The linked nautil.us article is a one sided poor summary of what is still an ongoing debate with strong beliefs on either side.
Two people are quoted:
* Jens-Christian Svenning, director of the Danish National Research Foundation’s Center for Ecological Dynamics in a Novel Biosphere at Aarhus University. He’s also the lead author on a recent paper published in Cambridge Prisms: Extinction that argues it was not climate change but rather human hunting that caused the extinction of most megaherbivores over the past 50,000 years.
and
* Felisa Smith, a conservation paleoecologist and professor at the University of New Mexico, believes that the human impact on megafauna extinction is no longer up for debate. “I think work over the past few decades has rather convincingly demonstrated that humans had a pretty substantial part in the extinction,” says Smith.
and ... no other views are given.
This, currently, isn't a slam dunk for one side, there are strong voices on the other side who can cite examples where humans certainly ate megafauna but not, apparently, enough to wipe them out and also point at concurrent pockets (eg: Tasmania) where there were megafauna, as yet no humans, and still the megafauna died out.
Could you provide some more details about the Tasmania example? Seems humans reached Tas "at least" ~40,000 years ago from my simple searching, which isnt too far off from the generalised 50,000 mentioned in the article.
This alternative scenario of extinction is even more relevant in areas where climate was the only plausible driver of megafauna extinctions—in areas where there was an absence of temporal human-megafauna coexistence such as in Tasmania
Climate-human interaction associated with southeast Australian megafauna extinction patterns
Some megafauna were still present when humans arrived (at least two taxa) .. but most had already disappeared from the record and (IIRC) no megafauna bones found in human sites (indicating Mmmm, lunch).
I mention this only to add to your informative post. Humans almost drove whales extinct because their rendered fat produced less fat for lamp fuel, and they are substantially pelagic. We almost drove bison extinct in NA in a matter of decades. We are driving massive numbers of species across trophic levels extinct, right now https://www.theguardian.com/environment/2023/dec/29/us-anima...
It isn't a choice, climate change related habitat changes probably contributed - which is also extremely pertinent today - but when you find the extinct species bones in human habitats it's a fair sign we were a contributing and possibly decisive cause.
Whales and bison were subject to very modern techniques. While sailing whalers did stress whale populations, it was the steam launch and exploding harpoon that really did the whales in. Bison were destroyed with rifles, which are new in themselves, but the mass-slaughter behavior was enabled by rail transport. Plus they were plenty stressed by competition with cattle, bred for rail transport, and enclosure of the prairie by barbed wire.
Earlier lithic-technology subsistence whale and bison hunting doesn't seem to have been a big problem for either. I won't say that early human hunting didn't contribute to or cause mega-fauna extinctions (in fact, it seems quite likely) but that's not highly analogous to these more recent events.
I agree, but while the technology wasn't the same, the timeframes were not comparable, either. As long the rate in of the selection pressure exceeds the ability of the population to adapt, it is just a question of time.
Here's my question: if humans caused megafauna extinction, why did this not happen in Africa? That's where many of the megafauna continue to live. But humans came from Africa.
The theory is that African megafauna evolved alongside humans, learned to fear them, and developed strategies to avoid them. Whereas other megafauna didn't, so when humans left Africa, they were defenseless.
Which is the norm for invasive species. I imagine humans specifically concentrated on megafauna because, why not go after the single big easy-to-find animal that will feed your family for weeks?
I was reading an article, some time ago, about Amazon Indians that actually like rotten meat. Apparently, it is quite nutritious, doesn't hurt them (maybe acquired immunity?), and is probably fairly easy to digest (it's halfway there, already).
Scavenging spoiled meat is a fairly classic natural trait, and even apex predators won't pass up an easy snack.
There's been a decent amount of research on the relation between stomach pH and diet, with animal species that have pronounced scavenger tendencies being on the lowest end of the spectrum, which puts an interesting light on the sort of diet the earliest humans may have had.
