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Evolution, Innovation, and Crisis at the Crossroads | Science
Urban Raccoons Rapidly Evolving Signs of Domestication
City-dwelling raccoons are undergoing rapid physical changes that suggest they are in the early stages of domestication, a pattern previously observed only in laboratory conditions and historical animal domestication. A new study found that raccoons living in urban environments have snouts that are 3.5 percent shorter than their rural counterparts—a hallmark trait of domestication syndrome, the collection of physical characteristics that emerge alongside the taming process.
Researchers gathered nearly 20,000 photographs of raccoons across the contiguous United States from community science platforms and compared urban and rural populations. The study suggests that the process of domestication is often misunderstood as a process initiated exclusively by humans through selective breeding. Instead, it begins when wild animals become habituated to human environments and develop reduced fight-or-flight responses in exchange for access to resources.
The researchers hypothesize that these physical changes trace back to mutations affecting neural crest cells—critical groups of cells during embryonic development that migrate throughout the body to form various tissues. These mutations could result in the shorter muzzle observed in urban raccoons, alongside other domestication traits including floppy ears and reduced pigmentation. “I’d love to take those next steps and see if our trash pandas in our backyard are really friendlier than those out in the countryside,” said one of the study’s co-authors, University of Arkansas at Little Rock biologist Raffaela Lesch.
Breakthrough in Preventing Pig-Organ Rejection
Scientists have achieved a significant milestone in xenotransplantation—the transplantation of organs from one species to another—by preventing a pig kidney from being rejected by its human recipient for 61 days. This represents the longest that a genetically modified pig organ has survived in a human body.
The recipient was a 57-year-old brain-dead man in the United States. Crucially, the transplanted kidney was accompanied by the pig’s thymus, a small gland that plays a critical role in immune system development. Researchers believe the thymus helped the recipient’s immune system recognize the donor organ as part of the body, preventing immediate rejection.
The pig kidney was engineered to lack the gene GGAT1, which produces a sugar called alpha-gal on cells. This sugar has been identified as a primary driver of organ rejection in previous pig-to-human transplants. However, rejection ultimately occurred through two separate immune pathways. The first appeared 33 days after transplantation, when antibodies attacked the organ. This was treated with pegcetacoplan, a drug that prevents immune cells from tagging pig cells for destruction. A second type of rejection emerged on day 49, involving inflammatory T cells infiltrating the organ’s surface, which was managed with immunosuppressants.
Despite the eventual rejection, Muhammad Mohiuddin, a clinician researcher at the University of Maryland School of Medicine, described the findings as “the first evidence of how to reverse rejection.” Researchers say the findings will improve outcomes not only for xenotransplantation but also for transplants between human donors and recipients.
Gene Therapy Reaches New Frontier with FDA’s Flexible Framework
The U.S. Food and Drug Administration has announced a new clinical trial pathway designed to accelerate the development of customized gene therapies for rare genetic diseases. The protocol, dubbed the “plausible mechanism” pathway, creates a regulatory framework for testing one-of-a-kind drugs that would have previously had little chance of reaching the market.
The initiative was prompted by the case of an infant known as Baby KJ, who was treated earlier this year with a personalized CRISPR gene therapy at Children’s Hospital of Philadelphia and the University of Pennsylvania. KJ suffered from a rare liver disorder caused by a genetic mutation that prevented his body from producing a key enzyme necessary for protein metabolism. Researchers used CRISPR technology—a molecular scissors that can locate and correct genetic errors—to design a unique drug tailored specifically to his genetic mutation. The therapy has dramatically improved his survival prospects.
The challenge in rare disease treatment is that traditional drug development requires large clinical trials to demonstrate efficacy, yet rare diseases affect too few patients to generate the statistical power required by conventional regulatory standards. Under the FDA’s new framework, researchers can now test a customizable drug platform where the mechanism remains identical but each patient’s therapy is tailored to their specific genetic mutation. This approach is being piloted with urea cycle disorders—conditions affecting the body’s ability to process protein and excrete ammonia—where genetic diversity permits testing across multiple genetic variants using a unified therapeutic framework.
”Nearly 30 years after the sequencing of the human genome, bespoke therapies are close to reality,” wrote FDA Commissioner Marty Makary and chief medical officer Vinay Prasad in a recent editorial.
Meltwater From Antarctica May Offer Unexpected Climate Protection
New research suggests that rapid melting of the West Antarctic ice sheet could paradoxically help preserve the Atlantic Meridional Overturning Circulation (AMOC), the system of currents that transports enormous quantities of heat to Europe and helps keep the continent habitable. While meltwater from Greenland is expected to weaken or collapse the AMOC by introducing light, fresh water that prevents the sinking of dense, salty ocean water, Antarctic meltwater arriving at a specific time could actually stabilize the current.
According to simulations conducted by researchers at Utrecht University in the Netherlands, if Antarctic meltwater were to arrive about 1,000 years before the peak of Greenland’s melting, the AMOC would weaken for several centuries but then recover over the following 3,000 years. Under such a scenario, the current would eventually regain strength as Antarctic meltwater tapered off. However, under more likely scenarios where the melting occurs simultaneously, Antarctic meltwater would accelerate AMOC shutdown.
Even in the optimistic scenario, the findings offer limited comfort. The AMOC would still decline by 60 percent, and a full recovery would require 3,000 years. Moreover, the rapid melting of the West Antarctic ice sheet would cause as much as three metres of sea level rise, flooding coastal cities worldwide. “Unfortunately it is not a consolation if one catastrophe might perhaps reduce the risk of another catastrophe,” remarked Stefan Rahmstorf, a climate scientist at the University of Potsdam.
Fossil Fuel Emissions Reach Historic High Despite Renewable Energy Growth
Global carbon dioxide emissions from fossil fuels are forecast to reach a record 38.1 billion tonnes in 2025, representing a 1.1 percent increase from 2024. When combined with emissions from cement production and land-use changes, total human-caused emissions are expected to reach 42.2 billion tonnes of CO₂.
Yet the figures reveal a more nuanced picture. Over the past decade, emissions have grown at just 0.3 percent per year, compared to 1.9 percent annually during the previous decade. Thirty-five countries have significantly cut their fossil fuel emissions while growing their economies—nearly double the number from the decade before.
The dramatic change reflects an unprecedented shift in global electricity generation. For the first time since the COVID-19 pandemic, electricity generated from fossil fuels is forecast to flatline or decline slightly in 2025—a remarkable development given that electricity demand increased sharply over the same period. Rather than resulting from economic recession, this decline has been more than offset by extraordinary growth in renewable energy, particularly solar power, which has expanded by nearly 500 terawatt hours in the first nine months of 2025 compared to the same period in 2024.
Solar power is growing faster than any electricity source in history, according to the clean energy think tank Ember. “We’ve had decades and centuries where fossil fuels were the only way that we could really grow our economy, and over the last decade, that’s changed for the first time,” said Nicolas Fulghum, senior data analyst at Ember.
The International Energy Agency suggested that emissions from energy systems could peak within the next few years based on current government policies. However, reaching peak emissions would not halt warming—it would merely slow the rate at which CO₂ accumulates in the atmosphere. To stop further warming, global emissions would need to reach net zero.