The future of driverless cars in America is a promotional booth with a surfboard and a movie director’s clapboard. Robotaxis have officially arrived in Los Angeles, and last week, residents lined up in Santa Monica’s main promenade to get a smartphone code needed to ride them. For now, the cars, from the Alphabet-owned start-up Waymo, won’t leave the tame streets of Santa Monica. But in the coming months, they’ll embark on a multi-month “tour” of the city, heading to West Hollywood, downtown L.A., and several other neighborhoods.

For the past decade, the two leading robotaxi companies, Waymo and Cruise, have been focused primarily on San Francisco and Phoenix, where they both already take paid passengers. But now they are expanding into new cities, adding millions more potential riders (and bystanders) into the mix. Last week, Cruise, a subsidiary of General Motors, launched its robotaxi service in Houston, and will also soon do the same in Dallas. In addition to L.A., where Cruise is testing and reportedly will soon expand, Waymo is kicking off in Austin, where Cruise already takes passengers.

In San Francisco in particular, the cars have jammed up in ways both silly and serious. Local protesters, fed up with the technology, have put cones on top of the cars to confuse their navigation system. But now the vehicles will face new challenges: As they move beyond their hometowns, their systems will be tested on new kinds of streets, with different driving cultures and different rules. They’ll have to drive in notorious L.A. traffic and notorious Houston traffic. Robotaxis haven’t had it easy in San Francisco, but the race to go national might still be bumpy.

If self-driving cars can handle San Francisco, they should ideally be able to handle anywhere. The city is “by far the toughest environment anywhere in the world to test such technology due to topography and complex street geometries,” Rahul Jain, a professor at the University of Southern California and the director of its Center for Autonomy and Artificial Intelligence, told me over email. Cruise says it chose to start there in part because of these challenges, which the company argues makes it a good place to build this technology. In San Francisco, I’ve ridden in cars made by each company, and in both instances, the cars navigated the streets with impressive ease. L.A. should be easier, but it poses new challenges in terms of traffic and driver aggression. Having lived and driven in both cities, I can confirm that L.A. drivers have more of a knack for speeding and changing lanes in tight highway traffic. “You have to be a little bit wild to be able to drive here,” Jain joked.

In L.A., Waymo cars won’t go on the highway, but the rollout still will not be easy. Both companies test their cars for many hours before passengers can start riding, but that doesn’t mean it’ll be perfect when the vehicles go fully operational; after all, they were likewise tested in San Francisco for many years. Both Waymo and Cruise may soon learn the ways that their computer-vision systems are and aren’t generalizable between cities, says Missy Cummings, the director of George Mason University’s Autonomy and Robotics Center: “They may have to retrain a bunch of their neural nets.”

As each other’s biggest competitor, both Cruise and Waymo appear eager to expand and signal that they are one step closer to robotaxi supremacy. I asked Cummings whether she thought these two companies should be taking passengers in Los Angeles. For Cruise, she offered a blunt no. She was softer when it came to Waymo: “I think it makes sense for them.” Cruise in particular has had a rough past few months in San Francisco—a Cruise car drove into wet cement, another collided with a fire truck, and a pedestrian was pinned under a vehicle earlier this month after it was initially hit by a human-driven car. (Cruise tweeted its account of the crash: Their vehicle “braked aggressively to minimize the impact,” and “at the request of the police the AV was kept in place.”) In August, Cruise was asked by California’s DMV to halve its operations in the city.

“Everything I see indicates Cruise has more issues with road safety, but it’s difficult to be sure, because the companies are so opaque with their data,” Phil Koopman, a professor at Carnegie Mellon University who specializes in autonomous-vehicle safety, told me. Cruise and Waymo are required to make some numbers public to regulators, reporting any accidents and, in California, disclosing the number of miles driven and any incidents in which a human had to intervene. The companies also release various safety research on their respective websites. But gaps remain: Researchers don’t have precise information about how many robotaxis are operating and where, for example. Nor do they have video footage of every crash.

