The 6,000-Year-Old Force Behind Dramatic Global Ecological Change

By Jeffrey Marlow | January 7, 2016 6:35 am
A ring of protected land around New Zealand's Mt. Taranaki is surrounded by pasture. Land use changes have likely been influencing species distributions for thousands of years, according to a new study. (Image: NASA/USGS)

A ring of protected land around New Zealand’s Mt. Taranaki is surrounded by pasture. Land use changes have likely been influencing species distributions for thousands of years, according to a new study. (Image: NASA/USGS)

It’s hard to deny that humans are shaping planet Earth: from atmospheric composition to urban heat islands and widespread habitat loss, “before” and “after” comparisons reveal pervasive changes. These alterations are among the justifications for the proposed “Anthropocene” geologic epoch, which recongizes the dominant role of human activity on a number of planetary parameters. And while the most dramatic changes have occurred since the Industrial Revolution, a new study suggests that our ancestors’ activities were having dramatic effects on biodiversity thousands of years earlier, long before coal-fired power plants kicked the Anthropocene into overdrive.

Kathleen Lyons, a Research Scientist at the Smithsonian’s National Museum of Natural History, led a small army of scientists in the study, published this week in Nature. The amount and variety of data – 80 collections of mammal and plant spatial occurrence data ranging from the present to 300 million years ago – represents the most comprehensive compilation of its kind. These 80 data sets came from 13 different researchers, were obtained from four modern-day continents, and spanned anywhere from four to 4500 kilometers. But as complex and sprawling as the data was, the analyses were deceptively simple.

Let’s take a South African assemblage of large mammal fossils, for example. At 103 different sites going back 12000 years into the past, samples were collected and species were recorded. All told, 48 different species were found during the survey, and their patterns of co-occurrence at each of the 103 sites were noted. By assembling such data, the researchers could examine species pairs: were both Species A and Species B found at site 1? What about Species A and Species C? Or A and B at site 78? Lyons compared this information to a randomized assortment of the 48 species and used a battery of statistical tests to determine if there was any real difference in how the spatial associations shook out.

There were three options: two different species could be randomly distributed, showing no discernable pattern; they could be segregated, preferentially occurring at different sites but rarely together; or they could be aggregated, showing up at the same sites more often than not. Returning to the South African large mammals, 1128 pairings were possible (47 + 46 + 45…); of these, most showed random distributions (1091), but there were noticeably more aggregated pairings (25) than segregated pairings (12).

The parameters for each of the 80 collections were different, of course – different number of species, spatial range, age range – but the pairwise comparison strategy was the same. And what emerged was an intriguing trend that took a dramatic turn several thousand years ago.

As with the South African samples, most old fossil compilations showed a preference for aggregated pairs over segregated pairs, revealing a more interdependent ecosystem with intricate species webs and a range of possible symbioses. But around 6,000 years ago (give or a take a couple thousand years – the precise timing is difficult to pinpoint), the pattern began to change, and species were more commonly found apart than together. Before the dividing line aggregated pairs outnumberd segregated pairs by 2-to-1; afterward, the relationship flipped.

So what caused the change? Lyons rules out dramatic climate variability associated with glacial-interglacial cycles and settles instead on anthropogenic factors. “The statistical confidence interval bracketing the breakpoint at 6,000 years ago,” the authors write, “encompasses the beginning of agriculture in North America around 8,000 years ago and the increase in human populations.” (Most of the more recent data sets came from North America.)

This is academic journal-speak equivalent of shouting from the rooftops, and Lyons highlights several possible roles that burgeoning human societies may have played. Hunting and domestication, agriculture, land use changes that could inhibit movement, and the intentional and accidental spread of species beyond native ranges could all have played a part.

The allegorical subtext of this study is difficult to ignore. Gregory Dietl, in writing a commentary for Nature, points out that Lyons’ data emphasizes the Anthropocene as a brave new world with no historical precedent. The urge to use the past as a guide to the present may not apply to ecological issues, making it tough to see how our actions will continue to fragment ecosystems and tug at the fabric of ecosystems around the world. Gaining a more causal understanding of what exactly changed several thousand years ago will be an important next step that may yield valuable clues to our uncertain future.


CATEGORIZED UNDER: environment, living world, top posts
  • Emkay

    What! no ridiculous comment from Uncle Al?

    • jvkohl

      Thanks for encouraging him. Perhaps I can help. “Analysis of 6,515 exomes reveals the recent origin of most human protein-coding variants” reported that approximately 73% of all protein-coding SNVs and approximately 86% of SNVs predicted to be deleterious arose in the past 5,000–10,000 years. With what is known about the links from atoms to ecosystems, the claim in “Nature” most clearly represents the claims of young earth creationists. Doesn’t it Uncle Al?

