Something Funny Happened In The Eocene

Taken from here. Removed on request

On this blog, I’ve often mentioned the tendency and the temptation to look at the past as if it’s just a prologue to the present. If that’s so, that would surely make the present a prologue to the future, which seems silly. In fact the past was the way the present used to be and we should appreciate the past in all its pastness. I sometimes joke that all the years after 1984 CE are just made up, because that year seems to be the peak of my reminiscence bump.

Consider, then, the above image. I can’t say I’m fully aware of every species of animal in it but I suspect that some of them are only included because they’re close to the ancestors of species we’re familiar with today. For instance, I spy tiny horses, but back in the day Hyracotherium wasn’t a tiny horse waiting for the grasslands to develop so she could get bigger and gallop across them as some kind of vaguely hare-like animal living in the leafy undergrowth of the rainforests, even though their children’s children’s children’s . . . children would be horses, zebras and donkeys.

The above scene is from the Eocene. This used to be thought of as happening immediately after the Chicxulub Impactor led to the deaths of all but the smallest dinosaurs, but nowadays the Palæocene has been inserted between that incident and the start of the Eocene, so it’s now seen as starting later than it used to be and doesn’t have the specialness of being immediately after the big kablooie. Because of the older idea that the dinosaurs (who used to be decidedly non-birdy) were cold-blooded and had died out because of climate change, i.e. it got too cold for them and they all died of hypothermia or something, I used to think of the Eocene as kind of cold and rainy. After all, if “warm-blooded” animals like mammals and birds were able to thrive during it and the dinosaurs, being cold-blooded, couldn’t, it seems to make sense that it was not very warm.

In fact, the opposite is the case. The Eocene was ludicrously and stupendously warm. It was so warm that there were tropial rainforests in the Arctic and the polar ocean was like a warm bath in temperature. It was hotter than the age of dinosaurs by far, and even in 24-hour darkness it stayed warm enough for there to be hot, steamy jungles. I find this utterly confounding, because in such conditions mammals would seem to be at a disadvantage compared to reptiles. They’d be expending loads of energy just trying to keep themselves cool enough not to succumb to heatstroke. Then again, maybe this is the answer. The reptiles maybe didn’t do so well because they were heated by the ambient temperature, whereas mammals were better at keeping their temperatures lower. Maybe the truth about mammals is that far from being warm-blooded, they were actually cold-blooded, in that they were kind of living self-refrigerators, and it was this which enabled them to survive such a sultry planet. But it still doesn’t make much sense to me, particularly because the lack of daylight which went on for months at a time at the poles still didn’t make it cold.

That, then, is one major odd thing about the Eocene, but it isn’t alone and it isn’t the only weirdness. The fact is that of all suspect times in the planet’s history, the Eocene is the best fit for the Silurian Hypothesis. If you just want a breakdown of that in general, feel free to follow the link, but the basic idea is that because we have quite good evidence for how our own civilisation is affecting the planet, we can look back into the past and find other times in the geological record where something similar happened, and perhaps conjecture that the reason it did so was that there was an advanced civilisation on Earth at the time. There are a number of candidates for this idea, but by far the best in terms of several different technosignatures coinciding takes place during the Eocene.

A technosignature is a sign, perhaps observable from another star system, that advanced technology is or has been in use on a particular planet or in a particular star system. It might be something like a planet with fluorine compounds in its atmosphere or an unusually high level of carbon dioxide as well as oxygen. I’ve just made those up by the way. At the moment, something a little suspicious has been noticed in stars near Tabby’s Star which may be along these lines. Tabby’s Star is a star with an unusual pattern of dimming which it was tentatively suggested might be evidence for a megastructure such as a Dyson Swarm around it. Simpler and better explanations have been offered for that individual star, involving dust and unusual but feasible patterns of comets, but it’s more recently been found that the pattern is found in stars near Tabby’s Star itself which are exactly the types of star expected to be suitable for life. Although it’s strongly tempting to imagine an interstellar civilisation based on this, this can amount to “a wizard did it”, i.e. it’s the go-to explanation for anything unexplained, and it’s not boring enough to be true.

The Silurian Hypothesis is named after the ‘Doctor Who’ monsters known as the Silurians. Perhaps coincidentally, these don’t date from the Silurian itself, although the name sounds cooler, but from the Eocene. They hibernate for millions of years before emerging from their slumber to find the mammals have taken over, so they actually belong here and are not aliens, but as befits the pulpy nature of Who, which it’s no worse for, this is all a bit thrown together like that bit in ‘City Of Death’ where life is supposed to have begun 300 million years ago rather than over ten times further back than that. But I can forgive that because it’s by Douglas Adams. The Silurian Period itself was before vertebrates had heaved themselves out of the water, or rather found themselves in increasingly shallow deoxygenated water until they were just squelching about in mud, so it doesn’t seem to lend itself that well to a race worthy of the name, but is actually named after a Pre-Roman Celtic tribe native to what has become Southeast Wales. It also happens to be found in the zoölogical name for catfish, the siluriformes, and the idea of vaguely vertebrate-looking aliens with tentacles on their faces instead of hands is quite appealingly exotic and perhaps creepy, but Doctor Who Silurians don’t look like that at all.

