The Legislative Assembly of Ontario, from www.ola.org   Two recent bills introduced in the Ontario Legislature are poised to gut environmental protections, and severely curb the authority of municipal planners. Here’s a summary of the tabled bills 5 and 17, focused on areas of relevance to architects. Bill 5: Repealing the Endangered Species Act, introducing regulation-free Special Economic Zones The omnibus Bill 5, Protect Ontario by Unleashing our Economy Act, 2025, is ostensibly aimed at stimulating the economy by removing barriers to development. One of its key components is replacing the province’s Endangered Species Act with a hollowed-out Species Conservation Act. The new act allows the government to pick and choose which species are protected, and narrowly defines their “habitat” as the nest or den of an animal—not the broader feeding grounds, forests, or wetlands they need to survive. Developers must currently apply for a permit when their projects threaten a species or habitat, and these applications are reviewed by environmental experts. This process would be replaced by an online registration form; when the form is submitted, a company is free to start building, including damaging or destroying habitats of listed specied, so long as the activity is registered.  The new Species Conservation Act will completely exclude migratory birds and certain aquatic species. “It’s a developer’s dream and an environmental nightmare,” writes environmental lawyers Ecojustice. Bill 5 also contains provisions for creating Special Economic Zones, where provincial and municipal laws do not apply—a status that the Province could claim for any project or proponent. This would allow work on these projects to be exempt from zoning regulations and approvals, as well as from labour laws, health and safety laws, traffic and speeding laws, and even laws preventing trespassing on private property, notes advocacy group Environmental Defence. The Bill specifically exempts the Ontario Place redevelopment from the Environmental Bill of Rights. As a result, explains lawyers from Dentons, “the public will not receive notice of, or have opportunity to, comment on proposals, decisions, or events that could affect the environment as it relates to the Ontario Place Redevelopment Project.” Advocacy group Ontario Place For All writes: “The introduction of this clause is a clear response to the overwhelming number of comments—over 2200—from the community to the Environmental Registry of Ontario regarding the Ford government’s application to cut an existing combined sewer overflow (CSO) that will be in the way of Therme’s planned beach. The application has the CSO emptying into the west channel inside the breakwater and potentially allowing raw sewage into an area used recreationally by rowers, paddlers, swimmers, and for water shows by the CNE. The Auditor General’s Report estimated the cost of moving the CSO to be approximately $60 million.” The Bill also amends the Ontario Heritage Act, allowing the Province to exempt properties from archaeological and heritage conservation requirements if they could potentially advance provincial priorities including, but not limited to, transit, housing, health, long-term care, or infrastructure. Another part of the bill would damage the clean energy transition, notes Environmental Defense. “Bill 5 would enable the government to ban all parts of energy projects that come from abroad, especially China. China makes the majority of solar panels (over 80 per cent), wind turbines (around 60 per cent) and control systems in the world,” it writes. “If enacted, Bill 5 would likely end solar power installation in Ontario and deprive Ontarians access to the cleanest source of new electricity available.” In the Legislature, Liberal member Ted Tsu noted, “They called this bill, Bill 5, the Protect Ontario by Unleashing our Economy Act. However, upon studying the bill, I think a more appropriate short title would be ‘don’t protect Ontario and use tariffs as cover to unleash lobbying act.’ That is a summary of what I think is wrong in principle with Bill 5.” Bill 5 has undergone its second reading and will be the subject of a Standing Committee hearing. Bill 17: Striking down green development standards, paring down planning applications Bill 17: Protecting Ontario by Building Faster and Smarter Act, 2025 aims to dismantle the City of Toronto’s Green Building Bylaw, along with limiting municipal authority in planning processes. These changes are proposed in the ostensible interest of speeding up construction in order to lower housing costs. The bill states that municipalities must follow the Building Code, and prohibits them for passing by-laws or imposing construction standards that exceed those set out in the Building Code. This seems to deliver a major win to development group RESCON, which has been lobbying to strike down the Toronto Green Standard. Fifteen municipalities in the Greater Toronto Area currently have green development standards. Non-profit group The Atmospheric Fund (TAF) notes that green standards do not slow housing construction. “In 2023, Toronto exceeded its housing targets by 51%, with nearly 96% of housing starts being subject to the Toronto