A small number of people alive today are actually chimeras: Conceived a fraternal twin but left alone in utero when their counterpart dies, they absorb their twin’s body through the placenta and are born with a complement of foreign cells with different genomes. In spite of all that, nothing we have ever seen in the natural world of would-be twins compares to the monkey just engineered by researchers at the Chinese Academy of Sciences. Born breathing and kept alive for 10 days, it’s highly chimeric, with up to 90 percent genetically distinct cells in some of its tissues. As the first living non-human primate chimera engineered in the laboratory (it’s been done in mice and rats before), it has major implications for basic and translational research, the researchers write. Cell

That’s not nail polish, and those aren’t colored contacts! It’s green fluorescence from foreign cells containing GFP proteins excited by light in the three-day-old chimeric monkey. Cell/Cao et al/CC-BY-SA

How much detail do people remember of their own birth or from their earliest years of childhood? For most of us, nothing at all. Our earliest, sketchiest memories tend to form well past our infant years—beginning around age two or three. Everything before then we forget, a phenomenon known as “infantile amnesia,” which has also been documented in other mammals like mice and rats. Now researchers at Trinity College Dublin have shown (in mice at least) that neurodivergent brain states linked to autism and sparked by maternal immune responses to infections during pregnancy can prevent infantile amnesia. Their study also shows that memories normally forgotten by mice after infancy can be permanently reinstated by tweaking brain cells with optogenetics. “Infantile amnesia is a reversible process,” they write. Science Advances

A curious combination of three lowly bacteria (Bacillus mucilaginosus, Bacillus megaterium, and Pseudomonas fluorescens) could be sufficient to “science the hell” out of the challenge of growing live crops on the moon, researchers at China Agricultural University in Beijing report. Using a simple sample of simulated lunar soil, they showed this combination of microbes boosted concentrations of phosphorus, a major plant nutrient, and promoted the growth of Nicotiana benthamiana—a close plant cousin of tobacco, chosen because it’s a good proxy for agricultural crops. It’s hard to say who will be more thrilled: Matt Damon or R.J. Reynolds. Communications Biology

Tobacco seedlings growing in the lunar regolith simulant. Yitong Xia

The danger with human language is that it allows us to construct narratives that are compelling even when they’re false. That could be the case with social media addiction, which some experts argue is not an addiction at all, preferring to call it “problematic use” rather than addiction. Don’t tell that to the attorneys general of almost every U.S. state, who joined a lawsuit against Meta last month premised on the notion that social media is addictive and claiming the company knowingly designed features into its apps that exploit our addictive personalities. Now researchers at Durham University in the United Kingdom are calling into question the related concept of digital detox—the idea that taking a vacation from your device is good for your mental health. Their research analyzing 51 moderate-to-heavy social media users aged 19–25 who digitally detoxed for a week suggests it may not improve wellbeing because it decreases positive emotions as well as negative ones. PLOS One

Researchers at New York University and an international collaboration known as the Synthetic Yeast Genome (Sc2.0) consortium have successfully combined seven different synthetic DNA chromosomes based on brewer’s yeast (Saccharomyces cerevisiae) into a single, super-synthetic yeast cell. The new strain has more than 50 percent synthetic DNA, survives in the laboratory, and appears to replicate normally—similar to wild-type strains of brewer’s yeast. “We decided that it was important to produce something that was very heavily modified from nature’s design,” senior author Jef Boeke at NYU Langone Health said in a press statement. “Our overarching aim was to build a yeast that can teach us new biology.” Cell

Scanning electron micrograph of the new synthetic strain of yeast with ~31% synthetic DNA. It displays normal morphology and budding behavior. Cell/Zhao et al

One of the ’omes we love best is the brain connectome, those maps revealing how all the neurons in a brain are hard-wired to each other, connected at their synapses. However there are lots of connections made between neurons that are controlled not by synapses but by neuropeptides. Now researchers at Cambridge University have developed a map of these so-called “wireless” connections in the C. elegans worm. Their map reveals 31,479 neuropeptide interactions between the worm’s 302 neurons—something they say will help scientists shed light on human emotions, the control of mental states, eating disorders, OCD, and PTSD. Neuron

In a surprising finding that at first seems hard to reconcile with the cliché image of the dulled, checked-out stoner of old, researchers at the National Autonomous University of Mexico found that people who regularly use marijuana actually tend to have more empathy and a greater understanding of others’ emotions. That conclusion is based on psychological assessments of 85 habitual cannabis users and 51 non-users as well as MRI brain imaging scans taken of a subset of both. The scans show the brain’s anterior cingulate region has stronger connectivity with brain regions related to sensing the emotional states of others, the researchers report, which has implications for therapy—suggesting marijuana could eventually treat everything from social anxiety to sociopathic behavior. Journal of Neuroscience Research