I currently think “old age” starts around 70? .Definitely 80.
Isn’t it funny how “older” gets older, the older you get?
I remember being in high school thinking 30 was “old.”
4 key issues to watch as world leaders gather for the Glasgow climate summit.
Does climate change seriously threaten to wipe out the human species if left unchecked? Examining our evolutionary past suggests it might once have been the perfect catalyst for our extinction. But now? Or is it Purely natural. Cycles that have been going on since earth began. Or did cavemen cause the last ice age to melt?
Countdown to doomsday.
On January 14 of this year, the Bulletin of the Atomic Scientists moved the hands of its Doomsday Clock one minute further from midnight (it’s now six minutes to midnight), encouraged, it was announced, by the “progress seen around globe in both key threat areas: nuclear weapons and climate change”.
First published in 1947, the bulletin was founded by scientists, engineers and other experts involved in the Manhattan Project. The clock continues to serve as a metaphorical countdown to the apocalypse – the annihilation of humanity – set for midnight.
Today, the bulletin’s Board of Sponsors, comprising no less than 18 Nobel Laureates, almost every one of them a physicist or chemist, sets the hands of the clock based on their reading of “threats to the survival and development of humanity from nuclear weapons, climate change, and emerging technologies in the life sciences”.
They’ve a much wider brief now, a longer list of threats, and, I guess, more reasons to be pessimistic.
Extinction-prone apes.
Around 500 million years ago, animal life was almost non-existent on Earth. Today, biologists recognize up to 6 million animal species.
Humanity – Homo sapiens – is just one among the 4,500 living mammal species; and some understanding of where we might be headed can be gleaned from where we’ve been – our evolutionary journey.
Our starting point as a group of two-footed, small-toothed, weakly-muscled, brainy “have-a-chat” apes is the ancestor we share with living chimpanzees some 7 million years ago.
(The two chimpanzee species are endangered, incidentally, because of the environmental destruction caused by us, their closest cousin).
Our evolutionary group – the hominins – diversified quickly after the split from the human-chimp ancestor, and through its multiple evolutionary iterations natural selection produced 25 or 30 two-footed ape species – undoubtedly with more to be found as anthropologists discover more fossils. All of these are now extinct, except us.
Those 7 million years represent only the last couple of minutes on a 24-hour clock of Earth’s 5 billion year history. The culling of 30 species to 1 in this short timeframe, or a more than 95% loss of hominin biodiversity, is worse than the worst mass extinction episode recorded in the fossil record: the Permian event some 250 million years ago.
But these mass events obscure the fact that, in the history of life, extinction has been a dominant theme, a continuous process. Evidence from the last 600 million years shows roughly one-third of existing animal species going extinct every 10 million years.
Seen in this context, the rate of extinction in the human evolutionary tree is striking, about three times faster than normal. This strongly suggests that we hominins are a highly extinction-prone mammal.
The blame game.
Why the dramatic loss of hominin diversity? What caused all these species to disappear? These are difficult and complex questions, but the answer may in part centre on the dramatic changes in climate that provided the backdrop for much of our evolution.
The last half million years or so in particular represent an episode of especially severe climate fluctuation, with intensely cold periods followed by warm phases, flip-flopping between the two on timescales of hundreds or thousands of years – in short, the worst bit of the 2.6 million-year Ice Age or Pleistocene Epoch.
The archaeological record of Europe suggests that vast areas were largely emptied of hominins during cold phases only to be recolonised during warm periods.
Hominins, pre-dating our own species, were living in Europe at latitudes as high as 53° north by 700,000 years ago.
The 53rd parallel runs from the United Kingdom east through the Netherlands, Germany, Poland, Belarus, Russia, Kazakhstan, China (Inner Mongolia), United States (Alaska), Canada and Ireland.
Many places at this latitude today experience temperatures as low as -40° Celsius. But the climate at that time was Mediterranean in character. Soon after, the planet plunged into another cold phase lasting 100,000 years, with vast areas of Europe covered by ice.