      • Emkay

        Perfect Uncle Al’ and I’m LMAO..
        by the way ‘never trust an atom, they make up everything’..

        • jvkohl

          I believe that is why folks from the Zechiedrich lab at Baylor can be trusted. They have linked atoms to ecosystems via the same model that I used. See: “Structural diversity of supercoiled DNA.” The structural diversity is nutrient-dependent and biophysically constrained by the physiology of reproduction in the context of RNA-mediated protein folding chemistry. Uncle Al refused to discuss that last time I ran into him at a Mensa gathering. He seemed “dumbfounded.”

          • Emkay

            I remember a line from my 8th grade history teacher that I have used all my life, when necessary..”I refuse to have a battle of wits with an unarmed person”…

          • jvkohl

            Some fun can be had with people like Uncle Al.

            PZ Myers is another example of someone with claims that he thinks show his superior intelligence.

            His most recent display of ignorance about RNA-mediated cell type differentiation in octopuses includes a diagram of biophysically constrained life history transitions that he has claimed link random mutations to evolution.

          • Emkay

            Whenever I read one of his posts I think about my favorite Albert Einstein quote.
            “The difference between genius and stupidity is that genius has it’s limits”..

          • jvkohl

            I tend to also include the difference between geniuses with and without common sense. Uncle Al has none. PZ Myers is intellectually challenged and also has no common sense.

          • CB

            “I tend to also include the difference between geniuses with and without common sense. Uncle Al has none.”

            Who is “Uncle Al” and what does he have to do with this article?

            “Multiple studies published in peer-reviewed scientific journals show that 97 percent or more of actively publishing climate scientists agree: Climate-warming trends over the past century are very likely due to human activities.”


          • jvkohl

            Thanks for asking. Uncle Alan Schwartz is known to me from my membership in Mensa to be a biologically uninformed science idiot and frequent antagonist of anyone who has enough common sense to make intelligent comments on topics like this.

            How/why are your links appearing when others are placed on hold — and lost in space?

          • CB

            “How/why are your links appearing when others are placed on hold — and lost in space?”

            I’m not sure! I used to have similar problems here. Maybe I’m on a whitelist? …or the link is on a whitelist?

            I thought you were talking about a different Al… apologies for the confusion.

          • jvkohl

            Thanks. One way to determine whether it is you or your links on a whitelist is to post a link to a google search for the term “RNA mediated.”

            If this blog does not want anyone to learn how serious scientists link atoms to ecosystems in all living genera, your post will be put on hold till it disappears.

          • jvkohl
          • jvkohl

            The google link to “RNA mediated” was not put on hold, which means others can now learn how serious scientists have linked atoms to ecosystems via what is currently known about biophysically constrained protein folding chemistry in the context of physiology of reproduction.

  • OWilson

    I guess it’s a lot more interesting here when there’s nothing on topic and a lot of nonsense is being spouted by a feel good circle group “ridiculing” a regular contributor here.

    I guess that what passes for intelligence these days :)

    • Emkay

      and subtle ‘hating is still ‘hating…

      • OWilson

        Nothing personal.

        This was my subtle dig at the moderator, who deleted my welll reasoned, respectful and on topic post about the new research showing that man has almost completely “terraformed” this planet, in ways we are only now discovering.

        An example I gave was tthe Amazon basin, where analysis of the vast areas of “the mysterious black soil” reveals a huge thriving preColumbian agricultural population, that dissapeared (decimated) around the 1500s.

        The point I made is that there is now a new scientific consensus that the AGWers favorite “rain forest” is not pristine at all, and the mix of the present flora and fauna is a direct result of man’s activities, including slash and burn, and extensive crop growing.

        These seems to upset the folks who want to believe the myth of the “noble Savage” living in a completely natural and benign garden of eden, versus today’s “devastators of the planet”. :)

        • Emkay

          Got’cha… lets hope Uncle Al does not weigh in on this thread.. Trying to read/understand his posts gives me a headache!

          • OWilson

            Just look for the satire. You’ll find some gems.

            The Great Wits of our time were rarely Politically Correct.

            They always managed to upset some folks who never quite “got it”.

            But therin was its intrinsic and delicious beauty :)

          • jvkohl

            Who are the “Great Wits?” What claims are you addressing with your comments that are so vague as to be meaningless to all who are not interested in philosophy, which is where more vague representations can be found among those who think they have a grasp of science. They have only the typical grasp of pseudoscience that they tout. Thanks again for providing an example of that fact.

