What Happened to Ancient Megafauna?
nautil.us
nautil.us
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.
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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).
Which species went extinct before then?
https://www.sciencedirect.com/science/article/pii/S030544032...
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
Nature Communications, 22 November 2019 https://www.nature.com/articles/s41467-019-13277-0
Discussed by authors: https://theconversation.com/did-people-or-climate-kill-off-t...
A better paper than your find that directly addresses the gap|overlap in Tasmanian megafaune|human record is:
Man and megafauna in Tasmania: closing the gap Quaternary Science Reviews (Jan 2012)
https://sci-hub.ru/10.1016/j.quascirev.2012.01.013
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).
Scavenging spoiled meat is a fairly classic natural trait, and even apex predators won't pass up an easy snack.
'Controlled' rotting.
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.
It has to be said that humans in particular have stomach acidity on the levels of scavenger type meat eaters.
https://journals.plos.org/plosone/article?id=10.1371%2Fjourn...
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.
>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 :)
[1] https://centerofthewest.org/2017/08/01/mandan-strong-spirits...
> 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.
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.
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.
Hunting pressure on already distressed species ( due to climate change ) over long periods of time seems like a likely explanation.
The complaint is not that humans were not a factor but rather that we were not the only one.
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 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.
Side bar, paleontology and paleoarchaeology still work with the archaeological record.
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.
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.
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.
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?
Hunting 1000s of years ago didn't include "don't kill the pregnant animals, or children". It meant "I'm hungry" and "food".
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).
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.
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.
It is this imho Animals in Africa are more scared by the sounds of people than lions.
https://www.nhm.ac.uk/discover/news/2023/october/human-voice...
And the bigger ones like Hippos are hyper aggressive to humans, allegedly they kill more people than any other African animal.
Though that may just argue that they were unable to adapt to climate change in NA fast enough rather than being hunted to extinction.
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.
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!
Wasn't the most devastating blow to Buffalo the campaign by settlers to slaughter them, since they were important to the native Americans?
Bison are in North America while buffalo (small b) are in Asia and Africa.
>Wasn't the most devastating blow to Buffalo the campaign by settlers to slaughter them
I hope everyone in the city of Buffalo, NY are OK lol
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.
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.
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.
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.
last mammoth died just 4000 years ago on an Arctic island - i.e. without humans they survived far longer even in pretty harsh conditions.
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.
[1]: https://en.wikipedia.org/wiki/Sapiens:_A_Brief_History_of_Hu...
Elephants and rhinos do survive in Asia.
A huge issue with "Jurassic Park" style cloning is that old DNA degrades very quickly
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.
"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.
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.
[1] https://www.cambridge.org/core/journals/cambridge-prisms-ext...