HomeEarthQuaternary Earth – The Age of Man Charles March 10, 2017 Earth, Series Quaternary Earth 2.58 Million Years Ago to the Present Day Mauricio Antón Woolly mammoths, woolly rhinoceroses and saber-toothed cats were some of the most iconic animals of the Quaternary Period. From the formation of our planet 4.6 billion years ago, we’ve come an unimaginably long way in the ‘Journey through the History of the Earth’. We’ve explored the wonders of life long past and the role it played creating the world we know today. Now we’re in the last leg of our trip through time, the geological period that persists to this day. In the fifteenth and final part of my series, we will be exploring the Age of Man, perhaps the most unique and incredible of all in the history of our world. Part 1: Hadean Earth – The Violent Creation of Our World Part 2: Archean Earth – Signs of Life Part 3: Proterozoic Earth – The First Animals Part 4: Cambrian Earth – An Explosion of Evolution Part 5: Ordovician Earth – Colonising a Barren Land Part 6: Silurian Earth – The First Breath of Air Part 7: Devonian Earth – The Age of Fishes and Forests Part 8: Carboniferous Earth – The Age Bugs Part 9: Permian Earth – The Age of Amphibians Part 10: Triassic Earth – The Rise of the Dinosaurs Part 11: Jurassic Earth – The Land of Giants Part 12: Cretaceous Earth – The Reign of Tyrants Part 13: Paleogene Earth – The Rise of Mammals Part 14: Neogene Earth – Human Ancestors Part 15: Quaternary Earth – The Age of Man Throughout its unimaginably long history, our world has seen enormous change. From devastating mass extinctions to unprecedented radiations of countless new species, the path of evolution has proven incredibly dynamic over the billions of years life has existed. Evolution has also proven to be a fragile thing influenced profoundly by even the slightest change to the Earth’s climate or geology. It is this constant state of change and unpredictability that ultimately gave rise to us. The Quaternary, meaning the ‘fourth’, retains its name from the now obsolete geographical timescale proposed by Giovanni Arduino in the eighteenth century, in which the Paleogene and Neogene periods comprised the Tertiary Period. Our current period refers to an ongoing period of regular glaciations or, in layman’s terms, ice ages. It consists of only two epochs, the Pleistocene and the Holocene, an interglacial period that persists to this day. Highlights Earth enters an ice age Homo erectus evolves Early humans colonize Eurasia Neanderthals evolve Modern humans appear Toba supervolcano erupts Glacial Advances Herald a New Ice Age Ulamm During the Last Glacial Maximum, which ended about 11,700 years ago, the Arctic ice sheet covered most of the British Isles and the entirety of Northern Europe. Earth has been ice-free throughout most of its history, even at the poles. Even Antarctica was, for the most part, home to temperate biomes at the time of the dinosaurs and, indeed, during much of the Palaeogene Period. However, our planet has also undergone at least five major ice ages over the last 2.5 billion years. We’re now living in the fifth one. No one is quite sure exactly what causes these glaciations, which typically last many millions of years. However, the reason these periods tend to last so long is probably down to both positive and negative feedback processes. In other words, ice sheets increase the reflectivity (albedo) of the Earth’s surface as such that much of the heat from the Sun is beamed back out into space. On the other hand, erosion caused by moving glaciers themselves mitigates these effects, helping bring about interglacial intervals such as the one of the last 12 millennia. By the beginning of the Quaternary, glacial advances had gripped much of the northern and southern hemispheres, with ice sheets reaching as far south as the north of France and perhaps even further. The last glacial period took place between 110,000 and 11,700 years ago, and is thus popularly referred to as the Ice Age itself. However, this event is, in scientific terms, known as the Last Glacial Maximum, and was only one part of a cycle that has persisted for the last 2.58 million years. During glacial periods, sea levels drop significantly, sometimes by hundreds of feet. These events allow land bridges to form, such as those that existed between Britain and Europe, Australia and New Guinea and Alaska and Kamchatka. Thanks to the appearance of these land bridges, the migration of both animals and humans alike were made possible. Just as camelids once moved from their native North American homeland into South America and Africa using the Bering Strait land bridge, humans migrated all over the world during the Last Glacial Maximum between 18 and 12 thousand years ago. A New Land of Giants Survives the Lingering Cold Charles R. Knight Woolly mammoths were widespread across Eurasia throughout much of the Quaternary