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What does 7 Billion People Mean?

Making Sense of 7 Billion People | Wired Science | Wired.com.

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On the last day of October 2011, the global population of an upstart branch of the primate order will reach 7 billion.review smartphone android

What does it mean?

In itself, not much: Seven billion is just a one-digit flicker from 6,999,999,999. But the number carries a deep existential weight, symbolizing themes central to humanity’s relationship with the rest of life on Earth.

For context, let’s consider a few other numbers. The first: 10,000. That’s approximately how many Homo sapiens existed 200,000 years ago, the date at which scientists mark the divergence of our species from the rest of Homo genus, of which we are the sole survivors.

From those humble origins, humans — thanks to our smarts, long-distance running skills, verbal ability and skill with plants — proliferated at an almost inconceivable rate.


Some may note that, in a big-picture biological sense, humanity has rivals: In total biomass, ants weigh as much as we do, oceanic krill weigh more than both of us combined, and bacteria dwarf us all. Those are interesting factoids, but they belie a larger point.

We are the .00018 percent, and we use 20 percent.

Ants and krill and bacteria occupy an entirely different ecological level. A more appropriate comparison can be made between humans and other apex predators, which is precisely the ecological role humans evolved to play, and which — beneath our civilized veneer — we still are.

According to a back-of-the-envelope calculation, there are about 1.7 million other top-level, land-dwelling, mammalian predators on Earth. Put another way: For every non-human mammal sharing our niche, there are more than 4,000 of us.

In short, humans are Earth’s great omnivore, and our omnivorous nature can only be understood at global scales. Scientists estimate that 83 percent of the terrestrial biosphere is under direct human influence. Crops cover some 12 percent of Earth’s land surface, and account for more than one-third of terrestrial biomass. One-third of all available fresh water is diverted to human use.

Altogether, roughly 20 percent of Earth’s net terrestrial primary production, the sheer volume of life produced on land on this planet every year, is harvested for human purposes — and, to return to the comparative factoids, it’s all for a species that accounts for .00018 percent of Earth’s non-marine biomass.

We are the .00018 percent, and we use 20 percent. The purpose of that number isn’t to induce guilt, or blame humanity. The point of that number is perspective. At this snapshot in life’s history, at — per the insights of James C. Rettie, who imagined life on Earth as a yearlong movie — a few minutes after 11:45 p.m. on December 31, we are big. Very big.

However, it must be noted that, as we’ve become big, much of life had to get out of the way. When modern Homo sapiens started scrambling out of East Africa, the average extinction rate of other mammals was, in scientific terms, one per million species years. It’s 100 times that now, a number that threatens to make non-human life on Earth collapse.

In regard to that number, environmentalists usually say that humanity’s fate depends on the life around us. That’s debatable. Humans are adaptable and perfectly capable of living in squalor, without clean air or clean water or birds in the trees. If not, there wouldn’t be 7 billion of us. Conservation is a moral question, and probably not a utilitarian imperative.

But the fact remains that, for all of humanity to experience a material standard of living now enjoyed by a tiny fraction, we’d need four more Earths. It’s just not possible. And that, in the end, is the significance of 7 billion. It’s a challenge.

In just a few minutes of evolutionary time, humanity has become a force to be measured in terms of the entirety of life itself. How do we, the God species, want to live? For the answer, check back at 8 billion.

Forget Mother Nature: This is a world of our making – environment – 14 June 2011 – New Scientist

Forget Mother Nature: This is a world of our making – environment – 14 June 2011 – New Scientist.

Humans have transformed Earth beyond recovery – but rather than look back in despair we should look ahead to what we can achieve

THE Holocene, with its mild climate so remarkably stable and good for us, is over. We humans have transformed Earth’s climate, geology, biology and hydrology so extensively, profoundly and permanently that geologists are proposing the formal designation of a new geological epoch: the Anthropocene.

