Extended Family

The mirror changed how we see ourselves. Now it’s changing our relationship with the rest of the animal kingdom.

Chimpanzee Mindy during a mirror self-recognition study conducted at the University of Southwestern Louisiana, 1992.
Courtesy Daniel Povinelli

THE CLEANER WRASSE charged toward the unknown fish, ready for attack. The stranger met her head-on. When she retreated, the stranger did too. In due time, she began darting, flipping upside down, and “dancing.” Eventually, she approached more slowly, turning her blue body sidewise, then sank, all the time watching.

What appeared to be a stranger was, in fact, her reflection peering back. Days after the first encounter, biologist Masanori Kohda placed his small research subject in a solution of eugenol, an anesthetic made from clove oil, and injected brown dye under the skin of her throat—a spot she couldn’t see directly. When, later, the wrasse again looked in the mirror, she swam to the bottom of her tank and began to scrape her marked scales against a rock. In nearby tanks, other fish that had been similarly marked did the same.

Kohda and his colleagues concluded that the fish had recognized their reflections, a claim that sparked an uproar when the team from Osaka City University released the findings in 2019.

The study made the cleaner wrasse the latest to join an expanding and controversial pool of animals reported to share a capacity once thought uniquely human. Great apes, dolphins, elephants, certain birds, manta rays, and, most contentiously, ants had all reportedly passed the mirror mark test, the standard gauge of self-awareness in animals since 1970.

The test itself is appealingly straightforward. Mark an animal somewhere it can see only with the aid of a mirror. If the animal then touches or investigates the mark on its own body, rather than on the mirror’s surface, it has recognized itself.

But recognition, scientists had long held, required a self-concept onto which the reflected image could be mapped. And that faculty was widely believed to be absent in most animals. They might experience color, pain, and pleasure, the thinking went, but without any sense of the self having the experience. They simply didn’t have the brains for it.

A cleaner wrasse in a research tank at Osaka City University, 2022.
Courtesy of Masanori Kohda

After the fateful 2019 study, however, the wrasse went on to pass multiple variations of the mirror mark test, accumulating evidence that now surpasses that for any other nonhuman animal.

Many researchers who had previously accepted the mirror test as the standard measure of self-awareness now began to look at it askance. The tiny fish had unwittingly shaken faith in a hypothesis the test’s creator had defended for half a century and whose root reached back further still: that self-awareness had developed just once in the animal kingdom.

Can printed ‘skin’ help to heal burns without scars?

Inks created with a patient’s own cells might one day help the body regrow tissues

Cells suspended in a water-based gel make up the “ink” in this 3D printer.
Source: WAKE FOREST INSTITUTE FOR REGENERATIVE MEDICINE

Ahand touches a scalding hot plate, sharp pain erupts and immediately, the body gets to work. Damaged cells send out distress signals; immune cells rush in. As inflammation subsides, a coordinated repair process begins. Eventually, collagen fibers aligned in tight parallel rows will replace much of the damaged tissue. The wound heals, but it does not resemble normal skin.

For a small burn or cut, a scar is a small price to pay for rapid healing that mitigates the risk of infection. But in larger burn wounds, scarring can be devastating.

Each year, 11 million people require hospital care for burns. Long after the wounds have healed, scarring can cause complications. Unlike the random, basket-weave pattern that makes normal skin flexible and resilient, scar tissue tightens as it heals and, once mature, grows more slowly than surrounding skin. This can hinder movement and, in children with extensive burns, interfere with normal growth and development. Severe scars often lack hair follicles, sweat glands and nerve endings, reducing the ability to experience touch and to regulate body temperature.

Normal skin contains collagen fibers that grow in a random basket-weave pattern shown here, while in scar tissue collagen fibers typically grow parallel to each other.
Source: STEVE GSCHMEISSNER / SCIENCE SOURCE

Scientists have long tried to develop ways to nudge the body to build healthy tissue instead of defaulting to emergency repair. In recent years, 3D bioprinting technology has emerged as one of the most promising approaches. By depositing patients’ own, pre-cultured skin cells suspended in an ink-like gel, these printers can create personalized skin substitutes, kickstarting the regeneration process. While it is early days, the technology is coming closer to clinical reality.

The key is accessing the body’s ability to rebuild, says wound healing researcher Johan Junker of Linköping University in Sweden. Our bodies, he says, “have been practicing this for millions of years, and we do it constantly, because our skin and every tissue in our body, more or less, always turns over. So why not just provide as good a set of building blocks as we can and then let nature do its thing?”

A Game of Cat and Mouse

A predator stalks Marion Island, and it weighs less than an ounce. Scientists are racing to stop it.

A wandering albatross and chick on Marion Island, 2023.
Source: Anton Wolfaardt/Mouse-Free Marion

At around nine months old, wandering albatross chicks leave their nests and take to the skies for the first time. Five years may pass before they again set foot on solid ground.

