The Extinct Ice Age Mammals of North America
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- Опубликовано: 6 сен 2024
- University of Washington Anthropology Professor Donald Grayson and recipient of the 2015 University Faculty Lecture Award delivers the University Faculty Lecture on April 28, 2016. Toward the end of the Ice Age, North America saw the extinction of an astonishing variety of often huge animals. Mammoths, mastodons, saber-toothed cats, lions, armadillos the size of small cars, sloths the size of elephants, beavers the size of bears, and many others were all gone by about 10,000 years ago. We do not know what caused these extinctions, but our knowledge of the Ice Age archaeology and paleontology of the deserts of western North America provides a novel opportunity to examine the common but contentious argument that people were behind all of them.
Donald K. Grayson, professor, Department of Anthropology, UW
04/2/2016
washington.edu/...
uwtv.org
After my retirement I became fascinated with Ice Age Extinction oh, but I have never been to a lecture because I always thought it would be full of college kids. Looking at the audience at the end of this video I see that there are many people my age interested in this. I may have to begin going to lectures
"History" is a Holocene thing, which is BS. Dogs were not even domesticated in this epoch. The last couple hundred years have just been a huge con. Less land mass to work with = problems.
Do it, I just retired also, yaaaay😃!!!!
This is a faculty lecture so I understand why there would be so many people of a particular age.. But please don't let something as inconsequential as "age" stop you from learning about what you're interested in!!! We possibly cannot know everything and we always learn, sometimes even though own introspection!!!
@@PacNasty0 Thanks now off you go, your cartoons are starting don't forget your KoolAid.
Fascinated by fake-a-saurses AHAHAHAHA
I really enjoyed this presentation! As much as it's very painful to me to sit in one spot for as long as this lasted, I would have doubled up on the pain med that I can safely double up on, and sat, rapt, throughout the whole thing!
This gentleman is so good at this, his voice clear, speech pattern smooth, pausing when things need to soak in a moment, yet lilting through the parts that are easily understood. His entire presentation was a joy to watch! I'm going to save this one and watch it over & over!
I hope you are able to heal and not deal with that pain. Exhaust all options
Nice to watch online.
What an eloquent, brilliant individual. I’m grateful to have heard this lecture. Thank you !!!
Yes he did a wonderful job. I'm going to search around and see if I can find more lecture by this man
Me and my son have been hunting a plyocene deposit on the Arkansas river. He’s found one Mastodon skull and one jaw bone. We find tons of bison skulls there. Hoping to find some of these now!
You gotta make vids on stuff like this man.
If you notice on the known locations of 90% of these species have been found in one particular formation in southern Florida. I'm fortunate enough to live within driving distance and anyone thats been there you are literally walking into the ice age. The amount of phosphorus material there is astounding.
Excellent presentation. Grayson provides the best arguments i have seen why hunter-gatherers could not have caused the magafauna extinction. Most of all, i love it when a researcher can simply say how we just don't know yet.
paleo indians did not cause extinction of mege fauna bc the first paleos that arrived were very FEW in number, and when living wild populations do not expand fast, but very slowly. It took thous of yrs for the paleo pop to grow, and by then all the mega fauna was gone. Another thing, why would the paloes kill off all the mega animals and not the smaller ones. Giant beavers were hard or imposs to hunt bc they always retreated to the water
@@jayvanslayer2787 All valid points. And also the extinct species included some bad ass big predators they certainly would not have hunted. The theory that an impact from space was at play has gained credibility since a huge crater was discovered 2 years ago west of Greenland, corresponding to that time period.
These animals had never ever seen a human being or anything remotely like a human being. They had evolved apart from humans. Therefore the animals likely did not have a fear of people. It was an entire continent of animals that acted like the Galapagos animals act. You could walk right up to them. And the ancestors of native americans were likely very skilled hunters. Do the math!!
@@bradhirsch4845 there is no way to say this for certain. I think there were people in north America during the last ice age. Possibly even before that
@@bradhirsch4845 that is an acceptable idea, but does not explain why mammoth lasted longer in East Siberia an area where human presence is older then in the America's.
But one does not asume skilled huntership, Megafauna has a slow reproductian rate, when you kill 5 animals a year of a species that reproduces a young every 5 years, the species goes in decline. Just look how fast the African elephant declined in just 150 years. 150 years is nothing impressive on the archeological timeframe.
I normally don’t watch entire lectures on RUclips. That being said, this was excellent and I enjoyed the entire lecture. 👍🏼👍🏼👍🏼
I agree great presentation...fascinating
As a big fan of the Megafauna, I enjoyed this presentation. Though I know not everyone enjoys it, younger audience and future paleontologist will.
Boyzilla Altarmore because they're more easy to brainwash
like any new discovery that goes against main stream beliefs ....its cruised lol
I don’t think Cenozoic animals get the love and attention that they deserve. Usually prehistoric = dinosaurs, but I find prehistoric mammals fascinating
I'm neither "younger" (not by a long shot!) nor a future anything, most likely - my school days are long over, though I still love to learn, and strive to learn something new every day. Yet I really enjoyed it! I loved how this presenter spoke, enjoyed the speech, itself, and loved the subject matter, and I'm "on the wrong side of 50," as I've seen it called.
So... you know, maybe not leave an ageist comment, eh?
@@andy11ink *citation needed
See, just look at the whole Qanon thing... it's not the young ones that are falling for that brainwashing, but the older people, in their 40s, 50s, 60s, and up! If you want to argue the whole "easier to brainwash" thing, you need to back it up with citations and reputable references.
I really loved the plants and ice age mammal connection. Intriguing
Me too.
I really liked the fact that you answered a lot of questions, but you also asked a lot of questions. An excellant presentation.
Note that there seems to be a weight limit of surviving big ancient mammals of under 150 pounds. Just like there was a maximum weight of the animals that survived the end of the Cretaceous of somewhat less (~50 pounds if I recall). Big animals cannot hide from other animals or from environmental catastrophes and need more food, so curtains to them...
Wellll not really, bison elk and moose weigh many times more than 150 pounds and they still here
although yes in this quaternary extinction event way more big animals than small animals went extinct, and that doesn’t mean that it was humans who did it
There’s a heavy element, tiny diamonds and charred layer in North America presumably from an asteroid or comet strike which sublimated or melted much of the Laurentide ice shelf almost instantly causing a climate and ecological disaster which seemingly ended the Clovis culture and many species.
