How Bad Was The Younger Dryas? Causes-Megafauna-Civilization

all right let's do this hopefully it's not too windy hopefully you can hear me guys how's it going pretty special backdrop huh Mount Hood look at the lengths I go to for a video incredible humans have lived through some pretty cold times and one of the coldest was definitely a period we call the Younger Dryas it didn't last very long just about 1,000 years but it started really abruptly and it ended really abruptly now the typical YouTube video on this subject is basically pseudo archaeological bollocks in my opinion wild unfounded claims unsourced videos tales of pyramid-building globe-spanning ancient civilizations that were wiped out in the Cataclysm to end all cataclysms and these evil archaeologists are just trying to keep it secret to protect their precious theses and $50,000 a year annual salary you tell from their contempt in my voice I think that's pure nonsense and the reality is that it's one of the most widely researched areas in the Paleolithic so I'm gonna today try my best to present the latest thinking on the subject we're going to talk about what caused it did it kill the megafauna how did humans react and then wrap it all up with a discussion of how bad was it really just a couple of caveats all sources are in the description you can check them out just look at the little number there's no secrets here no conspiracy and bear in mind I'll protect my microphone from the wind bear in mind that I'm no expert I don't pretend to be an expert I'm just a guy sitting on a rock with a wicked hat and nothing better to do with my time so take everything I say with a pinch of salt and by all means double-check what I say read the sources that's all highly encouraged so without further ado let's talk about the Younger Dryas [Music] so before I start it's worth quickly covering what was the Younger Dryas because I'm aware not everyone spends as much time on the internet as I do before the Younger Dryas life was on the up and up the height of the last ice age had ended about 8,000 years before and the Paleolithic inhabitants of the Northern Hemisphere were living through a 2,000 year warm period we call the bowling alley at Inter Stadium then out of nowhere things started to change between roughly twelve point nine and eleven point seven thousand years ago the climate of the northern hemisphere suddenly started becoming colder and drier to give you an example of how much Europe declined in temperature between two to six degrees C depending on how far north you go glaciers that had been melting after the end of the last ice age began to advance once again this temperature change may have occurred in just a few decades so that's really super quick in earth terms certainly a chilly time to be alive no doubt about that however it wasn't all doom and gloom recent evidence has shown that despite the overall decline in temperature summers still would have been short but warm you could sort of compare it to modern places that have very continental climates like Russia no doubt bloody cold in the winter but punctuated by very warm summer's these temperature changes largely affected the northern hemisphere in the southern hemisphere the picture is a tad more complex in Venezuela the climate cooled by around three degrees but in the Caribbean southern Africa Antarctica Australia and New Zealand the climate seems to have stayed about the same or even warmed slightly in a study of Australia's climate in the last thirty-five thousand years there was no evidence for cooling during the Younger Dryas and conditions may even have been wetter rather than drier so that gives you an idea of what the Younger Dryas was now why would the northern hemisphere get colder and the southern hemisphere stay about the same or maybe even a little bit warmer well that brings us to our first controversy what caused the Younger Dryas no video on the Younger Dryas is complete without a discussion of its causes this is probably the biggest area of debate the cooling of the Northern Hemisphere and warming of the southern hemisphere there's good evidence of ocean currents being disrupted a lot of the northern hemisphere is kept warm by tropical waters being carried north when these ocean currents are reduced obviously the North gets colder but the southern hemisphere gets warmer as warm water is trapped in the South changes in microscopic life also suggests that ocean currents had been disrupted as the last ice age came to an end and the glaciers started melting huge amounts of fresh water was dumped into the Atlantic and Arctic oceans in particular the drainage of this huge prehistoric glacial lake agassi's is believed to have been a significant factor there's been this really long-running debate for the past three decades as to what route this water took to the ocean did it flow east along the Lawrence River into the Atlantic or north along the Mackenzie River into the Arctic Ocean from what I've read it seems that the northern route along the Mackenzie River is more widely accepted due to the fact it might have reduced ocean currents by more than 30% compared to an estimated 15 percent from the Lawrence River physical evidence such as huge boulder pits along the McKenzie River provide further evidence of this huge amount of water being released this theory is not without its criticisms though firstly at the start of the allarod warming period sea levels rose by 20 metres over 500 years that's a lot this is called meltwater pulse one a however this didn't cause a breakdown of ocean currents quite the opposite it seems warm water from the deep ocean was released during this time meanwhile at the start of the Younger Dryas although sea levels were continuing to rise it doesn't have that same distinct pulse this might be because it isn't just the volume of water that is released which interrupts ocean parents but also where it is released meltwater pulse 1 a possibly deposited much of the water straight into the Caribbean along the Mississippi River as opposed to Lake Agassiz