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# Figure Out Where You Are With Nothing But a Watch and Protractor –

In a recent episode of MacGyver, Angus (yes, that’s his first name) finds his location in the desert using only a string, a protractor, and a watch. Is this actually possible? Basically, yes. (At least that’s what I told the show-runners as the technical consultant for the show.)

But you can do this, too. So now, for your super basic introduction to navigating the world. And don’t worry—this won’t be a full blown semester course on navigation, it’s just the basics.

### Longitude

If you want to find out where you are on Earth, you need some type of coordinate system. Humans like to use longitude and latitude. You need to understand these in order to actually navigate. Both longitude and latitude can be thought of as circles (but not actual circles). Let me start with a basketball as an example. It already has some lines on it, so I just need to add some extra to make it look like this.

The lines that are already on the basketball are like lines of longitude. They all cross through the top (North pole) and bottom (South pole) of the basketball. This means that all these lines of longitude form circles that have the same radius—the radius of the Earth. Longitude is basically a way of breaking the sphere into 360 degrees. However, we don’t measure longitude all the way to 360°. Instead we have 0 to 180° East and 0 to 180° West. The 0° value is in Greenwich, England, and as you move West you would be increasing in longitude West.

OK, but how do you measure longitude? This is where a clock comes in handy. Yes, a clock. To understand this measurement, you need to know two things: The Earth is spherical (mostly spherical, offer not valid in all US States) and the Earth rotates so that it appears the sun travels around the whole sky every 24 hours (again, not exactly true, but close enough).

Now suppose you are in Greenwich (where longitude is 0°). At some time during the day, the sun will be at its highest position in the sky (which will not be directly overhead). We can call this 12:00 noon. If you are in Greenwich, you can set your clock to the sun. Now your clock also says 12:00 noon. Next, you travel westward all the way to New Orleans (since it’s close to where I live). You repeat the same experiment by waiting until the sun is at the highest point. But wait. Your clock doesn’t say 12:00 noon, it says 6:00 AM since it’s still set on Greenwich time. Since the Earth is spherical, the sun is at its highest point in Greenwich, but maybe it hasn’t even risen in New Orleans.

In fact, if you know the difference in time between Greenwich noon (what your clock says) and local noon (when the sun is at the highest point), you can find your longitude. This time difference is essentially your longitude. You just need to convert from hours to degrees (which I will skip). But notice how important it is to have a clock to determine your longitude. Really, there is no way around it—that’s why the Longitude Act of 1714 was so important. It established a prize for the development of an accurate and portable clock. OK, technically the prize was for a method to determine longitude—but really, a clock of some type is the only practical solution (unless you have GPS).

But wait! What if you want to navigate at night when you can’t see the sun? Yes, this method can still work. However, you need to know something extra. If you know the time a star rises (or the moon, or a planet) with respect to the time it would rise in Greenwich then you are all set. It’s the same idea as using the sun at noon. Of course. the problem with this method is that most people don’t memorize the rise-times of different celestial objects.

### Measuring Lattitude

The lines of latitude also make circles around the Earth. However, they don’t all pass through the same points like the longitude values do. Instead, these are circles that are all parallel to the equator. If you look at my basketball above, the horizontal lines would be lines of latitude. Yes, I had to draw this on the ball.

Latitude is also measured in degrees but it starts at the equator which would be zero degrees latitude. As you move away from the equator (North or South), you increase your latitude degree such that New Orleans would be about 30°N. If you go to Sydney, Australia, you would have a latitude of 33.8°S since it is 33.8° below the equator.

OK, but how do you determine your latitude? This one is pretty straight forward—especially if you are in the Northern hemisphere. In short, you just need to measure the angular height of the North Star (Polaris) above the horizon. This works because the North Star is almost directly in line with the Earth’s axis of rotation. So, if you were at the North pole (and hopefully on ice), the North Star would be directly overhead with an angle of 90° above the horizon. If you traveled to the equator, the North Star would be exactly on the horizon and you would be at 0° latitude.

