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Our Early Ancestors Stalked Eight-Foot-Tall Sloths
- baxtr 9y agoWe have a “great” history for killing all big animals. So sad. But I guess they’ll grow back once we’re gone https://www.theatlantic.com/science/archive/2018/04/in-a-few-centuries-cows-could-be-the-largest-land-animals-left/558323/ https://www.theatlantic.com/science/archive/2018/04/in-a-few...
- twodave 9y agoWe have been in competition with the animals on this planet since we arrived. Commercialization has certainly caused some avoidable consequences to animal populations, and I agree we ought to take care of the earth as well as we can, but I just can’t get worked up on the animals’ behalf over our ancient ancestors killing them and using basically every part of the carcass in an effort to survive.
- titzer 9y agoOh don't worry, no one is expecting you to get worked up about it. It's just that we all tend to have this attitude that we are the pinnacle of nature's great evolutionary process, when pretty much all evidence suggests we're a bunch of bastards to most life on Earth--and each other, incidentally. Go humans?
- komaromy 9y ago> pinnacle of nature's great evolutionary process > bunch of bastards to most life on Earth seem almost synonymous, unfortunately.
- titzer 9y ago> seem almost synonymous, unfortunately. This is what I disagree with. Evolution is not a process that is maximizing anything. What survives just survives. We got stuck in a feedback loop that optimized brain size for evolutionary fitness, but we're stuck in a tiny fractal corner of a corner of a corner of the entire space of biological life. E.g. Tardigrades (https://en.wikipedia.org/wiki/Tardigrade https://en.wikipedia.org/wiki/Tardigrade) are extremely successful at survival in a huge variety of conditions, and very stable over millions of years without a lot of genetic drift. Similar for cockroaches. We don't consider these "pinnacles" of evolution just because of our arbitrary value system. Yet cockroaches (and all insects, really) serve extremely important jobs in ecosystems which would collapse without them. Humanism is blind and immoral, IMO.
- tome 9y ago> Humanism is blind and immoral That's a judgement that a human can make only because our species reached the pinnacle of evolution.
- nkrisc 9y agoI assume by "pinnacle of evulution" you mean the currently most successful species in terrestrial ecosystem on the planet Earth. Surely there is no "pinnacle" to all of evolution, whatever that would even mean. You seem to be implying that evolution is a process with some ideal, perfect outcome that can be achieved, or you're just being sarcastic. I can't tell but both are silly.
- tome 9y agoI didn't introduce the word "pinnacle" to this debate, titzer did. I just thought it was ironic that he/she was using his/her moral judgement to criticize the human species in such a way.
- titzer 9y agoI introduced it as a strawman, just trying to be terse. You embraced it to say that we must be at some kind of pinnacle to be able to make moral judgments. I started by pointing out facts; despite the perjorative term "bastards", it's pretty undeniable that humans have pretty much decimated every other form of life that is either a competitor or not a domesticated food source. As for "blind", that's not a moral judgment, whereas "immoral" clearly is. I admitted that both are my opinion, not fact.
- adrianN 9y agoAll creatures try their hardest to out-compete everything else. It's just that we're very good at it. On the other hand, we're also pretty much the only chance for terrestic life to survive the end of our solar system.
- nkrisc 9y agoThere is a lot of time for better chances to come along. Depending on the estimate, we're not yet halfway through the lifetime of the sun, that's plenty of time for a more successful successor to humans. And the Earth didn't even exist for much of the first half of the sun's lifetime.
- adrianN 9y agoThe lack of alien contact suggests to me that technological civilizations don't appear very frequently. So I'm afraid that we're somewhat of an evolutionary aberration and if we'd go extinct a replacement wouldn't arise.
- titzer 9y ago> All creatures try their hardest to out-compete everything else. When we take a wider look at life, this just isn't universal. If you look at ecosystems in very stable environments (e.g. caves), the ecosystem as a whole tends to come into balance over time, where species are not aggressively try to outcompete their competitors, but instead fit into comfortable little niches so that the system as a whole keeps functioning well. In fact, evolution works on the ecosystem scale as well, and systems with aggressive species tend to be very unstable and prone to crashes. In environments with constant change, then ecosystems are constantly changing and competition becomes more fierce, benefiting aggressive species. This is not always the case, so I don't think it's useful to assume that everything is trying to move as aggressively as possible; otherwise evolution would select against species with long gestation periods and tend towards shorter generations and faster growth.
- jessaustin 9y agoThere isn't any particular reason to privilege caves or other "stable" habitats. This is an incomplete understanding of them, anyway. Because caves are nutrient-poor, it is common that all animals there are extremely lethargic. That is not the same as lacking aggression or competition. Cave animals strive to survive as fiercely as anything in the jungle, just at a much slower pace. If a more active predator were to be stranded in a cave, it might eat everything it can find in a week, and then starve. Within months, other animals from more remote corners of the cave would scavenge its carcass and repopulate. To visualize this, watch one of those speeded-up videos of starfish and sea urchins. At our pace, they are sedentary. At their pace, it's Thunderdome all day every day.