There's an interesting bit about the Mandan tribe I've read about how dead floating bison were considered a delicacy [1]
>McKenzie observed something else as well. Once hauled from the water, the carcasses “were left for some time to Season into a flavor then carried home and at feasts are reckoned a great delicacy.” McKenzie found these ripened “float bison” revolting. But they were a delicacy – documented by many observers – for Missouri River peoples. The more rotten the flesh, the more appealing it was. “When the skin is raised you will see the flesh of a greenish hue, and ready to become alive at the least exposure to the sun,” McKenzie said, the meat, “so ripe, so tender, that very little boiling is required – the stench is absolutely intolerable.” The Indians preferred float bison “to any other kind of food.” It boiled up into a “bottle green” soup that the Mandans “reckoned delicious.” Indeed, McKenzie said, “so fond are the Mandanes of putrid meat that they bury animals whole in the winter for consumption of the Spring.”
I would love to know what kind of microbiome people have that can eat putrid meat. Or perhaps we all have that ability :)
rotting and aging are very different things. rotting is simply being consumed by fungus/bacteria, aging is a more complex process that involves controlling the liquid levels in the meat in order to make it last longer (wet aging) or taste better (dry aging)
There are fungus and bacteria in the aging process, just the temperature and humidity is controlled.
But, not sure of exact technical definition of 'rotting' is, or 'aging'. So we'd be debating different definitions.
I'd say generally both have fungus and bacteria, and 'aging' is under controlled conditions, and 'rotting' is just out in out door environment which is different temperature and humidity.
Controlled temperature and humidity makes all the difference when it comes to the speed at which bacteria can multiply. Aged meat has many orders of magnitude less bacteria than rotten one.
They perhaps had easier access to glacial melt, aka refrigeration? There’s an exhibit in the La Brea museum that shows hunters submerging mammoth meat in shallow waters as a form of preservation
And there is african extinct megafauna.for example the giant birds of madagascar whos giant eggshells inspired the bird roc in arabian folktales. I wouldnt be suprised if africa too is littered with human extinct megafauna which simply never had the reproductionrate or cleverness to keep up. Which is a great arg for the theory that one intelligent spezies breeds/uplifts all other creatures to intelligence.
Another theory-- there are lots of places in Africa where people cannot live due to disease (without modern medicine). This creates refuges for wildlife.
Somewhat speculative of course—the extant megafauna you’re referring to are somewhat endangered and but also don’t represent great sources of usable materials such as meat or skins. Additionally, many are quite dangerous — rhinos, hippos, and elephants to be specific.
> In zoology, megafauna (from Greek μέγας megas "large" and Neo-Latin fauna "animal life") are large animals. The precise definition of the term varies widely, though a common threshold is approximately 45 kilograms (99 lb), with other thresholds as low as 10 kilograms (22 lb) or as high as 1,000 kilograms (2,200 lb). Large body size is generally associated with other traits, such as having a slow rate of reproduction, and in large herbivores, reduced or negligible adult mortality from being killed by predators.
Thank you for saying this, I had the same thought. I am not a researcher in this area, but it's one I pay attention to, and I have not gotten the impression that the question is as settled as this article makes it seem.
Actually, what I should say is that I always read articles or watch videos that make it seem like a slam-dunk case from either side (human predation or climate change), which I interpret as a) signs of a contentious ongoing debate, and b) a suggestion that the real answer will be found to be a complicated interaction between these factors, and many others as well. As it is with most things, frankly.
I don't expect slam dunk evidence and that'd be an absurd projection onto anybody familiar with the paleontological record.
I do, perhaps foolishly, expect articles in the science domain, even if PopSci, to not behave as if a single recent paper in a field is the only paper of note and one that definitively sews up an ongoing debate.
I'd hope such an article would at least mention other equally recent papers that have both parallel and opposing views.
Darwin (1) near consistently included each and every argument & counter-argument to the point where it becomes boring and unreasonable to go any further (2) was absolutely explicit of what was NOT included to the point that there were redunant remarks about that!
---
The view of Smith is laughable, for the human population has changed by more than few orders of magnitude since those times.
Yet it would be plausible that a global MF ecosystem was distrupted somehow.
Another possible reason megafauna died: they eat plants and grew on top of an ecosystem where there was not much competition for plants, and then an increase in efficiency of bacteria, bugs, invertebrates and other compact herbivore species in consumption of the limited amount of plant food pulled the legs under them. Whales were not herbivores, and possibly therefore not subject to same mechanisms (though saying this sort of ruins the metaphor of pulling legs from underneath).