Green Standard. Overall, Toronto’s housing starts have grown or stayed consistent nearly every year since the TGS was implemented.” The group also notes that the Ontario Building Code’s energy efficiency requirements have not been updated since 2017, and that Ontario’s cities will not meet their climate targets without more progressive pathways to low-carbon construction. Also of direct impact to architects is the proposed standardization of requirements for “complete” planning applications. Under the tabled bill, the Minister of Municipal Affairs and Housing will have the power to govern what information or material is required (or prohibited) in connection with official plan amendments, zoning by-law amendments, site plan approval, draft plans of subdivisions, and consent applications. This would prevail over existing Official Plan requirements. Currently, the Ontario government is proposing that sun/shadow, wind, urban design and lighting studies would not be required as part of a complete planning application. The bills would also deem an application to be complete not when it’s accepted by a municipal planning authority, but solely on the basis of it being prepared by prescribed professional. The prescribed professions are not yet defined, but the government has cited Engineers as an example. Bill 17 proposes to grant minor variances “as of right” so long that they fall with a certain percentage of current setback regulations. (They are currently proposing 10%.) This would apply to urban residential lands outside of the Greenbelt. The Bill proposes amendments to the Development Charges Act that will change what municipalities can charge, including eliminating development charges for long-term care homes. The bill limits Inclusionary Zoning to apply to a maximum 5% set-aside rate, and a maximum 25-year period of affordability. Dentons notes that: “While not specifically provided for in Bill 17, the Technical Briefing suggests that, the Minister of Infrastructure will have authority to approve MZOs, an authority currently held only by the Minister of Municipal Affairs and Housing.” Environmental Defense’s Phil Pothen writes: “Some of the measures proposed in Bill 17—like deferring development charges—could help build smarter and faster if they were applied selectively to infill, mid-rise and multiplex housing. But the bill’s current language would apply these changes to sprawl and McMansion development as well.” He adds: “Bill 17 also includes provisions that seem aimed at erasing municipal urban rules and green building standards, imposing generic road-design standards on urban and suburban streets and preventing urban design. Those changes could actually make it harder to speed up housing—reversing progress toward more efficient construction and land use and the modes of transportation that support them.” The Bill would also amend the Building Code to eliminate the need for a secondary provincial approval of innovative construction products if they have already been examined by the Canadian Construction Materials Centre of the National Research Council of Canada. The Ontario government is currently seeking comment on their proposed regulation to standardize complete application requirements. They are also currently seeking comment on the proposed regulation that provides for as-of-rights within 10% of current required setbacks. These comment periods are open until June 26, 2025. The post New Ontario bills gut environmental protections, eliminate green building bylaws appeared first on Canadian Architect.

By Natalia Mesa Published May 23, 2025 | Comments (1) | Giant ground sloths Megalocnus rodens and Megalonyx wheatleyi at the American Museum of Natural History © Dallas Krentzel Giant sloths with razor-sharp claws and as large as Asian bull elephants once roamed the Earth, snacking on leaves at the tops of trees with a prehensile tongue. Now, scientists have figured out why they became so huge—and why these massive sloths didn’t stick around—according to a new study published in Science. Today, two sloth species dwell in Central and South America. But long ago, dozens of sloth species populated the Americas, all the way from Argentina to Canada. Like modern-day sloths, the smaller species were tree-dwelling. But the larger sloths? “They looked like grizzly bears but five times larger,” Rachel Narducci, collection manager of vertebrate paleontology at the Florida Museum of Natural History and coauthor of the study, in a statement. The larger sloths didn’t do much tree climbing, at risk of falling to their deaths. Instead, they survived by being terrifying; the largest sloths had long, sharp claws that they used to carve their own caves out of raw earth and rocks. But exactly why they got so large remained a mystery. To figure out how these sloths got so massive, researchers analyzed ancient sloth DNA and compared more than 400 fossils from natural history museums to create a sloth tree of life. The researchers traced the sloths’ origin to 35 million years ago. And, because the scientists were particularly interested in how sloths got their size, they estimated their weights by taking fossil measurements. The researchers concluded that the Earth’s