I highly recommend the book "Ghosts of Evolution" about the lingering effects of these extinct megafauna on our lives today. Many of our ecosystems and even many species evolved in response to their presence.
A major theme of the book is how many of the fruits we see today (especially avocados, osange oranges, honey locust pods, possibly mangoes and many other large fruits) originally evolved to be eaten by megafauna. The idea is they would eat the fruit whole and swallow the pit, and poop it out somewhere. Evidence for this is that many of the trees have defenses against non-megafauna eating the fruits, or others have out-of-proportion defenses against any living animal today, the fact that many pits will only grow if they have been scoured (for example by the digestive system of an animal), and that the pits often seem over-defended, and the fact that many of these fruits are not eaten by any living animals and often fall from the tree and rot in place.
This article is poorly written, bringing up Paraceratherium is disingenuous considering they went extinct 23 mya. It took 400 years after Columbus for the American Bison population to drop to near extinction, not 70 years.
Yes, I assume the bison of the Great Plains were somewhat nonplussed when Christopher Columbus landed on an island in the Caribbean.
The point being that Columbus is not the relevant marker, even though the article brought him up. In this sense the GP comment has a point, that's bad writing.
It is interesting that the bison continued to thrive (until the 1800s), and I guess I never thought about why they outlasted the Ice Age/predation thing that killed off the other large animals.
I'm curious. How do you figure the natives killed off all the tens of millions of megafauna given that extinction occurred when they had just arrived over the bering strait, numbering a few thousand across north and south america?
I read the summary reports by experts, and that's their explanation (incidentally, I'm not sure about counts, but "tens of millions" sounds high for most megafauna species -- their small numbers is part of their survival problem).
If I remember right, the last time I read this story was at the elephant exhibit at the San Diego Zoo, or perhaps the standing exhibit at the La Brea Tar Pits. I'm just an interested outsider, so that's good enough for me.
IIRC, the whole Bering Straits story is itself more complex than I learned in grade school. It was open longer, and was wider and bigger than originally thought. I believe humans came across in several waves that are genetically or archeologically separable. I read a lot of stuff in Science, and remember about 20%, and 50% of those memories are part-wrong, so take this with a grain of salt. ;-)
Brazil has a bunch of archeological sites much older than the last land bridge on the strait, of course several historians go histerical with the mention that prehistoric humans might have crossed the pacific by boat, so to them only the strait idea is valid and south american paleontologists are liars...
Or they just say that humans arrived here by unknown means, anyway we have 40.000 year old settlement sites, 40.000 years is time enough to extinguish whatever you want even if your population is in the hundreds...
I think some facts got mixed up. Perhaps they were talking about 70 years after America was founded? Still doesn't seem accurate.
Most of the interior US, especially the west, wasn't accessible until the rail roads came. It was my understanding most of the mass buffalo hunting was because of the railroads.
Agreed; the '500 remain' number seems to be most applicable to the beginning of the 20th century, which isn't really '70 years' from any historical milestone. (Google "500 buffalo remained", with quotes).
If you're wondering how overkilling can happen, the Romans killed 9,000 wild animals (lions, bears, etc) in one day during an opening event for the colosseum. And proceeded to sport kill thousands after: https://en.wikipedia.org/wiki/Colosseum
I can imagine exotic and big game has been the prime target of humans for a very long time.
I am inclined to give the benefit if the doubt in the whole " The only place megafauna has survived to some extent to the present day is in Africa where people traditionally have lived in harmony with nature". In many hands that would be hippy happy pseudo racist claptrap. And it might be but the next paragraph points to the more realistic "harmony with nature = avoiding humans"
I have severe doubts about the overkill theory - the fossil record is fairly sketchy and so many species died out within a few hundred thousand years of us arriving on the scene that exact timings are hard to believe. On top of which the practicality seems a bit hard - I can accept that some creatures might be defenceless against men and spears (giant sloths seem likely to lose out) but I am going to struggle seeing sabre tooth tigers as easy prey for man.
Climate change, Eco system collapse and diseases carried by apes and their dogs seem to hold the occam razor prize for most likely explanations. A spear through the kidneys would just be making a bad day at the office worse for megafauna.
"The only place megafauna has survived to some extent to the present day is in Africa where people traditionally have lived in harmony with nature."
Bullshit.
From what I understand it's attributable to megafauna evolving alongside humans as they emerged in Africa. They had time to "learn" how to survive in the face of this new predator. In places like North America humans slaughtered and multiplied faster than their prey could adapt.
Though by many standards I could be considered an environmentalist, I find the "harmony with nature" trope to be laughable. Nature is not harmonious; it is a vicious battle of killing, eating, and survival. We should absolutely preserve and protect our environment. We can never live in "harmony" with something that is far from harmonious.