          • OWilson

            Now you are just boring.


          • jvkohl

            I fail to see the humor in the suffering and death that philosophers and other biologically uninformed pseudoscientists have left us in the trail of their thought experiments.

          • OWilson

            Pikers compared to know it all statists who insisted they knew how to make the world a better place for everybody.

            100,000,000 or so in the last 100 years, between the three of them, I hear.

          • jvkohl

            Philosophers hear only want they “want” to hear. That’s why their opinions are worthless.

        • jvkohl

          Have you noticed the fact that posts with links are typically deleted? That fact is important to recognize but unlikely to be known to philosophers. No facts are likely to be known to philosophers, which is why they try to invent them and convince others that they have invented a biologically-based fact.

          • OWilson

            Ah, but facts are only relevant to knowledge, which may or may not lead to understanding, which in turn may or may not lead to wisdom.

            One who can recite the dates of every major battle, or the Periodic Table and the associated atomic weights, does not necessarily “understand” history, or chemistry.

          • jvkohl

            Top-down causation links atoms to ecosystems via facts, whether or not you understand the facts. That fact makes philosophers the least wise of any other biologically uninformed people on this planet. Thanks for providing an example of that fact.

          • jvkohl

            Re: “…the moderator, who deleted my well reasoned, respectful and on topic post about the new research…” OWilson

            You are not known to me as someone who has posted any well reasoned, respectful, or “on topic” opinion of new research. Perhaps, you should reevaluate the importance of your contributions.

          • OWilson

            As I said, this new line of research seems to upset the folks. :)

          • jvkohl

            You are not saying anything important to discussion of this topic.

          • OWilson

            You are not the arbiter of anything.

            If you want to be a moderator, get your own darn blog. :)

          • OWilson

            It was philosophers who first questioned their myths and tried to determine what life and the universe is all about.

            Science (a relatively recent term) was generally referred to as Natural Philosophy. Galileo and Newton were thusly described.

            Newton, considered by some to be the greatest scientist achieved fame by his treatise on “Natural Philosophy”.

            As science evolves from the practical into theoretical speculation, the metaphysical, it is merely returning to its roots.

            You sell philosophers short :)

          • jvkohl

            Re: You sell philosophers short :)

            They have stolen the soul of science, and all serious scientists know that.

            See “A Fight for the Soul of Science” in “Quanta Magazine”

          • OWilson

            Two replies?

            I’m honored.

            That will be “TWO” pennies please!

          • jvkohl

            I am a medical laboratory scientist who knows that philosophers have contributed nothing but nonsense to what is currently known to serious scientists about the links from atoms to ecosystems in all living genera that protect life from virus-driven entropy.

            If I knew 9 more philosophers who were willing to sell their souls to pseudoscience, I could probably find a buyer.

            Science does not evolve, and ecosystems do not evolve, which is why philosophers have always been worth a dime a dozen. Simply put, your thoughts here are worth less than the penny that is typically offered when someone says “a penny for your thoughts.”

          • OWilson

            You sound more like a climatologist, than a lab worker.

            Ever hear of a “thought experiment”?

  • ikihi

    “the most dramatic changes have occurred since the Industrial Revolution.”

    this statement is 100% factually incorrect.

  • ikihi

    the earth has had periods that were MUCH warmer than now. so your claim about post-industrial revolution warming being the worst is pure fantasy…

    • Jim

      This was about biodiversity and land use, not about warming. It’s no surprise that with massive changes in land use, animal populations will be affected.

    • Emkay

      As “Climategate” unfolds, the debate about global warming is now beginning to take a more prominent place in public awareness. While the e-mails that were hacked from East Anglia University’s computer have shown us how many of the so-called climate scientists had been virtually tripping over themselves to falsify the data, it would be appropriate to take a step backwards and look at the question of global warming from a broader perspective.

      Below I present five cogent facts (gleaned from reliable sources) that cast doubt upon the existence of global warming, adduced by looking at what real science has discovered about the Earth’s climate, by seeing how there is no real consensus among scientists in support of the theory, and by examining two instances where hoaxers have been caught red-handed trying to pass off lies to bolster the global-warming conjecture (the funding scams sometimes prevail)
      We will also see how plain common sense can sometimes help one see through some of these things.

      Fact #1: We are actually entering an ice age, not an age of global warming.