This subject is kind of about aliens, but in another way it isn’t. However, the circumstances of the Eocene suggest that if something did happen then it wouldn’t have originated from this planet, because it doesn’t look very promising. The non-avian dinosaurs, which had reached some kind of climax, had just been wiped out (fifteen million years is not necessarily a long time geologically) but the placental mammals hadn’t had time to get very far yet. The Eocene placental mammals were very diverse, because evolution had enabled them to radiate into the newly vacated ecological niches very fast, but there would later be a reckoning leading to most of those groups becoming extinct. Therefore it doesn’t seem very likely a technological civilisation would appear among them.

It should also be borne in mind that the Eocene is a long stretch of time compared to human history, from 56 to 33.9 million years ago or more than twenty-two million years. Taking the persistence of behavioural modernity as the starting point of our history (the likes of cosmetics, jewellery, cave art, burial customs and so forth), five hundred centuries ago, this is over four hundred times as long. Thus the geological record of a prehistoric civilisation would be quite short and abrupt.

I don’t want to repeat what I said in the original article here because my focus is a bit different, but for convenience’s sake, what we will leave in the geological record is a mark of the damage, though temporary, we’re doing to the environment and there are a number of possibilities. Firstly, light elements cycling through the biosphere and other cycles without technological intervention have a distinctive isotopic profile because they’re exposed to solar radiation and this changes the number of neutrons in their atoms, whereas the same elements buried deep underground are shielded from this by layers of rock which block the same radiation. Hence the nitrogen in fertilisers which has been mined rather than, for instance, being derived from guano as is traditional has different proportions of isotopes in it. The carbon implicated in anthropogenic climate change is also different because it was taken from coal and oil. Although many isotopes are unstable and will have disappeared from the record in millions of years, some are stable and will be preserved. There are also transuranic elements which are relatively stable, such as isotopes of plutonium and curium, whose half-lives are in the millions of years. Curium in particular doesn’t occur in any significant quantities on planets. Increased soil erosion also results in faster rates of sedimentation in rivers and estuaries, associated in part with the greater use of nitrogen fertilisers, and there are dead zones in the oceans as a result of nitrogen in this form allowing microörganism growth to outstrip the supply of oxygen. This can be seen to show up in the geological record, for instance at the biggest extinction of all at the end of the Permian, so it clearly does leave a mark. Incidentally, some scientists believe this is the main direct cause of mass extinctions. There are more rats and mice around than before, so an increase in the occurrence of particular fossils might be another sign. Technology is also able to create compounds more stable than those which arise without intervention, such as ones where chlorine and carbon are bonded, hexafluoroethane and sulphur hexafluoride, which will persist in the environment for hundreds of millions of years if not longer. Organic compounds formed biologically also have handedness, although in the case of amino acids these become mixtures over thousands of years, so the presence of steroids in mixtures of left- and right-handed forms, for example, would be a good sign. And of course there are plastics, although some of these are stimulating the evolution of bacteria which can digest them, or the proliferation of long-existing organisms who already could.

Ocean anoxia has occurred quite often in terms of the geological timescale of events. The aforementioned incident at the end of the Permian is one example. Others are seven such events, three of which were localised and minor, in the Cretaceous, and one in the Jurassic, often associated with an increase in carbon-13. There also seems to have been greater ocean sedimentation during these occurrences. There was also such an event in the Devonian, and particularly reminiscent of our time of deforestation, the loss of the Carboniferous rainforests is quite a 21st century event for so long ago.

But for some reason the Eocene has a cluster of such markers. The start of the Eocene 56 million years ago is officially marked by a sudden increase in the carbon and oxygen isotopes which in our time mark civilisation. For between one hundred and two hundred millennia, stable isotopes of carbon and oxygen other than the most common types both became more common. There was also global warming up to 7°C at the time. Vanadium, zinc, chromium and molybdenum all increased while this was going on, as did sedimentation in the oceans. Over the six million years after this, there were four more such events, although less dramatic, then forty million years ago there’s one more. The interesting thing about these is that the combination of unusual isotopes, global warming, apparent soil erosion and metals used in industrial processes all occur together, just as they are today.

