The Earth After Us

i-3e74c05bd3373b3b19d8353aac2e3b97-zalasiewicz_the_earth_after_us.jpgJan Zalasiewicz is a geologist active at the University of Leicester. His 2008 book The Earth After Us: What Legacy Will Humans Leave in the Rocks? is an interesting read even though the title does not correspond very well to the contents. Zalasiewicz does answer the question about what legacy humans will leave in the rocks. But on their own, these answers would only provide material for a magazine article. The bulk of the book is instead an introduction to geology which allows the neophyte to understand what will happen to the remains of today’s world as millions of years pass.

Having no geological training, I learned a lot from the book. An idea that I found particularly interesting was that sedimentary strata show a periodicity linked to the Earth’s movement through the solar system, the Milankovitch cycles. Another was that palaeontology’s source material is partly determined by what rocks happen to be currently available for inspection at the surface. Another was that anything that spends a lot of time at the surface of the Earth will soon erode away, which means that a few million years from now it will be impossible to study humanity’s hominid ancestry. Highland ecologies rarely fossilise.

But to me, the book’s take-home message is that humanity’s reign on Earth will mainly show up in the palaeontological record not as a stratum, but as an interface between geological periods. Such a period interface is defined as a place in a stratigraphic column where ecology shifts dramatically, many species go extinct and new ones evolve in their place. Zalasiewicz is quietly convinced that we are a blip on the timeline, with no chance whatsoever of sustaining our great numbers and high technology for more than another few centuries. To future geology, the heyday of Homo sapiens will just be one of several instantaneous mass extinction events in the planet’s history.

See also my review of Alan Weisman’s 2007 book The World Without Us.

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Invasive Species and Botanical Xenophobia


Summer temp journalists are here again. Today, Swedish Broadcasting’s radio news ran a really silly piece about invasive species. It made two main points: a new foreign species of plant or animal is discovered every month in Sweden, and some of them are poisonous. It’s basically a case of botanical xenophobia. The journalist also made the astonishing claim that these poisonous species pose a threat to the country’s biodiversity!

Poisonous plants and venomous animals are rare in Sweden, whose flora and fauna are quite poor because of the cold climate. On the other hand they are common in rich tropical biotopes. And the reason that biodiversity is plummeting in the Amazon certainly isn’t the presence of venomous frogs.

Invasive species of course increase an area’s biodiversity, at least in the short-term perspective. People are looking at ecology on the wrong scale level. Wait a thousand years before you decide whether a new arrival is good or bad. Almost all of Scandinavia was under two kilometres of ice until 10,000 years ago, which means that our ecosystem is a recent cobbling together of whatever species happened to be available when the ice melted. Nature’s way is continuous change. And to see a stable ecosystem re-established now, people would simply have to move out.

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De Profundis


Three cool pieces of science have been retrieved from the depths.

  • In the L’Atalante basin, one of the Mediterranean sea’s deep hypersaline anoxic basins, anoxic metazoans have been discovered. That means multicellular beings like you, Dear Reader, who live without oxygen. They’re loriciferans, Sw. korsettdjur, each less than a millimetre long. Instead of breathing like you, aided by endosymbiotic mitochondria, these beasties have another kind of power plant inside their cells similar to hydrogenosomes, that is, they’re chemotrophic.
  • In a bog on the high wooded hills of temperate Hanveden near Stockholm, my Mesolithic friends have now lifted sediment drill cores in which a paleobotanist has found seeds of Alpine mouse-ear chickweed, Cerastium alpinum, fjällarv. In a letter, Roger Wikell remarks that when those little flowers bloomed, the hilltop was a island in the Yoldia sea, part of an archipelago far from the mainland, and the retreating edge of the inland ice was not far away. Today, Alpine mouse-ear chickweed is a common feature of the mountain flora in northernmost Sweden around the polar circle. The various names of the plant all speak of frigid mountaintops.
  • From a cave in South Africa, two specimens of a new fossil hominin species.

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Blackbird Evensong

On Friday the blackbirds opened their concert season. Here’s what I wrote about them four years ago.

Oh, still my heart — I just heard the year’s first blackbird serenade! I opened the kitchen window a crack and listened to it while having my evening sandwich and cup of rooibos. I love the blackbird. It sings at the most unsettling time of the year.

These spring and early summer evenings, when the light never really fades and the blackbird sings its heart out… They fill me with a nameless urgency, a desperate itch for something I can’t put words to. Watching myself dispassionately from outside, I can see that it’s just the spring rut. But from the inside of my little mammal brain, oh man, it feels like I’ll have to walk to Kamchatka to ever find peace again.

Turdus merula, “solitary thrush”. In Swedish it’s koltrast, “coal thrush”. I hope to hear it on my deathbed one day.

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Scilla siberica


Spring is coming slowly, but it’s finally coming. These squills have been awakened by heat radiating from our house, but still they reach for the sun.

In other news, Discover Magazine continues to buy over top Sb bloggers, and I have finally learned the story behind the state of Oklahoma’s weird panhandled outline. Briefly put, it ended up that way because the state of Texas allowed slavery but the Union allowed it only south of a certain line. And so when Texas joined the Union, it ceded a ribbon of land that was north of the slavery line.