Yes, although I think the Clovis people survived, some aspects of the culture changed. Like the size of the points. Folsom is actually a very similar point, even fancier, but smaller...
@@nmarbletoe8210 flints sharper than steel, obsidian scapels are used in heart surgery.
This is a fabulous presentation - I know everyone will enjoy it!
I wonder what type of fossils fuels clovis was using to end that ice age.
mammoth coal just like me
Stone age politicians warned earth had maybe 12 years before it exploded if pottery and arrowhead production wasn’t centrally controlled by an all powerful socialist govt.
@@oddsman01 as a student of humor, i always appreciate a joke. it takes effort. but also as a student of humor i have learned that humor is the part of the ice berg we see. beneath the water is the serious subject holding the humor above the surface. here's the serious side of this. do you believe that the global warming happening at the end of the last ice age and the global warming we are now facing occurred in the same geophysical context?
The best and funniest guy ever to present an extinction video! 👏👏👏
We are still in an ice age. That's why the poles are filled with ice. What we are in right now is an interglacial period (or "glacial minimum"). The eras that people think of as "ice ages" are called "glacial maximums". In the 4.56 billion year history of the earth, the polar regions have been ice-free more than they have been ice-bound.
Yes we are absolutely still in an ice age. He is right by saying the current ice age started 2.6 million years ago, but wrong by saying it ended 10K years ago.
I was surprised he didn't say that.
How about an impact event between 12800 and 12600 years ago and the following global catastrophe?
Black Cast not one of those again :-)
@@agentumsilwersilwer5310 You mean like the Hiawatha impact? :)
The Younger Dryas Impact Hypothesis is one of the most interesting and promising scientific theories in Paleontology/Archaeology. If it’s true (and so far there hasn’t been any indication that it’s not) it is one of the most important revelations ever made and it implications for the history of our species are mind boggling.
It's still a worthwhile theory. Not sure why there seems to be so much resistance to it. As Grayson mentioned, doesn't mean it killed everything. Likely not. Need more time for the theory to develop as academics are studying this. Great presentation here! Excellent
it is the only explanation
almost every year we have tons of documentaries and movies about dinosaurs , and very few about prehistoric mammals . I'm getting sick of dinosaurs , I want more about prehistoric mammals
I have found these river rocks that when scrubbed, you can see paintings and sculptures,a few I have found show mammoth and human bonding.
One theory you don't hear about is the Gama ray burst from outer space. Which was a short big burst from a nearby stellar object. It radiated the western hemisphere. Killing the larger above ground animals
That's because it isn't a theory, it's bunk. The earth revolves around its north-south axis. Ever tried cooking a pig on just one side using a continually rotating spit?
Besides, similar megafaunal extinctions occurred in Australia, too.
@@markcynic808 OK...so extinctions multiple times in history and places can't exist? What school did you go too?
@@NormBaker.
The kind of school where, unlike yours, finger painting wasn't part of the curriculum for 14 year olds and "Special Needs" wasn't its prefix.
@@markcynic808 Oh hahaha! you are so clever and funny. That is so old has wrinkles.
@NormBaker.
What's really funny is an earlier statement here about a "Gama ray"- whatever that is - causing extinction of the above ground megfauna, but not moose, which presumably must have been burrowing animals back then.
The concentration of remains at choke points, like La Brea, had me thinking there was plenty of megafauna around-just like the Savanna today. We see the same mechanic with crocodile stake outs at water holes during the dry season. Plenty of big game, despite the visual paucity from any generic vantage. You just need to find its collecting points; water holes, creche valleys, high forest (moose). In a different realm that find of a large collection of remains suggested lots about Allosaurs previously unsuspected.
The more interesting question is why these extinct megafauna genera survived the six interglacial periods of the last 2.5 million years but not this current one. OR were there similar megafaunal extinctions during those interglacials we don't know about?
I live in the Sonoran desert and paleobotanists say the flora was much different >15,000 BP when most of the megafauna disappeared.
longlakeshore It is because climate change did NOT cause the late Pleistocene extinctions. Most of the extinct megafauna had a distribution that covered diverse habitats; they were quite adaptable.
The other problem with climate theories is they have to explain the wide variation in years of extinctions for American megafauna, Australian megafauna, and various island megafauna (notably New Zealand, Britain, and Madagascar). Did many events happen, each only affecting a specific island or continent? Why did they coincide exactly with human arrival in each of these places?
Because it was humans arriving with dogs, advanced brains, hunger and weaponry.
The comet impact over the great lakes region 13,000 years ago not only caused a rapid melting of the Laurentide glacier, there is evidence throughout North America that this air-burst explosion caused massive fires, leaving a discernable "black matte" layer in the soil. Below that layer, there are megafauna and Clovis points. Above it, no more Clovis and no more megafauna. The amount of fires and smoke would have contributed to a rapid cooling, impacting other parts of the world.
Hunting may have contributed, but the evidence for an ET impact, similar to the Tunguska event in 1905, is overwhelming. Aside from the amount of ET elements and compounds found within this layer (e.g., K40 and H3), there is corresponding evidence within the Greenland ice cores for the same time period, showing the debris and ejecta affected the climate for rest of the world, too.
@@DTavona Good point about the Black-Matt layer and Greenland.
The American lion. Wow we out competed the biggest cat ever. And their lame pride?. Even after migrating all that way. Right through their turf
I really liked this lecture.
I don't buy that we don't know why they left caches. People going on long in and out trips still do it today. Its all about energy efficiency. It also shows Clovis people had lots of foresight.
BrodyYYC But not enough foresight to go back and retrieve their stuff.
@@653j521: There are many things that could've prevented retrieval. But due to their size...the number of points that could be carried was severely limited. Combined with the fact that good lithic material is difficult to find...it would make perfect sense that they would resort to caching preforms throughout their territory.
@@653j521 Ha shit happens and it always did!
Thank you for this lecture, reminds me why I enjoyed anthropology classes in college. Would have liked to hear more about the earliest signs of homo sapiens in the Americas. Probably too controversial to say much about without offending one group or another.
Good stuff, very interesting. Enjoyed it!
I don't think it's controversial, it's science. Why would anyone not disclose scientific facts because they might offend someone? That's not how science works. You state the facts and if someone gets offended that's just too bad for them
Clovis is found everywhere, not just the southwest. Must be a thousand found in east Tn.
Right on. Here in SE Iowa many Clovis have also been found. If you look at a map of Clovis finds, they are all over the US.
