The 10 most intriguing science breakthroughs of 2023

Scientific evidence is pointing to obesity as a hormonal malfunction, as I wrote in December 2022. The malfunction can stem from a diet too high in sugar and refined starch, according to a recent study by endocrinologist David Ludwig of Harvard. Once controversial, the hormonal view is harder to deny now, since the new drugs work by mimicking the hormone GLP-1 (glucagon-like peptide).

Climate tipping points become clearer while there’s still time to act

Climate tipping points were also a big topic in 2023. These tipping points represent not just sudden changes, but the onset of reinforcing feedback loops. In the past, naturally occurring vicious cycles have turned our planet into “snowball Earth” or ushered in hot periods so extreme that more than 90% of all species went extinct.

Scientists warned many times this year of a looming feedback loop caused by humans. Researchers estimate that warming of just 1.5 C above pre-industrial levels could set off several global tipping points, including permafrost melt, burning of the Amazon rain forest and collapse of the Greenland and West Antarctic ice sheets.

Two 2023 studies also showed the slowing of a circulatory current in the Southern Ocean. These currents act like the planet’s beating heart, with cold polar waters drawing carbon, oxygen and heat downward and driving currents that connect all the planet’s oceans.

The slowing of that heartbeat might seem depressing, but there’s a glimmer of good news here: We’re still on the right side of all these potential tipping points, and the warnings have come while there’s still time to do something about it.

Physicists repeat a nuclear fusion feat
Over the summer, scientists said that they had liberated more energy from a peppercorn-sized capsule than they had beamed in with a set of lasers — a repeat of a feat they had first announced at the very end of 2022. As I wrote last summer, fusion is clean, the fuel is inexhaustible and cheap, and there’s no risk of a meltdown. The fact that humanity has finally captured the power source of the stars surely will go down in history.

The dark side is that these achievements used a facility whose primary purpose is the testing of weapons designed to kill millions of people. The clean energy hopes are secondary. The National Ignition Facility, located at Lawrence Livermore National Laboratory, is so embedded in the nuclear weapons industry that some physicists say we’d be better off investing in projects aimed exclusively at providing clean energy. A nuclear war would cause vastly more catastrophic climate change than we’re going to get from fossil fuel.

But the Livermore feat has given us a better understanding of the physics of fusion, and a surge in funding for fusion energy. Today, there are at least 30 startups working on nuclear fusion using billions of dollars in private money and government grants. Some would call them all long shots, but the need for clean energy calls for placing as many bets as possible.

Early arrival of humans in the Americas demands a rethink of history
Sometime in the prehistoric past, two adults and a child left a trail of footprints in the mud near what’s now White Sands, New Mexico. A new analysis of quartz grains and pollen show they took this walk between 21,000 to 23,000 years ago — thousands of years before humans were thought to have reached the Americas.

For years, the textbook story held that people first came to the Americas between 16,000 and 14,000 years ago, crossing a land bridge between Siberia and Alaska. The oldest established artifacts, from the Clovis site in New Mexico, date back 13,500 years. Over recent years, claims of earlier artifacts have been raised though nothing has been quite as carefully dated and undisputedly human as those footprints.

The new dates would mean people were already living in New Mexico during the peak of the last ice age. Figuring out how they arrived will require some new thinking. Researchers from Oxford have proposed that they got here by boat. If the footprint dates hold up, this or some other dramatically different story will become the new common knowledge.

A new telescope helps us see the universe when it was young
Astronomers estimate that our universe is about 13.7 billion years old, and because distant objects appear as they did long ago, astronomers have been able to see back to about the first billion years.

But that long-hidden first billion years was important. That’s when the stars and galaxies were lighting up and assembling themselves. In 2023 the James Webb Space Telescope started sending images from that formative time.

The JWST has shown us fragments of primitive galaxies, but to astrophysicist David Spergel, president of the Simons Foundation, the most interesting find from this era is the oldest supermassive black hole. It resides in a galaxy called UHZ1, which appears as it did 13.2 billion years ago — 470 million years after the Big Bang.

This black hole is comparable in mass to the whole rest of the galaxy combined, said Spergel. That’s surprising, since the black hole in the center of our galaxy constitutes just half a percent of the galaxy’s mass. The finding could help astronomers understand how supermassive black holes formed and their role in shaping the rest of the universe.

Giant gravitational waves rock the universe
In the spring of 2023, scientists from five distant parts of the globe announced the discovery of massive vibrations in space and time. The feat involved more than 20 years of precision observations of pulsars — burnt-out stars which emit beams of radio waves at a precise rhythm as they spin hundreds or even thousands of times a second.