One good argument against the existence of aliens is that we’re here at all. It seems that if a technology like ours arrived here in the æons of time over which life has existed on this planet, it would’ve caused serious damage to Earth’s ecosystem and perhaps wiped out all complex life, but there are no such incidents in our history. There’s also no species which isn’t related to all others, as might be expected if alien microbes had arrived on this planet later than the possibly first alien microbes to whom we might all be related. Hence we have to confront the rather disturbing prospect of a friendly habitable planet (at least to us) sitting here for countless millions of years without one single alien spacecraft landing on it, and that suggests there are no aliens, or at least no aliens yet. However, if there are recurring incidents of this kind in the geological record, the quandary becomes somewhat different, because instead of Earth never having been visited, the issue becomes the absence of alien microbes or other life forms on this planet. That issue, however, could be circumvented if it turns out these civilisations, which may of course never have happened, are actually from here, but the problem is then what animals they evolved from. The Palæocene is if anything even less promising than the later Eocene in this respect.

There are, then, three possibilities:

1. There has never been an advanced technological civilisation on this planet and the apparent technosignatures are just coincidences explained by other processes. This, being the most boring possibility, is the most plausible by far.
2. There has been at least one advanced technological civilisation which evolved from organisms already living here.
3. The planet has been visited and settled by advanced aliens.
4. There is a mixture of native and alien civilisations through our geological history.

The events of the Cretaceous may be more compatible with the idea of intelligent dinosaurs. The run up to the Cretaceous is many millions of years long, giving dinosaurs with human-like intelligence a lot of time to evolve, and some of the dinosaurs living today, such as parrots and crows, manage to achieve intelligence very similar to ours in spite of brains only weighing about thirty grammes compared to our fifteen hundred. However, the Eocene is more puzzling. The recent impact which had wiped out the larger dinosaurs did stimulate evolution, as mass extinctions often do, but it also caused the extinction of all larger animals, which are able to have larger brains, and it seems like it would’ve taken a long time for them to get that brain power back.

As a child, I made the following conjectures about past technological species here:

• At the end of the Permian period, a species of mammaliforms evolved human-like intelligence and founded a civilisation which had such a devastating effect on the planet that it caused a mass extinction.
• The coleurosaur (bipedal dinosaur with binocular vision and opposable thumbs – or at least I thought so at the time) Saurornithoides established a civilisation and wiped themselves out in a nuclear war, thereby explaining the iridium anomaly.
• The ancestors of dolphins had their own technological culture about twenty-five million years ago, which is the point when their brains reached ours in size.
• Homo erectus achieved an interstellar civilisation 800 000 years ago which only collapsed at the end of the last Ice Age.

I no longer believe in any of this, but I would want to modify the dinosaur one in particular, which I think is by far the most feasible, to incorporate Chicxulub, in that they could have moved an iridium-rich asteroid into orbit around this planet as a source of metals and accidentally crashed it into the Gulf of Mexico. The Cenozoic ones don’t line up with the events in the Eocene. Homo erectus evolved in the Pleistocene and the dolphins reached that stage in the late Oligocene, eight million years after the end of the Eocene.

The trouble with all of this is that it has a kind of quirky, eccentric sound to it and seems to be way outside of the scientific establishment. It’s particularly similar to tales of Atlantis and Von Däniken’s ancient astronauts, whichever version of the hypothesis you go with, apart from the first of course. On the other hand, why should we be the first, either in the whole Galaxy or on this planet? It seems arrogant to assume that, and on the whole we’re supposed to go with the Copernican Principle that there’s nothing special about us, and if there isn’t, maybe we aren’t the first, even on Earth. However, if there was a civilisation here during the Eocene, it seems unlikely it was from here, so maybe back then Earth was an outpost of the Pwqu Empire or something. After all, they left that giant mouth thing on that planet didn’t they?

Could it actually be Earth that was the cradle of interstellar civilisations at this time? There are reasons to suppose not. This would be the inverse of the possibility that aliens have visited this planet, because the chances are they would’ve left genetic traces as unrelated organisms. If the Galaxy had been filled by countless Earth colonies back in the Eocene, we’d be more likely to be living on one and find that there were two strains of life on it rather than the single one we observed. On the other hand, it is a bit odd that the first organisms on this planet seem to have been here during the Hadean, before Earth had even become even slightly habitable, so is it possible that all life in the Universe, or perhaps locally, is related and we’re looking at an extraterrestrial rather than a terrestrial common ancestor?

The kind of civilisation we’re looking for here is very much modelled after our own post-industrial, science-dominated culture, and it doesn’t follow that those would be the kind of societies which emerged millions of years ago. For all we know, and that phrase takes the proposition out of science because there’s no evidence but it’s still rational, civilisations may have evolved which were either very advanced in other ways or more cautious and reverent of Mother Nature. Maybe we don’t see evidence of civilisations like ours because we’re an anomaly, not because we are a community of sentient beings using technology but because of what we’ve done with it, or maybe other civilisations too went through an unsustainable industrial phase but ended up cleaning up after themselves. Nonetheless there is limited evidence for a civilisation in the Eocene, or perhaps a whole cycle of civilisations over millions of years, maybe collapsing due to unsustainability and environmental catastrophe before slowly making their way up the ladder, only to fall again millions of years later.