I( remember Clovis he was just 16 years old and weight 350lb 7' tall and it was not fat. he crash this party I was at in Cottage Grove Or. in 1972 and started to knock the crap out out everyone it was the most amazing thing I ever seen.
I believe there are more Clovis sites East of the Mississippi
@@jonwilliams23 Yes, but what was the distribution patterns of perhaps 10 K more occupation time of pre-clovis, that is a lot of time for a lot of things to happen here before clovis... and evidence is building.
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p.o p
Wow this video is awesome but it would be so much better if I didn't get a God damn ad about Ritz crackers and raid shadow legends every 5 minutes
Download AdBlock!! It works so well that I forgot that there is such a thing as ads!! I have not seen an ad in over a year. It's great!!
@@mrmcg9288 will do thanks
@@iambodybuildingyt221 You are welcome. Please tip off other people you come across that there is ad blocking apps out there that WORK and make your life so much better! AdBlock works great for me but there are many other apps available! Enjoy! : )
@@mrmcg9288 👍
Randall Carlson's and others' suggested comet impact theory is the best explanation for the demise of these large animals so far. Robert Shoch also suggests a theory involving a massive solar flare as the culprit to consider. One thing that most scientists today finally agree on is that human predation did NOT significantly contribute to their demise. In fact, it was the human race that was very much endangered in the late Pleistocene and the sudden extinction of these massive animals is one of the main reasons we can have a discussion about this today.
@54:11 There is plenty of evidence for this! The black mat (soot rich) layer is now identified throughout North and South America as far as 41 degrees south by Mario Pino, Kennett and colleagues. The Pilauco Bajo site shows clear evidence of changes known to be associated with the Younger Dryas impact event. These pieces of evidence included a black mat layer, 12 800 years in age, that coincided with the disappearance of the South American Pleistocene megafauna fossils, an abrupt shift in regional vegetation and a disappearance of human artifacts.
@55:26 How scientific of you. Doesn't work? You mean it doesn't work for your version of events. Obviously no one is saying that all of this megafauna dropped dead in one day!
The conclusion is today correct. We don't know for sure. It is also true that the evidence of an extraterrestrial impact followed by a massive fires and subsequent floods and fires is mounting.
comet theory not good at all bc why would a comet wipe out all the large animals and not the lesser animals. Must also realize that there were ice age mega fauna in eurasia
Actually there isn't any evidence of the impact, and there should be for something that supposedly generated hemisphere-wide climactic effects. The possible crater in Greenland isn't dated, and since it's under several thousand meters of ice it's not likely to be dated for quite some time. The Milankovich Cycle ended the ice age, changing the global climate, and megafauna have very specialized environmental needs. The disappearance seems to have been fairly gradual, which a cometary impact is not.
I don't see how human caused extinction is even debated. Mixed with maybe viral diseases and a couple years of weather conditions causing humans to hunt with more force...maybe better hunting tactics mixed with a possibility of discovery of poisonous material applied on weapons...mix and match some of these and I don't see how it wouldn't be the best explanation. Look how humans destroy entire species without even hunting them...back then we didn't have any moral values except survival.
All the other hypotheses have literally zero evidence. It's quite telling that only homo sapiens remained while the Neanderthals disappeared. It's quite telling everywhere we show up... species disappear...
@@Raydensheraj
@@jayvanslayer2787 some small animals did go extinct wym
This video holds the world record for ADs interruptions.
Starts at 2:42
Avocado story is awesome! Didn’t know that, what about Osage orange fruits? They had to evolve because of mammoths I think.
The dates for mammoths show that the farthest they were from eastern Canada, the longer that they lasted. This seems to be true for most, if not all, of those extinct animals. Also, since a comet or asteroid would only start the climatic disasters that would follow, we get different animals succumbing to different things at different times. The asteroid/comet would be earlier than given here, probably at near the start of the loss at 13,000 years or so ago. The erasure of the sites in the North-East of North America seems rather hard to explain otherwise... Perhaps there was more than one impact at different times?
This is one of most comprehensible videos on Ice Age megafauna in North America. Regarding the reason for the extinctions I would ask Professor Grayson to read my book 'Ice Age Extinctions, A New Theory' which was recently published.
A pole shift happening at the same time as an extinction is most likely a coincidence then it is a cause.
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"The rate of reversals in the Earth's magnetic field has varied widely over time. 72 million years ago (Ma), the field reversed 5 times in a million years. In a 4-million-year period centered on 54 Ma, there were 10 reversals; at around 42 Ma, 17 reversals took place in the span of 3 million years. In a period of 3 million years centering on 24 Ma, 13 reversals occurred. No fewer than 51 reversals occurred in a 12-million-year period, centering on 15 million years ago. Two reversals occurred during a span of 50,000 years." en.wikipedia.org/wiki/Geomagnetic_reversal
A. Randomjack,My theory explains why geomagnetic reversals accompany most mass extinctions. The reversals are not the cause of the extinctions. Both the extinctions and the reversals are the result of the Earth's core elements moving away and then back toward Earth-centricity. This happens when mass on the Earth's surface, either tectonic plates or ocean water (when forming polar glaciers) moves to high latitudes and then moves back to lower latitudes. This is why the geomagnetic reversals and excursions occurred, for example, when polar glaciers melted during the interglacials of the Pleistocene era.
Exactly. Caused by huge cosmic impacts.
@@johnstojanowski8126
The gelactic current sheet could4 be the trigger of a micro Nova event, may have hit alpha cantari in 2012.
@@a.randomjack6661 A coincidence that happens over and over again. I doubt it. It may not be the cause but it certainly is no coincidence.
Very interesting presentation engaging speaker with thought-provoking content he is funny and makes the information easily understood. Would have really enjoyed his lectures when I was in collage. Thank you for bro gong this to a wider audience.
10,000 yrs doesn't seem like a long time.. but when you think about it, it is.
You never thought of an impact event? There’s evidence in the geological records and in the sediment that holds dozens and dozens of mammoth bones. There’s one mammoth discovered that had two broken hips, an erection, and food that wasn’t putrified in the stomach. This means hit was hit by an enormous force, put under enormous pressure, then rapidly froze in about 8 hours. A 150 degree drop in temperature.
Absolutely! The theoretical impact (for which evidence is good evidence is mounting) seems to have been so violent and dramatic that it must have had a huge impact on the atmosphere. Enough to make this drastic (although most likely short lived) temperature drop possible. Basically a gaping hole in the atmosphere for a few minutes.