A spokesperson for Cruise defended its safety record via email, pointing to the company’s own research indicating its driverless cars are involved in 65 percent fewer collisions than human drivers are in a comparable driving environment. “Cruise drove 10x more miles than any other autonomous vehicle company in San Francisco last year,” the spokesperson added.

What that means is that we’ll likely see more of these kinds of incidents as the robotaxis, and Cruise in particular, spread beyond San Francisco. The most troubling prospect is that a new era in which self-driving cars are operating in even more cities may bring issues experts can’t predict. Noah Goodall, a senior research scientist at the Virginia Transportation Research Council, told me he was surprised that the vehicles have issues navigating emergency services. But that’s par for the course when you’re building something new. “When you’re creating a technology that’s safer, you’ll create other risks that are new that you didn’t have before,” he explained.

None of this is stopping Cruise or Waymo from slowing down. The two companies are in an arms race to advance their self-driving cars, a competition that is also between two industries. Waymo, which began as Google’s self-driving car project and is owned by Alphabet, is as Silicon Valley as start-ups come. Cruise, meanwhile, is owned by General Motors, a legacy automaker that hasn’t historically been anything like a tech company and is far less cash-flush.

Now driverless cars and their promise to reduce America’s road deaths is collapsing some of the differences between car companies and tech companies. “What Silicon Valley learned is the car business is a very, very sophisticated business, and it’s not really easy to design, engineer, manufacture, distribute a vehicle with critical safety systems and so many parts in it,” Lawrence Burns, a former GM executive and former adviser to Waymo, told me over email. “What the auto industry learned from this is that there’s extraordinary talent and capability in Silicon Valley for digital technology, software and experience design applied to the future of transportation.”

The robotaxi race is just one front on which Americans are seeing these changes up close. Electric cars are now so software-enabled that they are often described as “smartphones on wheels.” And many new cars for sale, including those from GM, are stocked with self-driving and autopilot features that far exceed what was available even a few ago. Los Angeles and Houston will bear witness to the next era of robotaxis, to whatever accidents and missteps they will surely make. They already are. Before Cruise even officially launched in Houston, three of its vehicles reportedly stalled at the same intersection, locking up traffic.

In the early 1990s, while studying preeclampsia in Guadeloupe, Pierre-Yves Robillard hit upon a realization that seemed to shake the foundations of his field. Preeclampsia, a pregnancy complication that causes some 500,000 fetal deaths and 70,000 maternal deaths around the world each year, had for decades been regarded as a condition most common among new mothers, whose bodies were mounting an inappropriate attack on a first baby. But Robillard, now a neonatologist and epidemiologist at Centre Hospitalier Universitaire de La Réunion, on Réunion Island in the Indian Ocean, kept seeing the condition crop up during second, third, or fourth pregnancies—a pattern that a few other studies had documented, but had yet to fully explain. Then, Robillard noticed something else. “These women had changed the father,” he told me. The catalyst in these cases of preeclampsia, he eventually surmised, wasn’t the newness of pregnancy. It was the newness of paternal genetic material that, maybe, the mother hadn’t had enough exposure to before.

Robillard’s idea was unconventional not only because it challenged the dogma of the time, but because it implied certain evolutionary consequences. Preeclampsia appears to be exclusive (or almost exclusive) to humans, and may have arisen as a by-product of the particularly aggressive ways in which our fetuses pillage their mother’s body for resources. So, Robillard and his colleagues posited, maybe the dangers it poses then pressured humans into developing a bizarre trait: being rather inefficient at conceiving offspring. Maybe, if humans aren’t terribly fertile, they need to have a lot of sex; maybe having a lot of sex repeatedly exposes a mother to her partner’s semen, inuring her to the molecular makeup of future offspring. If preeclampsia is a kind of immune overreaction, then perhaps unprotected sex is the world’s most unconventional allergy shot.

That, at least, is what Robillard and his colleagues contend—a notion that’s “a bit controversial, and a bit awkward,” Inkeri Lokki, an immunologist and reproductive biologist at the University of Helsinki, told me. She remembers a senior researcher in the field once framing the upshot of the hypothesis as “pick your partner early, and practice.”