This may actually give us some hope. If the influence of past civilisations is so difficult for us to detect today that even the most recent ones, forty million years ago, managed to poo in its own bed so seriously that it wiped itself out and the planet recovered so well we can’t even tell it was there nowadays, it suggests that Earth has very powerful capacity to heal itself, and has done so before from the very onslaught we’re committing today. However, there’s no longer any trace of any putative civilisation remaining, which is also food for thought. We could, geologically speaking, be so thoroughly gone that nobody will ever even know we existed.

To The End Of The Earth

It used to be thought that we were about halfway through our planet’s history, and that conditions would continue in the way they have in the last few hundred million years until the Sun becomes a red giant in something like five thousand million years’ time. Sadly, this is not now considered likely, but that’s not really because of us or any damage we might be doing to the planet’s long term prospects. It turns out that our Sun has something more hostile in store for us in less than an æon. And at this point I should probably explain my words.

Firstly, I still use the long scale with large numbers, so for me a billion is 10¹² and so on – 1 followed by twelve 0’s. The short scale, where a billion is 10⁹, 1 000 000 000, is American and when I say “American” I mean both continents. It’s fairly wasteful to use up the words for numbers on lower values, so I don’t do it. That said, ironically from an English-using perspective, the short scale does line up better with metric multiple prefixes such as giga- for “billion” and tera- for “trillion” and so on. There’s also already a perfectly good word, “millard”, referring to a hundred thousand anyway.

Secondly, the word æon, from the Greek word ‘αιων meaning “age” or “generation”, and sometimes translated in the Bible as “world” in a fairly pejorative way, is a unit of time lasting a thousand million, or millard, years. From the same root stems the word “eon”, which is a division of time above “era”, so I’ll talk about that too. Earth’s past history is divided on the longest temporal scale into eons, namely the Hadean, Archean, Proterozoic and Phanerozoic, this last being our current eon. From the Archean onwards, these are divided into eras (the well-known Palæozoic, Mesozoic and Cenozoic in the past 540 million years or so), periods (for example the Triassic, Jurassic and Cretaceous), epochs (in our case the Pleistocene, Holocene and probably the Anthropocene), ages, for example the Meghalayan which lasted from some time in the Bronze Age and might be considered to have finished in the 1950s, and finally chrons, which in the case of the current Sub-Atlantic started around the time Rome was starting to expand. It gets a bit confusing because of the archæological Three Age System of Stone, Bronze and Iron, and incidentally we are still in the Iron Age, which collides with the chrons.

With a couple of exceptions, Earth’s future is as yet unmapped as far as actual names for intervals of time are concerned, but it certainly isn’t unmapped according to scientific understanding, which of course could change easily. In fact it did just that in the past few years with the realisation that we haven’t got as long as we thought. I’ve already gone into a fictionalised history of the next two hundred million years which mainly amounts to Dougal Dixon’s work on ‘After Man’, ‘Man After Man’ and ‘The Future Is Wild’. This is somewhat feasible and somewhat based on science, though forty year old science, and has some degree of validity, but there is a firmer understanding of the probable near future, and also well beyond that until the Sun dies. Thus I’ll start with the next few million years.

It’s been proposed that we’re currently in the Anthropocene Epoch, but it isn’t clear when it started. The previous epoch, the Holocene, covered the time since the end of the last Ice Age, but in recent years it’s been reconsidered and now there’s a popular movement to divide the Holocene off from the past few years because of the major effect our own species is having on Gaia, hence Anthropocene – ‘ανθροπος + καινος = > human + freshness. All the epochs in the Cenozoic end in “-cene” because they’re relatively recent. The geological dating system uses “BP” to name particular fairly recent times, usually within the history of our genus Homo, which stands for “Before Present”, the “present” being defined as the year 1950. Consequently one suggestion is to date the Anthropocene from 1950. Another rather similar proposal is that it begin from the earliest nuclear weapons tests, since these have left a long-lasting change in the geological record by irradiating the world and changing its radionuclide signature. A third suggestion is that it begin with the Industrial Revolution, and finally Heather Davis has proposed that it start in 1492, since this is when Europeans began to conquer the rest of the world. Rupert Sheldrake, who articulated the Gaia Hypothesis, recently proposed that the Neocene will follow the Anthropocene in the near future, which basically coincides with the Singularity and marks the point where machines will sort the environmental problems we’ve created. This would make the Anthropocene ridiculously short, possibly less than a century, but Sheldrake embraces that, linking it to the acceleration of change, which may have started nearly an æon ago with the appearance of multicellular life. The future is of course unknown and our existence may have vast consequences of which we’re currently unaware and can’t anticipate, but there’s also what might be called the “geological future”, that is, the future as it will proceed assuming that human activity lacks major long-term consequences for the planet, which is probably less hubric and more Copernican, as it were.

