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Four scenarios for the next supercontinent
The arc of geological history is long, but it bends towards supercontinents – so, what will the next one look like?
- We're halfway through a 'supercontinent cycle'.
- The next one is due in 200-300 million years.
- Here are four plausible scenarios of what it will look like.
Moving at fingernail speed
How the American, African and European continents once fit together before the Atlantic – and may one day again, if and when the local 'Wilson cycle' reverses.
Credit: Jacques Kornprobst, after E. Bullard et al. (1965), CC BY-SA 4.0
For things so massive and seemingly immovable, continents are pretty hard to pin down. Of course, that's because they do move, if only at the speed at which your fingernails grow: about two inches (5 cm) per year.
Accelerate the film of Earth's geology, and you see the landmasses dance across the globe like islands of foam on a running bath. One peculiarity of our drifting continents is that they tend to combine, over massive amounts of time, into one single supercontinent. It helps that the Earth is round, unlike your bath.
Then, millions of years later, tectonic forces cause the supercontinent to break up again – only for the individual continents to recombine much, much later. All at fingernail speed.
The usual suspects
Norwegian map of what the supercontinent of Columbia/Nuna may well have looked like, 1,590 million years ago.
Credit: Bjoertvedt, CC BY-SA 3.0
Here's one question with an un-pin-downable answer: How many supercontinents have there been in Earth's deep past? At least three or at least seven; as many as 11 or perhaps even a few more. Like the continents themselves, scientific theories diverge. Here are some of the usual suspects (most recent first, ages are approximate):
- Pangea (300-180 million years ago)
- Gondwana (600-180 mya)
- Pannotia (630-540 mya)
- Rodinia (1.1 bya-750 mya)
- Columbia, a.k.a. Nuna (1.8-1.5 billion years ago)
- Kenorland (2.7-2.1 bya)
- Ur (2.8-2.4 mya)
- Vaalbara (3.6-2.8 bya)
That's if we spool back the tape. What happens if we fast-forward? Even though Pangea, the last supercontinent, broke up almost 200 million years ago, geologists are pretty sure there will be another one, but not for some time to come. Right now, we're about halfway through a 'supercontinent cycle'. The next one will be around between 200 and 300 million years from now.
John Tuzo Wilson (1908-93) refined and championed the theory of plate tectonics in the 1960s, when it was still controversial. He was the first non-U.S. citizen to become president of the American Geophysical Union.
Credit: UC Davis
That brings us to the next question with an answer that's hard to pin down: What will that next supercontinent look like? That is, of course, unknowable, as no one alive today will be around to check. But one can speculate. Using what we know about the tectonic forces that power the movements of continental plates, three scientists line up four plausible scenarios for the formation of the next supercontinent.
In "Back to the future: Testing different scenarios for the next supercontinent gathering," Hannah S. Davies, J.A. Mattias Green, and Joāo C. Duarte present four supercontinents, each the outcome of a different tectonic what-if.
Each scenario is a different combination of two basic drivers of continental conglomeration (and fragmentation): the supercontinent cycle itself, and the so-called Wilson cycle.
In 1966, Canadian geologist John Tuzo Wilson proposed that the Atlantic had opened up along a zone where another ocean had previously existed. A 'Wilson cycle' therefore describes the cyclical opening and closing of ocean basins. Since those aren't necessarily in sync with supercontinent cycles, they can lead to various outcomes – supercontinents of different shapes and at different types.
The next supercontinent will take shape when at least one ocean closes. That can happen in one of two ways:
- Introversion: the 'internal', expanding ocean starts to contract and closes up again; or
- Extroversion: the 'exterior' ocean keeps expanding, closing an 'internal' ocean elsewhere.
In the first option, the Wilson cycle and the supercontinent cycle coincide, creating the possibility that the new supercontinent will have more or less the same dimensions as the old one. In the second option, the Wilson and supercontinent cycles do not coincide.In their paper, the researchers line up and standardise the evidence for four well-known scenarios on future supercontinent formation:
- The closure of the Atlantic Ocean, leading to Pangea Ultima;
- The closure of the Pacific Ocean, giving rise to Novopangea;
- The closure of both the Atlantic and Pacific Oceans, creating Aurica; and
- The closure of the Arctic Ocean, forming Amasia.