What about the Southern hemisphere? Yeah, that’s a small problem. Unlike the Northern hemisphere there isn’t a star right on the axis of rotation. Instead you just have to approximate the location of the celestial South pole by looking at other constellations.

Finally, how do you get this angular height of the North Star? That’s where the protractor comes in play. Here’s what you do. Take a string with a weight to act as a plumb bob. Now hold the protractor upside down and aim the straight part towards the North Star. Boom. That’s it. The plumb bob will hang at the angle reading for your latitude. Now you aren’t lost.

Note that with my DIY sextant (and most others), the string would point to a value on the protractor that is not the angle above the horizon. Actually, you would have to take your angle measurement and subtract from 90° to get your latitude. Also, there is a straw on top of my protractor to assist with the aiming—and it looks cool.

Of course both of these methods work, but the key is precision. For latitude, just a 1° difference in measurement means a distance of 69.1 miles or 60 nautical miles. In fact, the nautical mile is defined by the size of 1 minute of a latitude (where there are 60 minutes in 1 degree). This means that the better your angle measurement, the better you will know your actual location. Sure, a protractor works, but a sextant does this even better. A sextant is essentially just a much better protractor.

That’s it. That’s the basics of finding out where you are on Earth. But there are many other cool and fun details; if you want to learn more, I can recommend this nice online course from Vanderbilt University—AstroNavigation (it’s free).

Read More On This At Science Latest

# The world’s oceans are under attack from man-made disasters

The mass death of marine animals in the Avacha Bay in Kamchatka was due to toxic algae, according to experts of the Russian Academy of Sciences. But there are also signs of technical pollution – increased concentrations of oil products and heavy metals in water. After natural disasters, the ocean recovers itself. And what are technogenic fraught with?

For most of its history, humanity has been more consumerist about the ocean. Only in recent decades has a new understanding begun to form: the ocean is not just a resource, but also the heart of the entire planet. Its beating is felt everywhere and in everything. Currents affect the climate, bringing cold or heat with them. Water evaporates from the surface to form clouds. The blue-green algae that live in the ocean produce virtually all the oxygen on the planet.

Today we are more sensitive to reports of environmental disasters. The sight of oil spills, dead animals and garbage islands is shocking. Each time the image of the “dying ocean” is strengthened. But if we turn to facts, not pictures, how destructive are industrial accidents on big water?

## Annushka has already spilled … oil

Of all oil product pollution, the majority is associated with everyday leaks. Accidents account for a small part – only 6%, and their number is decreasing. In the 1970s, countries introduced stringent requirements for tanker ships and restrictions on shipping locations. The world tanker fleet is also gradually being renewed. New vessels are equipped with a double hull to protect against holes, as well as satellite navigation to avoid shoals.

The situation with accidents on drilling platforms is more complicated. According to Peter Burgherr, an expert in assessing technological risks at the Paul Scherrer Institute, the risks will only increase:

“This is connected, firstly, with the deepening of wells, and secondly, with the expansion of production in areas with extreme conditions – for example, in the Arctic “. Restrictions on deep-sea drilling offshore have been adopted, for example, in the USA, but big business is struggling with them.

Why are spills dangerous? First of all, the mass death of life. On the high seas and oceans, oil can quickly take over vast areas. So, only 100-200 liters cover a square kilometer of the water area. And during the disaster on the Deepwater Horizon drilling platform in the Gulf of Mexico, 180 thousand square meters were contaminated. km – an area comparable to the territory of Belarus (207 thousand).

Since oil is lighter than water, it remains on the surface as a continuous film. Imagine a plastic bag over your head. Despite the small thickness of the walls, they do not allow air to pass through, and a person may suffocate. The oil film works the same way. As a result, “dead zones” can form – oxygen-poor areas where life is nearly extinct.

