Big problems of big animals: how our ancestors managed to extinct entire species

    20 Jul 2021

    Humankind lived not in harmony with nature. It destroyed megafauna wherever it appeared, even in primitive times.

    Let’s get acquainted with zoologist, Ph.D. in zoology Vitaly Gryshchenko’s opinion on how we, humans, become one of the reasons for the disappearance of mammoths and other species.

    ***

    Ernest Hemingway wrote in The Green Hills of Africa: “The continent ages quickly when we appear.” It is aptly said, but it should not only be about white colonizers who ruthlessly plundered the seized lands. In general, the appearance of people on the continent or island has caused irreversible changes in natural complexes. How this happened can be shown by the example of megafauna. So zoologists call a set of species of large animals weighing more than 45 kg.

    Scientists have long debated the causes of the mass extinction of animals at the turn of two geological epochs – the Pleistocene (2.6 million – 12 thousand years ago) and the Holocene (which began 12 thousand years ago, continues to this day).

    There are two main hypotheses: climate change (especially the end of the last – Wurm – glaciation) and the impact of humans, who, leaving Africa, quickly settled on the planet. Climate and other natural factors, of course, may also have had some negative effects on the fate of some species. Still, scientists are finding more and more evidence that our distant ancestors are directly or indirectly involved in this mass extinction. Analysis of data from the standpoint of ecology shows that neither the scale, nor the pace, nor its consequences cannot be explained only by the action of natural factors. Under normal conditions, the extinction of some species was offset by the emergence of others. Moreover, species diversity has gradually evolved, with more new forms appearing than old ones disappeared. Only with the advent of humans, this process was disrupted, and the irreversible impoverishment of the Earth’s biosphere began.

    The megafauna suffered the most. According to estimates by Ukrainian zoologist Pavel Puchkov, 78.8% of mammals weighing more than a ton died on various continents at that time, 66.7% – from 400 kg to 1 ton, 53.6% – from 150 kg to 400 kg, and only 16, 3% of species weighing 10-50 kg. (Humanity) gastronomic interest can be traced quite clearly.

    At least in the past, large and small animals died out in equal proportions. Small mammals known since the Pleistocene are now represented by the same or similar species. But proboscis and rhinos in Northern Eurasia have disappeared without a trace. This applies to many large animals on other continents. In addition, their mass extinction invariably began after the appearance of the first humans.

    The most famous representative of the extinct megafauna is the mammoth. During the last glaciation, several species of these giants were distributed in Eurasia, North America, and even Africa. The North American Imperial Mammoth reached a height of five meters and weighed up to 11 tons. The woolly mammoth that once occurred in our region was slightly smaller – up to three meters high. There are known and small species weighing less than a ton.

    Herds of mammoths roamed the vast expanses of the tundra, which occupied vast areas throughout the Northern Hemisphere. At least the fact that until recently, the extraction of mammoth tusks (they are well preserved in permafrost) was a serious type of fishing in Siberia speaks volumes about their numbers. Thus, in 1903, 57.6 thousand pounds of tusks were sold in Yakutsk (more than 26 thousand kilograms).

     Mammoth hunting was the basis of life for many people in the late Paleolithic (ancient Stone Age). Not only meat but also hides and bones were used. From them, in particular, housing was built. In the village of Mezhyrich near Kaniv in Ukraine, settlements of ancient mammoth hunters were excavated. It dates back to the middle of the XV millennium BC. What the hut looked like, the frame of which was made of the skulls and bones of these animals can now be seen in Kyiv at the National Museum of Natural History. The bones of a large number of mammoths were needed to build one house. Now consider that they, like other large animals, reproduced slowly. This is offset by low youth mortality and long life expectancy, but not in our case. It is much easier for hunters to hunt a young animal than an adult giant. According to paleontologists, at least half of the hunted mammoths were young and had not yet reached sexual maturity. And few of them managed to live to old age. From here, it becomes clear the scale of losses suffered by the population.

    Pavel Puchkov analyzed in detail the extinction of animals in the Pleistocene and concluded that the culprit was primarily man. It has wiped out many large mammals, which has led to drastic changes in natural complexes.

    The fact is that herbivorous giants such as mammoths have been edificators of ecosystems. An edificator is a species that creates an ecosystem or significantly changes it. Oak forest is impossible without oak, the Sargasso Sea is impossible without sargassum algae, and after the death of coral polyps, all the magical diversity of coral reef disappears. Beavers are edificators; they contribute to waterlogging of the forest. Herds of herbivores maintain the vegetation of the steppes and savannas in a normal state.

    E.g., a big problem for the remnants of the Eastern Europe steppes is the lack of ungulates. Because of this, the vegetation gradually degrades, the accumulation of dead plant mass leads to severe fires. (We’ve written about a thick layer of turf, herbaceous plants on a surface that simply did not allow moisture, as one of the central steppes elements, here).

    One of the main edificators of the African savannah is the elephant. Their herds dilute tree and shrub vegetation, prevent overgrowing grassy areas. Similarly, the mammoth was the main edificator of pasture ecosystems in a massive area in the Northern Hemisphere. His disappearance was a disaster for many other animals. There was a whole complex of species characteristic of the tundra, which is called mammoth fauna. These included, in particular, a wild horse, a woolly rhinoceros, a horned deer, a ram, and a cave lion.