straining north into the Arctic Ocean other scientists argue changing ocean currents alone might not be enough to cause this really sudden Younger Dryas they're changing ocean currents combined with reduced warmth from the Sun and altered atmospheric conditions best explain the sudden downturn in temperature and there's also those that believe it was caused by an asteroid impact the highly controversial Younger Dryas impact hypothesis states that an asteroid or perhaps a fragmented asteroid exploded above North America at the start of the Younger Dryas this was the trigger for the destabilization of the ice sheets that led to the interruption of ocean currents and possibly triggered widespread wildfires as evidence for this archeologists have cited the presence of black layers of soil and increased presence of various forms of minerals such as nano diamonds platinum and magnetic microspheres the arils micros Ferrell's which is impossible to say and these are argued to be evidence of an extraterrestrial impact evidence of biomass burning has been found in the spikes of combustion aerosols in the soil and ice of the Antarctic Greenland and Russia which suggests that perhaps as much as 9% of the Earth's biomass was consumed by fire since 2007 when the first academic paper was published many other papers have reported similar signals particularly of these spikes in platinum layers data to the Younger Dryas such as in mexico greenland chile and most recently south africa more and more sites are discovered each year and I think it's fair to say it is becoming less controversial these studies have been conducted by real scientists from world leading universities such as Harvard so it's really not for me a guy who sits on rocks reading off a notebook to say that they're wrong but I do really strongly reject the accusation that's often thrown around on YouTube that the critics of this theory are just old fuddy-duddies who can't accept new evidence for example the earth certainly doesn't need an asteroid impact for its temperature to vary the Younger Dryas was one of three quick declines in temperature during the end of the last ice age so with ease all caused by asteroids the earth is constantly being bombarded by small asteroids and comets and all of these things so the presence of these impact markers does not necessarily mean there was a cataclysmic impact they can also be caused by volcanoes studies have replicated them just creating campfires and all sorts of other natural processes could be responsible the dating of these sites is sometimes problematic at barbra Creek the Younger Dryas boundary was said to be 100 centimeters below the surface yet at debts more than 100 centimeters charcoal was dated to ten and a half thousand years ago this is later than the Younger Dryas so can the dating really be relied on in the case of magnetic micros Farrell's I just can't say that there's no consensus as to their exact nature some are reported as round and smooth others rougher others tear-shaped are these all evidence of an impact this ambiguity can lead to really confusing results in a blind test of the Younger Dryas impact to different laboratories reported different results and the one that did report a spike in these magnetic balls found them in a layer dated to 1300 years after the Younger Dryas other sites also suggests these impact proxies are not unique to the Younger Dryas at Bull Creek the spike in nano diamonds was genuinely reported at the Younger Dryas boundary but also at 3,000 years ago and in modern times so are these good evidence of an impact we'd surely have noticed the modern one as for the black mats they are black due to an increase in or gas carbon not all Younger Dryas sites have them but in a study of 97 sites in north america two-thirds did these blank mats can be caused by wetland marshy conditions and are common to various periods of time in a study of 13 black mattad sites dated between 6,000 and 40,000 years ago ten of the 13 black layers showed an increase in alleged impact markers so either we are bombarded very frequently by these asteroids or it could be that wetland conditions happen to be better at preserving these tiny minerals for some reason I don't mean to harp on about all the criticisms but it's just that these are rarely discussed and other YouTube videos and frequently just dismissed out of hand so did an asteroid caused the younger triose in my opinion the case hasn't been made yet but I was honestly surprised by how many scientific papers are coming out maybe not in direct support of it but at least suggesting we should look at it more seriously so I'm gonna keep an open mind is certainly not for me mr. nobody to dispute the findings of Harvard scientists time will tell I suppose but what I do seriously take issue is in a lot of these videos talking about the Younger Dryas every new paper is accepted as if there's no debate in science as if these things aren't extremely complicated it's only right that we demand a really high level of evidence for new theories otherwise how do we know what's true anyway onto controversy number two how come all the mammoths are dead [Music] in the Pleistocene there were all sorts of huge animals that span the globe such as mammoths woolly rhinos giant sloths calico Thea's which looks super cool to me and the giant Irish elk that surprise-surprise lived in Highland and also practically everywhere else sadly in our time these huge beasts are no more and there has been a long-running debate as to whether humans or climate change events like the Younger Dryas killed them off particularly with regards to megafauna in the Americas let's start with the evidence for humans killing everything if we are to assume that humans were the driving force behind these extinctions then it stands to reason that the timing of their extinctions would mirror human expansion starting in Africa then Eurasia then Australia then the Americas this is exactly the pattern we see in the archaeological record 125,000 years ago Homo sapiens were still largely confined