The consequences of such disasters can be direct – for example, contact of oil with the eyes of animals makes it difficult to navigate normally in the water – and delayed. Delayed ones include DNA damage, impaired protein production, hormone imbalances, damage to immune cells, and inflammation. The result is stunted growth, reduced fitness and fertility, and increased mortality.

The amount of oil spilled is not always proportional to the damage it causes. Much depends on the conditions. Even a small spill, if it fell during the fish breeding season and happened in the spawning area, can harm more than a large one – but outside the breeding season. In warm seas, the consequences of spills are eliminated faster than in cold ones due to the speed of the processes.

Accident elimination begins with localization – for this, special restrictive booms are used. These are floating barriers, 50-100 cm high, made of special fabric that is resistant to toxic effects. Then comes the turn of water “vacuum cleaners” – skimmers. They create a vacuum that sucks the oil film along with the water. This is the safest method, but its main disadvantage is that collectors are only effective for small spills. Up to 80% of all oil remains in the water.

Since oil burns well, it seems logical to set it on fire. This method is considered the easiest. Usually the spot is set on fire from a helicopter or ship. Under favorable conditions (thick film, weak wind, high content of light fractions), it is possible to destroy up to 80–90% of all pollution.

But this should be done as quickly as possible – then the oil forms a mixture with water (emulsion) and burns poorly. In addition, combustion itself transfers pollution from water to air. According to Alexei Knizhnikov, head of the environmental responsibility program for WWF-Russia business, this option carries more risks.

The same applies to the use of dispersants – substances that bind oil products and then sink into the water column. This is a fairly popular method that is used regularly in case of large-scale spills, when the task is to prevent oil from reaching the coast. However, dispersants are toxic by themselves. Scientists estimate that their mixture with oil becomes 52 times more toxic than oil alone.

There is no 100% effective and safe way to collect or destroy spilled oil. But the good news is that petroleum products are organic and are gradually decomposed by bacteria. And thanks to the processes of microevolution in the places of the spill, there are more precisely those organisms that are best at coping with this task. For example, after the Deepwater Horizon disaster, scientists discovered a sharp increase in the number of gamma-proteobacteria, which accelerate the decay of oil products.

## Not the most peaceful atom

Another part of oceanic disasters is associated with radiation. With the onset of the “atomic age,” the ocean has become a convenient testing ground. Since the mid-forties, more than 250 nuclear bombs have been detonated on the high seas. Most, by the way, are organized not by the two main rivals in the arms race, but by France – in French Polynesia. In second place is the United States with a site in the Central Pacific Ocean.

After the final test ban in 1996, accidents at nuclear power plants and emissions from nuclear waste processing plants became the main sources of radiation entering the ocean. For example, after the Chernobyl accident, the Baltic Sea was in first place in the world in terms of the concentration of cesium-137 and in third place in terms of the concentration of strontium-90.

Although precipitation fell over land, a significant part of it fell into the seas with rain and river water. In 2011, during the accident at the Fukushima-1 nuclear power plant, a significant amount of cesium-137 and strontium-90 was released from the destroyed reactor. By the end of 2014, the isotopes of cesium-137 had spread throughout the Northwest Pacific.

Most of the radioactive elements are metals (including cesium, strontium, and plutonium). They do not dissolve in water, but remain in it until the half-life occurs. It is different for different isotopes: for example, for iodine-131 it is only eight days, for strontium-90 and cesium-137 – three decades, and for plutonium-239 – more than 24 thousand years.

The most dangerous isotopes of cesium, plutonium, strontium and iodine. They accumulate in the tissues of living organisms, creating a danger of radiation sickness and oncology. For example, cesium-137 is responsible for most of the radiation received by humans during trials and accidents.

This all sounds very disturbing. But now there is a tendency in the scientific world to revise early fears about radiation hazards. For example, according to researchers at Columbia University, in 2019, the plutonium content in parts of the Marshall Islands was 1,000 times higher than that in samples near the Chernobyl nuclear power plant.

