Tag Archive: Extinction


All of the last week’s quotes are from the same non-fiction book, Once and Future Giants by Sharon Levy. Rather than my usual “who said it under what circumstances” I’m just going to give extended quotes this week, with the part tweeted in italics.

“Conventional wisdom long held that the megafauna fell victim to a warming climate at the end of the last glacial peak of the Ice Age. According to this theory, rising temperatures led to changes in vegetation, altering habitat in ways that proved fatal to many large herbivores and in turn to the dire wolves, American lions, and saber-toothed cats that had preyed on them. Today many scientists believe ancient people were responsible for the extinctions, an idea raised with dramatic flair by paleoecologist Paul Martin.

“From the beginning, people have seen what they wanted to see in the bones of America’s extinct monsters. The devout seventeenth-century colonists who found the first pair of mastodon molars were convinced that they had discovered the remains of a human giant, proof that the David and Goliath story was true.”

Healthy populations of giant herbivores shape the landscapes that sustain them. But the mastodon at the close of the Pleistocene was so rare it was environmentally insignificant.”

Seeds that drop to earth beneath the parent’s canopy are doomed: easy targets for predators such as rodents and insects that swarm around fruiting trees. The few that survive to sprout will be shaded to death by the tree that produced them.”

The clash between elephants and people is as old as our species. To hold on in the long run, elephants need that precious commodity, land.

“Cats, large or small, are the ultimate carnivores: they have lost most of their cheek teeth, except for two or three carnassials that slice against each other, ripping meat away from tendon and bone. A cat’s mouth was made to eat meat and little else.”

“Whoever back at headquarters had come up with the color-coding scheme should try to live with it.” Sue Ann Bowling, Tourist Trap. Penny’s thoughts. The color coding was applied both to the clothing of clients and to the collars, harnesses, and dogsleds – but the two sets of coding caused some major color clashes.

I bought Once and Future Giants by Sharon Levy after seeing a review on a science blog. It is indeed an excellent book, though at times it seems that it covers almost too many topics. All, however, have one thread in common: our present ecosystems were to some extent broken by the extinction of large mammals, which can have a profound impact on their environments. Who expected, for instance, that the re-introduction of wolves to Yellowstone would have a positive impact on songbirds and possibly, if the wolves spread far enough, on antelope?

The book attracted me primarily because of the debate on whether the Pleistocene megafauna (mammoth, mastodon, saber-tooth cats, dire wolves, and ground sloths, among others) died out because of climate change or because of overkill by humans, as proposed by Paul Martin. I have Martin’s book, and have been more than half convinced by his arguments. Certainly it has seemed unlikely to me that the warming at the end of the Pleistocene was enough in itself to trigger the extinction of a large number of animals who had survived similar transitions from glacial to interglacial repeatedly in the past. In fact, if we ignore the last fifty years, all the evidence is that it was warmer than the Recent during at least some past interglacials. But Martin very definitely writes as an advocate for his theory, glossing over the problems.

Sharon Levy has written a more balanced book, and one that tends to agree more with my own conclusions. Yes, the changes in climate at the close of the last ice age undoubtedly stressed the Pleistocene megafauna. But the major difference between the last warming and the ones that had happened before was that human beings had emerged as a major predator, and one against whom the large herbivores had no natural defenses. As she points out, the Clovis people need not have killed many mammoths or ground sloths. But human predation, unlike predation by most animals, tends to target healthy animals, often pregnant females. This disrupts the natural social groupings of herbivores, already under stress from climate and habitat change. As the herbivores are killed off, the large carnivores may well die off from starvation. Some of the environmental effects brought about by humans, such as those caused by fire, may also be partly to blame.

The idea of re-wilding, of introducing either the original species (as wolves were reintroduced to Yellowstone) or a surrogate is even more controversial – but the controversies are even more political than the reintroduction of the wolf. Predators are an important part of ecosystems – but people simply do not want to live with animals capable of killing large prey. Neither do they want large herbivores, such as camels or elephants, to compete with domesticated animals for food. The mustang problem is an example of both.

A less well-known problem is certain aspects of the protection of endangered species. In some cases animals or plants stressed by the ongoing changes in climate need to be relocated closer to the poles or to higher elevations – but this is often prohibited by the very laws meant to protect them.

I’m fond of the large megafauna, and would love to see a mammoth in person. In fact the terraformed landscape of Falaron in my own novel Tourist Trap, based on ice-age North America, reflects that wishful thinking. But I have to confess I’d have my doubts about living with the creatures of the Ice Age, or with introduced African lions.

Follow

Get every new post delivered to your Inbox.

Join 489 other followers