[Read: The pregnancy risk that doctors won’t mention]

Foreign genetic material aside, a mother’s body has every reason to be wary of a fetus. Pregnancy is an intergenerational struggle in which the fetus tries to pillage all the nutrients it can from the mother’s tissues, while the mother tries to keep some of her own resources in reserve.

For most mammals, the two parties easily reach a lasting stalemate. Among humans, though, the fetus starts “with the upper hand,” Amy Boddy, an evolutionary biologist at UC Santa Barbara, told me. Whether it’s because of the extreme nutritional demands of our energy-guzzling brain, or just a constraint of how the primate lineage evolved, no other developing mammal invades quite as vigorously as the human embryo does: Through two waves of invasion, our placental cells burrow so deeply into the lining of the uterus that they breach its muscular layer, where they unfurl, melt, and rewire an entire set of blood vessels until they widen and relax. In the process, tissues liquify, and cells are forced apart, all to get an enormous amount of “blood delivered to the placenta,” Julienne Rutherford, a biological anthropologist at the University of Arizona College of Nursing, told me.

The fetus thrives in these conditions—but it also asks so much of the mother’s body that it almost invites pushback. Preeclampsia, then, at least when it appears prior to 34 weeks of gestation, is arguably a manifestation of a human mother’s defenses wising up to the invasion, then kicking into overdrive. When researchers examine tissue samples in early-onset preeclampsia cases, they tend to find that the placenta has been prevented from invading the uterus thoroughly enough, Haley Ragsdale, a biological anthropologist at Northwestern University, told me. Now at risk of starving, the fetus tries to juice more from mom—in part by raising maternal blood pressure, preeclampsia’s hallmark symptom. (High blood pressure that arises in the last few weeks of pregnancy can signal late-onset preeclampsia, but researchers generally think the causes are distinct.)

Why exactly the placenta’s invasion flags in early-onset cases remains contentious, Offer Erez, an ob-gyn at Soroka University Medical Center, in Israel, told me. One possibility, as Robillard and others argue, is that a mother’s immune system, unaccustomed to her partner’s particular blend of molecules, codes the fetus as foreign, and dispatches a fleet of defenses to waylay the threat. If that’s indeed the case, a logical workaround might involve familiarizing her body with those foreign substances—and nipping her overreaction in the bud.

[Read: Pregnancy is a war; birth is a cease-fire]

Semen could do the trick: It’s chock-full of paternal material, and introduced into the vaginal tract, where a legion of immune cells and molecules roam. It also contains signaling molecules that might be able to mollify the maternal immune system. Repeat exposures with no harm send a clear message: I am safe, says Gustaaf Dekker, who leads the department of obstetrics and gynecology at Northern Adelaide Local Health Network, in Australia, and who has collaborated for years with Robillard.

In the past three decades, Dekker, Robillard, and their colleagues have amassed a large amount of evidence to support that idea. Across several populations, the risk of early-onset preeclampsia seems to be higher among couples conceiving for the first time; it’s also higher among people using donor sperm and eggs. The risk also seems lower among couples who have a lot of penetrative or oral sex before they get pregnant—at least, if they skip the condoms, some studies suggest. There’s even evidence that repeat exposures to seminal fluid can make female mice more tolerant of cells sampled from their mates.

From an evolutionary perspective, the theory goes even further. If it is important to indoctrinate the maternal immune system with semen, “that is a strong selective pressure” for humans to adopt a suite of behaviors to facilitate that exposure, says Bernard Crespi, an evolutionary biologist at Simon Fraser University, in Canada, who’s collaborated with Robillard. Our bodies’ combative approach to placentation could help to explain our semi-monogamous nature, our comparably low fertility among mammals, and our comparatively large testes, which can provide a generous supply of sperm. It may even have influenced the unusual ways in which the female human body conceals its own fertility. Unlike other mammals, we don’t regularly enter an obvious period of heat, or visibly signal when we ovulate—both traits that encourage more frequent sex in pursuit of reproduction. If repeat couplings are just kind of our thing, maybe it’s because they make our pregnancies that much safer.