to Africa and animals in Africa were on average 50 percent smaller than all other continents from 100,000 years ago large animals in Eurasia start decreasing in size this was a time when not only Homo sapiens had left Africa but also Neanderthals and Denisovans had spread across the continent between 100,000 and 40,000 years ago animals rapidly decreased in size in Australia when did humans arrive about 60,000 years ago whilst all this is going on regardless of changes in climate large animals remained abundant in the Americas until right at the end of the Pleistocene when you guessed it humans arrived the timing just seems too perfect not to be connected and on top of that we also have great evidence of humans hunting these large animals the most recent discovery being an 82 foot long five foot deep pit dug by hand outside Mexico City that contained the remains of 14 dead mammoths dated to around 15,000 years ago archaeologists these animals were scared into the pit by paleo Americans perhaps using fire before butchering them this is really one of the top lines of 2019 and what is really fascinating about it is that all 14 of the mammoths had their left shoulder blades removed that that particular bone have some significance to the people that hunted these animals just interesting that all 14 were missing it however this is not to say that climate did not play an important role for example one study suggests that animals in Africa started declining in size around 4 million years ago when small australopiths or even pre Australopithecus these tiny relatives of ours and their primitive tools were definitely not top of the food chain so much more likely explanation is that expanding grasslands shrank the habitat of megafauna that lived on shrubs and trees and similar plants though the authors do concede that the evolution of more powerful hominins like Homo erectus may have sped up their extinction around the 1.5 million year ago mark in the Americas using the frequency of radiocarbon dated sites as a proxy for population a 2018 study suggested that in what is now the u.s. a mammoth horse and saber-toothed cat populations declined during the Clovis period before the Younger Dryas which implies that humans were responsible however populations of mastodon and ground sloths did not decline until the Younger Dryas which suggests that for some species climate change was a driving factor in their extinction it's also possible that it was the warm period before the Younger Dryas the bowling-alley rod that put a strain on many of these animals ancient DNA analysis shows a really complicated picture of localized extinctions migrations and replacement that closely mirrors the timing of warm periods rather than cold snaps like the Younger Dryas I've got to admit when I read this this really struck out to me as something that made a lot of sense after all these animals had lived through the last ice age so why would a return to those cold conditions threaten them it's possible that climate change forced certain species into various refugia where their preferred habitat remained shrinking their natural ranges and when conditions improved they were unable to expand as they had done in previous times due to the presence of the new top predator humans this created isolated pockets of megafauna that just gradually became extinct one by one as they were picked off by humans or fell victim to disease and further habitat loss I hope I showed that the the causes of these Pleistocene extinctions is really complicated the causes probably vary by species and by region there's probably no single answer to it but I will say this my final thought on that issue if humans were not involved in any way shape or form then it's hard to explain how megafauna in New Zealand survived until the 13th century when the Maori arrived and mammoths survived on Wrangell island off the coast of Siberia until about 2,000 BCE that's after the construction of the Great Pyramids think about that for a second when Egypt was starting to flourish as a civilization mammoths still walk to the earth and that's really very fun north in our planet so if it was the the cold conditions that really wiped these guys out how do we explain that anyway other than making mammoths - how did humans react to the Younger Dryas I can't possibly hope to cover the entire world so I'm just gonna pick four places that show a variety of different adaptations Japan the American Rockies Britain and the Levant so starting with Japan during the Younger Dryas it seems life in Japan did not change significantly the main change seems to have been a slight migration southward in contrast to the bowling alley rod there are no confirmed sights in the northernmost island of Hokkaido subsistence strategies didn't seem to change much either animals like the secret beer remained popular on the menu there did seem to be a small decline in population but not enough to disrupt trade or isolate communities and technologies such as pottery will still widely practiced all in all you could say that the Younger Dryas had a small effect on Japan but nothing too dramatic in the Americas the Younger Dryas saw the transition from the Clovis culture which spans North America practically coast to coast to more regional traditions in the Rockies and Western Great Plains this new tradition is called the Folsom culture the Rockies were probably very sparsely populated during the Clovis period most archaeologists i'ts contain just a few points very rarely do we see large sites such as caches of tools and the odd mammoth kill site like dent for example where 15 mammoths were recovered with Clovis points still overall the impression is one of a very large empty landscape occupied by highly mobile groups of hunter-gatherers the Folsom culture which starts to appear around twelve thousand eight hundred BP just at the cusp of the Younger Dryas also has many isolated and sparsely populated sites but they seemed to be using the landscape more intensively some sites become larger they were staying longer and local