The tyranny of chance.
Biologists have identified various intrinsic features of mammal species that increase their chances of extinction. They include traits such as: large body size narrow ecological breadth (i.e. specialist feeders). low abundance, or sparse numbers of individuals, in the landscape as well as fluctuation in population over time.
Hominins are large mammals. Estimates of mass and stature for many Ice Age species would easily qualify them for spots on the front row of a rugby team … and that’s just the females!
Large mammals are slow to mature and reproduce, and normally have one offspring at a time. While many extinct hominins were, like our own species, omnivorous, those living in cold climates relied heavily on animal food, as have recent hunter-gatherers such as the Inuit. This represents a narrowing of the dietary niche on a par with many carnivores.
Estimates of population size from this period are remarkably low, with perhaps only 5,000 individuals in warm phases, plummeting to 1,000 or less during the cold stages, probably for the whole of Europe.
If around today, these individuals would be part of an endangered species, vulnerable to rapid extinction. And all of this applied to our own species as well for all but the last little bit of our brief evolutionary history.
Evolutionary game-changer.
Around 10,000 years ago, something unprecedented occurred that altered the course of our evolution: we invented farming. This massive change in dietary, social and economic behavior, a cultural shift known as the Neolithic Revolution, shaped the future course of our own, and the planet’s, evolution in remarkable and unpredictable ways.
It resulted in anatomical, physiological and genetic changes that massively altered our evolution.
Our domestication of plants and animals, and the large-scale clearing of land, altered the history of many others as well. It paved the way for a rise in infectious disease, and social changes such as occupational specialisation, writing, standing armies and empires, long distance trade, money and markets.
But the most profound shift of all was an explosion in human population, the result of greatly improved food security resulting in a dramatic lowering of infant and childhood mortality.
In Europe, from a base of perhaps only 5,000 Ice Age hunter-gatherers, the take-up of farming from approximately 8,000 years ago sharply increased population growth to an estimated rate of 3% per annum, from a long-term average of zero.
This is roughly three times today’s global annual growth rate. From a population of less than 100,000 people worldwide, we have grown in less than 10,000 years to almost 7 billion.
Moments lost in time.
Seen in its broadest context, the history of life on Earth soberly demonstrates that the vast majority of organisms that ever lived, perhaps 99% of them, no longer do. It also shows that mammal species normally last 1-2 million years before extinction inevitably bumps them off.
Yet, unlike most mammals, including our dozens of extinct hominin cousins, we have escaped the vulnerabilities of a small and massively fluctuating population.
The simple, but profound act of growing our own food delivered us the food security that ensured most of our children survived and our population grew.
In effect, farming gave our species level assurance that the biological isn’t always inevitable. The odds have shifted to such a degree that we may now be, with or without climate change, extinction-proof.
Humans Have Been Changing The Environment Since Prehistoric Times.
GAINESVILLE —Although early civilizations did not clear land for convenience stores, strip malls or housing developments, they did change the land to suit their needs and overused natural resources long before the industrial revolution, archaeologists have shown.
Liz Wing: A portrait in persistence – Florida Museum Science (ufl.edu)
“We are able to see quite a change in animal remains through time. We believe some of these changes are the result of overexploitation of resources,” said Elizabeth Wing, a curator at the Florida Museum of Natural History at the University of Florida. “We think of overexploiting resources as a product of industrial nations, but we see evidence of this during pre industrial times in many places.”
Wing and her son Stephen, an ecologist at the University of California at Davis, presented a paper in March to the American Society of Archaeology detailing how they used remains of bones, shells and teeth to show how civilization changes natural resources.
Early humans changed their environment through the domestication of animals, hunting and irrigation, Wing said. Remnants of raised fields and long dried-up irrigation canals can still be seen at sites in Bolivia, and elsewhere across the world, through aerial photography that reveals a crisscrossing of lines across the land.