> Defined as large-bodied terrestrial mammals with a mean adult body mass of 2,200 pounds or more, today’s remaining megaherbivores comprise the likes of elephants, rhinoceroses, giraffes, and hippopotamuses.
Was there difference in hunter-gatherers in europe/asia/americas compared to africa? Why hadn't the ancient elephants, giraffes, etc been hunted to extinction?
> I think work over the past few decades has rather convincingly demonstrated that humans had a pretty substantial part in the extinction
A substantial part in the extinction? What does that mean? The extermination of the buffalo in the US required industrial scale resources ( guns, railroads, etc ) along with the migration of millions of europeans and habitat loss ( via farming ). It was a conscious and intentional effort. Are they claiming something similar happened throughout much of europe, asia and americas more than 50,000 year ago?
> “When we restore forests, we can’t just think about the trees,” he says. “We must think about the animals that belong there.”
This. The most devastating blow for the buffalo, wolves, bears, etc was habitat loss. It was ultimately what did them in. Did ancient hunter-gatherers alter their environment to such a degree to wipe out herds of giant animals from entire continents?
I have a hard time believing that hunter gathers in tiny tribes traveling on foot with primitive weapons could have hunted and wiped out entire species of large animals from continents. I wish they would give more specifics.
> Was there difference in hunter-gatherers in europe/asia/americas compared to africa? Why hadn't the ancient elephants, giraffes, etc been hunted to extinction?
Consider that African megafauna have co-existed with early hominids and eventually humans for millions of years. They may have simply adapted to human predation successfully enough to survive, as one factor.
Whereas in North America and elsewhere you have the sudden (on the evolutionary time scale) arrival of Homo Sapiens who are likely already very skilled and advanced hunters among a population of prey animals that have never experienced such a predator.
It’s also possible that in tandem, climate change was less severe in Africa than elsewhere over the last 50k years.
Interesting though, that seemingly unlike North America's Mammoths and Mastodon's, African Elephants never became a concentrated target for hunting enough to be driven into extinction.
Though that may just argue that they were unable to adapt to climate change in NA fast enough rather than being hunted to extinction.
Whereas in North America and elsewhere you have the sudden (on the evolutionary time scale) arrival of Homo Sapiens who are likely already very skilled and advanced hunters among a population of prey animals that have never experienced such a predator.
On some islands off the Northern coast of BC, there are dwarf deer that locals just walk up to, and smack on the head with a baseball bat. Right or wrong, it sort of highlights the point.
Right, we're a native species to Africa, so its whole ecosystem evolved with us.
I think of this when I hear about "poachers" killing animals in African nature reserves. How often is that hunter gatherers who been there for thousands of years, and whose hunting is/was really part of the ecosystem?
They also start breeding at < 2 years, can have multiple litters per year of 10+ piglets. Rhinos mature at 5 years (10 for males) and the gestation period for a single calf is 15 months.
Seems like there isn’t a strong definition for “megafauna.”
In zoology, megafauna (from Greek μέγας megas "large" and Neo-Latin fauna "animal life") are large animals. The precise definition of the term varies widely, though a common threshold is approximately 45 kilograms (99 lb), with other thresholds as low as 10 kilograms (22 lb) or as high as 1,000 kilograms (2,200 lb).
Not a strong definition but still sufficient to exclude squirrels and even wild pigs are on the very low end.
You raise a good point as I would have expected “mega”fauna to have implied hundreds of kilograms at least. Under 100 and as low as 10 kg seems to take away any true meaning from the label.
Open season has been now called for wild "super" hogs in some areas, and that makes a difference. Pregnant sows, young hogs are now OK to kill any time in these areas.
Hunting 1000s of years ago didn't include "don't kill the pregnant animals, or children". It meant "I'm hungry" and "food".
Not all megafauna are herd animals on the scale of American buffalo. Others were limited to smaller areas or less numerous to begin with, and the ones that survive are probably those that started off most numerous. African elephants are hanging on by a thread, relative to their original number they're down something like 98%.
Africa is also _huge_ - around four times the size of the entire continental USA - and suffered perhaps less during the Ice Ages than Northern America or Eurasia, where megafauna would have been squeezed by both the ice - and associated climate changes further south - and a hungry and increasingly innovative human population.