Taurid meteor stream, that still comes by twice a year, has dropped off a few, several times. Just a few years ago, Russia received a few during the fly by.
What? No. They found buttercup SEEDS, not plant matter.
There is ZERO evidence of rapid drop in temperatures. None.
Mammoths we're often caught in mud and bogs and frozen before decomposition though. They literally lived in a freezer.
Besides... Not sure how something that would burn and vaporize everything would somehow freeze mammoths. And no, you do not punch a hole in the atmosphere to cause sudden freezing. 😂
Mammoths, such as the Beresovka Mammoth, were feeding on the edges of river banks that collapsed beneath them. Where there is permafrost, only the top 1-2 feet of soil melts, and it easily flows on the frozen ground below, This flowing soil buried the mammoth, and many others. Other frozen Alaska and Siberian megafauna include muskoxen and horses.
Brilliant and very funny speaker! Thank you!
Hmm, I thought they found Clovis sites in the east. I remember something about a Clovis site on the eastern shore of Maryland and in Delaware.
There are more Clovis sites in just the tidewater region of Delaware,Maryland, and Virginia than in all of the states West of the Mississippi. The Clovis people were Solutreans from Europe.
Clovis points are the holy grail to replicate in the art of flintknapping. I haven't reached the level of chipping yet.
There are more Clovis sites in the east than in the west, several more.
@@danamcalister Solutrean from Spain And France look just like Clovis. Alot of the eastern sites are older than Clovis.
Very interesting,all i knew about glyptodons before was from the Flintstones! :)
He said the Ice age lasted 2.5 million years ago to 10000 years ago, but it hasn't actually ended. The last major glaciation ended 10000 years ago. We're in an interglacial period of the same ice age. There's still ice sheets on the poles today, thus, it's still an ice age.
Don't think presence of ice at poles is how ice ages are defined.
@@idunusegoogleplus How would you define it?
@@MrChosenmarine glaciers would have to cover far more than just the poles, with vastly more land covered with ice except the warmest equatorial/tropical regions. So no we are not in an ice age, in fact we are much warmer now than 10000 years ago and thus why we can have widescale agriculture. If we were in an ice age most farms would have frozen crops in Europe.
What I don't understand is that, if the extinction of mammoths and saber tooth cats, among other fauna, was caused by overhunting by a handful of primitive humans with spears and stone axes, then why, after guns were invented hundreds of years ago, weren't elephants, lions, tigers and bears completely wiped out as well? They still exist, even though humans had multiplied a million fold and created weapons of mass destruction. I don't think this theory holds a drop of water.
Careful! You're applying too much logic to the subject matter.
Check out suspicious observers channel.
Because he’s totally wrong 😳 he’s unfortunately wasted his entire career working on the basis that Clovis were the first people to inhabit the America’s - and oops, they 100% weren’t. Not even close !!
Rather embarrassingly a whole generation of academics like this dude wasted their careers because they were so sure that Clovis were first that (and this isn’t a joke) THEY DIDN’t BOTHER LOOKING. Literally they didn’t dig just a bit deeper past Clovis relics because - well what was the point ?
I’m struggling to think of a worse faux pas in the whole history of scientific discovery than that which these fools have committed over the last 40 years 🤦🏼♂️
30:59 That adorable little Homo Sapiens sleeping in class was pretty cute. Sometimes we apes need some down time.
Those sabre teeth were presumably meant to take a large chunk of flesh out of a megafauna perhaps from a leg or stomach resulting in the disabling of the prey and it’s eventual death after a few days with big cats hounding the animal much like wolves hound bison nowadays. I would imagine with such large food sources the cats would be in prides for maximum efficiency.
The extinction may have been caused by diseases released when the ice age melted and released the microbes that had been dormant long enough for many species to loose immunity to them.
That is a very interesting thought, thank you. A microbiome frozen in place for tens of thousands of years certainly would present as a new set of organisms. I wonder if anybody is doing research along that line? We are just recently beginning to understand and research the microbiomes. Again, very interesting theory.
@@ruthamos2312 Yes, and now we are becoming much more aware of pandemic pathophysiology, and not just in humans. Immune system naiveté could play into extinctions, and just look to how European diseases devastated vast numbers of the first peoples cultures that had existed here post clovis, to get a better sense of such widespread pathogenic population decline rapidly. Think about how much indigenous oral history knowledge transfer was wiped out suddenly, and how that harmed the people that managed to survive.
There were many ice age melts exactly the same as this one during the last few hundred thousand years where the same animals made it out just fine. What caused those microbes in the last melt? I’ve wondered this myself though
There is so much wrong with this presentation, but I first want to thank the presenter for clearly and pleasantly sharing his thoughts (whatever their merits) and thereby allowing a serious discussion of this important topic. First, let me say that he omits very important extinctions and glosses over surprising survivors. But it is his general theses, namely, that (a) humans could not have been responsible for the collapse of the American megafauna, and (b) there cannot have been Africa-like herds of megafauna in Pleistocene North America, which must be refuted. The learned professor suffers from myopia in his attempts to view the ancient world. Humans, especially hunter-gatherer groups, are incredibly sophisticated hunters.
The evidence of their hunting might not be great after thousands of years for a variety of reasons, including hunting methods that don't lend themselves to preservation (such as all-wood arrow shafts and tips as in New Guinea), cultural practice relating to butchering and disposal of game (do they just cut out the meat they can carry when game is plentiful or do they remove meat and bones?), and simply chance (how many evidences of hunting are preserved and how many of those are likely to be found by and correctly identified by paleontologists?).
What few people realize is the simplicity that lies behind any mass extinction that doesn't affect all members of a faunal community (e.g. we lost mammoths, mastodons, gomphotheres, ground sloths, camels, horses, and tapirs in what is now the USA, but camels and tapirs survived in South America, and elephants (mammoths were just elephants) survived in much of Asia and most of Africa; also, Eurasia lost its muskoxen, but North America retained them). And here it is: more animals died than were born for long enough to ensure no more could be born.