“Channels to distribute water can be seen in the landscape,” Wing said. “We think that these changes went way back, probably more than 1,000 years. This is a way to see the impact that humans have had on the landscape. I don’t think that we have any habitats that haven’t been modified in some way or another by people.”
Many may not realize how extensively early settlers changed the environment, mainly because of persisting beliefs that primitive societies kept the land intact and lived simply with nature.
“There is still the idea of the ‘noble savage’ that is pretty instilled in people’s minds,” Wing said. “Not that I feel that people aren’t noble, but we have been changing the Earth for millennia.”
Evidence of these changes is seen in the environment and in thumbnail-sized bits of shell, bone and teeth found at archaeological sites and cataloged at the museum. Through comparison with other collections at the museum, Wing can tell what species were eaten by early humans and how these species changed over time due to human interference.
“When most people think of archaeology, they think of stone tools and pottery,” Wing said. “But animal remains are equally important as these stone artifacts, ceramic artifacts and other cultural remains. Since most animal remains at a site are the residue from meals, this provides insight into how people lived on a day-to-day basis.”
These small pieces of bone are crucial in determining the diet of early people and how this diet changed the land through hunting, farming and transporting non-native animals to these sites.
“This gives us a better insight into the use of natural resources and the effect we have on these resources,” Wing said. “We look at both biological and anthropological aspects, such as farming and development of domestic animals.”
Although early humans changed their landscape, modern people have altered the environment to a much greater extent, through dams, construction, industrial farming and pollution, ways that early people could probably not comprehend.
“All changes wrought by people are not necessarily detrimental to other plants and animals,” Wing said. “In fact, some changes improve conditions for some organisms. The point is, people have made great changes in the world from early times and archaeology can document some of these.”
The long reach of the past: did prehistoric humans shape today’s ecosystems?
We all know humans are having a massive impact on the planet.
Our effects include altering the Earth’s rotation by damming large amounts of surface water; changing the composition of the atmosphere by punching a hole in the ozone layer and adding vast amounts of CO2, methane and other pollutants; transforming the composition and temperature of the oceans; and clearing large tracts of land and removing or dramatically altering vast numbers of terrestrial and aquatic ecosystems in the process.
Plenty of these changes are plain for all to see; others are more obscure, but no less significant.
And, with the COP21 UN Paris Climate Change Conference just around the corner, politicians, policy makers and NGOs are again turning their attention to reaching an agreement that aims to keep global temperature change to below 2° Celsius.
A major issue for scientists studying the Earth’s physical and biological systems is just how great the influence of humans has been and for how long its been happening.
Our global destructive impacts mean that potentially any organism or ecosystem, and many of the earth’s physical systems like erosion, soil formation and water cycles, carbon and nitrogen cycles, and climate, have been affected in some way by human activity.
But can we disentangle the effects of human activity on these systems and organisms from natural signals and cycles?
I’d argue we probably can’t – that human impacts are just too wide ranging and too ancient, and that our disruptive and destructive effects have reached every part of the planet.
This means that probably every scientific study of any contemporary system or living organism catalogues the effects of our species and its economic activity in some way.
If we go back far enough to a time when humans didn’t exist, we have the potential to understand how the world looked and how natural systems behaved before we were around.
Problem is that the information we get is from the very incomplete and often biased geological record, in the form of fossils and various archives of climate and environmental change like isotopes recorded in ice or cave stalagmites.
And, of course, many organisms alive in the past are now extinct: the planet looked very different even just 20,000 years ago at the peak of the last major cold stage of the Ice Age or Pleistocene epoch.
Scientists like me who study extinct organisms and long lost ecosystems wonder whether large scale human impacts like those we see today are truly confined to the period following industrialization.
Did the ‘Anthropocene’ really begin 215 years ago?
Or does the environmental legacy of our Palaeolithic ancestors reach into today’s world?