International scientific panels will ultimately decide whether to recognise the new epoch, and it could be a decade or longer before we get a final ruling. Nevertheless, it’s high time that we – and I do mean all of us – take stock of the new Earth we have created. One reason to do this is to help answer a basic geological question: will the Anthropocene last long enough to justify its designation as a new epoch, or will it remain a mere geological event akin to the impact of an asteroid? It will also help us answer a more profound question: what do we do now?

The first lesson of history is simple: the Anthropocene was a long time in the making. Significant human alteration of the biosphere began more than 15,000 years ago as Palaeolithic tribes evolved social learning, advanced hunting and foraging technologies, and the use of fire, and used them to open up forested landscapes and kill off megafauna.

These Palaeolithic human impacts were significant and extensive, but they were minor compared with the impact of the rise of agriculture more than 8000 years ago. By domesticating plant and animal species and engineering ecosystems to support them, humans introduced a wide range of unambiguously anthropogenic processes into the biosphere.

Human alteration of Earth systems tends to be far more extensive and complex than one would expect based on numbers alone. Even 8000 years ago, with a population of just 10 million or so, humans had already altered as much as a fifth of Earth’s ice-free land, primarily by using fire to clear forest. The reason small populations had such extensive impacts is that early agriculture emphasised labour efficiency. Early farmers did not use the plough, and that meant constantly shifting cultivation to the most fertile areas. As a result, most of the landscape was in some stage of recovery, giving rise to “semi-natural” woodlands. These were among the first anthropogenic biomes, or “anthromes“.

In this way, human populations were able to increase and expand for millennia, converting vast tracts of pristine forest into semi-natural woodlands and less productive land into rangeland. As populations grew larger and more dense they created ever more intensively transformed anthromes by tillage, irrigation, manuring and cropping. By 1750, more than half of the terrestrial biosphere had been converted into anthromes, leaving an ever greater permanent record in soils, sediments and the atmosphere. This process ultimately gave rise to the densely populated village and urban anthromes most of us live in today.

The rise of industrial systems in the past century has transformed the majority of the terrestrial biosphere into intensively used anthromes dominated by novel ecological processes. Now more than 7 billion strong and growing, we continue to transform the last wild biomes into anthromes – a process that must end soon as we reach the limits of the usable biosphere. Already, more than 12 per cent of Earth’s ice-free land is used continuously for crops and 16 per cent for livestock.

Thus we find ourselves in the Anthropocene. Today, even if the population were to decline substantially or land use to become far more efficient, the extent, duration and intensity of human activity has altered the terrestrial biosphere sufficiently to leave an unambiguous geological record differing substantially from that of any prior epoch. Earth’s biodiversity, biogeochemistry and evolution are now profoundly reshaped by us – and are therefore in our hands.

There will be no returning to our comfortable cradle. The global patterns of the Holocene have receded and their return is no longer possible, sustainable or even desirable. It is no longer Mother Nature who will care for us, but us who must care for her.

This raises an important but often neglected question: can we create a good Anthropocene? In the distant future will we be able to look back with pride?

We have seen what we can do, and it is awesome. In just a few millennia, humanity has emerged as a global force of nature – a networked system of billions of individuals creating and sustaining an entirely new global ecology. We live longer than ever, and our average standard of living has never been higher. These unprecedented achievements clearly demonstrate the remarkable ability of our social systems and technologies to evolve and adapt, often to changes we ourselves have induced.

Yet it is also easy to see what we have lost and are even now destroying. Wild fish and forests are nearly gone. We are warming the atmosphere, melting the ice caps, acidifying the ocean, polluting land and sea, driving species to extinction and inducing invasions by species from around the world – and in some areas leaving only a wasteland of monocultures and weeds. Clearly it is possible to look at all we have created and see only what we have destroyed.

But that, in my view, would be our mistake. We most certainly can create a better Anthropocene. We have really only just begun, and our knowledge and power have never been greater. We will need to work together with each other and the planet in novel ways. The first step will be in our own minds. The Holocene is gone. In the Anthropocene we are the creators, engineers and permanent global stewards of a sustainable human nature.