Pangea Ultima: keystone Africa
'Ultimate' Pangea would be a remake of the 'old' Pangea, more or less.
Credit: Pilgrim-Ivanhoe, reproduced with kind permission
'Ultimate Pangea' will come about via an introversion scenario, with the closing of the Atlantic and the re-formation of the 'old' Pangea – sort of. Introversion is the 'classic' scenario for supercontinent formation; in fact, Pangea itself was likely formed by introversion, with the closing of the Rheic and Iapetus Oceans.
Africa is the key continent here; first by colliding with Europe to form the new continent of Eurafrica, and ultimately as the keystone tying South and North America, Europe and Asia together. Remnants of the Atlantic and Indian oceans reincarnate as the 'ultimate' Mediterranean, closed off from the world ocean by East Antarctica.
Novopangea: Rift becomes Ocean
How Novopangea might come to be: the Pacific closes and a new ocean forms along the East African Rift.
Credit: Pilgrim-Ivanhoe, reproduced with kind permission
A 'classic' extroversion scenario leads to the closure of the Pacific Ocean, and to a 'new' Pangea – not just a re-forming of the old one. The East African Rift keeps growing, developing into a new ocean, replacing the Indian one. East Africa gets stuck against India's west coast.
Aurica: America in the middle
Two Wilson cycles in sync with a supercontinent cycle, and hey presto: Aurica.
Credit: Pilgrim-Ivanhoe, reproduced with kind permission
The Aurica scenario presupposes two Wilson cycles in sync with the supercontinent cycle. Both the Atlantic and Pacific Oceans close, helping to form the supercontinent of Aurica, with the Americas in the middle.
This requires the opening-up of at least one new ocean – for example, at a large rift along the present-day border between India and Pakistan. This new Pan-Asian Ocean, merged with the Indian Ocean, pushes these areas apart, turning them from next-door neighbors into lands on either side of Aurica.
Australia is now entirely landlocked, between Antarctica, East Asia, and North America. Europe and Africa have collided with the Americas from the other side. To the south, Madagascar stubbornly continues its separate course.
Amasia, the Arctic supercontinent
In the Amasian scenario, almost all continents would be joined 'at the top'.
Credit: Pilgrim-Ivanhoe, reproduced with kind permission
The Arctic Ocean closes. Almost all continents are joined at the 'top of the world', with the exception of Antarctica, the only one not drifting northward. It'll be a short hop from North America to North Africa, with Southern Europe acting as a land bridge in between. South America has repositioned itself, with its western edge against the eastern flank of North America.
These images produced by Pilgrim-Ivanhoe, reproduced with kind permission. Original context here. Images based on the aforementioned article: Back to the future: Testing different scenarios for the next supercontinent gathering, by Hannah S. Davies, J.A. Mattias Green and João C. Duarte, published in Global and Planetary Change (Vol. 169, October 2018).
Strange Maps #1064
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How would the ability to genetically customize children change society? Sci-fi author Eugene Clark explores the future on our horizon in Volume I of the "Genetic Pressure" series.
- A new sci-fi book series called "Genetic Pressure" explores the scientific and moral implications of a world with a burgeoning designer baby industry.
