Comment by defrost | Hacker News Reader

Comment by defrost | Hacker News Reader

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.

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

Climate-human interaction associated with southeast Australian megafauna extinction patterns

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).

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.

It sounds like you are agreeing.

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.

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?

To be fair it probably took some time to figure out methods to make mammoth steak last for weeks without refrigeration

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.

Humans do it today with steaks. 'aged' steaks are basically rotting. They are tender.

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)

I'd say not 'very different', just scale.

'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.

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.

>Scavenging spoiled meat is a fairly classic natural trait, and even apex predators won't pass up an easy snack.

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.

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 :)

[1] https://centerofthewest.org/2017/08/01/mandan-strong-spirits...

Probably approaches like jerky and pemmican.

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

Once humans figured out how to cook meat over a fire, it probably didn't take too long to figure out how to preserve meat using smoke and less heat.

Butchering and elephant and cutting down enough wood without steel or iron seem pretty hard. But I guess if you have enough people you can do it.

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.

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.

Where do we draw the megafauna line? Do gazelle count?

Apparently, yes…

> 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.

https://en.m.wikipedia.org/wiki/Megafauna

Why is 'fauna' termed as neo-latin? Is it a modern coinage?

Yeah, invented by Linnaeus to complement flora. Flora itself is only a couple centuries older.

Another theory-- there are lots of places in Africa where people cannot live due to disease (without modern medicine). This creates refuges for wildlife.

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.

You're not wrong but it's kind of absurd to expect slam dunk evidence of any kind of causal link in the archaeological record.

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.

I agree.

Side bar, paleontology and paleoarchaeology still work with the archaeological record.

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!

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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).

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