Tech
The Mysterious Math Behind the Brazilian Butt Lift
In the history of gluteal enhancement, Mexico City stands out. It protrudes. It was here, in 1979, that a plastic surgeon, Mario González-Ulloa, first installed a pair of silicone implants designed specifically for the buttocks. The textbook Body Sculpting with Silicone Implants calls González-Ulloa the “grandfather of buttock augmentation.” The early 2000s saw a new generation of Mexico City buttock transformation luminaries, notably Ramón Cuenca-Guerra. In his 2004 paper “What Makes Buttocks Beautiful?” Cuenca-Guerra laid out four characteristics that “determine attractive buttocks” as well as the five types of “defects,” with strategies for correcting each one. I, for instance, have defect type 5, the “senile buttock.” (González-Ulloa’s depiction of this took the form of charcoal nudes contrasting “the typical ‘happy buttock’”—high, rounded, dimpled—with its counterpart, the low-slung, drooping “sad buttock.”)
While I understand the value of standardizing procedures and setting guidelines for surgical practice, I tripped over Cuenca-Guerra’s methodology. How and by whom had the determinants been determined? Like this: 1,320 photographs of “nude women ages 20 to 35 years, as seen from behind” were presented to a panel of six plastic surgeons, who “pointed out which buttocks they considered attractive and harmonious, and features on which this attractiveness depended.” Oho!
I thought it would be interesting to talk to Cuenca-Guerra about the notion of a visually ideal female figure. As something that could or should be surgically created (or, in the case of the senile buttock, re-created). As something that even exists. I sent an email using the address on a more recent journal paper. There was no reply. Ramón Cuenca-Guerra’s buttocks are in worse shape than mine. He has been dead for some time. I was able to reach a colleague of his, José Luis Daza-Flores. Here was the third generation; just as Cuenca-Guerra had studied under González-Ulloa, Daza-Flores had studied under Cuenca-Guerra, extending the lineage and making Daza-Flores, I guess, “the son of buttock augmentation.”
Daza-Flores collaborated with Cuenca-Guerra on a paper called “Calf Implants,” in which the team did for the lower leg what Cuenca-Guerra had done for the butt: laid out “the anatomical characteristics that make calves look attractive” and the “defects” to be addressed. Here again, plastic surgeons were recruited to judge images—2,600 of them, a vast photographic millipede of female legs.
The paper took an unexpected turn. Referring to a marked-up photograph of a lower leg deemed attractive, the authors tried to show that its measurements conformed to what is known in mathematics as the divine proportion (or golden ratio)—1.6 (I’m rounding it off) to 1. When you divide a line into two parts such that the whole length divided by the long part is equal to the long part divided by the short part, both those ratios will be 1.6 to 1. I found an illustration of the divine proportion on a website called Math Is Fun (and convincing no one). The golden dividing line splits the length such that one chunk is roughly two-thirds and the other is around one-third. The ancient Greeks divided the “ideal” face into similarly proportioned thirds. This was the first time I’d seen the divine proportion applied to a leg.
The paper contained sentences like this: “Seventeen women had thin legs, in the shape of a tube, and a mere 1:1.618 ratio in the A-P and L-L projections.” Though I confess to not grasping the particulars of the discussion, I believe that to be a mathematically precise description of cankles.
Tech
The Best Presidents’ Day Deals on Gear We’ve Actually Tested
Presidents’ Day Deals have officially landed, and there’s a lot of stuff to sift through. We cross-referenced our myriad buying guides and reviews to find the products we’d recommend that are actually on sale for a truly good price. We know because we checked! Find highlights below, and keep in mind that most of these deals end on February 17.
Be sure to check out our roundup of the Best Presidents’ Day Mattress Sales for discounts on beds, bedding, bed frames, and other sleep accessories. We have even more deals here for your browsing pleasure.
WIRED Featured Deals
Branch Ergonomic Chair Pro for $449 ($50 off)
The Branch Ergonomic Chair Pro is our very favorite office chair, and this price matches the lowest we tend to see outside of major shopping events like Black Friday and Cyber Monday. It’s accessibly priced compared to other chairs, and it checks all the boxes for quality, comfort, and ergonomics. Nearly every element is adjustable, so you can dial in the perfect fit, and the seven-year warranty is solid. There are 14 finishes to choose from.
Tech
Zillow Has Gone Wild—for AI
This will not be a banner year for the real estate app Zillow. “We describe the home market as bouncing along the bottom,” CEO Jeremy Wacksman said in our conversation this week. Last year was dismal for the real estate market, and he expects things to improve only marginally in 2026. (If January’s historic drop in home sales is indicative, that even is overoptimistic.) “The way to think about it is that there were 4.1 million existing homes sold last year—a normal market is 5.5 to 6 million,” Wacksman says. He hastens to add that Zillow itself is doing better than the real estate industry overall. Still, its valuation is a quarter of its high-water mark in 2021. A few hours after we spoke, Wacksman announced that Zillow’s earnings had increased last quarter. Nonetheless, Zillow’s stock price fell nearly 5 percent the next day.