Tiny deviations in the timing of those pulses revealed this long-sought background of gravitational waves. The scientists say the waves are being stirred up by supermassive black holes spiraling toward each other or perhaps more exotic phenomena — defects in the fabric of space known as cosmic strings.

Einstein first predicted gravitational waves would ripple space, but proof of their existence wasn’t announced until 2016. The 2023 discovery was of much longer waves cresting and falling over periods of years. Finding them took a combined effort from scientists in the US, Europe, China and Australia. Such collaboration is becoming more common as scientists take on ever more ambitious projects — ones too costly for individual countries to pull off alone.

A cure for sickle cell disease
For decades, medical research neglected sickle cell disease, though it caused severe pain and early death for thousands of people, mostly of African descent. But 2023 brought two new treatments that rely on extremely sophisticated gene alterations, including the very first FDA-approved treatment using the gene editing technique known as Crispr.

Sickle cell disease is caused by a genetic variant that produces abnormal hemoglobin — a protein in red blood cells. The cells become misshapen and can clog or inflame blood vessels. Patients could be cured with a bone marrow transplant, but only about 25% of people with sickle cell can find a matched donor. Both new therapies use different ways to alter the DNA in bone marrow cells restoring the ability to make normal hemoglobin.

These aren’t practical solutions yet for most of the world, let alone most of the 40,000 people in the US with severe symptoms — one therapy, known as Casgevy, costs more than $2 million, and the other, known as Lyfgenia, $3.1 million. (Despite the cost, one major insurer has already agreed to cover Lyfgenia.) But it’s a step in the right direction for a disease that’s gotten too little attention.

Reading the minds of the severely paralyzed
In May, scientists announced they’d learned to decode people’s thoughts from brain scans, with an AI system as interpreter. The findings, which I described in this column, could restore the ability to communicate in people who are so profoundly paralyzed they can’t speak or write.

This so-called locked-in syndrome happens for various reasons — especially strokes or neurological diseases. When the condition is temporary, people sometimes describe a harrowing ordeal — one man remembers being frozen in place while his wife and a doctor debated whether to remove life support and let him die.

In the new system, published in Nature Neuroscience, the researchers had volunteers lie in a brain scanner while listening to podcasts. The AI system analyzed connections between the brain scan patterns and the words. Eventually the AI could turn brain patterns into words. When the subject heard, “I don’t have my driver’s license yet,” the system read the brain to say, “She hasn’t even started learning how to drive.” The translation was imperfect but still eerily accurate. For those who find themselves trapped in frozen bodies, this could be a powerful tool restoring the ability to communicate.

ChatGPT learns to play doctor
In years of reporting, I’ve talked to doctors around the world about mind-boggling technological advances, but rarely have I heard so much astonishment and wonder in their voices as whey they talked this year about the feats of ChatGPT-4. Though an earlier version of ChatGPT debuted in late 2022, it was really in 2023 that we started to get a sense of what large language models could do.

ChatGPT can diagnose complex medical issues, ask for tests and work-ups, and even get a perfect score on most medical licensing exams. But there’s something alien about its reasoning. It won’t necessarily ace a test unless it’s told specifically to do so, said Andrew Beam, an assistant professor of biomedical informatics at Harvard. It performs better if you tell it to imitate the smartest person in the world.

There are risks to trusting AI too much in diagnosis or recommending treatments, but there’s also vast potential to help doctors become smarter, faster and better at what they do.

Intelligent life is found on Earth
A new study released in November toppled the myth that only humans can imagine the past and future, while animals live in the moment. Rats, it turns out can imagine and plan ahead. As I wrote in this column, the newest findings may explain observations of city rats bringing slices of pizza into subway cars where they can eat away from other hungry rats.

The last 10 years have brought a paradigm shift in how humanity sees other animals, with a wealth of findings showing that many kinds of creatures can think, reason and solve problems in a way once believed to be unique to humans. That now includes farm animals. One study showed pigs are empathetic enough to free trapped companions. Cows were potty trained — a finding that showed they have a body awareness also thought to be beyond them. Goats understand what it means when humans point at things.

Humans dream of finding intelligent life in the cosmos, but our experiences here on Earth show we’re not that good at recognizing it when it’s right in front of us.

Let’s hope 2024 brings another year of breakthroughs — including the discovery of some truths that have been hiding right under our noses.