past climate was a big factor. Thirty-five million years ago, the first ancestor of modern-day sloths, which lived in what is now Argentina, was roughly the size of a large dog. Sloths hardly changed in size for 20 million years, and lived on the ground. Then, during a warming period around 16 million years ago, sloths adapted by evolving smaller physiques due to their need to keep cool. Then, as Earth cooled down again—which it’s been doing on and off for the past 50 million years—sloths started to get bigger and bigger. They also started to migrate, fanning out from Argentina throughout North and South America, and even up to Alaska and Canada. These new habitats presented challenges that the sloths met, in part, by bulking up. This new size also helped them keep warm and stay safe from predators. “This would’ve allowed them to conserve energy and water and travel more efficiently across habitats with limited resources,” Narducci said. “And if you’re in an open grassland, you need protection, and being bigger provides some of that.” They reached their most massive size during the Pleistocene Ice Ages, which spanned roughly 3 million to 12,000 years ago, shortly before they disappeared. Scientists aren’t completely sure why sloths went extinct, but they do have some guesses. Early humans migrated to the Americas around 20,000 years ago. Larger ground-dwelling sloths likely became a prime, meaty target for early humans, and being on the ground became a liability. Larger sloths were the first to go, but tree sloths didn’t escape unscathed. Over time, more and more species of tree-dwelling sloths went extinct, too. Two species survived in the Caribbean until around 4,500 years ago—until humans wiped them out. Now, sloths mostly keep to Central and South America, but thankfully aren’t on the menu anymore. Daily Newsletter

Laurie Baker never advocated an imitation of his architecture. He instead intended that his design principles would generate a truly Indian architecture. ‘Be honest and truthful in design, material usage, construction, costs, and about your own mistakes,’ he wrote as one of 20 guiding principles, which he duly respected in his projects. His last major commission started as the Navayatra community living centre, and became the Laurie Baker Centre for Habitat Studies (LBC), a place where his design ethos and philosophy live on.  The project started in 1994, when Baker was 77 years old. Keith Saldanha, an economist based in Canada, decided to relocate to the southern Indian state of Kerala and build a community centre dedicated to fostering creative abilities for children with special education needs. Having purchased a three‑and‑a‑half‑acre site in Vilappilsala, outside the city of Thiruvananthapuram, Saldanha named his project Navayatra, or ‘a new journey’, and reached out to Baker. He had heard of the British‑born Indian architect, whose full original name was Lawrence Wilfred Baker, because his work in the region had been gaining traction. Baker was rigorous in applying his own design principles (Laurie Baker Centre) The small yet densely populated state of Kerala, created in 1956, had become known as a ‘model of development’ in the ’70s. An extended period of political stability under the able stewardship of successive communist governments led to significant improvement of human development parameters, including health, education and housing, despite low economic growth. Baker’s cost‑effective design philosophy and work resonated with the holistic welfare ideology of then chief minister Chelat Achutha Menon, who commissioned him to design several welfare projects, despite his ‘unconventional’ building methods. After he retired in 1985, Achutha Menon founded the Centre of Science and Technology for Rural Development (COSTFORD), a non‑profit, with Baker as its chief architect. His innovative approach to sustainable and cost‑effective architecture emphasised the use of local resources, labour and harmony with the natural environment. ‘Always study your site: its soil, topography, water, climate and neighbours (noisy temples, smelly factories, etc)’ was another of Baker’s principles. In his sketch for Navayatra’s masterplan, Baker meticulously noted the natural features; his proposal made the most of the complex topography, preserving the prominent granite rock formations as well as the scattered coconut and mango trees. The abandoned quarry pit was turned into a rainwater harvesting tank, which catered to the water requirement of the new centre all through the year. Functional spaces were housed on the high rock outcrops so that the natural drainage would not be disturbed and to curtail foundation costs.  Construction began in 1996, with a meandering pedestrian path connecting the different buildings. Each one is unique, but they are held together by the consistent use of exposed brick and the verdant landscape. The canteen hugs the rocky edges of the large granite quarry pit, with steps descending from its kitchen to the water body. The circular array of bedrooms in the guest house preserves the existing trees, while the undulating roof of the dormitory mimics the adjacent rock formations. The curved, perforated brick walls, while appearing irregular, are meticulously designed to respond to the site’s visual context and prevailing breezes. Baker’s rejection of rigid geometries made his spaces fluid, dynamic and adaptable. Each space appears to flow seamlessly into the next, a quality particularly exemplified in the dormitory.  