The paternal-immunity hypothesis is not the only possible explanation for early-onset preeclampsia, and for some researchers, it is far from the strongest one. Fathers could be playing a different role in the condition. Some evidence suggests that certain males pass down DNA that predisposes their offspring to implant a bit differently in the womb, Laura Schulz, a women’s-health researcher at the University of Missouri School of Medicine, pointed out to me. And Carlos Galaviz Hernández, a geneticist at CIIDIR Unidad Durango, in Mexico, told me that immune compatibility may matter, too: The mother might be able to better tolerate some partners, analogous to the way that organ transplants are more successful if certain molecular signatures match. In some cases, the mother’s DNA may be the dominant force. Certain women, for instance, seem genetically predisposed to developing the condition, regardless of whom they partner with.

Jimmy Espinoza, a maternal-fetal-medicine specialist at UTHealth Houston’s McGovern Medical School, also pointed out to me that the idea Robillard has championed has its own scientific issues. In recent years, especially, other teams of researchers have found evidence that seems to directly contradict it—in some cases, finding that some people may reduce their chances of preeclampsia if they switch to a different partner for a subsequent child. (Dekker and Robillard argue that several of these studies had issues, including possible misdiagnoses and not distinguishing enough between early- and late-onset preeclampsia.)

All of these ideas may have some truth to them—in part because preeclampsia, like cancer, is a catchall term for different disease pathways that manifest similarly at their tail end, Andrea Edlow, a maternal-fetal-medicine specialist at Massachusetts General Hospital, told me. And despite evidence to the contrary, “I still support the hypothesis,” Dekker told me. In his opinion, “nobody has come up with a better one.”

Even if the semen hypothesis turns out to be correct, it’s hard to know what to do with that information. Breakthroughs are desperately needed: Although preeclampsia has been documented for millennia, diagnostics, treatments, and preventives are scant. Maybe better understanding paternal exposures will someday lead to preconception vaccines, or targeted immunotherapies for people deemed high risk. Today, though, the idea’s most actionable takeaways are very limited. In Robillard’s ideal world, clinicians would recommend at least six months of sexually active cohabitation, or at least 100 sexual encounters, before conception; pregnant people would also routinely disclose their sexual history with their partner to their doctor, and changes in partners would be noted in medical charts. Unsurprisingly, “it’s been an uphill battle” to sell some of those ideas to colleagues, Dekker told me.

Edlow, for one, generally supports the idea of paternal tolerance. But “it’s not something I would talk to patients about,” she told me. Sarah Kilpatrick, the chair of the department of obstetrics and gynecology at Cedars-Sinai, in Los Angeles, feels similarly. There’s just not quite enough evidence to build a recommendation, she told me—and designing a large clinical trial to rigorously test these ideas is difficult, especially for a condition with such serious risks.

[Read: Childbirth is no fun. But an extremely fast birth can be worse.]

Plus, a pre-pregnancy injunction to have more sex to lower the risk of preeclampsia can only really apply to a very specific audience. It assumes heterosexuality; it implies monogamy. Even the amount of sex that Robillard advocates for could pose a challenge for some couples who meet those criteria. And heterosexual, monogamous couples hardly represent the full universe of people who are getting pregnant—among them people who are pursuing single parenthood, who get pregnant through intrauterine insemination or in vitro fertilization, who are seeking donor sperm or embryos, and who get pregnant quickly or perhaps unintentionally. And although the chances of preeclampsia may be slightly elevated in some of those cohorts, in the broadest terms, “why person X gets it, and why person Y doesn’t get it, we just don’t know,” Kilpatrick told me. Plus, a clinical strategy that pushes for, or even seems to justify, long-term sexual monogamy puts medical professionals in the position of actively prescribing a very specific and limited vision of human sexuality, Rutherford, the biological anthropologist, told me.

Frankly, Edlow told me, “I don’t want to take this condition that affects pregnancy and make it all about men’s sperm.” There may yet be other ways to trigger tolerance, or keep the maternal immune system in check. Preeclampsia, for whatever reason, may be an evolutionary snarl our lineage got tangled up in. But to address it, or even solve it, people may not need to bend to evolution’s whims.