- twodave 9y agoAs a human, I want humans to have great lives. Part of that means taking care of your things. People like to say, "The Earth doesn't belong to us, we belong to the Earth," but I would contend we are best equipped to take care of it, and it's for our own benefit. Taking ownership of the little piece of it we interact with on the daily isn't all that daunting of a task.
- defen 9y agoBig animals that evolved alongside us (elephants, lions, hippos, etc) have not been wiped out. Most of the North American big mammals got wiped out because they were suddenly exposed to human big-game hunters who had been hardened by thousands of years of living in the Siberian wastelands. Those North American animals didn't have the benefit of a long genetic memory telling them that the soft hairless ones are actually the most deadly predators on the planet...
- code_duck 9y agoHunger will make you do some crazy things. I can only imagine the feeling in a Paleolithic society when your group succeeded in taking down something like a mammoth - it’s like completing a major contract which will have your whole family living well for months. A prey animal is naturally as important a resource for humans as it is for a tiger. Of course, like many ancient traditions this looks completely different in modern times.
- gruglife 9y agoBig foot did exist
- MarkG509 9y agoBut, when did Sloths lose their energy? I have seen videos[1] of Sloths crawling/slithering slowly across a road, and cannot imagine they were ever a formidable or challenging target for (pre-)humans. [1] https://www.youtube.com/watch?v=ES32UFlPOUA https://www.youtube.com/watch?v=ES32UFlPOUA
- nkrisc 9y agoI don't know the answer to your question but I wouldn't compare modern sloths to ancient ones. They're each adapted for completely different environments.
- oregondan 9y agoThat's exactly the point of the question, though: when/how did sloths transition from "ancient" to "modern"? If ancient sloths were massive and formidable prey, as per the article, what happened? Were there always smaller and/or slower sloth varieties, and we just killed all the giant ones? EDIT: As always, Wikipedia comes through [1]. There were species of different sizes, with tree sloths always being smaller than ground sloths [2], the giant of the article [1] https://en.wikipedia.org/wiki/Sloth#Evolution https://en.wikipedia.org/wiki/Sloth#Evolution [2] https://en.wikipedia.org/wiki/Ground_sloth https://en.wikipedia.org/wiki/Ground_sloth
- dexen 9y agoAlternatively it could be argued that increasing temperatures and abundance of food favored smaller animals (including our very low-tech ancestors), which pushed the proverbial mammoths out of their ecological niche and into the oblivion. The smaller the animal, the larger skin_surface:body_mass ratio, thus higher heat loss. The smaller the animal, the shorter the intervals between feedings it can tolerate. A large-bodied animal can go for longer period of time without food, especially if equipped with slow metabolism. In contrast, smaller body and faster metabolism requires frequent feeding, but also allows an animal to out-compete slower, larger ones both in food search, and by out-breeding them. For any given body plan, an animal can only cover distance roughly relative to its body size; the smaller animal, the harder time it will have to find sufficient food on sparse, hardy cold-climate vegetation. On the other hand, once denser, warm climate vegetation takes hold, it allows smaller herbivores to live in higher density, and with higher breeding rate. If I remember my biology right, the more an animal has specializations for particular environment or niche, the slower it will adapt to changed circumstances, both in body build, and in behavior & seasonal migration patterns. Last but not least, a predator population requires certain density of prey to be sustainable. Once plant food becomes abundant due to warming up, and herbivore population grows, the population of predators can be established, and cull the large bodied animals unadapted to heavy predation.
- cmrdporcupine 9y agoWell, sure, I'm sure climate changes helped push North American megafauna populations over the edge -- except the TFA speaks specifically about archaeological evidence of specific hunting events, including human foot prints following giant sloth foot prints in a pattern which implies stalking and hunting and even the sloth rearing up to defend itself.
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- stevecalifornia 9y agoThe reason we believe that humans wiped out the mega-fauna is because the megafauna of North America all disappeared within a millennia of humans arriving from the land-bridge. It's possible they all coincidentally disappeared but unlikely.
- haZard_OS 9y agoLike the Kangaroo, the giant sloth build can be considered OP when played on specific maps (which are themselves limited to specific servers). https://youtu.be/TrsaXzmqShM https://youtu.be/TrsaXzmqShM
- anon949714 9y agoThere is decent evidence recently on a possible astroid impact and massive "flood" overland tsunami from the Arctic. https://en.wikipedia.org/wiki/Younger_Dryas_impact_hypothesis https://en.wikipedia.org/wiki/Younger_Dryas_impact_hypothesi...