But despite this high concentration, there is no evidence of significant health effects that would prevent us from, say, eating Pacific seafood. In general, the influence of technogenic radionuclides on nature is insignificant.

More than nine years have passed since the accident at Fukushima-1. Today, the main question that worries specialists is what to do with radioactive water, which was used to cool fuel in destroyed power units. By 2017, most of the water had been sealed off in huge cisterns onshore. In this case, groundwater that comes into contact with the contaminated zone is also contaminated. It is collected using pumps and drainage wells and then purified with carbon-based absorbents.

But one element still does not lend itself to such cleaning – it is tritium, and around it most of the copies break today. The reserves of water storage space on the territory of the nuclear power plant will be exhausted by the summer of 2022. Experts are considering several options for what to do with this water: evaporate into the atmosphere, bury or dump into the ocean. The latter option is today recognized as the most justified – both technologically and in terms of consequences for nature.

On the one hand, the effect of tritium on the body is still poorly understood. Which concentration is considered safe, no one knows for sure. For example, in Australia the standards for its content in drinking water are 740 Bq / l, and in the USA – 76 Bq / l. On the other hand, tritium poses a threat to human health only in very large doses. Its half-life from the body is from 7 to 14 days. It is almost impossible to get a significant dose during this time.

Another problem, which some experts consider a ticking time bomb, are barrels of nuclear fuel waste buried mainly in the North Atlantic, most of which are located north of Russia or off the coast of Western Europe. Time and sea water “eat up” the metal, and in the future, pollution may increase, says Vladimir Reshetov, associate professor of the Moscow Engineering Physics Institute. In addition, water from spent fuel storage pools and waste from nuclear fuel reprocessing can be discharged into wastewater and from there into the ocean.

## Time bomb

Chemical industries pose a great threat to communities of aquatic life. Metals such as mercury, lead and cadmium are especially dangerous for them. Due to strong ocean currents, they can be carried over long distances and not settle to the bottom for a long time. And off the coast, where the factories are located, infection primarily affects benthic organisms. They become food for small fish, and those for larger ones. It is the large predatory fish (tuna or halibut) that get to our table that are most infected.

In 1956, doctors in the Japanese city of Minamata faced a strange illness in a girl named Kumiko Matsunaga. She began to haunt sudden seizures, difficulties with movement and speech. A couple of days later, her sister was admitted to the hospital with the same symptoms. Then polls revealed several more similar cases. The animals in the city also behaved in a similar manner. Ravens fell from the sky, and algae began to disappear near the shore.

The authorities formed the “Strange Disease Committee”, which discovered a trait common to all infected: the consumption of local seafood. The plant of the Chisso company, which specialized in the production of fertilizers, fell under suspicion. But the reason was not immediately established.

Only two years later, the British neurologist Douglas McElpine, who worked a lot with mercury poisoning, found out that the cause was mercury compounds that were dumped into the water of Minamata Bay more than 30 years since the start of production.

Bottom microorganisms converted mercury sulfate into organic methylmercury, which ended up in fish meat and oysters along the food chain. Methylmercury readily penetrated cell membranes, causing oxidative stress and disrupting neuronal function. This resulted in irreversible damage. The fish themselves are better protected from the effects of mercury than mammals due to the higher content of antioxidants in the tissues.

By 1977, authorities counted 2,800 victims of Minamata Disease, including cases of congenital fetal abnormalities. The main consequence of this tragedy was the signing of the Minamata Convention on Mercury, which banned the production, export and import of several different types of mercury-containing products, including lamps, thermometers and pressure measuring instruments.

However, this is not enough. Large amounts of mercury are emitted from coal-fired power plants, industrial boilers and home stoves. Scientists estimate that the concentration of heavy metals in the ocean has tripled since the start of the industrial revolution. In order to become relatively harmless to most animals, metallic impurities must travel deeper. However, this could take decades, scientists warn.