Period, while their close relatives, the mastodons, dominated North America. It’s not strength or intelligence that allows a species to survive as much as it is its ability to adapt to extreme conditions. Throughout the history of evolution, countless millions of species have failed to adapt, disappearing off the face of the Earth to make way for more successful organisms. The Quaternary glaciations may have seen global cooling on an enormous scale, but they also saw the expansion of important environmental niches. Charles R. Knight Also known as the Irish elk (though its habitat was much wider-reaching), megaloceros was the largest deer that ever lived. Larger animals, particularly those with thick coats of hair or fur, are generally better equipped to survive in cooler climes. Many iconic megafaunas that we know today, such as elephants and rhinoceroses, had tundra-dwelling counterparts throughout much of the Quaternary. Woolly rhinos and mammoths, for example, are very much like their modern relatives, albeit much better adapted to the cold. Mammoths, for example, were among the most successful species of their time, spanning much of the globe and living even in places where winter temperatures regularly reached −50 °C. The last mammoth died a mere 4,300 years ago in Wrangel Island. Robert Bruce Horsfall Doedicurus (foreground) and glyptodon were gigantic armadillos that coexisted with the first humans to arrive in South America. The Pleistocene, the first of the two Quaternary epochs, saw a new land of giants colonize the Earth. Mammoths reigned across Eurasia, while their close relatives the mastodons ruled in North America. Other examples include the megaloceros with its 12-foot antlers (3.6 metres), the largest species of deer that ever lived. Beavers, lions and bears also broke records. Despite the effects of the Great American Interchange, South America was still home to unique giants of its own, such as the elephant-sized ground sloth megatherium and the car-sized glyptodonts, which were relatives of modern armadillos. Roman Uchytel Thylacoleo was a carnivorous marsupial that was endemic to Australia. It likely preyed upon its contemporary, the diprotodon, which was the largest marsupial that ever lived. Australia, which had enjoyed tens of millions of years of isolated evolution, also saw the appearance of enormous ancestors to its current fauna. Among the most notable was the 6.6 foot-tall (2 metres) procoptodon, a giant kangaroo, and the diprotodon, a truly bizarre marsupial that grew larger than a hippopotamus. John Megahan Haast’s eagle likely preyed upon moas, giant flightless birds that were endemic to New Zealand until their extinction at the hands of the Māori some 600 years ago. It wasn’t only mammals that broke size records during the Pleistocene Epoch. Various bird species also grew to enormous proportions, such as the North American teratornis, a bird of prey twice the size of the modern Californian condor. Many of the carnivorous flightless birds, such as the terror birds (phorusrhacids), that had appeared during the Neogene, still terrorised the Americas. Meanwhile, in New Zealand, moas reigned supreme as they had done for some 15 million years, only to be wiped out a mere 600 years ago by the arrival of the Māori people. Early Man vs. Prehistoric Beast Tim Vickers We all share a common ancestor that lived around five-million years ago. During the Early Pleistocene, the genus homo, to which modern humans belong, appeared in East Africa, possibly emerging from the australopithecine genus, which went extinct at around the same time. Among the earliest progenitor of the modern human race was homo habilis, one of the first animals to learn how to use basic tools. Although there remains a great deal of debate regarding the taxonomic classification of early hominids, the Old Stone Age (Palaeolithic) was undoubtedly in full swing by at least two million years ago. Homo erectus, or upright man, for example, learned how to make basic tools and light fires some 1.9 million years ago. There’s even strong evidence that homo erectus built the first campfires and cooked their food, possibly as part of social gatherings. Pixabay Neanderthals formed small communities of hunter gatherers, coexisting with saber-toothed cats and woolly mammoths (background). Several unique human species existed during the Pleistocene, including the Neanderthals, all of which are now extinct save for modern humans. Our own species, that being homo sapiens, appeared some 280,000 years ago, coexisting with many of the iconic ice age animals, such as woolly mammoths and sabre-toothed cats. While modern humans, along with most other members of the genus homo, evolved in East Africa, the Neanderthals were an offshoot that evolved in Eurasia, their own ancestors having originally evolved in Africa too. The Neanderthals, which appeared at about the same time (or perhaps even