Whale Bones Trawled Up From Bottom of Baltic Sea


I’ve written before about a recent whale vertebra that someone had dropped into a lake far from the sea in northern Sweden. This past summer, fishermen trawling off the country’s southern coast caught two old whale bones, and they’ve turned out to belong to a grey whale, a species that’s been extinct in the Atlantic since the 17th century. An unidentified whale beached itself and died in the area in 1709. Radiocarbon will tell if the newly found bones are likely to belong to that animal.

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Ancient Beetles Will Date Mesolithic Shorelines


I got a great letter from Reggae Roger Wikell, which I publish in translation with the permission of Roger and Mattias Pettersson with the awesome metal hair. For context, note that these two scholar friends of mine are the area’s foremost authorities on Mesolithic sites that have ended up on mountaintops due to post-glacial shoreline displacement. The lithics there are mainly quartz.

Not all that glitters is quartz.

Yesterday we had a planning meeting with Dr. Risberg [quaternary geologist and the Stockholm area’s main shoreline displacement guy]. We’re going to core bogs at high elevations and target some critical bits of stratigraphy. Our goal will be to catch datable material (thank you, the Berit Wallenberg foundation, for generous funding). Thanks to Accelerator Mass Spectrometry [a radiocarbon method] we can now date birch pollen and the pretty little forewings of beetles. We know they’re there. I saw them myself in the 90s when we got our first cores from the bogs.

Isn’t it just too awesome to catch a glimpse of an Early Mesolithic summer — the glinting of the blue-green forewing that’s been resting in the sediment for 10 000 years. Those bugs buzzed for a summer and the sun glinted then too in their chitinous armour. A clear blue Ancylus summer whose sea-breeze soughed in the birches, the golden seeds of which are also common in the deepest sections of the sediment core…

Not all that glitters is quartz.

Let’s roll / Roger

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The Value of Biodiversity

Occasioned by a comment on my recent entry on the movie Avatar and the Gaia hypothesis, here’s a re-run of a blog entry from March 2006.

As comments to a recent entry, I’ve had an interesting discussion about environmentalism with a friend. We both agree that biodiversity and ecological systems should be preserved. But we disagree as to the reason for this.

If I understand my friend correctly, her opinion is that we should preserve biodiversity because it is precious (or even holy?) without reference to the needs and wishes of humans. Let’s say she feels biodiversity is an abstract good.

My opinion is that there is no such thing as abstract good. My reason for thinking we should preserve biodiversity is that it would be dangerous and aesthetically dissatisfying for humans if we lost it. I believe that the concept of value is only at all applicable from the perspective of an intelligent observer.

Consider the planet Octavia, far, far away. It sported a radiant ecosystem with innumerable species of exquisite beauty — until yesterday. A nearby star and the local black hole bumped uglies, producing an extended shower of hard radiation, killing every living thing on Octavia as the planet rotated. The planet now has innumerable fossils of exquisite beauty. And in a few years, Octavia’s entire star system will be swallowed by the black hole, obliterating it.

Now, is this a tragedy? No. It’s a non-event. Let me add two crucial pieces of information.

1) The smartest being that ever evolved on vibrant Octavia was a blue armadillo-like creature with the brains of a fish. And it didn’t suffer one bit when the radiation hit it.

2) No intelligent being from another star system ever came close enough to Octavia to even notice that it had life.

Or consider a species of yellow toad restricted to a single valley in Papua New Guinea. Its habitat is severely threatened by logging, and chances are it’ll be extinct in a few years. The passing of this rare toad species is of no practical concern to humans, and the locals won’t miss it. But people in the West, like me, will mourn the toad. Not because it had any intrinsic value, but because it was a fun animal to study.

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Population Will Come Down — We Choose How

It’s time for the annual Global Population Speak Out. We all know that in order not to crash the planet we need to consume less energy and raw materials and we need to emit less pollutants. But it doesn’t seem to be generally known that nothing an affluent Westerner does can have anywhere near as beneficial an effect on the future environment as not having kids. Riding a bike to work, recycling milk cartons, turning off the outdoor lamp before you go to bed — all of those green efforts of yours will be swamped and obviated if you have that extra kid.

Think about it. If there were only a few million people on the planet, then we wouldn’t have to worry about consumption or pollution. The problem is partly our environmental footprint per capita, but more the sheer number of people on the planet.

So, as I once wrote, for a person to produce more than two children is unethical. If you want lots of kids, then adopt — preferably from an affluent country, as you only make things worse if you move people from cultures with a small environmental footprint to a land of big cars and hamburgers.

We need to give little girls worldwide a good education, because that makes them have fewer kids when they grow up. And we need to combat various religious organisations that sow doubt about the efficacy and moral acceptability of contraceptives.

The population will not continue to grow for ever, nor remain constant on a high figure for very long. Sooner or later the human population will come down. It’s up to us to decide if this should happen through contraception and a global single-child policy or through a catastrophic die-off.

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Great flocks of fieldfares (Turdus pilaris, björktrast) are hanging around Boat Hill, feeding off the frozen parkland rowan berries instead of migrating. They’re so ruffled up against the cold that they’re hardly recognisable as the streamlined summer birds we’re used to. Their cousins the blackbirds sit alone like big black apples here and there in the leafless underbrush, waiting for the singing season.


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