Erle C. Ellis is an associate professor in the department of geography and environmental systems at the University of Maryland, Baltimore County

Volcanoes wiped out Neanderthals

Volcanoes wiped out Neanderthals, new study suggests.

ScienceDaily (Oct. 7, 2010) — New research suggests that climate change following massive volcanic eruptions drove Neanderthals to extinction and cleared the way for modern humans to thrive in Europe and Asia.

The research, led by Liubov Vitaliena Golovanova and Vladimir Borisovich Doronichev of the ANO Laboratory of Prehistory in St. Petersburg, Russia, is reported in the October issue of Current Anthropology.

“[W]e offer the hypothesis that the Neanderthal demise occurred abruptly (on a geological time-scale) … after the most powerful volcanic activity in western Eurasia during the period of Neanderthal evolutionary history,” the researchers write. “[T]his catastrophe not only drastically destroyed the ecological niches of Neanderthal populations but also caused their mass physical depopulation.”

Evidence for the catastrophe comes from Mezmaiskaya cave in the Caucasus Mountains of southern Russia, a site rich in Neanderthal bones and artifacts. Recent excavations of the cave revealed two distinct layers of volcanic ash that coincide with large-scale volcanic events that occurred around 40,000 years ago, the researchers say.

Geological layers containing the ashes also hold evidence of an abrupt and potentially devastating climate change. Sediment samples from the two layers reveal greatly reduced pollen concentrations compared to surrounding layers. That’s an indication of a dramatic shift to a cooler and dryer climate, the researchers say. Further, the second of the two eruptions seems to mark the end of Neanderthal presence at Mezmaiskaya. Numerous Neanderthal bones, stone tools, and the bones of prey animals have been found in the geological layers below the second ash deposit, but none are found above it.

The ash layers correspond chronologically to what is known as the Campanian Ignimbrite super-eruption which occurred around 40,000 years ago in modern day Italy, and a smaller eruption thought to have occurred around the same time in the Caucasus Mountains. The researchers argue that these eruptions caused a “volcanic winter” as ash clouds obscured the sun’s rays, possibly for years. The climatic shift devastated the region’s ecosystems, “possibly resulting in the mass death of hominins and prey animals and the severe alteration of foraging zones.”

Enter Modern Humans

Anthropologists have long puzzled over the disappearance of the Neanderthals and the apparently concurrent rise of modern humans. Was there some sort of advantage that helped early modern humans out-compete their doomed cousins? This research suggests that advantage may have been simple geographic location.

“Early moderns initially occupied the more southern parts of western Eurasia and Africa and thus avoided much of the direct impact of the … eruptions,” the researchers write. And while advances in hunting techniques and social structure clearly aided the survival of modern humans as they moved north, they “may have further benefited from the Neanderthal population vacuum in Europe, allowing wider colonization and the establishment of strong source populations in northern Eurasia.”

While the researchers stress that more data from other areas in Eurasia are needed to fully test the volcanic hypothesis, they believe the Mezmaiskaya cave offers “important supporting evidence” for the idea of a volcanic extinction.

Horned turtles butchered to extinction

* 20:00 16 August 2010 by Wendy Zukerman

The giant horned turtles of the Pacific became extinct later than we thought – and we were to blame.

The half-tonne meiolaniid turtles were thought to have died out 30 to 40,000 years ago. With no signs of human interference, climate change was blamed.

Now butchered turtle remains have been found in the South Pacific island nation of Vanuatu. Carbon dating shows that the most recent bones are between 2890 and 2760 years old. Humans arrived 3000 years ago: “Within 200 years, the turtles were gone,” says Trevor Worthy of the University of New South Wales in Sydney, Australia, who identified the bones.

via Horned turtles butchered to extinction – environment – 16 August 2010 – New Scientist.