Naming things doesn’t necessarily give you any control over them though.

The most obvious issue in the relatively near future is anthropogenic climate change. It isn’t clear whether what we do to the climate is far-reaching enough to end the recent spate of ice ages, of which there have been five from the Pleistocene onwards so far. It might even trigger one, because if Antarctic icebergs spread far enough they may reflect more heat into space and cool the planet. There are various ideas about the next ice age. The most popular seems to be that it will happen anyway, in about fifty millennia, which is when it’s “scheduled”. More recently this has been questioned, and some climatologists believe there will still be another ice age but that it will be in a hundred millennia, because by that point climate will have returned to the point where it would’ve been without our technology as it has recently been. Of course it may also be that we or our machine successors will just “re-wild” most or all of the planet and things will get back to “normal”. This degree of uncertainty regarding even the relatively near geological future might be seen as indicating that this is just idle speculation, but in fact it may not be because certain things are well-known and established scientific facts it seems unlikely we’ll be able to avoid, such as entropy, and those can be predicted fairly confidently.

A lot of this is covered in the popular video ‘Timelapse Of The Future’:

I’ve covered this before here, and there are similarities between this post and that one and its successor, but I hope I’m saying something fresh here too.

Fifty thousand years from now, the day will be one second longer. This is because the lunar tidal action on Earth gradually slows our rotation. I’ve previously been curious about how long it would take before the year has exactly three hundred and sixty-five days, and if this change is linear, leap years will become unnecessary by the time each day is fifty-nine seconds longer, almost three million years from now, and before that date they could be rarer, say every five years by six hundred millennia from today. To be honest, I find the idea that the Gregorian calendar would still be in use by then absurd, but there are similar assumptions made about the likes of long-term contracts and economic planning, so maybe it will, and Y2K is an example of a problem caused by assuming such things would not be in place for longer than a few years.

A quarter of a million years hence, Lō’ihi will break the surface of the Pacific Ocean, although it may of course be either deeper or shallower by then depending on which way sea levels go. This is the next Hawaiian island, to the southeast of Hawai’i itself. This will continue as the Pacific plate and the hotspot shift over many millions of years and the islands to the northwest erode away. By six hundred millennia from now, the chances are that an asteroid one kilometre in diameter will have hit us, although this could happen at any time. The energy released by this would be equivalent to around sixty times the detonation of every nuclear weapon in the world. There’s a modelling tool for asteroid impacts here.

Around a million and a quarter years from now, a red dwarf star called Gliese 710 will be very close to the Solar System, less than a quarter of a light year away. By two million years hence, judging by previous events when this has happened, the ocean will once again be alkaline enough for coral to recover. This acidification occurs because of the increase in atmospheric CO₂. Ten million CE will be around the time the Afrikan Rift Valley will be flooded and the new continent, which Dougal Dixon named Lemuria, will start to move across the Indian Ocean. Also by this time, even without a mass extinction most species around today will have died out and, I hope, been replaced. Fifty million years from now the map of the world will look roughly like this:

(I actually think this is exaggerated in the sense that it assumes the rate of continental drift to be faster than it in fact is).

Around 200 million years from now, there will be a new supercontinent, whose exact shape is hard to predict because nobody knows much about which way Antarctica will move. This restores the planet to the situation as it was before the dinosaurs evolved, and makes for a large amount of desert with extreme temperatures near the centre of the continent, very hot during the day and very cold at night. It will also increase the amount of oxygen in the atmosphere, and means a single world ocean and a single landmass covering 29% of Earth’s surface. While this continent is in place, the Hadley cells either side of the Equator will move to 40° either side of it. This will increase the already high percentage of desert land by a further 25%. This supercontinent will have broken up by about 450 million years from now, leading to the kind of climate found here during the Age of Dinosaurs, and also at around this time the likelihood of a mass extinction from a gamma ray burst, which will cause it to rain concentrated nitric acid, means it’s likely to have happened by about this time.

There may just be time for another supercontinent to form about 600 million years from now, by which time there will be no more total solar eclipses because of our satellite’s widening orbit, but there will still be annular eclipses where some of the Sun’s surface remains visible.