Read Laurie Baker’s Reputations essay Discarded materials such as cut bricks, glass bottles, stone chips, timber pieces and broken tiles, all sourced within a 5km radius of Vilappilsala, were repurposed throughout the site, and local labour was employed. Baker had an in‑depth understanding of brick, timber and stone, which he deployed in myriad ways. He himself facilitated training, in collaboration with his engineer and constant companion PB Sajan. ‘Laurie Baker firmly refused ostentation and decoration for its own sake,’ recalls Sajan, ‘yet his buildings were never dull. There would always be an element of surprise, either in the use of an ordinary material or the geometrical interpretation of space. He believed in the intrinsic beauty of all things, living and non‑living.’     The spaces designed by Baker must be appreciated in light of his design philosophy. The 20 principles of architecture that he advocated in his writing and talks are an amalgamation of his Quaker beliefs and the Gandhian ideal of commitment to social justice and non‑violence; he believed architecture should be a non‑violent insert into the land and local ecology. This new aesthetic was refreshingly non‑invasive, even if it alienated some contemporary modernists. Baker’s innovative adaptation of local craft techniques was both playful and resourceful. His designs, frugal and pragmatic, were driven by a desire to be cost‑effective – rather than the expression of purely stylistic choices.  The programmatic needs of Navayatra evolved and translated into the construction of new structures, including accommodation for invited artists and a residential space for the client. There was no electrical connection on the site; all activities took place in the daytime. The extensive use of perforated walls helped to keep the spaces cool and well ventilated. The dormitory, on the higher western edge of the site, is the last structure Baker designed for Navayatra. It was the primary learning and living quarters for the tutors who conducted classes. Its semi‑open terrace, nestled in the undulating roof, proved an ideal learning and interactive space. Its completion in 2002 marked Baker’s last site visit to Navayatra.  PB Sajan continued work on the site, designing, for example, the two small structures along the pathway at the entrance, for which Baker gave his approval. Both were experiments to test concrete roof slabs using bamboo reinforcement instead of steel rods. The centre continued to function as a vibrant community space for a couple of years, but once Saldanha moved out, due to deteriorating health, managing Navayatra became difficult. At the same time, COSTFORD, still under the guidance of Laurie Baker, required a dedicated space. The architect welcomed Saldanha’s offer to sell Navayatra, with a view to turning it into an independent centre for learning that would focus on innovation and research in alternative building technologies, but financial constraints, as well as Baker’s failing health, delayed the process. Two years after Baker’s death in 2007, Kerala’s finance minister sanctioned 8 million rupees (£70,000) to purchase the land. The Laurie Baker Centre for Habitat Studies was inaugurated in October 2009; Sajan has since been the director of both COSTFORD and the LBC. The centre encourages the appropriate use of natural resources, disseminates non‑conventional and eco‑friendly design strategies, and provides hands‑on training in innovative construction methods. ‘The thrust is not to propagate a “Laurie Baker architecture” but to understand the sound principles behind his life’s work,’ explains KP Kannan, chairman of LBC and COSTFORD, ‘and apply them to questions of housing and inclusive development.’  Due to the steep spike in construction over the decade, Kerala faces an acute shortage of sand (because of uncontrolled sand mining), granite (quarrying of hills is rampant) as well as bricks (as suitable clay is becoming scarce). The LBC’s research on, and advocacy of, alternative and low‑energy construction materials has led them to turn to mud and bamboo, while continuing to explore the use and potential of recycled materials. Sajan and the COSTFORD team designed additional buildings for the LBC, including an office annexe and a four‑storey library used for research. They also added spaces for workshops and for treating bamboo to Baker’s original masterplan, and the entire centre has been availed of electrical and plumbing connections for a better work environment.  