> I have a hard time believing that hunter gathers in tiny tribes traveling on foot with primitive weapons could have hunted and wiped out entire species of large animals from continents
One thing humans could was starting fires that would drive many animals into a designated killbox, among other ways of "cheating". Humans were uniquely capable (at this size scale, at least) to both hunt species in excess to their need and cause outsized damage to their habitat in the process.
The default is to outpace your need. Imagine if we evolved to somehow hunt just enough meat. There’d be some of us with less efficient systems for controlling that behavior that end up starving while they think they are bringing in enough food. Thats no good for reproductive fitness. Overshooting on the other hand is good.
Another factor, symbiotic relationships tend take much longer to evolve that carefully balanced relationship between symbiont and symbiont. Parasitic relationships tend to evolve sooner and its also not uncommon the parasite overshoots and kills off its own host.
You are of course correct. In North America at least though, I do not believe many people are confused. The term “buffalo” is used much more commonly than “Prarie Bison”. I am not defending it but it is ubiquitous to the point that everybody knows what people mean when they say “buffalo”.
If somebody said “buffalo” to me, I would assume they meant bison ( unless I had additional context ). If they meant Asian or African buffalo, I would expect them to say “water buffalo”.
Again, I am not arguing what is correct. I am commenting on what I think people, as a group, understand.
True for the American bison (as far as I know), but there used to be a bunch of species in Eurasia which went extinct or had their range dramatically reduced as part of the broader extinction of megafauna discussed in the article.
Thinking out loud… I wonder if it could still be true based on the fact that the larger the animal, the longer the gestation period.
For small animals like rabbits, it’s about 30 days - so their chances of “multiplying like rabbits” is obvious - you’re not going to wipe out rabbits faster than the supply.
As you move up the size scale, the gestation period gets longer and longer, and each kill gets harder to replace (wales come in at around 18 months!). Kill a mega-sloth and its chances of species survival dramatically drop!
They don't know any particular specifics. Our understanding of human organization during the late pleistocene and early Holocene is poor, bordering on non-existent. However, I don't find it particularly hard to imagine humans as a major factor, even if I have some doubts about this particular argument.
First, you have to understand that about the late quaternary extinctions, we know not all quaternary extinctions were anthropogenic. Ecosystems were experiencing a lot of different stressors around that time, and by the time extinction actually happens there may have been only small populations left for centuries or millennia. Ecological resilience is also a bit of a funny thing. You might think that you make 10 species extinct has 10x more impact than just 1 extinction, but there isn't a linear relationship. In many ecosystems, there's very little impact from most local extinctions as the graph thins out until all the systemic resilience is gone and the whole thing suddenly collapses into a new state. Did that proximate cause(s) of the last extinction cause the rapid shift?
Fantastically deadly hunters like humans that are specialized to megafaunal hunting being able to push the most vulnerable and stressed parts of the ecosystem over the edge isn't an obviously absurd argument to me.
> I have a hard time believing that hunter gathers in tiny tribes traveling on foot with primitive weapons could have hunted and wiped out entire species of large animals from continents. I wish they would give more specifics.
This made me recall having read something related to it in the book Sapiens [1]. Indeed, I went looking and quoting from chapter 4
> All the settlers of Australia had at their disposal was Stone Age technology. How could they cause an ecological disaster? There are three explanations that mesh quite nicely.
> Large animals – the primary victims of the Australian extinction – breed slowly. Pregnancy is long, offspring per pregnancy are few, and there are long breaks between pregnancies. Consequently, if humans cut down even one diprotodon every few months, it would be enough to cause diprotodon deaths to outnumber births. Within a few thousand years the last, lonesome diprotodon would pass away, and with her the entire species. [...]
> The second explanation is that by the time Sapiens reached Australia, they had already mastered fire agriculture. Faced with an alien and threatening environment, they deliberately burned vast areas of impassable thickets and dense forests to create open grasslands, which attracted more easily hunted game, and were better suited to their needs. They thereby completely changed the ecology of large parts of Australia within a few short millennia. [...]
> A third explanation agrees that hunting and fire agriculture played a significant role in the extinction, but emphasises that we can’t completely ignore the role of climate. The climate changes that beset Australia about 45,000 years ago destabilised the ecosystem and made it particularly vulnerable. [...]