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Tribalism and discrimination<p>One question the "Genetic Pressure" series explores: What would tribalism and discrimination look like in a world with designer babies? As designer babies grow up, they could be noticeably different from other people, potentially being smarter, more attractive and healthier. This could breed resentment between the groups—as it does in the series.</p><p>"[Designer babies] slowly find that 'everyone else,' and even their own parents, becomes less and less tolerable," author Eugene Clark told Big Think. "Meanwhile, everyone else slowly feels threatened by the designer babies."</p><p>For example, one character in the series who was born a designer baby faces discrimination and harassment from "normal people"—they call her "soulless" and say she was "made in a factory," a "consumer product." </p><p>Would such divisions emerge in the real world? The answer may depend on who's able to afford designer baby services. If it's only the ultra-wealthy, then it's easy to imagine how being a designer baby could be seen by society as a kind of hyper-privilege, which designer babies would have to reckon with. </p><p>Even if people from all socioeconomic backgrounds can someday afford designer babies, people born designer babies may struggle with tough existential questions: Can they ever take full credit for things they achieve, or were they born with an unfair advantage? To what extent should they spend their lives helping the less fortunate? </p>
Sexuality dilemmas<p>Sexuality presents another set of thorny questions. If a designer baby industry someday allows people to optimize humans for attractiveness, designer babies could grow up to find themselves surrounded by ultra-attractive people. That may not sound like a big problem.</p><p>But consider that, if designer babies someday become the standard way to have children, there'd necessarily be a years-long gap in which only some people are having designer babies. Meanwhile, the rest of society would be having children the old-fashioned way. So, in terms of attractiveness, society could see increasingly apparent disparities in physical appearances between the two groups. "Normal people" could begin to seem increasingly ugly.</p><p>But ultra-attractive people who were born designer babies could face problems, too. One could be the loss of body image. </p><p>When designer babies grow up in the "Genetic Pressure" series, men look like all the other men, and women look like all the other women. This homogeneity of physical appearance occurs because parents of designer babies start following trends, all choosing similar traits for their children: tall, athletic build, olive skin, etc. </p><p>Sure, facial traits remain relatively unique, but everyone's more or less equally attractive. And this causes strange changes to sexual preferences.</p><p>"In a society of sexual equals, they start looking for other differentiators," he said, noting that violet-colored eyes become a rare trait that genetically engineered humans find especially attractive in the series.</p><p>But what about sexual relationships between genetically engineered humans and "normal" people? In the "Genetic Pressure" series, many "normal" people want to have kids with (or at least have sex with) genetically engineered humans. But a minority of engineered humans oppose breeding with "normal" people, and this leads to an ideology that considers engineered humans to be racially supreme. </p>
Regulating designer babies<p>On a policy level, there are many open questions about how governments might legislate a world with designer babies. But it's not totally new territory, considering the West's dark history of eugenics experiments.</p><p>In the 20th century, the U.S. conducted multiple eugenics programs, including immigration restrictions based on genetic inferiority and forced sterilizations. In 1927, for example, the Supreme Court ruled that forcibly sterilizing the mentally handicapped didn't violate the Constitution. Supreme Court Justice Oliver Wendall Holmes wrote, "… three generations of imbeciles are enough." </p><p>After the Holocaust, eugenics programs became increasingly taboo and regulated in the U.S. (though some states continued forced sterilizations <a href="https://www.uvm.edu/~lkaelber/eugenics/" target="_blank">into the 1970s</a>). In recent years, some policymakers and scientists have expressed concerns about how gene-editing technologies could reanimate the eugenics nightmares of the 20th century. </p><p>Currently, the U.S. doesn't explicitly ban human germline genetic editing on the federal level, but a combination of laws effectively render it <a href="https://academic.oup.com/jlb/advance-article/doi/10.1093/jlb/lsaa006/5841599#204481018" target="_blank" rel="noopener noreferrer">illegal to implant a genetically modified embryo</a>. Part of the reason is that scientists still aren't sure of the unintended consequences of new gene-editing technologies. </p><p>But there are also concerns that these technologies could usher in a new era of eugenics. After all, the function of a designer baby industry, like the one in the "Genetic Pressure" series, wouldn't necessarily be limited to eliminating genetic diseases; it could also work to increase the occurrence of "desirable" traits. </p><p>If the industry did that, it'd effectively signal that the <em>opposites of those traits are undesirable. </em>As the International Bioethics Committee <a href="https://academic.oup.com/jlb/advance-article/doi/10.1093/jlb/lsaa006/5841599#204481018" target="_blank" rel="noopener noreferrer">wrote</a>, this would "jeopardize the inherent and therefore equal dignity of all human beings and renew eugenics, disguised as the fulfillment of the wish for a better, improved life."</p><p><em>"Genetic Pressure Volume I: Baby Steps"</em><em> by Eugene Clark is <a href="http://bigth.ink/38VhJn3" target="_blank">available now.</a></em></p>
It's hard to stop looking back and forth between these faces and the busts they came from.