Built primarily with mud and bamboo, the new office annexe and library serve the functional purpose of the centre, but stand out from Laurie Baker’s original designs and fail to blend into his original masterplan, even though they do follow nearly all his design principles. Baker liked to advise to ‘use common sense and have fun designing’, but the playfulness feels absent, as these two new buildings are primarily concerned with showcasing construction techniques. As a result, they compromise on spatial quality. While all of Baker’s structures were strategically positioned in relation to one another, the library seems isolated; it is conspicuous instead of blending in with the older brick buildings and the landscape. The play of light and darkness, the fluidity of spaces and the meticulous attention to detail, which are the salient hallmarks of Laurie Baker’s designs, are also missing in these new additions. The temporary sheds used for training sessions and workshops could have been envisioned as thatched pavilions instead of pitched blue tarpaulins.  What makes LBC’s success, however, is the strength of its educational programmes: the sharing of knowledge about alternative building technologies with architecture students, and the willingness to build on existing research and their own archive, which is made accessible to all visitors. Students, professionals and construction workers all come here to learn about dry rubble stone masonry, building with mud, bamboo treating and joinery, brick arches and walls, including Baker’s much loved rat trap bond, as well as the preparation of lime plasters. The centre is interested in further researching water management and establishing a permanent material lab and research space for scholars and professionals. In his lecture ‘Truth in Architecture’ at Thiruvananthapuram’s College of Engineering in 1982, Baker critiqued the resource‑intensive architecture that was starting to mushroom in the city. The indiscriminate use of concrete, excessive ornamentation and overconsumption of resources were popularly understood as a marker of status. Baker foresaw the impending crisis that such excesses would trigger. What he anticipated has only accelerated. In the face of the climate emergency, Kerala confronts significant challenges, including diminishing natural resources and rising construction costs coupled with sluggish economic growth. Ahead of its time, Baker’s practice advocated a pragmatic and reasonable use of resources – ‘don’t rob national resources and do not use them extravagantly and unnecessarily,’ he wrote in his list of principles. To this day, Baker’s philosophy represents a vital rallying call to interrogate contemporary notions of modernity.  This article was featured in the May 2025 Circularity issue. Purchase your copy here

Cabin in Woods | © Egemen Karakaya Set on the Kozak Plateau near Pergamon in western Turkey, Cabin in Woods by Ediz Demirel Works presents a compelling investigation into the relationship between architecture, landscape, and inhabitation. Modest in scale but conceptually rigorous, the 36-square-meter structure explores dualities in materiality, spatial experience, and construction technique. Its design resists conventional tropes of vernacular mimicry, opting instead for conscious contrast. This architectural gesture neither disappears into the land nor dominates it but negotiates a dynamic tension between embeddedness and autonomy. Cabin in Woods Technical Information Architects1-2: Ediz Demirel Works Location: Kozak Plateau, Pergamon, Izmir, Turkey Area: 36 m2 | 387 Sq. Ft. Completion Year: 2025 Photographs: © Egemen Karakaya The identity of the structure is shaped by the interplay of two opposing tectonic approaches in terms of materials, construction techniques, production methods, and the contrast between locality and foreignness. – Ediz Demirel  Cabin in Woods Photographs © Egemen Karakaya © Egemen Karakaya © Egemen Karakaya © Egemen Karakaya © Egemen Karakaya © Egemen Karakaya © Egemen Karakaya © Egemen Karakaya © Egemen Karakaya © Egemen Karakaya © Egemen Karakaya © Egemen Karakaya © Egemen Karakaya Design Intent and Conceptual Framework The cabin occupies a terrace wall from a former vineyard, utilizing the dry stone retaining wall as a literal and conceptual foundation. This gesture roots the project within the existing agricultural topography, establishing a minimal intervention approach. Yet from this grounded base, the cabin rises as an artificial insertion. Its steel frame and corten cladding introduce a formal and material vocabulary foreign to the rural surroundings, underscoring a deliberate dialectic between context and object. At the heart of the project is a sunken conversation pit, an introspective space that anchors the plan and serves as the primary social node. This recessed area draws the inhabitant downward into the landscape, offering a tactile and spatial contrast to the protective shell above. The lowered core reframes domesticity in spatial terms, allowing for a gathering space that privileges horizontality, intimacy, and thermal mass. Around this core, other functional programs such as wet areas, storage, and circulation are deployed as appendages. Above, a mezzanine floor is delicately inserted within the steel shell, creating zones for sleeping and working without compromising the spatial clarity of the core below. Spatial Organization and Experiential Strategy Despite its compact footprint, the cabin achieves a high degree of spatial complexity. This is accomplished not through planimetric manipulation but through sectional richness and the careful calibration of