      The possibility that we could soon be entering, not a period of global warming, but instead, an ice age, was being discussed back in the seventies before a lot of this scientific kookiness began (See next paragraph). The impetus for this idea came from the early 1900’s, when Serbian scientist, Milutin Milankovitch realized that the amount of solar insulation reaching the Earth and how it is distributed over the Earth’s surface determines the Earth’s climate (not CO2, as global warming advocates today maintain). He also discovered that ice ages are governed by three orbital cycles of the Earth, namely: 1) the 26,000-year period of the precession of the equinox where the Earth literally wobbles on its axis, which is combined with the advance of the perihelion (the point at which the Earth is closest to the sun) to produce a 21,000-year cycle; 2) the 40,000-year cycle of the variation of the tilt of the Earth’s axis from between 22 to 24.5 degrees; and 3) the 90,000 to 100,000-year cycle of change of the eccentricity of the Earth’s elliptical orbit from nearly circular, to an eccentricity of 0.06, and back again.

      This, coupled with the fact that at the present time in geological history, the northern hemisphere has the predominance of its landmass situated in or near the polar regions which allows for the buildup of huge glacial formations on land, has caused a 90,000-year period of glacial advance in the northern hemisphere, followed by a 10,000-year interglacial warm period, all of which has been going on for the last two million years. We are presently at the end of the 10,000-year interglacial. Exactly when the next period of glacial advance will start is not known. It could already be under way now. (1)

      Milankovitch’s theory was reconfirmed during the 1970s when a study by Imbrie, Hayes, and Shackleton based on sea-sediment cores came out, and still remains classical theory to this day. It is well worth the time of the reader to look into Milankovitch’s theory. I myself find it fascinating how the changing tilt of the Earth, its wobble, and the changing eccentricity of the Earth’s orbit over time, as well as the added effect of continental drift, determine ice ages, with the implications being, I think, much scarier than the global warming bugaboo stories. It also suggests, ironically, that if global warming were indeed true, it should be something to be welcomed rather than something to be alarmed about, because the temperature rise that such warming would supposedly cause might tend to offset the glacial advance.

      Fact #2: Cosmic radiation has a much larger role in determining climate than CO2.

      In 1997, Danish scientists H. Svensmark and E. Friis-Christensen discovered that cosmic rays ionize air molecules, transforming them into condensation nuclei for water vapor, causing cloud formation, which in turn, causes cooling. When the solar wind emanating from the sun is strong, it tends to shield the Earth from the cosmic radiation, causing fewer clouds and warming of the Earth. When the solar wind is weak, more clouds form and the Earth tends to cool. The average length of solar activity cycles is 11 years. The current sunspot cycle is weaker than the preceding cycles, and the next two cycles (22 years) are expected to be even weaker, meaning more clouds and colder, not warmer, weather.

      Fact # 3: There is no consensus among scientists that global warming exists.

      Over 31,000 scientists have signed a petition stating that there is no convincing evidence showing that greenhouse gases are causing or will cause catastrophic heating of the Earth.

      Fact # 4: The “Hockey Stick” Hoax.

      American scientist Dr. Michael Mann was discovered to have faked the data to try to show that the 1990s was the warmest decade in history and totally eliminate from the climate record the well-documented medieval warming from 700 to 1300 AD, when temperatures were actually much warmer (eight degrees average) than now. The temperature curve from 1000 to 1900 AD in Mann’s reconstruction is relatively flat and then spikes upward like the bend in a hockey stick. The intent of the fakery was to demonstrate that human industrial activity caused the purported increase. The fakery was exposed by two Canadian scientists, McIntyre and McKitrick. McKitrick actually showed that Mann’s computer program generated hockey-stick curves even when random data were inserted.

      Fact # 5: Al Gore has been proven a fraud in a British court.

      In October 2007 the High Court in London, England identified nine errors in Gore’s movie ‘An Inconvenient Truth’ which were so much at variance with accepted scientific truth that the UK Government ended up having to send a notice to every secondary school in England making clear the errors in the film. One of the lies is that low-lying Pacific coral atolls are already being flooded due to sea level rise caused by global warming, when there is no scientific evidence of any such sea level rise at all. Another lie is that polar bears, in order to find ice that has melted away, are being killed by swimming long distances, when in actual fact, the amount of ice in the Beaufort Sea where this is supposed to be taking place has actually grown in the last 30 years. There were in fact at least 35 lies that were found to be in Gore’s movie, although only nine of them were actually presented in court. Many feel that Gore was only financially motivated, in that he netted over $54 million for his efforts.

      What ‘common sense’ can tell us about global warming.