This sounds too obvious, right? But it's not, and greater minds have failed to grasp it. The animals which went extinct did not do so all at once. Yes, most seem to disappear by X date in North America or slightly later in South America, but, as pointed out in the presentation, there were seemingly random holdouts in other areas. All it would take for humans to be the proximal cause of the extinction of a species is for whatever pressures humans place on that species to be just enough more to cause a negative birthrate. When that happens and is sustained for centuries, animals which birth fewer young and whose young take longer to raise are doomed, but so are animals which might have an average amount of young for a larger animal but which live in already strained conditions (low densities due to competition with other animals, fragile environments, etc.). Think of the old saying about the straw that broke the camel's back. It comes from the reality that there will always be a tipping point: a camel's back can only sustain X amount of weight, and, in truth, it would be possible to cause a failure by placing that maximum amount of weight on the camel and then adding a single straw.
If you look at extinctions around the world, you find that they do not correlate with unusual or even sever climate change. Muskoxen survived the end of the ice age just fine in the North American Arctic and in Siberia only to become extinct in Siberia thousands of years before the present. Elephants survived in China, Southeast Asia, South Asia, and parts of the Near East (in addition to virtually all of Africa) until the rise of Rome (more or less), but they were lost in Europe, the Americas, and northern Asia. However, if you focus on post-Pleistocene extinctions and extirpations, you can find a pattern: the elephants of Eurasia, which survived the transition to the Holocene, begin to disappear from the Chinese heartland the the Near East before the time of Christ. Some centuries later, the elephants of North Africa are gone. By the time of European colonialism, wild Asian elephants do no exist west of India or north of Nepal and South China and they are gone from populous Java. By the dawn of the 21st century, wild Asian elephants are virtually extinct in China, Vietnam, Cambodia, Laos, and are so fragmented in much of Indonesia, Burma, and India as to be nothing more than isolated genetic islands of wild elephants. In Africa, they are similarly fragmented; the bush elephant is almost completely confined to heavily managed game parks, and the forest elephant, though less managed, is vanishingly rare. Rhinos have fared worse. 3,000 years ago, they were found from the extreme west of the Indian subcontinent all the way to the Yangtze in China, and from the Yangtze all the way to Java. By 1,000 years ago, the three species of Asian rhino were gone from China and were contracting to the north and east within India. By 10 years ago, the Indian one-horned rhino numbers in the low thousands, the majority of which occupy a single park in India's extreme northwest; the lesser one-horned rhino (renamed the Javan rhino for the following reasons) had lost its last continental population of rhinos in the 2000s and was reduced to fewer than 100 individuals in the far west of Java; the Sumatran rhino, which, again, was actually once found from China to Indonesia, was similarly reduced to a tiny number of individuals, most in Sumatra, with little hope of surviving the century.
As sad as it is to say, for all of our wonderful extant megafauna (three elephants and the rhinos of Africa and Asia), they have not birthed more offspring than the adults they've lost for at least the last 3,000 years. In other words, they are going extinct. They are functionally already extinct. We who are having this discussion just happen to be witnesses to the later stages of an extinction event that began thousands of years ago. If it can take 4,000 years to kill off the biggest game animals on the biggest land masses, how long would it take to do so on land masses which are much smaller? The answer, obviously, is less time would be needed. If, then, humans were the straw breaking the camels back in the Pleistocene, what difference might there be for game that had never been hunted by hominids versus game that knew humans as predators? Again, if you look at the distribution of extinction sin the Old World, you'll see that the areas where modern humans went first (Africa, the Near East, South and Southeast Asia) show fewer extinctions than areas where primates were newer members of the fauna (Europe, Siberia). When they crossed into North America, not a single game animal would have recognized them as predators. Hunting would have been dangerous only because of the other dangerous predators, which, no doubt, these first humans would have hunted aggressively for both defensive reasons and, likely, religious reasons. If they entered 15,000 years ago (a rounded number, but I think it's likely they arrived earlier than is generally accepted), all they would have to do is cause enough extra deaths each year for a a few thousand years, and all the megafauna would go extinct. Importantly, they needn't hunt any one animal much in order to accomplish this. If mammoths could only sustain a 10% mortality rate, and humans made it a 15% mortality rate, the mammoths would go extinct in a matter of centuries, but the vast majority of all mammoths right up to the end would die of natural causes.
Because the above IS why the megafauna went extinct (and continue to do so), it will never be possible to prove. But we can infer this truth by looking at when megafauna have become extinction, which megafauna became extinct, and where they became extinct. Here's a summary:
Mammoths and rhinos are extinct in Europe by the end of the Pleistocene.
In North America, only three land herbivores of 750 lbs or more survive (elk, moose, bison); all others are extinct by the end of the Pleistocene EXCEPT the ground sloths of the Caribbean, which live on for thousands of years into the Holocene.
In South America, no herbivores of more than 750 lbs survive to the present; all are dead by 10,000 years ago (with the possible exception of one gomphothere, about which claims are made for a late survival)
In Asia, the last mammoths survive until 8-9,000 years ago on the mainland, but on one arctic island they survive till the rise of modern civilzation.
In Africa, most big game survives into the Holocene, but on Madagascar, all giant lemurs, giant flightless birds, and hippo species are killed off between 1,000 AD and 1700 AD.
In Australasia, all giant marsupials, giant land turtles, and some giant flightless birds become extinct 40,000 years ago (some 30,000 years before any other continent loses its megafauna), however, this only applies to the mainland: on offshore islands, such as New Caledonia, giant land turtles survive until a few thousand years ago.
In New Zealand, the giant flightless birds and giant eagle (among other species) survive until about 1200-1300 AD.
In the Galapogos Islands, where humans never lived, giant tortoises and giant lizards continue until the islands' discovery by Europeans.
No one event can correlate to the loss of all animals over 200 pounds in Australia 40,000 years ago, the death of all but three herbivores larger than 750 pounds in the Americas 10,000 years ago, and the similar loss in Europe about the same time. Nor can it correlate with the retention of megafauna in Madagascar, NZ, Cuba, etc. until well into the Holocene. But if you correlate these extinction events with the coming of man, you begin to see a patter. Modern man hits Europe about 40,000 years ago (if not earlier), and the megafauna are gone within a few ten thousand years. He reaches the Americans 12-20,000 years ago, and the megafauna disappear within a few thousand years. He reaches the Caribbean about 5+ thousands years ago, and then the last ground sloths, whose Florida cousins 70 miles away had been extinct for 6k years, disappeared--same for NZ and Madagascar 800 y.a. We did it!