some time before) modern humans, were also advanced tool users and may have even mastered language. Nandaro Archaeological remains show evidence that both Neanderthals and modern humans once built rudimentary huts made from mammoth bones and skins. Like the Neanderthals, early modern humans also built rudimentary structures out of wood and mammoth tusks and wore clothes to keep warm in the cold climes of Ice Age Eurasia. However, only early humans managed to migrate to the Americas and Australasia, around 13,000 and 50,000 years ago respectively. Neanderthals, by contrast, typically lived in small and relatively isolated communities, and were never particularly great in number. As such, due to competition with homo sapiens and, possibly, interbreeding, they disappeared around 40,000 years ago. Man Rises to Dominance with the New Stone Age Diego Delso One of the best-known Neolithic sites in Europe, Britain’s Stonehenge was built sometime between four- and five-thousand years ago. The current geological epoch began around 11,700 years ago. The Holocene refers to the ongoing interglacial period, beginning at the end of what is popularly known as the last ice age. It also coincides approximately with the end of the Old Stone Age, which is also known as the Palaeolithic. These prehistoric periods refer to human history rather than geological and evolutionary history. By the beginning of the Mesolithic, the Middle Stone Age, mankind had spread across most of the globe, and was already well-established in the Americas and Australasia. They continued to coexist with many of the iconic ice age animals, but this was soon to change as a result of a warming global climate and increasing human encroachment from the beginning of the Holocene. The Mesolithic remains a vague term, since it’s largely defined by the progress of pre-agricultural cultures around the world, which evolved in isolation on separate timescales. More relevant was the Neolithic, which began, in certain areas, at the dawn of the Holocene Epoch. This was the time when mankind truly rose to dominance as the Neolithic Revolution started to transform the face of our world. Pixabay By the year 2000, more than a third of all the land on Earth had been given over to agriculture to sustain the soaring global population. Also known as the Agricultural Revolution, this period saw the first domestication of plants and animals and, thus, the first agriculture. Although hunter-gatherer societies persisted and, in some isolated cases, continue to do so to this day, many cultures around the world underwent a transition to animal-rearing and crop growing. Populations boomed as a result, forming the foundations of modern civilization. Although a mere footnote in terms of the enormous amount of time we’ve been here, the Neolithic Revolution was the direct progenitor to the world we live in today. Hard on the heels of early technological advancement was the Bronze Age and then the Iron Age, as mankind learned how to smelt metal ore and create everything from advanced tools to ancient works of art. NASA This photograph, taken from the International Space Station, illustrates the way mankind has redefined the face of the planet. The development of modern human cultures sped up at an unprecedented rate through the Holocene. Vast swathes of land were given over to farming, populations boomed and civilization spread throughout Eurasia and beyond. As mankind came to dominate almost every corner of the globe, countless species disappeared in what is now known as the Holocene Extinction Event. Consequently, the path of evolution was forever changed, and no longer would nature alone sculpt our planet’s future. Conclusion Once upon a time, we were nought but microscopic organisms living in a very different world to the one we know today. Over more than 3.5 billion years, the story of life on Earth has developed and transformed on an unprecedented scale, ultimately giving rise to mankind and its incredible technological (and, sadly, often destructive) advances. We have now reached the end of our journey through the history of our world, a time when the development of our species has become the defining influence in the Earth’s future. Mankind has, without doubt, left its mark upon the world like no other species before it. Traces of our progress will remain long after we’re gone. The probes we’ve sent into space will likely continue their eternal journeys through the cosmos after even the Earth itself has been incinerated by the Sun. No matter our living future; the human race has put its eternal stamp on our tiny and insignificant corner of the Universe. This is the legacy of the evolution of our world. Leave a Reply Cancel ReplyYour email address will not be published.CommentName* Email* Website Please enter an answer in digits:9 + twelve = This site uses Akismet to reduce spam. Learn how your comment data is processed.