Then, unfortunately, a major catastrophe will ensue. Up until this point, a process referred to as the carbonate-silicate cycle has kept considerable amounts of carbon dioxide in the atmosphere. Rain dissolves this gas and acidifies, landing on rocks and gradually dissolving them. Calcium and bicarbonate ions are washed into the ocean, where it’s incorporated into the hard parts of organisms such as plankton, molluscs and coral. This sinks to the ocean bed, where it’s buried and ends up in the magma under the crust. Volcanic eruptions then return this to the atmosphere as carbon dioxide. But the Sun is gradually getting brighter, and by this time the light will be strong enough to start weathering the rocks faster than their carbon can be released back into the air, and will also start to dry the land, reducing rainfall and therefore carbon reaching the sea. The rocks will also harden, slowing continental drift and since that’s responsible for throwing up new volcanoes along the edges of the plates, these will erupt less often. At a certain point, around 600 million years from now, one form of photosynthesis known as C₃ will cease to operate due to insufficient carbon dioxide in the atmosphere. This will lead to a gradual decline and eventual extinction, first of green herbs such as annuals, then deciduous trees, then broad-leaved evergreens and finally conifers. I would expect that during this time, evolution would lead to other plants occupying their vacant niches. That said, there’s still C₄ photosynthesis, which can function at a lower level of carbon dioxide, and there are many plants which use this type, particularly those in the spurge family, and they already look quite alien and futuristic:

Photograph of Euphorbia helioscopia, taken in Machida city, Tokyo, Japan. Croped & resized.
Date
17 May 2006
Source
Own work
Author
Sphl

Water vapour is a much more powerful greenhouse gas than carbon dioxide and consequently this evaporation of water from the oceans and elsewhere will start to raise surface temperatures. Because of less photosynthesis, oxygen will also fall and therefore the ozone layer will break down and there will be more oxidation at the surface due to more ultraviolet light penetrating to ground level, removing even more oxygen from the atmosphere. By 850 million years or so in the future, C₄ photosynthesis will become impossible and the cycle run by the sun through plants will cease to function. This means that only animals who don’t breathe oxygen or rely on plants for food, directly or indirectly, could survive. This would, for example, include worms living in geothermal vents at the bottom of the ocean who feed on bacteria. However, the ocean will also be disappearing and once the average surface temperature exceeds 47°C 1.1 æons from today, the amount of water vapour in the atmosphere will start to run a feedback loop through the greenhouse effect, causing runaway evaporation from the oceans and a slide into a situation where the only life which can survive will be in places like lakes and caves at the tops of mountains or near the poles, and finally not even that. 1.6 æons from now only bacterial and archeal life will remain, and 2.8 æons hence even the poles will be at 150°C.

I find this all rather claustrophobic and suffocating, which is a bit of a weird reaction. I look around at the trees in the park, the people, badgers and spiders in this household, note that I can breathe the air and that there is evidence of human activity all around in the form of houses, roads, vehicles, furniture, whatever, and it really saddens me that it will come to an end so soon, but I also find it weird because we’ve got 800 million years to go. However, they used to think that Earth would stay in about the same state for about as long as it had already existed, so theory has robbed us of three or four æons of life. There’s only enough time for another two supercontinents, by contrast with maybe ten which have happened before on this world. But the future is in fact unknown and may not be like the past, or continue trends which began then. We have intelligent tool-using life now, and those tools may find a way to lengthen our stay, or alternatively hasten our demise. Also, if some of us were to leave this planet permanently and entirely to settle elsewhere, that gives us more hope, if hope is the word. But a Doomsday Argument-like scenario makes that unlikely. Then again, maybe it isn’t up to us. Maybe another species of animal will start to invent more advanced tools and technology before the carbonate-silicate cycle breaks down. Maybe there will even be such beings around as it starts to happen. Who knows? The future is unknown.

Plastic Pollution And Hope

Plastic pollution is infamous. We all know about the North Pacific Garbage Patch, marine wildlife eating plastic and starving for lack of real food and not to use plastic straws, although that last issue is ableist. It also needs to be put in context, and the context is not good.

First, plastic straws. Some people need these because they are unable to lift cups or sterilise reusable straws and can injure themselves or choke on straws which are soft but of biological material such as pasta or bamboo. The degree of pollution from plastic straws is also something like 0.013% (I didn’t look that up so I may be wrong, but it’s tiny) of total ocean pollution from plastic. In fact, the majority of plastic pollution in the ocean is from fishing nets, floats and the like, which is not surprising because the function of fishing equipment is to catch fish, and it’s therefore doing its job after being discarded. The Garbage Patches, and there are several, for instance in the Atlantic, are also not visible to the casual observer in those areas because most of the plastic is too small to see, even microscopic, and it’s also quite diffusely spread. This isn’t to say that there aren’t huge quantities of plastic waste from decades ago washing up on beaches all over the planet or that they don’t do terrible harm to wildlife and ourselves, but the nature of the patches is somewhat different from what people expect. They’ve also been increasing tenfold every year since the end of the Second World War.