This graph shows this well.
upload.wikimedia.org/wikipedia/commons/d/d4/Large_Mammals_Africa_Australia_NAmerica_Madagascar.svg
He’s spent his entire career in the safe knowledge that it was “Clovis first” and therefore, like so many other academics didn’t bother looking deeper or further. It’s amazing that these guys had careers as they literally set science back 30 years with their presumptive rhetoric. Embarrassing isn’t even close…..
but then why did mammoths die out in europe at the same time as they did in north america, when humans arrived in europe many tens of thousands of years before america
@Train 2noplace there is more evidence that humans were hunting extant megafauna in north america bison, moose, elk and deer than there is of the extinct megafauna yet the extant megafauna are still here
@Train 2noplace there was a region in alaska that mammoths were in that humans came into 14000+ years ago, the mammoths there coexisted with them for over 3500 years and then went died out 10,500 years ago, which is around the time mammoths became pretty widely extinct in eurasia and north america, which doesn’t really make sense if humans were said to overkill whatever megafauna was in the region that they went into in only a few centuries when the evidence shows they coexisted for quite a few millennia
also, i don’t see how the mammoth habitat really deterred humans if there is evidence that we hunted them
same with south america, there was megafauna in a region in patagonia a few of which were the giant ground sloths the giant jaguar and short faced bears, humans arrived in that region and they coexisted from 14600 to 12300 years which is 2300 years with the megafauna there, and then once the warming phase comes at 12300 years the megafauna go extinct within only 200 years
Great lecture, the YD Impact theory has come a long way though, and deserves more attention and not to be dismissed.
the direwolf is no longer considered a member of the genus Canis, but of a new genus Eunocyon
Absolutely fascinating!!!
Can you put some more ads in this videos please???
somebody make a time machine already!
If a time machine is ever invented, the first time period I’m gonna visit is the ice age.
I'm working on it. Should be done next week.
My hope is that the aliens (c'mon, there's no other logical explanation as to who are controlling these vehicles) that the Pentagon admit exist, most likely have amazing HD footage of Earth's history, including that of prehistoric creatures. I could care less about the aliens themselves; I just want to see ancient history with my own eyes, and if aliens really have been observing Earth, you KNOW they've been recording everything on some advanced, VR HD recording equipment.
Started to lose me @5:33 when you independently declared that the ice age ended 10,000 years ago. Many of us believe we are still in the Late Cenezoic Ice Age and currently live in an interglacial period known as the Holocene epoch.
“We still don’t know any more than (Wallace) did about why they went extinct.” I think Randall Carlson & Ben Davidson might have something to add to the conversation if academia would deign to listen.
Loved this! How I miss attending lectures in Kane Hall!
29:10 "It is a herd animal. If You find one skeleton You find a bunch more" That not only says that it was a herd animal, but they all died at the same time. What was that catastrophic event?
A deluge. A massive deluge.
These people are brainwashed to reject any and all catastrophe hypothesis for some bizarre reason. Impacts from space are as natural as the sunrise, yet all these "educated" people refuse to believe they could have happened recently. Christ, there's video of a space rock ripping through the atmosphere, seen from a hundred different angles, that would have killed hundreds of thousands of people had it been a more steep angle and located over a large city...and that just happened a few years ago. Chelyabinsk, Russia.
I bet we could get a direct hit tomorrow, and these morons will try to tell you that nothing hit anywhere... It's pretty pathetic.
The date for humans in America has been pushed back recently to 23,000 years ago. So I'm still betting on human predation. That and the fact that the mega fauna in Australia also disappeared when humans hit the ground makes it seem fairly obvious why they died out. Especially when the animals had survived so many prior warming and cooling cycles before.
How long has Sasquatch existed in North America?
Watch some of the geocosmic rex vids here on YT.
Don’t tell the presenter !!! Probably it’ll be pushed back a fair bit more too….
He’s wasted his entire career promoting “Clovis first” because, well, everyone knows they were the first inhabitants. It’s one of the most embarrassing episodes in the field of scientific discovery.
They literally DIDN’T BOTHER digging deeper 🤦🏼♂️ they were so wrapped up in what they knew that they forgot to look for anything else 😳
He is totally misrepresenting the comet impact theory as a single event. The group doing this work have identified multiple events over the time period of the Younger Dryas and the two periods prior. Research is ongoing.
I'm hip to more impacts. Which group do you refer to for research?
Thank you for the warning.
I might not watch this if it is so biased.
@@bubbahubba7238 no still great presentation. Just its kind of up in the air if it was one impact or several impacts. Randall Carlson on Joe rogan. Had a great presentation stating that it happened very quickly whatever it was. Doesnt really make a whole lot of diff either way in my opinion
@@anthonyhewitt9397 what was the state of the hypothesis five years ago?
@@anthonyhewitt9397 Randall Carlson has some MAJOR Issues with his hypothesis. Explain how one of the largest Clovis sites in the world sits on top of a Scabland megaflood bar near Wenatchee if the flood that created it also wiped out the Clovis? Simply not possible. The Clovis came AFTER the floods just as dating done in the Scablands confirms.
They have moved on to the multiple impact hypothesis simply because a single one like they originally claimed could not do everything they claimed it did.
Strange how the megafauna extinction events of different continents and of varied epochs, coincide with the first appearance of humans in each, rather than the same epoch. Mmm, very strange, a shame it's not in vogue. It goes against our ancestral narrative of the noble savage though, doesn't it?
@Dirty Magic11 yeah I don't doubt the younger dryas narrative, but I think given the "circumstantial" disappearance of megafauna around the world at differing times on each continent, but tied in relatively close with homosapiens appearance, is a bit of a smoking gun. It has just fallen out of vogue these days with the noble savage narrative and colonial white guilt being our religion, that the data is never viewed through an unbiased worldview, neither for or against.
Btw, the disappearance of predators is to be expected when they're beginning to be out competed for their specialist food and especially if it disappears, they will be right behind it into extinction.
I'd say there were potentially multiple factors, as with most things complicated
Great presentation overall but the ET impact theory was not presented fairly. A singular impact is not the theory because it would not cause the massive extinctions around the globe. Multiple impacts are a possibility and on more than one occasion. The last 100000 years (especially the younger Dryas period) is a fascinating time period and much respect to Grayson for very clearly stating that the answer is not known and requires further intense study.
I remember hearing about a research dig that found a mammoth frozen I believe in Alaska. The mammoth had blue bell flowers or something still in the belly. It appeared to be instantly frozen they said. Sure maybe man wiped out animals, but maybe there was a pole shift that caused massive cold air to freeze areas.