views, light, and thresholds. A singular horizontal aperture cuts through the shell, framing a panoramic view of the forested hills. This gesture provides more than visual access; it actively orchestrates a dialogue between the interior and the broader ecological context. The facade, punctuated with small cantilevered openings, introduces sculptural moments that protrude into the landscape. These elements operate simultaneously as light sources, thermal breaks, and spatial cues. They animate the exterior envelope while mediating the inhabitant’s sensory experience from within. The strategy reveals an architectural sensibility attuned to the nuances of perception, perspective, and phenomenology. The sunken core, in particular, reinforces this experiential ambition. It is not merely a spatial curiosity but a site of temporal deceleration, a hearth-like void where fire, conversation, and reflection converge. In this sense, the project subtly reinvigorates domestic rituals through spatial articulation, encouraging modes of living that prioritize gathering and grounding over visual spectacle. Material Strategy and Construction Logic The architectural language of Cabin in Woods is structured around a deliberate contrast between local, irregular materials and prefabricated, controlled systems. The foundation, comprising a reinforced concrete slab cast directly into the existing dry stone terrace, extends the material logic of the landscape. This decision grounds the structure physically and symbolically, linking it to the region’s vernacular heritage. Conversely, the corten steel cladding and the structural steel frame are fabricated off-site and assembled locally. This bifurcation in construction methods aligns with the project’s conceptual division. The base engages the earth and honors the irregularity of place, while the shell expresses a technological detachment and formal precision. With its evolving patina and atmospheric depth, the use of corten adds a layer of temporal expression to the architectural language. It ages, oxidizes, and marks time, introducing a poetic dimension to the otherwise industrial envelope. Such a contrast is not merely aesthetic. It reflects a broader interrogation of architectural identity—how buildings can simultaneously belong, estrange, settle, and provoke. The tectonic opposition between ground and shell becomes a vehicle for this inquiry, inviting reflection on how architecture positions itself in relation to site and memory. Contextual and Critical Significance Beyond its immediate programmatic function as a short-term rental, Cabin in Woods engages with urgent disciplinary questions. How should contemporary architecture respond to rural contexts without defaulting to nostalgia? How can compact dwellings foster depth of experience without resorting to over-programming? And how might architecture embrace contradiction as a generative force rather than a problem to be resolved? Ediz Demirel’s response is measured yet assertive. Rather than dissolving into the landscape, the cabin asserts its autonomy while acknowledging the terrain. The project frames its site not as a passive backdrop but as an active participant in the architectural narrative. Its minimal footprint, precise detailing, and tectonic clarity demonstrate how small-scale interventions can yield disproportionately rich spatial and conceptual outcomes. Cabin in Woods Plans Floor Plan | © Ediz Demirel Works Section | © Ediz Demirel Works Elevations | © Ediz Demirel Works Details | © Ediz Demirel Works © Ediz Demirel Works Cabin in Woods Image Gallery About Ediz Demirel Works Ediz Demirel Works (EDWorks) is an Istanbul-based architectural studio founded in 2022 by Ediz Demirel. The practice focuses on small to medium-scale projects integrating design, construction, and development. EDWorks emphasizes material experimentation, site-specific strategies, and balancing traditional craftsmanship and contemporary tectonics. Notable projects include Cabin in Woods and Pergamon House in the Izmir region. The studio’s approach reflects a commitment to architectural clarity and contextual sensitivity. Credits and Additional Notes Design Architect: Ediz Demirel Site Architects: Ediz Demirel, Tuna Ökten

The Council on Tall Buildings and Urban Habitat (CTBUH) has unveiled the winners of its 2025 Award of Excellence. The annual award series seeks to honor built and unbuilt tall buildings that “respond to current global challenges and demonstrate the vital role of tall buildings in the 21st century.” The 2025 winners span 20 countries and 20 categories. According to the organizers, the 2025 projects “exemplify creative and technical leadership across the gamut of sustainable vertical urbanism.” “This year’s cohort demonstrates not only technical sophistication and design ingenuity but also an ability to respond to the circumstances shaping the world right now—from regional issues and economic challenges to the accelerating climate crisis,” according to Javier Quintana de Uña, CEO of CTBUH. “These projects prove that tall buildings and the vertical urbanism they engender can instigate better quality of life, ecological resilience and urban equity simultaneously. That’s the direction ou...