In the face of dual strikes over the summer from writers and actors unions, many Hollywood studios retreated rather than negotiating for a quick resolution, delaying some of their biggest fall blockbusters. Movies such as Kraven the Hunter, Dune: Part Two, a Ghostbusters sequel, and others were booted from 2023. That left gaping holes in the calendar, prompting serious fears of another setback for theaters after they’d just begun to bounce back from the pandemic. Then came Taylor Swift.

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On August 31, the singer, who is in the midst of a global tour, announced that a concert film would be released in theaters October 13—a canny move that essentially saved exhibitors’ necks for the rest of the year. Taylor Swift: The Eras Tour is a 168-minute rendering of an experience that millions missed out on, filmed by Sam Wrench over the course of three performances at SoFi Stadium, in Los Angeles. Swift independently financed the movie (at a cost of about $10 million to $20 million) and is presenting it as a one-of-a-kind event: You can only see it Thursdays through Sundays, your ticket costs $19.89 (a reference to Swift’s birthday and the album named for it), and you can get a free poster.  

Presales were immediate and enormous, with AMC Theaters’ ticket app crashing right as sales began and AMC’s stock briefly spiking after the announcement. The hype built to levels approaching that of Barbie’s release last summer, and some box-office tracking briefly predicted a record-smashing $145 million opening. Although lower, the final number was still remarkably robust. The Eras Tour grossed about $97 million last weekend, according to early estimates, which immediately makes it the most successful concert film of all time. The next highest, 2011’s Justin Bieber: Never Say Never, made only $73 million total; The Eras Tour could end up tripling that figure.

The emphasis on presales is probably why it came in slightly below expectations. Much of Swift’s army of fans made sure to book well in advance, meaning there was less walk-up traffic than a typical release might get. But the film won an A+ CinemaScore, which indicates positive word of mouth, and its competition over the next few weeks will be relatively thin: mostly awards-focused films aimed at older audiences (including Martin Scorsese’s Killers of the Flower Moon, Sofia Coppola’s Priscilla, and David Fincher’s The Killer). Every other blockbuster had been moved out of the way, either because of studio intransigence during the strikes or simply to dodge the Swift tidal wave (The Exorcist: Believer jumped up one week to avoid it).

For Swift, the release is a home run, partly because she negotiated a favorable split with AMC, getting 57 percent of ticket sales. By not working with a major studio, she doesn’t have to sacrifice any gross to them, and she doesn’t have to rely on their marketing arm (nor does she need to, given that she commands enough of a following herself). But the Eras film is an even bigger win for the theater chains, which keep 100 percent of concessions sales (which is where profit really lies for them) and, more important, can shore up their business in what was looking like a dire moment.

[Read: The 22 most exciting films to watch this season]

The releases of Barbie and Oppenheimer in the summer of 2023 were a moment of total joy for companies such as AMC and Regal, luring back droves of ticket-buyers and reminding them of the communal thrill of going to the movies rather than waiting to watch them at home. The Eras Tour is another fine example of that experience, with fans encouraged to sing, dance, and swap friendship bracelets during the showings—in fact, Swift guaranteed a 13-week exclusive theatrical window as part of negotiations.

For traditional studios, The Eras Tour might be the most profound example of the money that’s been left on the table because of dragged-out negotiations with the Writers Guild of America and the Screen Actors Guild. The WGA strike finally ended on September 27, on terms regarded as massively favorable for the union, but the long duration of that labor action was almost entirely due to studios refusing to even negotiate: Once honchos such as Bob Iger and David Zaslav got in a room with the union, talks wrapped in a manner of days. The same song and dance is now playing out with SAG, further holding up the release calendar and production on some of next year’s blockbusters. In the meantime, theaters and celebrities are finding ways to sell tickets and make money without the help of a Disney or a Warner Bros. The story of Hollywood ticket sales in 2023 has largely been one of a successful bounce-back, but that’s despite studio inaction, not because of it.

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