Makes me think of the movie the day after tomorrow where the northern part of the U.S. has to evacuate and in England when they evacuated the king the helicopters fell cause it froze as the air was super cold. Makes ya wonder if that ever could happen. Or ever has happened.
This is so fascinating I love it
Fantastic! Thank you for sharing!!
Why does Grayson assume that the great basin area was always desert? There is topographical evidence in satellite photos that it was not always desert.
You're absolutely right about that. I find it shocking how many experts use selective bias in their presentations.
He's not assuming, the geological evidence is generally clear what the climate was at the level they're excavating. If you see tree roots in your dig it's obviously wasn't a desert at that time. What he is referring to is that **at the time he's talking about** it was a desert, as it is now. Want confirmation? Joshua trees are desert plants and the sloths were eating Joshua tree fruit, the evidence of which is in the copralites.
There was was a catastrophe during the Clovis Period in which there was electric Plasma exchange between the Earth, Venus and Mars. North America remained unpopulated until 5 thousand B.C.
The answer, "We Don't Know" may drive people nuts lol but that's completely separate from whether or not it's true. Sometimes, usually, the most HONEST answer is; "I don't know."
Pretending we do inserts a placeholder, at the very least, in the answer spot. Which stunts further examination, especially the amount of examination some topics deserve.
That's why it's ALWAYS better to admit when we don't know an answer, despite how "nuts" it drives us, because it keeps that spot as open as possible for everyone to continuously try to fill with open, honest investigation.
Yes, and that is what scientific method is. But even scientists are human, and subject to confirmation bias degrees and funding biases that can be strong inducers of denial of the vast amount of mystery that we just don't know yet. As usual, assumptions abound, but many are false summits on the path ahead.
Oddly some of the locations of these animals were under a mile if ice during the ice age. That makes no sense. You should place them there before the ice age or perhaps during a post glaciation period.
I would like to have seen a date of distribution from one site to another noted on the map. Many of the animals here came from the far North to South. Knowing the date of distribution would allow you to calculate how quickly they were moving through geography until finding a preferred habitation site and thus avoiding the great basin. I've always understood that loss of species from 10 to 18 thousand years ago was caused by the things noted here as well as catastrophic flooding from rivers generated by the ice age. Melting caused huge lakes to form until they were suddenly released when they could no longer be contained. There is absolute evidence that was the case. I also understand there was a mini ice age that turned the continent into a dust bowl. There is ample evidence of that as well. I guess that could also have been caused by an asteroid or volcano. Very interesting lecture for a novice like. Thanks.
I’m glad we don’t know exactly why they went extinct, gives us something to look forward to when they do find out. Me personally, I think it’s a mixture of many things. I do wonder though, in 5,000 years, what proof would there be that we hunted deer, or overfished the seas??
There would be genealogical proof I think because scientists can see population declines and bottlenecks in genomes.
I can’t remember what I was watching but it talked about corrupted DNA from inbreeding in Neanderthals or dinosaurs I forget what exact subject was… but I think that’s also a likely scenario for the mega fauna at end of ice age. They split into small groups where inbreeding and corrupt dna does them in like species today, platypus etc.
Woke leftists have to dream up fake "science" to make humanity look bad. Science is now dead. They`re more concerned about perverts and rappers than scientific facts and reality. Civilization is doomed unless leftists are stopped immediately!
re-watched this today, I was a little upset about some of his facts, but seeing how it is 6years old I believe I can overlook small inconsistencies with what they teach today
Good lecture. Better lecturer! University of Washington you guy rock!
Also, I have a theory that if human did no exist, elephants and lions would have become the dominant animals due to them spreading across the world and into the Americas, and everywhere they went, they completely took over the ecosystem
Wow! I really disagree with you.
What else you got?
Let's see if we disagree about more things.
I thought this was excellent thank you !
Great lecture! Thank You!
People with spears slaughtered millions of very, very large animals, faster than they could reproduce? Yeah, no.
Now I'll have to watch Ice Age! I guess ice age researchers have done their homework to conclude that the Great Basin had a lower abundance of grasses and fruit bearing trees and other vegetation to support large herbivores in numbers. Maybe the frequency of volcanic activity disfavored sod building and disrupted the evolution large herbivore food sources? Might dig into that. Lucky students who take his classes.
The highest concentration of Clovis sites and artifacts is around the Chesapeake Bay area of Virginia, not in the southwest.
Right?!
He was talking about Clovis sites with mammoth remains wasn’t he?
What's with the adverts?. This is from a University (or was it posted privately?).
Younger Dryas, a passing comet, 12,800 years ago, wiped out half of life on earth. Some small animals escaped extinction. Incredibly some humans held on. Sorry, humans didn't extinct most of those critters.
Complete bogus. Younger Dryas is supposed to be a minor climactic event, not a comet impact. The extinction event at the time you give was only localized to the Americas (at the exact moment humans were first arriving there, funnily enough...)
@@HuckleberryHim Lol you cant say complete bogus when you say clovis were the first to come into north america which is a compete lie, plus there has been sooo much evidence piling up over the decades that supports some type of meteor/comet impacts
@@21LAZgoo You don't have to subscribe to Clovis-first to still take ~15,000 years ago to be the start of the significant peopling of the Americas. We may find more and more robust evidence for earlier occupation, but what is important to us is when this became *significant*, not just any marginal trace.
The problem with meteor/comet impacts again is that they would have been repeated localized events. You would need one to explain the Americas, another to explain Australia, yet another to explain western Eurasia, and so on. This is so ridiculous on the face of it it shouldn't even require elaboration, especially when human movements line up PERFECTLY, PRECISELY with these dates and locations.
Those events happened practically yesterday; do we still see an epidemic of meteor and comet impacts today? Just a couple of magically convenient ones a few thousand years earlier for which there is only weak evidence (in spite of their recency)? Seems like a million times weaker of a hypothesis than just humans being humans.
