Humanity on the Edge of Extinction | Anders Sandberg | TEDxVienna

[Music] my job is to think about the end of the world it's a great job there is so much to think about this lovely round lake is Lake Monaco gam in Quebec in Canada it's about 70 kilometers across and about 200 million years ago a rock the size of the Emma quite literally hit the earth that was not a good day to be around in Canada and of course if it had happened today it would have been an even worse day not just in Canada but worldwide it would have ignited fires hundreds of kilometres away and it would have lost a dust up into the stratosphere dust that would have remained for at least a few years probably about a decade which would have made it hard to grow any crops worldwide we would be starving it would definitely not be good if that happened and of course there 884 known objects orbiting roughly around the Earth's orbit about this size or larger none of them known to be on a collision course but given time one of them is going to hit however it happens rather rarely probably chance that once every ten million years or so so the chances for tomorrow are pretty good back in 1918 the soldiers coming back home from the first world war were carrying something else with them home influenza the 1918 influenza was one of the worst pandemics we ever seen the virus which was probably in transmitted from birds into a navvy human influenza genome it killed 50 to 100 million people that's more than the humans actually killed during the war it would probably not have happened with us us human having a war weakening our immune defenses starving many people and then using modern railway transport to bring people around and of course the real problem is demyx are still happening the Black Plague might be in the far past but we had some close calls with SARS and Ebola and there might be other things happening because of our bio technological skills we are able to construct new influenza viruses and people actually for research purpose I have made pandemic influenza in the lab and let's just hope we can keep it in the lab and that nobody with a bio lab at home thinks hey I can do that too that would not be good and that would harm us robbery the strongly another bad thing which I'm fortunate in the news I grew up in the 1980s when it was not uncommon to lie in bed at the evening the night of thinking the missiles might be in the air tonight and every other pop song on the top charts we're about nuclear war then 1991 arrived the Berlin Wall fell and everybody forgot about the missile missiles in their silos which might be a bit of a mistake because many of them are still there and the world governance is not exactly looking that stable again the threat here is not so much the direct effect of nuclear weapons horrific as we might be but rather the effect that happens when you get the suit from burning cities getting up in the stratosphere causing a nuclear winter similar to an asteroid winter in simulations it looks like again for a few years you can't do agriculture in the northern hemisphere we would starve this kind of lovely in the scenarios is what I deal with every day and generally existential risk threat to our entire future and global catastrophic risk nearly threat to much of the world are really on the researched there is more research and dung beetle reproduction than about human extinction and although I do like beetles I collect beetles I think it shows that our priorities might be slightly wrong indeed we humans are probably much more dangerous to ourselves the nature is and we need to deal with this better the good news is many of these risks might actually be fixable and we might increase our resiliency today I'm going to talk about one little question that sometimes come up many of these disaster sinners are unlikely to kill everybody somebody's going to be holed up inside a big warehouse and with a can opener and the containers full of ravioli they are going to survive just fine Tasmania might be a rather nice place in the case of a nuclear war I'm in northern hemisphere and some Preppers of course thinking but they need to just stock up on guns and the toilet paper and the ravioli cans and hide in a cave in the mountains somewhere and then they can take over world afterwards the question is how many survivors would we actually need in order to repopulate the world if something went really bad ecologists care a lot about this they call it minimum viable population and it's a big thing in conservation biology we want to understand how many pandas or Tigers or other endangered animals do we need to have in our reservation in order to be fairly certain they are not going to die out so ecologists are doing simulations we're using software like the vortex 10 I got on my slide in order to calculate how many individuals are needed maybe we even need to move them into captivity in order to breed more of them because they can't survive on their own and the biggest problem when you have a really small population is that you might run out of luck the next generation if you have Ravi for a few individual individuals might have many more males than females which means that the effective breeding population is much smaller you might be unlucky with the weather climatic or environmental fluctuations might hit you you might lose genetic diversity which means that inbreeding is a problem and of course nudist sources might happen once a species has a small population because much more vulnerable and if then it can start circling the drain hence the name vortex for that software so what is human minimum viable population it's interesting there isn't a number in the literature we actually don't know I don't believe that the Adam and Eve is a viable minimum population that happened with a bit of divine intervention in the past we know that hunter-gatherer bands have numbered in about a hundred people but it's unclear whether in just a small band of hunter-gatherers could actually colonize the world in ecology if you ask ecologist in general if you have a large mammal breathing Rob is slowly it needs a lot of food how many individuals would we need to preserve they would say well five thousand give or take this is kind of a standard guess but it's extremely uncertain for smaller animals that breed faster you can actually get away with much smaller populations but some animals need a lot more so what can we do to figure out how many humans we need to really sell keep safe in the case of a huge disaster one way is of course to try to look at history so we know north and south america was colonized by rober small population we know that because they underwent a genetic bottleneck about ten thousand years ago or a bit before that depending on which archaeological field you like people moved over mariya then a land between Alaska and Siberia which at the time was dry land and a small pack of humans got down there and it seems that it might have been as few as 70 people in the individual and population this is controversial but it sort of seems that it was a very small group so