needed. $\endgroup$ – kingledion Jan 21 '17 at 18:11
  • $\begingroup$ @kingledion Then it would help if you edited the question to describe one location. The phrase think the Peruvian Andes or African Rift mountains leaves it ambiguous as to exactly how large the threat is. $\endgroup$ – Zxyrra Jan 21 '17 at 19:07
  • $\begingroup$ One of the problems in tropical Africa is sleeping sickness, which kills the cows, and thus makes harder to produce food. But it is harder to protect animals than humans. $\endgroup$ – b.Lorenz Jan 22 '17 at 8:17
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I assume from the question text that there is no doubt to these people that it is the mosquitoes that spread the disease, without necessarily knowing how, other than having to be bitten by them. (I believe diseases began to be associated with mosquitoes in the mid XIX century and the first to be positively identified as mosquito-borne was nearing the end of that century, after microbiology started and the malaria parasites were discovered, so you might want to revise that, but that is beyond the question)

In addition to the very good b.Lorenz ideas:

Since they know about the mosquitoes, they might have begun to look into their life cycle, and realize that the easier way to get rid of them is taking them out at the larvae stage. You might want to have a tree species in some areas of the rain forest, with the properties of the Indian neem. Maybe they use the oil of the fruits and seeds much like they were used in India (cosmetics and traditional medicine), and accidentally discover the larvicidal property, or maybe they find out that water in the areas with those trees have less larvae and start looking into why that is. [ http://malariajournal.biomedcentral.com/articles/10.1186/1475-2875-8-124 ]

Complete draining of flood plains is certainly out of the question, but the rain forest takes care of maintaining good soil absorption. The problems would begin exactly with deforestation and agriculture, but a civilization that begun and developed all the way to Iron Age living in the forest and later the flood plains, and realizes the importance of eliminating mosquito breeding grounds, might start elevating the ground destined to crops and developing intricate drainage systems that will keep the water in motion, diminishing the amount of larvae greatly. This could be aided by trading with the other (drier) areas you mention, which could bring them equally or more efficient crops to the ones they used to grow on the unmodified flood plains, which need less soil moisture. Assuming they get the crops to survive the rains (through many generations of selective farming), they could even have a much greater yield than in the highlands and savanna, making them a population and trading superpower in the region... (sorry, got carried away).

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To expand on what others have already said. I have been to the Ecuadorian Amazon jungle, the natives there use the smoke from certain plants to shroud themselves and their houses from mosquitoes, which mostly rely on smell to find their targets.

I don't know if the smell actually bothers mosquitoes, or if it simply makes them ignore people, but it gets the job done.

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  • $\begingroup$ Do they fill their houses with smoke, or do they use the smoke outside the hosue or to to guard the entry-way? $\endgroup$ – kingledion Jan 24 '17 at 21:39
  • $\begingroup$ The burn the leaves inside their houses. According to what they told me, it's also useful for making sure spiders and other insects don't nest in their roofs which are made of dry leaves. $\endgroup$ – Miguel Bartelsman Jan 24 '17 at 22:02

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