@@HuckleberryHim there is evidence for earlier occupation, humans were in north america at least 24,000 or more years ago. the thing with the megafauna collapsing 14800 years ago in north america is that which ever animals were in north america that were also in europe and also including some other animals collapse at that exact same time (but not complete extinctions) 14800 years ago because of their habitats changing from the abrupt warming that happened then, you probably wont accept this but theres also hueyatlaco in mexico which has a 250,000 year old carved mastodon pelvis and other 250,000 year old bones which are butchered as well, and also tools and spears which are in a 250,000 year old stratum layer but because it got covered up you will think of it as being extremely controversial. at the time of the start of the younger dryas, there is a lot of ice thousands of feet thick covering over some of the united states and also over some of europe, and there some sites that were under the ice at the time which in my opinion could be impact sites based off how they look and some dates, but because no one has really done any sampling there i cant be certain. theres lac st jean, which shows evidence for a sudden catastrophic outflow and there were microspherules found in pennsylvania which were of a specific rock type that showed evidence of being blasted into the air at temperatures of 2200 degrees C or more 12900 years ago, and the rock type is the 1.5 billion year old qubecia terrain and right in the middle of it is that crater looking lake st jean. theres also lake nipogon which shows sudden catastrophic outflows as well, although this is speculation from my part on where the bigger pieces of those impacts couldve went. the clovis culture also disappears at the start of this event, and populations of humans on all continents start declining all at the same time at the start of the YD event. so this wasn’t a minor climate event, temerpatures dropping by like 12-14 degrees Fahrenheit in a few years and collapses happening right at the boundary means this was a huge event.
@@21LAZgoo Humans had barely evolved as a distinct species/subspecies, let alone left Africa, by 250kya. That is a pretty extreme date; it could be that there is just a stubborn refusal among the mainstream of researchers to entertain these ideas, but from everything I know right now, the chances of a date this old are a big zero. I'm not closed-minded but it would be hard to believe.
What do you propose happened? A very large comet passed very close? Presumably it sounds like there were multiple impacts around the world. If this is around 15,000 years ago, it could explain American extinctions, and you say there was a European collapse, so it could explain that too. But if this was truly a global event, not only would the evidence be incredibly obvious (it happened basically yesterday, again), but it would coincide with global extinctions. Maybe it is more local and Europe and the Americas just received major impacts? South America is a pretty skinny target, did it get hit at the exact same time as North America? Does this all coincide with unrelated climatic phenomena, too, or is YD caused by this?
I still think it was in large part due to the comet strike on the glacier. This created the Carolina bays. Only seen clearly with lidar. About the diminutive size of herd animals making them not herding in behavior. I went to England in 1996, and Muntjaks had been introduced. Very small Southeast Asian deer. Obviously herding and very tiny. Picture a cat being chased by a large dog. The cat runs under a car and is safe. Safety in numbers is the answer, because the tiny deer have lots of eyes looking for trouble. The comet effected the breeding genetic diversity, and took a while to come forth after the genetic bottleneck caused by the comet.
One thing that also happens during these types of events is that the atmosphere can be literally displaced temporarily. This causes upper atmospheric gasses and partial vacuum to instantly freeze anything in it's proximity.
Imagine if you will an impact so severe so powerful that the atmosphere is literally blown away allowing the atmosphere relative to space to rapidly fill the void. Instant freeze dried Mammoth.
Cool talk. Thanks!
I downloaded this Thank you
I once heard that Mammoth wool was found in the ground and used as Barbecue meat
We have a research project that tries to answer his unanswerable questions. So far, so good. A ways to go. Lots more promising evidence that keeps us smiling. Only 150+ lines of evidence so far.
the idea that ancient humans hunted any animal to extinction with bows arrows and spears is hilarious
This dudes presentation hasn’t aged well. What a waste of his whole career !! “Clovis first” has become the biggest joke in science. guys like this literally didn’t bother digging deeper because what was the point ! Everyone knows Clovis were first. Thank the lord the anthropologists in east Africa didn’t stop digging when they found Lucy or we’d be 30 years behind in our knowledge- EXACTLY as we are with American paleoanthropology….
I think we all know what happened at this point lol not that hard to figure out but its difficult for mainstream archaeologists to come out and say it bc its too scary.
When he gets to the end, and starts dismissing extinction theories, it reminds me of why I dislike academics. The ATTITUDE with which he does it is off putting. If you're not going to take legitimate hypotheses seriously just because you disagree with them, why are you allowed to be at a university?
Has he not thought that there could be a combination of causes?
The comet that hit 13, 000 ago was a series of broken up large pieces. The main impact was across the 10,000 foot deep ice across Canada and greenland. Also smaller pieces hit across europe and the middle east. There was another comet impact 600 years later. The first impact caused rapid melting of ice which raised the oceans 300 feet almost instantly. As you see many of these animals were found dead in herds probably from the flooding. Many of the mammoths and mastodons were found with broken legs as though something knocked them over where they stood and food was found in their mouths and stomachs obviously flash frozen. Clovis hunters completely disappeared at the same time. Humans couldn't have killed millions of bison, mammoths and 75% of all large mammals in a few short years. Couldn't be done with less than a billion hunters in that time frame. Also they didn't kill the large mammals in south america, europe and africa at the same time.
And we read about the millions of tons of fossil ivory taken from millions of mammoths found washed together and exposed by modern flooding and human activity. Literally train loads of tusks were sent to markets in eastern europe back a half a century ago and a little longer. Flooding seems to best explain how thousands of these giants were found entangled together in hard deep mud.
Good lecture & presentation on such an interesting subject, but the speaker was a bit obsessed with time & constantly watching his wrist clock. I guess when some people get old, seems they start counting the minutes left in life.. I notice that alot with old people my age who wear watches.
We have the description of the upper yellowstone river from the lewis and clark expedition and it sounds like the African savanna
Disconcertingly the subtitle transcription flashes and vanishes several seconds before the audio it captures. Synchronize, please.
Thank you for uploading this.
truly splendid presentation
Very interesting & entertaining presentation, the crowd not so much.
47:00 my first thought looking at the "spear tip" stuck in the ribs, was how could they possibly generate enough force even on level ground to stick that in there?. I am aware of spear slings but still probably a mating thing
Great information great video one complaint I can’t stop looking at how uneven this guys beard is why not just shave it into a goatee or get rid of it if you messed it up that bad?
Correction:since 80s we know thare there were way earlier migration waves into Americas than Clovis culture. But of course it doesn't explain extinctions (except maybe mammoth)
Also, pointy things on plants is not always an effective defence mechanism against herbivores(see camel, giraffe)
But I guess they will preffer a plant without spikes when they are available
Great lecture! Thanks for the upload
Beautiful melodic voice
22:45 I think is Mauricio Anton not "A. Turner"
do you other videos like this one? this is super!
This was a fascinating lecture. But that messed up collar keeps distracting me.