So the extinction was on a very different timescale from your buffalo example, but an extintion nonetheless. In the ellipses the book briefly points to some evidence to support these theories.
> Was there difference in hunter-gatherers in europe/asia/americas compared to africa? Why hadn't the ancient elephants, giraffes, etc been hunted to extinction?
One theory is that they gradually adapted as humans developed.
Once humans spread out to other continents the change was too rapid for the megafauna on those continents to adapt.
Also there were megafauna extinctions in Africa, just over a longer period of time. Then humans expand out of Africa, and within a few tens of thousands of years most of the extra-African megafauna are gone.
>I have a hard time believing that hunter gathers in tiny tribes traveling on foot with primitive weapons could have hunted and wiped out entire species of large animals from continents
last mammoth died just 4000 years ago on an Arctic island - i.e. without humans they survived far longer even in pretty harsh conditions.
> Was there difference in hunter-gatherers in europe/asia/americas compared to africa? Why hadn't the ancient elephants, giraffes, etc been hunted to extinction?
They are guessing. Probably a ton of compounding factors rather than a single one. Ice age (probably a big one for anything not in Africa), hunting, habitat compression, food competition, etc. I'm also guessing :)
One idea I had a while back is this: with all our modern technology in stem cell research, gene modification and cloning, shouldn't it be possible to recreate actual living clones from prehistoric dinosaur DNA? I mean, sure, these giant wild animals could potentially become dangerous, but how about we confine them to a remote island or so?!
Good idea, like a park of something? The most difficult part would be naming it. You could go for something like Cretaceus Park, but it doesn't sound too good.
Oh, a park! Like, where people come and can look at the creatures for an entrance fee? Yeah, sure why not. Also like your naming idea, perhaps something a little catchier?
Imagine a new generation of kids that likes dinosaurs and can actually see them roaming.
Can't wait to see the look on their faces when I tell them that I was into dinosaurs when they were still underground
One thought I always had about reviving prehistoric animals is that I feel we've come to understand that animals live in a symbiotic relationship with microorganisms. Some even have specialized diets. Then there's the so called epigenetics. So besides the missing microbiota there may be other factors that are missing and can't easily be recreated.
Coming from the other direction, there's a book about all the plants that were dependant on megafauna for processes like seed dispersal that are sorta hanging around still called "The Ghosts of Evolution".
The (Nautilus) article is confusing in the way it conflates "megaherbivores" (herbivores weighing more than 1 [metric] ton) and "megafauna" (any animal, regardless of what it eats, weighing more than 45 kg[1]).
Also: "Giant ground sloths, musk oxen, and short-faced kangaroos: All have gone the way of the dodo" -- A) Of those three animals, only the giant ground sloth was big enough to qualify as a megaherbivore; and B) musk oxen are very much not extinct!
[1] Which I assume is a translation of an older definition using 100 lb as the lower limit.
It's always seemed patently obvious to me that humans were the primary cause of megafauna extinctions. First and foremost because the timing of extinctions aligns so closely with the arrival of humans in a given region, but also because the climate has changed dramatically over the past few million years or so, with cooler or warmer periods happening frequently over geological timespans, yet we don't see similar extinction events happening around climatic cycles / events other than those that happen to align with the arrival of humans in a given region. The Mammoths of North America for example survived numerous cycles of warming and cooling, some far more drastic than the most recent ice age and subsequent warming period, so why was it only the most recent one that caused their extinction? We already have control data for the effect climate had on megafauna populations, the only variable left is us humans.
This is not about assigning blame, says Svenning. “People who lived thousands of years ago never had access to the full picture. These things took place across long time scales and big spatial scales over which no one had an overview; whatever people did, it was difficult to see the consequences. Plus, of course, people just had to survive the best they could.” - lol even
This guy (https://www.youtube.com/@Antonio_Zamora) makes a very solid argument that in the Younger Dryas a meteorite impactor hit the ice sheet over the Great Lakes, sending huge ice chunks flying that created elliptical craters that then quickly refilled that are called the Carolina Bays, and which are ubiquitous in the South East, and which point back at the impact point(s) (I think he says there were two impact points) in Michigan. The amount of energy delivered by all those ice chunks seems to have been several megatons (of TNT) per square mile. Enough chunks were ejected, and carolina bays formed, to have likely caused an extinction event.
