Two lost ancestors turn up in our DNA, and a dementia trial that worked

That lineage split off from our ancestors around 800,000 years ago, close to when Neanderthals and Denisovans diverged from each other. A second, even older population, dubbed the "super-archaic" ancestor, traces back some 1.8 million years and appears to have interbred with Denisovans in Eurasia over 200,000 years ago, before that Denisovan DNA made its way into us too. "We were actually able to find and map genomic locations in modern humans that are from this ghost lineage and show that this ghost ancestry is in all modern humans, not only in Africans," said Berkeley graduate student Yulin Zhang 5.

Beltre was one of 1,200 participants aged 60 to 77 in LatAm-FINGERS, the first trial testing a culturally adapted lifestyle intervention against cognitive decline in Latin America. Rather than treating dementia once it arrives, the trial went after the risk factors that raise the odds of it happening at all, pairing exercise programs with brain training against a control group that got only general health advice. The intervention group came out with statistically better thinking skills. It builds on the Lancet Commission's 2024 estimate that 14 modifiable factors, including smoking, social isolation, and inactivity, together account for 45% of dementia cases worldwide. "I felt that I wanted to move on to interventions to really show that if you do something, you can change the risk," said Dr. Miia Kivipelto of the Karolinska Institute, who has spent decades pushing this approach 18.

Studying clonal raider ants, whose brains hold about 60,000 cells compared to a mouse's roughly 100 million, Daniel Kronauer's team found two chemical signals that push ants toward either tending larvae or leaving the nest to forage, with the balance shifting as individual ants age. Those same neuromodulatory systems overlap with the ones mammals use for parental behavior, systems that originally regulated feeding and hunger. "Our work is a prime example of how evolution seldom invents things from scratch," Kronauer said. "Evolution takes what it has and works with that, sometimes in very surprising ways" 15.

The study, published in the Journal of Drug Issues, looked specifically at naturalistic use, meaning people making their own choices in everyday life rather than dosing under clinical supervision. "There has been a growing interest in psilocybin for therapeutic purposes, and previous clinical research has indicated it has potential benefits for improving mental health," said Anita Cservenka of Oregon State University, who led the study 36. Her team wanted to know whether that clinical promise showed up in the real world, among people who also drink one of the most widely used and riskiest substances on earth.

The turnaround came from treating poaching as organized crime rather than isolated incidents: a Special Anti-Poaching Task Force formed in 2021 paired forest and police intelligence, while drones, thermal imaging, and electronic surveillance backed up the guards on foot. Sandeep Kumar, a 1989-batch Indian Forest Service officer now serving as Assam's Principal Chief Conservator of Forests, helped lead the effort, alongside women forest guards known as the Van Durgas who patrol vulnerable stretches and gather intelligence from surrounding villages. The threat hasn't vanished entirely, one rhino was poached in 2023 and two in 2024, but 2025 was another zero-poaching year 119.

Researchers in China redesigned the structure so nearly the whole chip does useful work: a honeycomb lattice built from magnetic rods splits electromagnetic waves into distinct "valley" states, and the team arranged four versions of that pattern in a repeating cycle so each region carries its own signal while simultaneously blocking its neighbor's reverse-traveling waves. The result is four independent microwave signals traveling side by side through a single insulator-free chip, with no wasted space acting only as a barrier. The team describes it as "a design strategy for ultracompact topological photonic circuits, with potential for high-density integrated optics" 83.

Ursula K. Le Guin, taking up the question at the start of her sixties, argued that aging strips away a kind of beauty that was never really earned and replaces it with one that is: "For old people, beauty doesn't come free with the hormones, the way it does for the young. It has to do with bones. It has to do with who the person is" 132.