This issue is at the Centre of one of the most hotly contested questions in palaeontology and archaeology, namely, the extinction of the Pleistocene ‘megafauna’.
But its a lot broader than this issue of course and it cuts to the core of who we are as a species, the way we have evolved, and lengths we’ll go to ensure our own survival; some would argue even our future survival.
Some scientists have also suggested that the Ice Age megafauna extinctions set the stage for the planet’s sixth major extinction event, which is unfolding before our eyes.
During the last phase of the Ice Age, between roughly 50,000 and 10,000 years ago, almost 200 species of mammals went extinct across the globe.
That’s half of the world’s mammals weighing more than 44 kg perishing in what was an instant in the long history of life on the planet.
A growing body of highly contested research suggests that humans may indeed have dramatically shaped the diversity of living mammals in the deep past, just like today, leaving us an impoverished natural legacy. And, let’s not forget that humans with our average body mass of close to 70 kg are megafauna as well.
While our species is obviously still here, we remain the chief suspect in the extinction of our close cousins the Neanderthals, Denisovans, and probably other relatives around this time.
The megafauna debate has been highly polarised for decades: humans being blamed on one hand, and natural climate change on the other.
Environmentally altering activities like burning the landscape by ancient hunter-gatherers in places like Australia, for example, have proven very difficult to establish, and their possible impacts hard to separate from natural climate cycles.
Yet other studies suggest that Ancient Aborignal Australians were one of the major agents involved in dispersing baobab trees in northern Australia; so our environmental impacts can be quite surprising.
And the chronology of human settlement and timing of megafauna disappearance in Australia remain uncertain: significant barriers to resolving the extinction question with any certainty.
So again, a major difficulty is the poor quality of the information we have from the fossil, archaeological and ancient environmental records.
The spectre of the confounding effects of natural and human-induced environmental signals remain all too real even for the Ice Age.
Another way to approach the question of human environmental change in the past is to construct mathematical models to look at changes over time and the influences of natural cycles and changes compared to human facilitated ones.
A battery of such studies is beginning to point firmly to the prehistoric human colonization of new parts of the planet as a major driver of extinction and environmental change; possibly the leading cause of the megafauna extinctions.
New research published over the last couple of months by Soren Faurby of the Museo Nacional de Ciencias Naturales Madrid and Jens-Christian Svenning of Aarhus University has also pointed the finger squarely at humans.
In an interesting twist, they modelled what worldwide diversity patterns of mammals might look like in the absence of past and present human impacts, based on estimates of the natural distribution of each species (5,747 of them) according to its ecology, biogeography and the current environmental template.
They found prehistoric human-driven extinctions in addition to recent ones were probably an important influence on present global mammal diversity patterns.
They even suggested that areas normally thought by ecologists to be biodiversity hotspots, like mountains, may in fact reflect their role as refuges for species otherwise affected by hunting and habitat destruction, rather than reflecting a natural pattern.
I’m satisfied that a strong case exists that humans did play a role in these extinctions and that there truly is a link between what our Palaeolithic ancestors were doing to the environment and what we’re doing today.
The difference now of course is that with an expected almost 10 billion people by 2050 and the remarkably destructive technology we possess we’re doing damage on an unprecedented scale and face a future on a planet with an irreparably damaged biosphere and dramatically altered atmosphere.
This video Qesankh Maa Kheperu discusses how the more you focus
on an idea or concept the more it takes shape in the physical word. https://www.youtube.com/watch?v=cprxP4PyRgQ
The Basics of Climate Change.
Climate change: evidence and causes | Royal Society
The science everyone needs to know about climate change, in 6 charts (theconversation.com)
DNA evidence proves climate change killed off prehistoric megafauna (theconversation.com)
Climate change wiped out Australia’s megafauna (theconversation.com)
Global Warming Provides A Marvelous Excuse For Global Socialism.
Dire Straits (Brothers In Arms) – Bing video