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Brain-wide Mammalian Decision Making Map, Ant Xenoority Reproduction, and Smartphone Hemorrhoids Study
Three science stories explored
In this episode of World, the Universe and Us from New Scientist, hosts Rowan Hooper and Penny Sarche discuss three distinct science stories. First, scientists publish the first complete brain-wide activity map of a mammal, revealing that decision making is distributed across many brain regions rather than localized, with implications for intuition and artificial consciousness. Second, entomologists report a remarkable ant reproductive strategy in which Iberian harvester ant queens lay eggs that become workers from a hybrid species and males of another species, a system termed xenoarity. Third, a small study connects smartphone use on the toilet with a higher risk of hemorrhoids, driven by longer time spent sitting and reduced pelvic floor support. The discussion links experimental design to broader questions about consciousness, evolution, and health.
Introduction
World, the Universe and Us brings three science stories from neuroscience, entomology and health, examining how new research challenges our assumptions about brains, reproduction, and everyday behavior.
Distributed decision making in the brain
Researchers conducted a large-scale collaboration across 12 labs to map activity from more than 650,000 neurons across a mouse brain as the animal performed a decision-making task. The task involved driving a striped target toward a center using a Lego steering wheel, with bias introduced by varying target contrast and trial blocks that favored one side over another. The result is the first brain-wide map of a complex behavior in a mammal, showing that decision making emerges from widespread communication across cortical and subcortical regions rather than from a few specialized areas. Early signals related to the decision were present even before the action, suggesting anticipation and a potential neural basis for intuition.
Consciousness, perception, and intuition
Experts discussed what consciousness means in this context. The study uses an intermediate definition focused on perception and reportability of a stimulus, rather than a philosophical notion of qualia. The findings raise questions about how cognition and movement are linked and what this might mean for developing artificial consciousness or better AI systems that emulate human decision making and perception.
Ant xenoarity: birth of aliens in an ant colony
In a surprising finding, Iberian harvester ants queens were observed producing workers that are hybrids with a different species, while the males produced by the queen are clones of the other species. The term xenoarity is introduced to describe this reproductive strategy in which the queen can lay eggs that become her own species’ offspring and also males from another species. The researchers traced mitochondrial DNA to the Iberican mother but found paternal genomes from the other species in the cloned male offspring. An extensive lab effort with 50 colonies over two years finally produced the required males to study their development. The discovery challenges assumptions about species barriers and points to a broader diversity of reproductive strategies in ants, with potential links to evolutionary biology and hybrid vigor.
Health note: smartphones and hemorrhoids
A linked study investigated whether smartphone use on the toilet increases hemorrhoid risk. Involving 125 participants awaiting colonoscopy, the study found that smartphone users spent more than five minutes on the toilet about five times more often than those not using phones. About two-thirds admitted to taking their phones to the bathroom. Importantly, the study did not find a strong link between straining and hemorrhoids, and other data suggest different associations. The proposed mechanism is that sitting on a toilet without pelvic floor support increases pressure in a key region, contributing to hemorrhoid risk. The researchers plan further work, including studying college students, to better isolate causation from correlation.
Implications and outlook
Experts discuss the broader implications for autism and schizophrenia research using mouse models, the potential relevance to consciousness research and AI, and practical health guidance stemming from the hemorrhoids study. The conversation also highlights the importance of collaborative and cross-disciplinary approaches in tackling complex biological questions and the evolving understanding of how evolution shapes cognition and reproduction.