    Some ecologists believe that modern natural areas (including steppes, deciduous forests, taiga) in Eastern Europe are not entirely natural because they are of anthropogenic origin: they were formed due to the destruction of large herbivores, similar to the African savannah.

    Climate change does not explain the extinction of mammoths. They have successfully survived more and more warming in the Pleistocene (sometimes the climate was even warmer during the interglacial period than it is now). In Europe, it ceased to occur before the glacial landscapes finally disappeared. The appearance of a new active super predator, Homo sapiens, was fatal for them. But on remote Arctic islands, where there were no people, these animals survived for another 5,000 years after extinction on the mainland. Calculations show that Paleolithic hunters could destroy all the mammoths of Eastern Europe in just a thousand years.

    America’s nature has not been lucky twice. At first, it was devastated by the ancestors of the Indians, and then, thousands of years later, the white settlers finished off what was left. The first people to enter the continent hunted mainly big game. This is evidenced by the numerous remains of bones and large spearheads of the Clovis culture (one of the first archaeological cultures in North America, which existed about 13 thousand years ago). They could reach 20 cm in length. Hares and other small things are not used with such weapons. These tips were made of flint and obsidian and sometimes of other minerals. Spears with them were an effective and multifunctional weapon. Especially if you remember that then there was a list-thrower – a kind of stick or board with a focus on one end and a handle on the other. With its help, it was possible to throw light spears with great force at a distance of up to 150-200 meters. According to the Spanish conquistadors, the Mexican list-thrower Atlat punched the cuirassiers of soldiers. No matter how thick the skin of large animals is, it is certainly not stronger than iron armor.

    It is believed that the favorite prey of the Clovis culture were proboscis mammoths and mastodons. In North America, 12 sites of slaughter and carcass processing of these animals by Clovis hunters have already been identified. The consequence of human appearance did not take long – mammoths, mastodons, homotheria, gliptodonts, terracotta, and many other representatives of the Pleistocene megafauna of North America soon became extinct. Similarly, South America and Australia were devastated. In the islands of New Zealand, the Maori exterminated several species of giant moa ostriches. In Madagascar, the victim of the aborigines was another giant flightless bird – epiornis, which reached three meters in height.

    People caused tremendous damage to nature immediately after their appearance in new lands. On the one hand, having discovered a “paradise corner” with an incredibly rich hunting fauna, they intensively “collected cream.” And the high efficiency of hunting and the wealth of resources contributed to the rapid growth of the tribe and its settlement. And there was no need to fight among themselves for hunting grounds. More rational ways of using nature appeared later when easily accessible prey disappeared and problems began. On the other hand, local animals were often initially defenseless against a new effective predator. They did not yet have appropriate behavioral responses that helped to protect themselves from humans. They were produced only after some time; if they had time.

    For example, muskoxen are good at defending themselves during a predator attack. The herd is lined up in a tight circle, exposing the horns; the calves remain in the middle. Try to reach them, come on. In addition, these animals are not limited to passive defense, and from time to time, attack the enemy and return to the group. This is excellent protection against predators. But it turns into collective suicide when a pack of Homo sapiens hunters, not a pack of wolves, approaches the muskoxen.

    That is why the megafauna of Africa suffered the least. Elephants, hippos, and rhinos have survived to our time. This is because they have long coexisted with the ancestors of modern man and managed to “grind.” But as recent research by a group of European scientists has shown, six things were not so simple here either. The significant negative impact of humans on biodiversity began millions of years before our time in the Pliocene (5.3 – 2.6 million years ago). And involved not only modern intelligent man – Homo sapiens, but also our distant ancestors – Homo erectus and even an older species – Homo habilis.

    From fossils, researchers have studied the diversity of predators in East Africa (where Homo originated and evolved over the past four million years) and analyzed the main causes that could lead to its decline: the development of human mental activity, changes in vegetation, and climate. The species diversity of large carnivores (weighing more than 21 kg) in East Africa is higher than anywhere else in the world. But even here, it was more extensive before the Pleistocene. It turned out that the rate of extinction of small predators remained unchanged over the years, while for large, it grew rapidly. Computer simulations have shown that this can be due to both the gradual development of the brain in ancient hominids (a family to which the genus Homo belongs) and the reduction of forest area, but not climate change. The final answer was found by using data from other continents for comparative analysis. The version with forests has disappeared. Further simulations showed that a clear relationship between the rate of extinction of large predators and the volume of the brain in the hominid began to appear after reaching a particular threshold value of its size. This volume already allowed hunting. Scientists suggest that the ancestors of humans first ate the remains of predators’ food, then began to take a prey, driving them away (this is called kleptoparasitism), and later became hunters themselves. Since small predators often catch prey and small size, and large – on the contrary, kleptoparasitism on the part of humans had a much more significant negative impact on the latter. And the real problems began when people themselves started to hunt herbivores and compete for prey.From all this, we can draw an important conclusion: the negative impact of people on nature continues all the time after their appearance on the planet. And this was not hindered by the primitiveness of tools and technical means, a low level of social development, or a low number of people. You can often hear that the problems began only with the development of civilization, but the primitive man lived in harmony with nature. This is just a myth. At all times, such “harmony” was very relative and short-lived and quickly disappeared with changing conditions. This means that we have no way back in nature protection. It is impossible to return to “paradise on earth” because it never existed. We can only move forward – to create this harmony based on science and the mind of humankind.

    Leave a Reply

    Your email address will not be published.