Now the main way to deal with such pollution is high-quality cleaning systems at enterprises. Mercury emissions from coal-fired power plants can be reduced by using chemical filters. In developed countries this is becoming the norm, but many third world countries cannot afford it. Another source of metal is sewage. But here, too, everything depends on money for cleaning systems, which many developing countries do not have.

## Whose responsibility?

The state of the ocean is much better today than it was 50 years ago. Then, at the initiative of the UN, many important international agreements were signed that regulate the use of the resources of the World Ocean, oil production and toxic industries. Perhaps the most famous in this row is the UN Convention on the Law of the Sea, signed in 1982 by most countries in the world.

There are also conventions on certain issues: on the prevention of marine pollution by dumping of wastes and other materials (1972), on the establishment of an international fund to compensate for damage from oil pollution (1971 and and harmful substances (1996) and others.

Individual countries also have their own restrictions. For example, France has passed a law strictly regulating the discharge of water for factories and plants. The French coastline is patrolled by helicopters to control tanker discharges. In Sweden, tanker tanks are labeled with special isotopes, so scientists analyzing oil spills can always determine which ship was discharged from. In the United States, a moratorium on deep sea drilling was recently extended to 2022.

On the other hand, decisions made at the macro level are not always respected by specific countries. There is always an opportunity to save money on protective and filtering systems. For example, the recent accident at the CHPP-3 in Norilsk with the discharge of fuel to the river, according to one version, occurred for this reason.

The company did not have equipment to detect subsidence, which led to a crack in the fuel tank. And in 2011, the White House Commission to investigate the causes of the accident on the Deepwater Horizon platform concluded that the tragedy was caused by the policy of BP and its partners to reduce security costs.

According to Konstantin Zgurovsky, Senior Advisor to the WWF-Russia Sustainable Marine Fisheries Program, a strategic environmental assessment system is needed to prevent disasters. Such a measure is provided for by the Convention on Environmental Impact Assessment in a Transboundary Context, which has been signed by many states, including the countries of the former USSR – but not Russia.

“The signing and use of SEA allows in advance, before the start of work, to assess the long-term consequences of a project, which makes it possible not only to reduce the risk of environmental disasters, but also to avoid unnecessary costs for projects that can be potentially dangerous to nature and humans.”

Another problem that Anna Makarova, Associate Professor of the UNESCO Chair “Green Chemistry for Sustainable Development” draws attention to, is the lack of monitoring of waste burials and mothballed industries. “In the 90s, many went bankrupt and quit production. Already 20-30 years have passed, and these systems began to simply collapse.

Abandoned production facilities, abandoned warehouses. There is no owner. Who is watching this? ” According to the expert, disaster prevention is largely a matter of managerial decisions: “The response time is critical. We need a clear protocol of measures: which services interact, where the funding comes from, where and by whom the samples are analyzed. “

The scientific challenges are related to climate change. When ice melts in one place, and storms begin in another, the ocean can behave unpredictably. For example, one of the versions of the mass death of animals in Kamchatka is an outbreak of the number of toxic microalgae, which is associated with climate warming. All this has to be studied and modeled.

So far, the ocean has enough resources to heal their “wounds” on their own. But one day he may present an invoice to us.

# Scientists told what the food of the future will look like

Danish scientists suggest that in the future, meat will be replaced by more healthy and environmentally friendly seafood – algae, shellfish and tiny fish. The research results are published in the journal Frontiers in Psychology.

Beef farming does not fit well with the concept of sustainable development adopted in Western countries. At the same time, not all people are ready to give up meat in order to preserve the climate.

Researchers from the University of Copenhagen studied consumer behavior in food choices and made a prediction of how it can be influenced and how to replace meat in the European food basket.

It is known that meat products have a special meat flavor, which the Japanese call umami. This taste is created by monosodium glutamate, and the human tongue has special L-glutamate receptors that pick it up. Product manufacturers make good use of this – monosodium glutamate is included in food additives of the E600 – E699 group.