We in the West are often able to push all the stuff that used to confront us directly in the streets of our cities and towns out of sight in distant parts of the world. We do that with slave labour to some extent, although conditions are not good for many people here either, and also with our waste. We seem to fondly imagine that our plastic is recycled when in fact an awful lot of it is shipped to remote countries where it’s just dumped and incinerated, so it isn’t our own children who are born with congenital issues to the same extent or our own older people who are dying of occupational cancers so much, or our own rivers which are full of plastic waste.

English: Top 15 most toxic places to live
Date
16 October 2009
Source
http://www.mnn.com/earth-matters/wilderness-resources/photos/the-15-most-toxic-places-to-live/citarum-river-indonesia

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By, Chief on Oct.16,2009 @11:23pm

This is the Citarum River in Java, often called the world’s most polluted river. Although the water beyond the barrier is clear, there are plenty of stretches of this watercourse which are typically as crowded with plastic waste as seen in the foreground. As well as the visible stuff, the water is high in several toxic metals including lead, mercury and arsenic, and also organic compounds leached from the plastic and from other industrial sources such as phthalates, sulphites and polychlorinated biphenyls.

A theme is emerging here. Although the easily visible portion of the plastic pollution looks shocking and sensationalises the problem to the sighted human observer, these are in a sense only the tip of the iceberg. Clearly the fact that turtles eat party balloons and starve, terrestrial animals get trapped in waste and suffocate and so forth are very serious problems, something else is going on at a microscopic scale which is more insidious and pervasive. In both these rather spectacular incidences of plastic pollution, a major issue is not the visible but the invisible, in two different ways. There are microplastics and there are isolated compounds from those plastics and other sources. It’s also notable that even these huge piles of waste are invisible to us in the richer parts of the world because we’re treating the Third World as a carpet under which we can sweep the stuff we’d prefer not to see, but even here there is microscopic and chemical waste interfering with the local ecosystems, including ourselves. It really makes more sense to see the separated molecules of plastic pollutants as one end of a scale, passing through microplastics and ending with massive boulders of polystyrene being washed up on beaches. But there is also a power law involved. The largest fragments of plastic have relatively small surface areas and there are relatively fewer of them. As their size decreases, their number and influence increase disproportionately, partly because smaller objects have larger surface areas.

And at this point I want to mention hormone disruptors. Certain compounds in the environment interact with hormone receptors, and at this point I should probably go into how hormones work. Hormones are signalling molecules which act at a distance within the body. They’re generated and released by organs, often specialising in producing those compounds but sometimes being produced by other organs such as the stomach, kidney or heart. When they reach their target cells, they either pass through the cell membrane and reach the surface of the nucleus or contact specialised molecules on the surfaces of the cells and cause them to send a second message into the cell. This leads to genes being expressed which weren’t before or being inhibited when they were previously expressed, ending in the cells doing various things differently than before. For instance, adrenalin speeds up the heart rate and causes blood vessels to relax in some places and constrict in others, redirecting blood flow to the organs needed for a flight-or-fright response, thyroxin accelerates metabolism and insulin increases the uptake of glucose from the bloodstream. Some hormones are primarily developmental in their function, such as growth hormone, two sex hormones found in the embryo which conversely discourage and encourage typical female or male tissues and structures in the reproductive system, and of course the well-known sex hormones oestrogens, androgens and progesterone, among others. In order to have a hormonal action, a compound need not closely resemble any hormone secreted in the body, and of course whereas I’ve been thinking of human physiology as I’ve been writing this, most or all multicellular organisms have their own hormones. For instance, insects have hormones which cause them to shed their exoskeletons and plants have hormones which cause them to grow faster or develop roots. I’m not sure if sponges have hormones, but fungi have so it seems likely that they would, in some form. Anyway, the takeaway from this is that a substance needn’t be similar to a hormone to have hormonal action.

Apart from hormones produced by the bodies of organisms themselves, there are two major environmental sources of hormones. Plants are one of these. For example, there used to be a species of plant which produced thyroxin directly but it went extinct in 1976, and there is an Afrikan plant which produces vitamin D (which is a hormone chemically similar to oestrogen and other steroids). In particular, for some reason I don’t understand, although there are plenty of artificially synthesised chemicals which are hormonally active, they all seem to be oestrogenic. These are collectively referred to as xenoestrogens, and are present, for example, in toiletries and cosmetics, and are both ingested and absorbed by the surfaces of animals’ bodies, including humans but also others. It’s possible that there are other anthropogenic hormones in the environment but I haven’t come across any, and I’m not sure if this is due to publicity, bias in research or that these compounds simply don’t exist. In any case, xenoestrogens include several pollutants in, for example, the Citarum River, such as polychlorinated biphenyls and phthalates, and these are of course well-known. DDT and dioxin are also oestrogenic but since they’re quite toxic anyway this is probably less relevant.