The sloth family tree once sported a dizzying array of branches, body sizes and lifestyles, from small and limber tree climbers to lumbering bear-sized landlubbers.  Why sloth body size was once so diverse, while today’s sloths are limited to just two diminutive tree-dwellers, has been a long-standing question. Scientists have proposed that sloths’ body size might be linked to a wide variety of factors: habitat preferences, diets, changes in global temperature, or pressure from large predators or humans. Sign up for our newsletter We summarize the week's scientific breakthroughs every Thursday.

Sloths once came in a variety of sizes and lived in multiple settings in many parts of the world. A study in the journal Science examined sloth evolution over the past 35 million years, investigated multiple factors driving their growth and expansion throughout the world, and concluded that human hunting starting around 15,000 years ago drove their dramatic decline.Today, only six species within two genera remain. All are relatively small (especially compared to their largest ancestors) tree-dwellers that primarily live in the tropical rainforests of South and Central America.“These species are a tiny remnant of a once diverse American clade that was mostly made up of large-bodied species,” according to an editorial summary that accompanied the paper. Ancient Sloths Were Once WidespreadThat’s a huge contrast to sloth life during the late Cenozoic. During that period, more than 100 genera of sloths lived in a wide range of habitats and a variety of sizes, topping out at nearly 20 feet tall and weighing several tons.To investigate this diversity — and to track where, when, and why it collapsed — a team of scientists examined fossil measurements, DNA and protein sequences, and advanced evolutionary modeling. In doing so, they reconstructed sloth evolutionary history across 67 genera. They then investigated whether evolutionary changes in size were linked to habitat, diet, climate, predation, or other ecological pressures.Habitat Drove Sloth SizeThe findings show that habitat appeared to be a major driver in shaping their body size evolution. The earliest sloths were large and grazed on the ground. Some species adapted to tree dwelling and developed smaller body sizes. However shifts in both sloth size and dwelling didn’t happen in a straight line. The species size grew or shrunk as the climate warmed and cooled, and as ecosystems shifted from grasslands to woodlands.The species thrived for tens of millions of years, exhibiting the most variety in body sizes in the Pleistocene, which began about 2.6 million years ago.Ancient Humans Caused Dramatic DeclineThen, starting about 15,000 years ago, the creature experienced “a sudden and dramatic decline,” according to a press release.The researchers report that decline doesn’t mesh with any major known climate events. "Size disparity increased during the late Cenozoic climatic cooling, but paleoclimatic changes do not explain the rapid extinction of ground sloths that started approximately 15,000 years ago,” according to the paper. However, it does coincide with the expansion of humans into the Americas. The likely conclusion is that human hunting drove the extinction of the larger, ground-based sloths, while the smaller ones related to today’s creatures escaped by taking to the trees.Article SourcesOur writers at Discovermagazine.com use peer-reviewed studies and high-quality sources for our articles, and our editors review for scientific accuracy and editorial standards. Review the sources used below for this article:Before joining Discover Magazine, Paul Smaglik spent over 20 years as a science journalist, specializing in U.S. life science policy and global scientific career issues. He began his career in newspapers, but switched to scientific magazines. His work has appeared in publications including Science News, Science, Nature, and Scientific American.