There's a real danger in getting misinformation from YouTube channels. The Younger Dryas Impact Hypothesis has been extensively refuted multiple times. The latest such paper (https://doi.org/10.1016/j.earscirev.2023.104502) is pretty exhaustive in exploring the history of these ideas and how they fall short.
"A series of publications purport to provide evidence that..."
So even published papers contain such "misinformation", it isn't specific to Youtube. I have no training in the areas of archaeological evidence, so I don't know what to make of the paper, but it looks like people are just arguing about evidence of whether there was an asteroid impact.
It's interesting though that the title of the paper is called "Complete Refutation" of the hypothesis and not of the evidence. If you're nit-picky enough you'd notice that the YDIH isn't a "scientific" hypothesis per se since hypotheses about what happened in the past doesn't really give testable predictions, and actually what they did in the paper was to refute all the evidence of the hypothesis -- but it seems to me it's still theoretically possible for new evidence to come up that definitely supports YDIH.
Also, AFAICT this only rules out the asteroid impact. It still doesn't rule out the possibility that the abrupt climate changes during the Younger Dryas causing stress to the megafauna population, which presumably is another thing.
My comment was responding specifically to the parent comment about the impact hypothesis, not the overkill hypothesis in TFA. The title is a bit sensationalist, but I get the impulse for gimmicky titles.
My reading of the paper was that it attacks even the need for there to be any special explanation for events around that time period as the 'evidence' for something major happening, from impacts to global wildfire, is simply missing.
You clearly didn't even take a look. Zamora is not a run of the mill YouTube loony but a published academic. I'll look at the paper you linked, but you should look at Zamora's papers too.
I only see one paper linked on the channel, which is a substandard paper in a low impact journal. Beyond that, his website documenting his independent research also includes sections on the occult and psychic phenomena. What did I miss?
I'm still digesting the full paper [1] but it looks like the gist is that when you put all the previously published data together, the timing of megafauna extinction statistically lines up with human arrival better than climate change.
The most important pieces of evidence they seem to look at is fungal spores in fossilized poop and sedimentary ancient DNA:
> Further, other studies show contrasting patterns. For example, a sedimentary ancient DNA (sedaDNA) study from the Yukon shows strong megafauna decline between 21 and 14,500 years ago, prior to the loss of the mammoth steppe biome and the Younger Dryas. In addition, as already mentioned, many extinct megafauna species have last occurrences in the Early or even Middle Holocene, that is, during the relatively stable climate of the Holocene, meaning that a climatic cause for their extinction is unlikely given their previous survival through numerous, massive climatic shifts throughout the Pleistocene, including long and warm interglacial periods.
> An increasing number of studies look at local and regional dynamics in the overall abundance of large herbivores at high spatiotemporal resolution using dung-associated fungal spores. Many of these are able to pinpoint declines to timeframes where the climate was stable, for example, North America ~14–13,000 years ago, prior to the Younger Dryas cooling, and 41,000 years ago in Australia at a time of no substantial climate change
These techniques are still very new and they're so sensitive that they should be taken with a grain of salt, sedaDNA especially since it amplifies tiny snippets of DNA found in permafrost. We assume permafrost behaves like an annually laminated sediment but that's controversial and archaeology/paleontology have had plenty of problems before with DNA snippets and contamination.
Two people are quoted:
* Jens-Christian Svenning, director of the Danish National Research Foundation’s Center for Ecological Dynamics in a Novel Biosphere at Aarhus University. He’s also the lead author on a recent paper published in Cambridge Prisms: Extinction that argues it was not climate change but rather human hunting that caused the extinction of most megaherbivores over the past 50,000 years.
and
* Felisa Smith, a conservation paleoecologist and professor at the University of New Mexico, believes that the human impact on megafauna extinction is no longer up for debate. “I think work over the past few decades has rather convincingly demonstrated that humans had a pretty substantial part in the extinction,” says Smith.
and ... no other views are given.
This, currently, isn't a slam dunk for one side, there are strong voices on the other side who can cite examples where humans certainly ate megafauna but not, apparently, enough to wipe them out and also point at concurrent pockets (eg: Tasmania) where there were megafauna, as yet no humans, and still the megafauna died out.