At the same time, umami is present in the taste of some plant foods – walnuts, broccoli, tomatoes, shiitake mushrooms.

“A lot of people just crave the taste of their minds,” the study leader, Professor Ole G. Mouritsen of the Department of Food Science and Consumer Behavior, quoted a press release from the University of Copenhagen. a small amount of animal products such as meat, eggs and milk, along with vegetables. However, alternatives to juicy steak could be considered, of which there are many.”

The authors suggest looking for alternative sources of protein and healthy fatty acids among seafood, especially those with huge renewable reserves, but still not fully exploited. The researchers estimate that only sprat can meet 20 percent of Denmark ‘s protein needs.

“And sprat fishing will help avoid the over-exploitation of more well-known fish species such as cod, flounder and salmon,” explains the professor.

In addition to the sprat, there are many small benthic species of fish – gerbils, gobi, which can serve as a source of protein, as well as seaweed and cephalopods.

Scientists note that today, out of ten thousand types of algae, only 500 are used as food, despite the fact that they are incredibly rich in beneficial nutrients and vitamins. The picture is the same for cephalopods – about 30 out of 800 species are used for food in the world.

“It has a lot to do with our culture and traditions,” says Mouritsen. “It takes time to change our eating habits. We’ve eaten and cooked meat for over a million years. So while seaweed, squid and shellfish contain important fatty acids and vitamins and taste great, we are still reluctant to classify these species as food sources.”

The authors believe food technology, which has long used the two main flavors, sweet and meat, in food flavorings, will help make seafood more attractive.

“Sweetness signals the brain for calories and survival, while umami signals that we are consuming something good for the muscles. However, many seafood, seaweed and vegetables have their own great taste,” the scientist notes.

In particular, according to researchers, many vegetables develop a sweet and umami flavor during fermentation – this can be used to develop a rational diet for the future.

# Modern tribes living in isolation from civilization

On July 1, 2014, seven members of the Amazon tribe emerged from the jungle and made their first contact with the rest of the world. This was due to a terrible and tragic necessity. Despite 600 years of Portuguese-Brazilian history, this tribe emerged only to mend relationships with its new neighbors.

According to Survival International, there are still about 100 so-called non-contact peoples in the world, although their real number is probably higher. Sources of these figures include observations from aircraft flying over isolated areas and reports of people living in the vicinity in contact with the natives.

In fact, “non-contact” is a bit of a misnomer, as it is likely that even the most isolated tribe in the world interacted with outsiders in some way, whether face-to-face or through tribal trade. However, these peoples are not integrated into the global civilization and retain their own customs and culture.

## Non-contact people

In general, non-contact tribes show no interest in communicating with the outside world. One of the possible reasons for this behavior is fear. At the same time, the researchers note that non-contact peoples are excellently oriented in the forests and are well aware of the presence of strangers.

The reasons why a group of people might want to remain isolated can vary, but in many cases they just want to be left alone. Anthropologist Robert S. Walker of the University of Missouri (USA) also considers fear to be the main reason why non-contact tribes do not get in touch with civilization.

In today’s world, tribal isolation can be romanticized as opposing the forces of globalization and capitalism, but as Kim Hill, an anthropologist at Arizona State University, says, “There is no group of people who are voluntarily isolated because they think it’s cool not to have contact. with no one else on the planet. “

## Is it worth being friends?

Technically speaking, most of these tribes had contact with the outside world in one way or another. The so-called “most isolated tribe in the world” first established contact with civilized society in the late 1800s, although they have since preferred to keep apart.

In Brazil, over the Amazon forests are regularly flown over wooded areas where tribal tribes live, not only out of anthropological curiosity, but also to ensure that illegal deforestation does not occur, as well as to confirm the survival of wildlife after natural disasters.

Tribes have the right to self-determination and the land on which they live. Since the arrival of strangers would radically change their way of life, and they clearly would not want it, it is believed that it is best for the outside world to stay away, and the peoples could determine their own future.