- A quarantine project gone wild produces the possibly realistic faces of ancient Roman rulers.
- A designer worked with a machine learning app to produce the images.
- It's impossible to know if they're accurate, but they sure look plausible.
How the Roman emperors got faced<a href="https://payload.cargocollective.com/1/6/201108/14127595/2K-ENGLISH-24x36-Educational_v8_WATERMARKED_2000.jpg" ><img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yNDQ2NDk2MS9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTYyOTUzMzIxMX0.OwHMrgKu4pzu0eCsmOUjybdkTcSlJpL_uWDCF2djRfc/img.jpg?width=980" id="775ca" class="rm-shortcode" data-rm-shortcode-id="436000b6976931b8320313478c624c82" data-rm-shortcode-name="rebelmouse-image" alt="lineup of emperor faces" data-width="1440" data-height="963" /></a>
Credit: Daniel Voshart<p>Voshart's imaginings began with an AI/neural-net program called <a href="https://www.artbreeder.com" target="_blank">Artbreeder</a>. The freemium online app intelligently generates new images from existing ones and can combine multiple images into…well, who knows. It's addictive — people have so far used it to generate nearly 72.7 million images, says the site — and it's easy to see how Voshart fell down the rabbit hole.</p><p>The Roman emperor project began with Voshart feeding Artbreeder images of 800 busts. Obviously, not all busts have weathered the centuries equally. Voshart told <a href="https://www.livescience.com/ai-roman-emperor-portraits.html" target="_blank" rel="noopener noreferrer">Live Science</a>, "There is a rule of thumb in computer programming called 'garbage in garbage out,' and it applies to Artbreeder. A well-lit, well-sculpted bust with little damage and standard face features is going to be quite easy to get a result." Fortunately, there were multiple busts for some of the emperors, and different angles of busts captured in different photographs.</p><p>For the renderings Artbreeder produced, each face required some 15-16 hours of additional input from Voshart, who was left to deduce/guess such details as hair and skin coloring, though in many cases, an individual's features suggested likely pigmentations. Voshart was also aided by written descriptions of some of the rulers.</p><p>There's no way to know for sure how frequently Voshart's guesses hit their marks. It is obviously the case, though, that his interpretations look incredibly plausible when you compare one of his emperors to the sculpture(s) from which it was derived.</p><p>For an in-depth description of Voshart's process, check out his posts on <a href="https://medium.com/@voshart/photoreal-roman-emperor-project-236be7f06c8f" target="_blank">Medium</a> or on his <a href="https://voshart.com/ROMAN-EMPEROR-PROJECT" target="_blank" rel="noopener noreferrer">website</a>.</p><p>It's fascinating to feel like you're face-to-face with these ancient and sometimes notorious figures. Here are two examples, along with some of what we think we know about the men behind the faces.</p>
Caligula<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yNDQ2NDk4Mi9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTY3MzQ1NTE5NX0.LiTmhPQlygl9Fa9lxay8PFPCSqShv4ELxbBRFkOW_qM/img.jpg?width=980" id="7bae0" class="rm-shortcode" data-rm-shortcode-id="ce795c554490fe0a36a8714b86f55b16" data-rm-shortcode-name="rebelmouse-image" data-width="992" data-height="558" />
One of numerous sculptures of Caligula, left
Nero<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yNDQ2NTAwMC9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTY1NTQ2ODU0NX0.AgYuQZzRQCanqehSI5UeakpxU8fwLagMc_POH7xB3-M/img.jpg?width=980" id="a8825" class="rm-shortcode" data-rm-shortcode-id="9e0593d79c591c97af4bd70f3423885e" data-rm-shortcode-name="rebelmouse-image" data-width="992" data-height="558" />
One of numerous sculptures of Nero, left
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PARME staff archaeologists excavating a burial site at the Tamanache site, Mérida, Yucatan.
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