resources were used more intensively one site Lindenmayer particularly stands out over 600 stone points were found this is very different to Clovis period sites occupation of valleys was also popular amongst Folsom groups perhaps because these activists natural funnels for migrating animals furthermore Clovis and Folsom assemblages overlap in the northern USA dispelling the idea that Clovis people were wiped out by a cataclysm and replaced by Folsom groups over in Britain the archaeological record for the Younger Dryas contains a little mystery we have found plenty of burials before the Younger Dryas plenty of burials after but absolutely none during it no human remains whatsoever at first it was explained away as a sampling error archaeologists just hadn't found any yet but after so many years of searching now this is becoming harder and harder to accept we also know that Britain hadn't been abandoned because we find other evidence of human activity like worked bone so there are a few possible ways we could explain this first sampling error is still possible second the ancient British abandoned higher ground to live along the coast which has since been swallowed by the sea third burial practices happen to change to X carnation instead of inhumation fourth caves that had been used for burial perhaps became harder to access as glaciers and ice expanded in more mountainous regions and number five perhaps the ground became too cold and hard to actually dig into northern Europe did suffer a population decline during the Younger Dryas so this smaller population combined with perhaps some of these other factors may explain the disappearance of his ancient Brits bodies finally in the Levant human society had been undergoing a revolution for many thousands of years before the Younger Dryas called the broad-spectrum revolution humans were using local resources so intensively that they were able to abandon nomadic lifestyles and settle into permanent villages with stone buildings and everything actually made a whole video on the origins of Agriculture or at least one theory behind its origins for anyone interested it's flying up in the cards you know where it is I don't know anything about chickens or farming in some ways the Younger Dryas interrupted this process people in the southern Levant may have returned to a more mobile lifestyle perhaps moving once a year with the seasons still the core elements of their lifestyle remained though harvesting wild grains and nuts hunting small game that reliably reproduced and the building of stone villages however it could be argued that the Younger dress was a catalyst for human development as the climate dried Woodlands shrank and grasslands expanded it is possible that these Natufian as we call them gradually switched to exploiting more and more grasses and relying less and less on nuts this set the scene for the emergence of domestication and true agricultural societies that occurred once the Younger Dryas ended and the warm wet conditions of our time period the Holocene began this is all still up for debate it's very complicated but as I said it's possible that rather than pausing human development the Younger Dryas was an essential piece of it so now that I've got all of those points out of the way let's try and answer the question how bad was the Younger Dryas was it caused by a cataclysmic asteroid impact probably not but it's possible did it wipe out all the large animals on earth definitely not maybe it was responsible for some of them going extinct but definitely not the full range of large animals that existed in the Pleistocene did it destroy human civilization again no if you lived at a very northernly latitude you would have been affected by it definitely and you probably would have moved further south but humans adapted to it in a wide variety of ways some it really affected some it didn't affect so much and some it may have even been the catalyst for human civilization so it's really a mixed bag now there's one more thing I've got to say on the human civilization front I know people are gonna talk about it in the comments so I've got to bring it up rising sea levels so before the Younger Dryas in that bowling alley rod at the start of that there is a meltwater pulse one a where sea levels were estimated to have risen by 20 meters over 500 years that is a lot in earth terms and geological terms that's very rapid sea level rising is 20 meters in 500 years enough to wipe out a globe spanning civilization I think not they're not very they can't be that advanced if that level of sea rise is going to scrub every trace of them from the planet what about after the Younger Dryas there's another alleged pulse melt water pulse 1b that's estimated to have risen sea levels by a mere 40 millimeters a year there's four centimeters I mean is that enough to scrub every trace of a globe spanning civilization off the planet I can't believe it I can't believe it guys there's definitely plenty of archaeological sites that are buried under water and it would be great if we knew about them was Atlantis destroyed by a mere four centimeters a year please please come on let's be realistic here anyway thanks so much for watching the video big thanks to my patreon for supporting me as always particularly my top tier patreon here consider supporting me I put a lot of research into this video I climbed a bloody mountain don't let the Sun fool you it's extremely cold and windy where I am right now and so linkers and all that stuff is down below and I'll see you at the next video bye quick sip of tea absolutely essential when climbing mountains to have a tea Christ that's hot what a fantastic place Mount Hood Oregon visit it thanks again patreon I'm rambling I'm rambling

Channel: Stefan Milo

Views: 376,126

Rating: 4.571671 out of 5

Keywords: History, Archaeology, anthropology, folk tales, stefan milo, american history, ancient history, world history

Id: 5B4INyco0ZU

Length: 28min 15sec (1695 seconds)

Published: Tue Dec 03 2019

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