      If what I’ve presented above hasn’t shaken any belief you might have had in global warming, then I would suggest that you just use your common sense. Contrary to what seems to be implied by global warming advocates, if all the ice in the oceans of the world melted, it would not change the sea level one bit. Liquid water and floating ice displace exactly the same volume of water. Do the following experiment: allow some ice cubes to float in a pail or glass of water and measure the water level, and then see what the water level is after they’ve melted. You’ll find that the water level is exactly the same. Of course, if it ever got hot enough for the land-based glaciers to melt, that would be a different story . . .

      One might also ask ‘common sense’, if the CO2 level were actually increasing, wouldn’t that tend to cool the Earth instead? Since increased levels of CO2 tend to spur plant growth, wouldn’t this increased growth tend to have a cooling effect on the climate, due to the fact that more incident radiation is being transformed into biomass, as happens when plants absorb sunlight? An increase of CO2 would therefore also tend to increase food supply, and consequently, help alleviate hunger in the world.

      In conclusion, the sooner this notion of global warming is gotten rid of, the better. There are many urgent things in the world that need to be dealt with, such as the world food shortage, the massive lack of development particularly in the Third World countries, and the whole accelerating world economic collapse. If we were to take a clear-headed, scientific look at these problems, instead of having our vision distorted by some ideological viewpoint or arbitrary theory, we would be much better at dealing with these very real problems.

      List of Sources

      (1) Laurence Hecht, “The Coming (or Present) Ice Age,” 21st Century Science & Technology Special Report: The Coming Ice Age. 21st Century Associates, November 1997.

      Gregory F. Fegel, “Earth on the Brink of an Ice Age,” Pravda RU

      Zbigniew Jaworowski, “Solar Cycles, Not CO2, Determine Climate.” 21st Century Science & Technology.

      “Global Warming Petition Project.”

      John L. Daly, “The ‘Hockey Stick’: A New Low in Climate Science.”

      Christopher Monckton of Brenchley, “35 Inconvenient Truths.”

      • Dan Imler

        There are indeed urgent things in the world. These are the results, not the causes. Despite your opinions and assertions, the changes in land/water/air and the alterations in ecological systems, regardless how small, will mount and create a substantially different environment, for which we are not well suited. What we believe or disbelieve will not matter. Climate change, like most people, will reveal its true self over time by its actions and effects.

        • Emkay

          Not my opinions and assertions..did you happen to glance at the list of sources of the points made in my post?.. but to be sure, earth’s climate has always changed, is changing, and will continue to change.. in fact, the only thing that is truly permanent, is change..
          Mother Nature, a few thousand years from now, will shake us off like so many fleas on a dogs back.. enjoy your time here..

      • onlymho

        while I also discount AGW, a concern over the statement “Since increased levels of CO2 tend to spur plant growth, wouldn’t this increased growth tend to have a cooling effect on the climate, due to the fact that more incident radiation is being transformed into biomass” exists relative to reduction of forest area (now reduced by an estimated 50% from recent peak) leaving far less biomass influence to take advantage of the acknowledged increase in CO2 – looking forward to your thoughts

    • CB

      “the earth has had periods that were MUCH warmer than now.”

      That’s true!

      …each and every one of which was caused by increases in CO₂.

      If you understand polar ice sheets have never before in Earth’s history been able to withstand CO₂ so high, how likely is it they will today?

      “The continent of Antarctica has been losing about 134 billion metric tons of ice per year since 2002, while the Greenland ice sheet has been losing an estimated 287 billion metric tons per year.”

  • Bob Juniper

    In six months this theory will found incorrect and a new one presented which will be found incorrect and……..

  • Sinibaldi

    A sky full of thoughts.

    As a concept

    in the sky

    full of dreams,

    as a beautiful

    moment that

    always appears

    with the sound

    of a fine bird….

    Francesco Sinibaldi

  • Billy Pham

    Nonsense everyone knows the planet was only created a few thousand years ago when God made it. Your data predates Noah and his ark this is preposterous there is just no way…

    Unfortunately yes no matter how ridiculous and sarcastic I try to sound I still feel I must let the people that read this know it is a joke


The Extremo Files

The Extremo Files traces the science that is pushing the boundaries of biology, from the deep sea to outer space to the brave new world of synthetic biology.

About Jeffrey Marlow

Jeffrey Marlow is a geobiologist exploring the limits of life, from the role of microbes in global elemental cycles to the possibility of life beyond Earth and the brave new world of synthetic biology. He received his PhD from the California Institute of Technology and is currently a Postdoctoral Scholar at Harvard University, where he studies the inner workings of methane-metabolizing organisms.


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