Ancient sloths came in a variety of sizesDiego Barletta A cooling, drying climate turned sloths into giants – before humans potentially drove the huge animals to extinction. Today’s sloths are small, famously sluggish herbivores that move through the tropical canopies of rainforests. But for tens of millions of years, South America was home to a dizzying diversity of sloths. Many were ground-dwelling giants, with some behemoths approaching 5 tonnes in weight. Advertisement That staggering size range is of particular interest to Alberto Boscaini at the University of Buenos Aires in Argentina and his colleagues. “Body size correlates with everything in the biological traits of an animal,” says Boscaini. “This was a promising way of studying [sloth] evolution.” Boscaini and his colleagues compiled data on the physical features, DNA and proteins of 67 extinct and living sloth genera – groups of closely related species – to develop a family tree showing their evolutionary relationships. Unmissable news about our planet delivered straight to your inbox every month. Sign up to newsletter The researchers then took this evolutionary history, which covered a span of 35 million years, and added information about each sloth’s habitat, diet and lifestyle. They also studied trends in body-size evolution, making body mass estimates of 49 of the ancient and modern sloth groups. The results suggest sloth body-size evolution was heavily influenced by climatic and habitat changes. For instance, some sloth genera began living in trees – similar to today’s sloths – and shrank in body size as they did so. Meanwhile, three different lineages of sloths independently evolved elephantine proportions – and it seems they did this within the last several million years, as the planet cooled and the growth of the Andes mountains made South America more arid. “Gigantism is more closely associated with cold and dry climates,” says team member Daniel Casali at the University of São Paulo, Brazil. Many of these diverse sloths disappeared during two stages: one around 12,000 years ago and the other around 6000 years ago, says Boscaini. “This matches with the expansion of Homo sapiens, first over the entire American supercontinent, and later in the Caribbean,” he says — which is where some giant sloths lived. Notably, the only surviving sloth species live in trees so are much harder for humans to hunt than massive ground sloths. The idea that humans were the death blow for ancient megafauna is well-supported, says Thaís Rabito Pansani at the University of New Mexico, who wasn’t involved in the study. “However, in science, we need several lines of evidence to reinforce our hypotheses, especially in unresolved and highly debated issues such as the extinction of megafauna,” she says. The new evidence shores up this story. “Sloths were thriving for most of their history,” says Casali. “[The findings] teach us how a very successful [group] can become so vulnerable very quickly.” Journal reference:Science DOI: 10.1126/science.adu0704 Topics:evolution

Photo Credit: NASA New Study Uses AI to Reveal Dry Origins of Mars’ Mysterious Slope Streaks Highlights AI maps 500,000 Martian slope streaks with no signs of water New study links streaks to wind and dust, not liquid brines Findings reshape Mars exploration and contamination concerns Advertisement The origin of Recurring Slope Linea, the long, dark markings that stretches across the slopes of Martian surface for hundreds of feet, has been a topic of debate for a long time. They appear during warmer season and they were seen as one of the most compelling signs that liquid water might still exist on Mars, suggesting a rare pocket of habitability on an otherwise arid planet. However, this view has been challenged by a new study by a group of researchers Brown University and the University of Bern. Using machine learning and leveraging satellite images, they have found evidence about the dry processes being the origin of these streaks.Machine learning breakthrough brings new evidencesAccording to Adomas Valantinas, a postdoctoral researcher at Brown who coauthored the research with Valentin Bickel, a researcher at Bern, a big focus of Mars research is understanding modern-day processes on Mars, including the possibility of liquid water on the surface. This study reviewed these features but found no evidence of water. Their model favours dry formation processes.Valantinas and Bickel integrated over 86000 high-resolution satellite images with a machine learning algorithm for analysis. They created the first global map of Martian slope streaks, cataloguing over 500,000 individual features across the planet's surface. This database enables an unprecedented statistical analysis for the origin and location of these streaks.Researchers used the complete streak map to compare the locations of these features with environmental factors like wind speed, temperature, dust accumulation, and surface hydration. They did not find any correlation between the streaks and water or frost. Rather, these features are more common in areas with high wind activity and dust deposition.Future of Mars explorationThis study provides insights in understanding the surface activities of current Martian environment. The streak sites were used to be treated with caution because of environmental contamination concerns. Ruling out the possibility of liquid water as origin of streaks, the study almost cancels out the probable risk of Earth based contamination. For the latest tech news and reviews, follow Gadgets 360 on X, Facebook, WhatsApp, Threads and Google News. For the latest videos on gadgets and tech, subscribe to our YouTube channel. If you want to know everything about top influencers, follow our in-house Who'sThat360 on Instagram and YouTube. Further reading: Mars, Recurring Slope Lineae, RSL, NASA, Brown University, University of Bern, Machine Learning, Planetary Science, Mars Exploration, AI in Astronomy, Dust Activity, Martian Habitats Gadgets 360 Staff The resident bot. If you email me, a human will respond. More Related Stories