maybe the answer is 70 people not so fast there might have been a lot of groups of people trying to move or at least moving around the following in the game and fishing and some of them succeeded the last one all the previous one had failed may might have been much large groups but they went extinct with no an archaeological evidence but one small group were successful filled the prairies of North America went across Panama went down into South America and eventually became all the Native American people so we can't use that number really well another interesting number is actually from South America we're in a very have been number of small tribes that have been contacted by civilization this has generally not been good for them typically the population has collapsed very strongly off during countering civilization not just because civilized people are nasty but because we have a lot of diseases we have been spreading around the world that many of these smaller populations don't have any defense against that means that we suffered tremendous kept disastrous collapse and then they many of them start to recover not all of them but this gives us another number of how many people in that survive the first collapse in a tribe or need that in order to actually recover and in this data it suggests it's about 108 people of course it's much better if more of people survive it's even better if they have a large population increase if modern health care had really helped some things move up so this gives us another kind of evidence we can of course look into totally different approaches some of my friends in the space movement or really can't wait to get away from his dangerous planet they really want to settle Mars or maybe even go further away so how many people should you put on your space org and there is a number of simulations and models of literature more if they believed that well for a 200 year mission to the Stars where you have several generations living on your starship you need about 150 people Smith said no you need 40,000 it better be a big spaceship a more recent paper Mari and argued that yeah actually you want to avoid overcrowding because even a large spaceship gets Rover overcrowded if people have too many kids and also you don't want to start out to known as small because you get a lot of inbreeding he believed 14,000 it was necessary which is a large spacecraft now in this more science fictional scenario we can also be think about all sorts of high-tech assumptions actually doing sex selection so during most of the tree trip it's mostly females and using an insemination in order to get genetic diversity that might actually make the population much more stable I did my own work because I was not entirely happy with this so I did my kind of same apocalypse not as good graphics as the modern narasimha games but quite an interesting topic so I simulated small scientists and I tried to simulate what happens if you do you agriculture society hunter-gatherers high-tech societies I quickly found out that a lot of data me literature about the owner paleo demography what how many people could live at the impasse society was actually wrong not because our key role is are stupid but because we're not too keen on math and as my colleague andreas during demonstrating in speech need this situation there are formulas you can use when you find the ages of bones in a cemetery and calculate what was the population structure what was the birth rate and death rate at different ages and these formulas work really well as long as the population stays stable this is in the classical papers by the mathematicians who worked it out and nobody really reads those boring footnotes about applicability so many workers will just assume me but yeah populations were stable but small populations whether there are survivors in a post-apocalyptic world or a small crew in a spaceship or the people living in the early medieval South Germany they are fluctuating going up and down a lot the population you find in the cemetery are generally much sicker than the population living in the village next door and if the village is growing you're not going to find a lot of young people so I needed to take that into account there are also all sorts of modeling complications like what is the interval that women can give birth to how do we organize the families because we generally want to avoid incest who are we starting people are their average population from Earth right now or we selected to be really useful so one can complicate this endlessly which I have of course in my academic papers but the good news is the ecology seem to be roughly right if you want a 90 percent certainty that the initial population will survive and thrive a thousand years later five thousand people is enough this is much more than you can get into your nuclear bunker it's a small town or maybe a bigger aircraft carrier but the small town is probably more likely to function really well obviously if after the disaster people also have a lot kids and they survived really well it works better another important thing here is that it might be useful to split into smaller groups partially because we don't get along with two large groups even five thousand people and they are hard to deal with but it's also safer because there might still be a epidemics or allergy sources around so if one smaller group and the fails others can take over but they need to stay in touch a so called meta population is much more stable now looking back given all this what should we be doing well first of all I think we should just get to know our neighbors how many of us do you know the names of all our neighbors and what we do we might want to hug them we want to be on friendly terms with them maybe not too friendly depending on who they are but the point is in most disasters people are saved medically by their neighbors and in a crisis they can really save you besides also storing up on non-perishable food which is good idea anyway if there is a small disaster we might also want him to actually work hard on our memory not just store all our information on DNA which might last very long time but also in some solid books that you can read without electricity small populations have a hard time written in the technology civil society in general is amazingly resilient and that's where we should start rather than getting a gun rack in the cave and we want to work on boosting our resilience as a society and avoid the threats because many of these frets like nuclear war or in an artificial panic are probably avoidable in other way since better to avoid them that way than having a survival publish and finally my job might be to research these things but it's your job everybody's job to save humanity and our civilization thank you [Applause]

Channel: TEDx Talks

Views: 135,797

Rating: 4.6933866 out of 5

Keywords: TEDxTalks, English, Global Issues, Deextinction, Disaster relief, Population

Id: O-WXOaAnipM

Length: 15min 28sec (928 seconds)

Published: Thu Dec 14 2017

Reddit Comments

[u/peoplesodumb]

Good riddance.