The young albatrosses navigate the Southern Ocean with a specialized sense of smell, locating squid and other prey up to 12 miles away. Their ability to hear infrasound may help guide their flight paths: the ocean’s low-frequency growls can travel thousands of miles, announcing large crashing waves and accompanying strong winds. Wanderers circumnavigate Antarctica two to three times a year on these winds, covering roughly 75,000 miles. By weaving between fast and slow layers, they stay aloft with barely a wingbeat.

Over the course of a 50-year lifespan, one may travel 5.3 million miles—the equivalent of 11 trips to the moon and back. But the drive to mate means that, from the age of about 10 onward, every other year adult albatrosses will navigate back to the pinpricks of land where they were born to reunite with their mates and raise a single chick. For many of the world’s wandering albatrosses, that place is Marion Island.

Located halfway between South Africa and Antarctica, Marion Island is not a stereotypical island paradise: it is windswept, cold, and constantly wet. The island is the summit of a huge underwater shield volcano rising 3 miles from the seabed. Marion’s Mascarin Peak coughed up gas and lava stones as recently as 2004. Usually, though, the island’s slopes are dusted with snow. Further down, where the albatrosses nest, marshy plains ripple with cushions, ferns, and other low-lying plants that can survive the Roaring Forties, the notorious westerly winds. To the northeast, Marion’s sister island, the tiny, cliff-edged Prince Edward Island, is visible on the horizon.

Despite—or because of—their desolation, these islands have long been the breeding sites of millions of rare seabirds: parades of penguins, fleets of burrowing petrels, and, of course, rookeries of wandering albatrosses. Then, in the early 19th century, humans disembarked, bringing with them an unlikely predator.

A king penguin colony on Marion Island, 1972.
Valdon R. Smith/Antarctic Legacy of South Africa

Some 200 years after its accidental arrival, the tiny house mouse has discovered what cats and men had long known: for all their aptitude at sea, pelagic birds make for easy prey. In 2019, photographer Thomas Peschak visited Marion Island to document the increasingly brazen mouse attacks. “In this landscape of black and green and grey, there is this red that pops out at you all of a sudden,” he recounted on the National Geographic podcast Overheard. “You come around this boulder, and you are literally looking at a bird that has been scalped.”

Since Peschak’s visit, bird casualties have mounted. If left uncontrolled, experts predict the mice could drive 18 of the islands’ 28 bird species to local extinction, some within the next three decades. That would wipe out a third of the global breeding population of wandering albatrosses and white-chinned petrels. Over time, the island itself would become ecologically unrecognizable. And so scientists and conservationists have hatched a plan to save the seabirds and restore Marion’s imperiled ecosystem.

Inspired by past eradication programs, South Africa’s Mouse-Free Marion Project aims to rid the island of mice once and for all. Standing in its way are turbulent sub-Antarctic weather conditions, 30,000 hectares of craggy mountains, boot-sucking bogs, and the harsh reality that success is guaranteed only if every last mouse is killed.

Achieving lasting remission for HIV

People infected with HIV must take antiretroviral drugs for life. But promising trials using engineered antibodies suggest that ‘functional cures’ may be in reach.

A digital illustration of an HIV-infected T cell. Once infected, the immune cell is hijacked by the virus to produce and release many new viral particles before dying. As more T-cells are destroyed, the immune system is progressively weakened.

Source: KATERYNA KON / SHUTTERSTOCK

Around the world, some 40 million people are living with HIV. And though progress in treatment means the infection isn’t the death sentence it once was, researchers have never been able to bring about a cure. Instead, HIV-positive people must take a cocktail of antiretroviral drugs for the rest of their lives.

But in 2025, researchers reported a breakthrough that suggests that a “functional” cure for HIV — a way to keep HIV under control long-term without constant treatment — may indeed be possible. In two independent trials using infusions of engineered antibodies, some participants remained healthy without taking antiretrovirals, long after the interventions ended.

In one of the trials — the FRESH trial, led by virologist Thumbi Ndung’u of the University of KwaZulu-Natal and the Africa Health Research Institute in South Africa — four of 20 participants maintained undetectable levels of HIV for a median of 1.5 years without taking antiretrovirals. In the other, the RIO trial set in the United Kingdom and Denmark and led by Sarah Fidler, a clinical doctor and HIV research expert at Imperial College London, six of 34 HIV-positive participants have maintained viral control for at least two years.

These landmark proof-of-concept trials show that the immune system can be harnessed to fight HIV. Researchers are now looking to conduct larger, more representative trials to see whether antibodies can be optimized to work for more people.

“I do think that this kind of treatment has the opportunity to really shift the dial,” Fidler says, “because they are long-acting drugs” — with effects that can persist even after they’re no longer in the body. “So far, we haven’t seen anything that works like that.”

People with HIV can live long, healthy lives if they take antiretrovirals. But their lifespans are still generally shorter than those of people without the virus. And for many, daily pills or even the newer, bimonthly injections present significant financial, practical and social challenges, including stigma. “Probably for the last about 15 or 20 years, there’s been this real push to go, ‘How can we do better?’” says Fidler.