Wacksman does see a bright spot—AI. Like every other company in the world, generative AI presents both an opportunity and a risk to Zillow’s business. Wacksman much prefers to dwell on the upside. “We think AI is actually an ingredient rather than a threat,” he said on the earnings call. “In the last couple years, the LLM revolution has really opened all of our eyes to what’s possible,” he tells me. Zillow is integrating AI into every aspect of its business, from the way it showcases houses to having agents automate its workflow. Wacksman marvels that with Gen AI, you can search for “homes near my kid’s new school, with a fenced-in yard, under $3,000 a month.” On the other hand, his customers might wind up making those same queries on chatbots operated by OpenAI and Google, and Wacksman must figure out how to make their next step a jump to Zillow.
In its 20-year history—Zillow celebrated the anniversary this week—the company has always used AI. Wacksman, who joined in 2009 and became CEO in 2024, notes that machine learning is the engine behind those “Zestimates” that gauge a home’s worth at any given moment. Zestimates became a viral sensation that helped make the app irresistible, and sites like Zillow Gone Wild—which is also a TV show on the HGTV network—have built a business around highlighting the most intriguing or bizarre listings.
More recently, Zillow has spent billions aggressively pursuing new technology. One ongoing effort is upleveling the presentation of homes for sale. A feature called SkyTour uses an AI technology called Gaussian Splatting to turn drone footage into a 3D rendering of the property. (I love typing the words “Gassian Splatting” and can’t believe an indie band hasn’t adopted it yet.) AI also powers a feature inside Zillow’s Showcase component called Virtual Staging, which supplies homes with furniture that doesn’t really exist. There is risky ground here: Once you abandon the authenticity of an actual photo, the question arises whether you’re actually seeing a trustworthy representation of the property. “It’s important that both buyer and seller understand the line between Virtual Staging and the reality of a photo,” says Wacksman. “A virtually staged image has to be clearly watermarked and disclosed.” He says he’s confident that licensed professionals will abide by rules, but as AI becomes dominant, “we have to evolve those rules,” he says.
Right now, Zillow estimates that only a single-digit percentage of its users take advantage of these exotic display features. Particularly disappointing is a foray called Zillow Immerse, which runs on the Apple Vision Pro. Upon rollout in February 2024, Zillow called it “the future of home tours.” Note that it doesn’t claim to be the near-future. “That platform hasn’t yet come to broad consumer prominence,” says Wacksman of Apple’s underperforming innovation. “I do think that VR and AR are going to come.”
Zillow is on more solid ground using AI to make its own workforce more productive. “It’s helping us do our job better,” says Wacksman, who adds that programmers are churning out more code, customer support tasks have been automated, and design teams have shortened timelines for implementing new products. As a result, he says, Zillow has been able to keep its headcount “relatively flat.” (Zillow did cut some jobs recently, but Wacksman says that involved “a handful of folks that were not meeting a performance bar.”)
Tech
Do Waterproof Sneakers Keep the Slosh In or Out? Let WIRED Explain
Running with wet feet, in wet socks, in wet shoes is the perfect recipe for blisters. It’s also a fast track to low morale. Nothing dampens spirits quicker than soaked socks. On ultra runs, I always carry spares. And when faced with wet, or even snowy, mid-winter miles, the lure of weatherproof shoes is strong. Anything that can stem the soggy tide is worth a go, right?
This isn’t as simple an answer as it sounds. In the past, a lot of runners—that includes me—felt waterproof shoes came with too many trade-offs, like thicker, heavier uppers that change the feel of your shoes or a tendency to run hot and sweaty. In general, weatherproof shoes are less comfortable.
But waterproofing technology has evolved, and it might be time for a rethink. Winterized shoes can now be as light as the regular models, breathability is better, and the comfort levels have improved. Brands are also starting to add extra puddle protection to some of the most popular shoes. So it’s time to ask the questions again: Just how much difference does a bit of Gore-Tex really make? Are there still trade-offs for that extra protection? And is it really worth paying the premium?
I spoke to the waterproofing pros, an elite ultra runner who has braved brutal conditions, and some expert running shoe testers. Here’s everything you need to know about waterproof running shoes in 2026. Need more information? Check out our guide to the Best Running Shoes, our guide to weatherproof fabrics, and our guide to the Best Rain Jackets.
Jump To
How Do Waterproof Running Shoes Work?
On a basic level, waterproof shoes add extra barriers between your nice dry socks and the wet world outside. If you’re running through puddles deep enough to breach your heel collars, you’re still going to get wet feet. But waterproof shoes can protect against rain, wet grass, snow, and smaller puddles.
Gore-Tex is probably the most common waterproofing tech in footwear, but it’s not the only solution in town. Some brands have proprietary tech, or you might come across alternative systems like eVent and Sympatex. That GTX stamp is definitely the one you’re most likely to encounter, so here’s how GTX works.
The water resistance comes from a layered system that is composed of a durable water repellent (DWR) coating to the uppers with an internal membrane, along with other details like taped seams, more sealed uppers with tighter woven mesh, gusseted tongues, and higher, gaiter-style heel collars.
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