This is where we get to Alex Jones’s famous “gay frogs”. There is an issue with this sound bite which I’d like to deal with first. Amphibians usually have external fertilisation. They release their gametes into water where they unite with each other and become spawn and then tadpoles. During the mating season, male frogs usually hormonally develop an urge to hug any object which is roughly the diameter of another frog, including reeds and other items. They tend to hug other frogs, including female ones, because of this urge. However, they can’t really be “gay” because their reproductive process doesn’t work that way. Therefore Alex Jones is wrong. Nonetheless, these chemicals do alter the sexual development of many species, for example including whelks, who tend to become the same sex and don’t reproduce asexually (I can’t remember which sex), so then they just don’t reproduce.

Compounds which occur at the bottom of the food pyramid and are not metabolised or digested will often be absorbed directly by organisms on the next level, and this means they are higher in carnivores than in herbivores, and higher in those than in plants, which is a reason for eating only plants, although I also eat fungi, and they’re in a different and somewhat confusing position in the chain. This means that the oestrogenic action of compounds is likely to be stronger in carnist humans than other species, although it’s also likely to be high in, for example, whales and predatory sharks. I’m not going to cover the influence of xenoestrogens across the board because there are so many of them, but I do want to look at PCBs (polychlorinated biphenyls) and phthalates, because they’re particularly common.

PCBs are related to PBBs – polybrominated biphenyls – which are used as flame retardants in a wide range of items with which we come into daily contact. Both classes of compounds are oestrogenic and accelerate female puberty. Like many other compounds which dissolve easily in fats and oils but not water, the body tends to modify them to make them more water-soluble and therefore easier to excrete in sweat and urine. Perhaps for this reason, they tend to cause chloracne in large quantities – they’re being passed out through the skin, which they irritate. Dioxins also do this. However, PCBs cause liver damage like many other toxins and tend to accumulate in adipose tissue: they’ve been found concentrated in whale blubber for example. In a way it’s sad that we know that because I can’t imagine that info was gathered non-violently, although I suppose it might have been a biopsy. PCBs are, unsurprisingly, also carcinogenic in many species, including us, and they also impair cognitive development in humans. Their industrial function is as coolants and in dye-line paper. Monsanto was of course the main producer.

Phthalates are plasticisers: they increase the flexibility, longevity and transparency of plastics. They’re used in coatings, including enteric coatings for medication, floor and wall coverings, electric cables and wiring, among other things. They’re not acutely toxic. However, research has rather surprisingly shown that xenoestrogens are more hormonally active in smaller doses than larger ones, which brings allergies to mind although I’ve no idea if that’s connected. It does also correspond to the general theme of smaller things having more influence than larger ones. Because they’re designed to be durable, phthalates take a long time to break down and so are persistent in the environment. Once again they’re oestrogenic and also anti-androgenic, and found in fast food, fats and oils. However, there is an interesting caveat to all this.

Phthalates have stimulated evolution. An organism known as Ideonella sakaiensis has been found living in the sediment of a Japanese PET bottle recycling plant in 2016. It can break down phthalate as a way of fuelling its respiration, and is new to science. I would suggest this is an example of evolution, and it makes me wonder about what else might evolve at some time in the near future to deal with many plastics. There are plans to grow this bacterium as a way of biodegrading PET. There is also a Japanese fungus, Pestalotiopsis microspora, able to break down polyurethane, as can the mould Aspergillus tubingensis, and the moth caterpillar Galleria mellonella can digest polythene. This last one normally eats beeswax, so it’s a small step to being able to digest polythene which is chemically rather similar to waxes. In fact polythene is basically a special form of paraffin wax.

The philosopher Heather Davis (I may be playing it fast and loose with the word here but she is an academic, and seems to be into cultural theory) explores the impact of plastic on the future with a particular focus on queer theory and the Anthropocene. She notes that certain plastics have a feminising influence on karyotypically male fetuses and that they make physical reproduction less likely in individuals. Since she links her thought to Donna Haraway’s Cyborg Manifesto, I consider her approach quite fruitful. I don’t want to rip her ideas off so I’ll just link to her Vimeo lecture on ‘The Queer Futurity Of Plastic.’

These things allow some kind of hope. The idea of plastic pollution in the environment preventing reproduction and choking animals sounds pretty apocalyptic, but in fact it may be the human proclivity for stories which want there to be a neatly tied-up end to our own or the planet’s story. In reality, things might not be so neat, but that very fact means that evolution might find a way to overcome the existence of plastic in the environment and even benefit from it. I find Davis’s attitude a little flippant, but even so I think she’s onto something, and it’s excellent to wring hope out of such an apparently despair-inducing prospect as life choking, being poisoned and starved because of plastic.