Historically, the affairs of the tribes with which we contacted did not work out right after the meeting. The reason is isolation – they simply lack immunity to many common diseases.

Moreover, there is a documented history of the first contacts that led to epidemics. Today, researchers are urging not to come into contact with tribal peoples due to the Covid-19 pandemic. According to National Geographic, the coronavirus is getting closer and closer to the Amazon tribes.

However, some anthropologists believe that isolated populations are not viable in the long term “and” well-organized contacts are today humane and ethical. The fact is that there are many cases when, soon after peaceful contact with the outside world, the surviving indigenous peoples quickly recovered from demographic disasters. It should be noted that this argument is rejected by most indigenous rights advocates and is somewhat lacking in evidence.

## Sentinelese

“The most isolated tribe in the world” lives in the Andaman Islands off the coast of India. Having come into contact with civilization in the 19th century, the tribe has since remained isolated and hostile to outsiders – the last official attempt to establish contact was made in 1996.

All further attempts to establish contact were not made, not only to protect the tribe from disease, but also because the natives tend to shoot arrows at anyone who comes too close. In 2018, American missionary John Chu decided to bring the word of God to the Sentinelians. However, the Tuzenians did not like his visit and they shot him.

Today, this non-contact people remain a hunter-gatherer society that does not know agriculture. They have metal tools, but they can only make them from iron, which is extracted from nearby shipwrecks.

This tribe has remained isolated for so long that the languages ​​of neighboring tribes are incomprehensible to them, and the language of their own tribe remains unclassified. Scientists believe that the world’s most uncontacted tribe has existed in isolation for several hundred, if not thousands of years.

## Javara tribe

The Javara tribe is another isolated people in India, also living in the Andaman Islands. They are a self-sustaining hunter-gatherer society and are reportedly quite happy and healthy.

In the early nineties, the local government presented a plan to introduce the tribe into the modern world, but recently it was decided to abandon it, even though recently there has been more communication between Jaravasi and outsiders due to the increase in settlements near their villages.

In 1998, members of the tribe began visiting the outside world. This contact caused two outbreaks of measles in a tribe whose inhabitants did not have immunity to it. The tribe is also increasingly being visited by lost tourists and new settlements nearby.

## Vale do Javari

The Javari Valley in Brazil is an area the size of Austria and is home to about 20 indigenous tribes. 2000 people out of 3000 living there are considered “non-contact”. There is very little information about these tribes, but researchers know that the natives use agriculture along with hunting, and also make metal tools and pots.

In the 1970s and 1980s, the Brazilian government pursued a policy of establishing contacts with isolated tribes, but this was put to an end by the history of the Mathis tribe from the region. As a result of the diseases to which they were subjected, three of the five villages of the tribe were wiped off the face of the earth, and their population declined sharply. Today, the threat to these isolated tribal peoples comes from miners and lumberjacks.

## New Guinea

There is very little information about these isolated peoples, as the Indonesian government has done a good job of keeping people out of the highlands. However, some tribes have come into contact with the civilized world over the past century, while remaining rather isolated and retaining their traditions.

One of the most striking examples is the Dani people and their history. Located in the heart of Indonesian New Guinea, the tribe is in contact with the outside world, but retains its customs. This people is known for amputation of fingers, in memory of already dead comrades, they also widely use body paint. Although Dani has been in contact with the rest of the world since 1938, they give researchers an insight into the people we have yet to meet.

## Congo

Over the past century, contact with many of the Congo’s forest peoples has been infrequent. However, it is assumed that many isolated tribes still exist. The Mbuti, or “pygmies,” are a contiguous but isolated people who can give us an idea of ​​how other, unknown to scientists, non-contact tribes can live.

Mbuti are hunter-gatherers who perceive the forest as the parent that provides them with everything they need. They live in small, egalitarian villages and are mostly self-sufficient, but they trade with outside groups. Today their lifestyles are threatened by deforestation, illegal mining and genocide against the pygmies.