I likewise find the "harmony with nature" idea to be laughable, but for a very different reason. If "nature" has any meaning at all, then we are part of it. Other animals are perfectly happy to change their situation to their benefit. Beavers, for example, can create lakes by choking off rivers. Are they living "in harmony" with nature? That feels like a strange question to me, and so I wonder why it shouldn't feel like a strange question when the beavers are replaced by humans.
Beavers, in some sense, must, because their impacts have had plenty of time to get back at the beavers if it was going to. That doesn't mean they didn't ruin it for some other species.
It's kind of the idea that the most successful parasites can't kill their hosts too efficiently or quickly, because then they run out of places to live. If you screw up your environment like that, it'll come back to haunt you.
Animals without a natural check on their population and resource consumption can also experience a population boom followed by a sharp decline and even collapse, possibly extinction.
I wonder, could you create a closed form of the final solution by allowing only a portion of the nonrenewable resources to be consumed? At least, this should remove the sudden discontinuity in the slope of the nonrenewable resources function.
> I wonder, could you create a closed form of the final solution by allowing only a portion of the nonrenewable resources to be consumed?
You may not be surprised to hear that that was my original, much desired goal, but after much thought and experiment I realized that the abrupt discontinuity caused by the exhaustion of the nonrenewables is real, for the reason that, in practice, the rate of nonrenewable use increase as their exhaustion approaches, creating an abrupt knee that resists conversion to a closed form.
> At least, this should remove the sudden discontinuity in the slope of the nonrenewable resources function.
But that abrupt end to nonrenewables is real -- it reflects the fact that the growing colony becomes increasingly reliant on them as their exhaustion approaches. So the knee can't be removed without changing the meaning of the equation.
Oh, well -- as it turns out, there are many very common differential equations that resist conversion to closed form. Orbital systems with more than two bodies are a classic example. Another one is the integral to the common exponential function that gives us the normal distribution -- very commonly used in statistics and elsewhere, but no closed form. All applications of the normal distribution use a numerical algorithm called the "error function" to produce results -- all of them approximate, and having the drawback that they cannot be symbolically differentiated or integrated.
Maybe a much more skilled mathematician that I am could find a way around this obstacle, but I doubt it.
The concept of harmony can refer to lions not chasing gazelles, which is certainly unrealistic , but it can also mean sustainable and balanced. Nature is certainly vicious and ever changing, but there is a balance in the bigger picture, and man is making (or let's say, is at risk of making) excessively disrupting changes. If that's the meaning, that's certainly not laughable.
The notion of "nature in balance" is selection bias. There are certainly places where nature is not sustainable and balanced. Look for example at what happens with the introduction of invasive species (which may happen these days because of humans, but I imagine the opening of the Bering's Strait land bridge would have lead to a similar disruption.) Pre-human nature only appeared balanced because it had had a long time to equilibrate, not because of some innate quality.
Normally, I considered "harmony with nature" to be roughly equivalent to "Nash equilibrium that won't make human extinct". In other words, human has to make way for "nature" (to a certain extend), or risk being wiped out in the long run.
Nature will always be fine, whether humanity as we know it survives is the problem.
I was watching Survivorman the other day and he said something along the lines of, "I don't live in harmony with nature. I fight nature every day in order to survive."
Africa has historically had much lower population density, well below Malthusian limits. Less population pressure from humans may have contributed to the survival of megafauna.
The lower population pressure in Africa is a reflection of parasites that evolved with humans there. By escaping from Malaria carried by African mosquitos and parasites carried by tsetse flies and the like humans lived longer, more fertile lives. The resulting population pressure outside Africa let humans kill the megafauna.
The lower population density in Africa wasn't some kind of harmony, it was a result of awful disease.
Now that many diseases are under control, Africa's population is exploding in a region where birth control was never relevant before. It is already overpopulated and still has birthrates that more than double population with each generation. Soon it will be the most overpopulated region in the world. The megafauna will require heroic efforts to save.
A major theme of the book is how many of the fruits we see today (especially avocados, osange oranges, honey locust pods, possibly mangoes and many other large fruits) originally evolved to be eaten by megafauna. The idea is they would eat the fruit whole and swallow the pit, and poop it out somewhere. Evidence for this is that many of the trees have defenses against non-megafauna eating the fruits, or others have out-of-proportion defenses against any living animal today, the fact that many pits will only grow if they have been scoured (for example by the digestive system of an animal), and that the pits often seem over-defended, and the fact that many of these fruits are not eaten by any living animals and often fall from the tree and rot in place.