Word: brained
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Dates: during 2000-2009
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What this ought to mean is that social animals have bigger brains than solitary ones, and the research has indeed suggested as much. A landmark 2007 paper called "Social Brain Hypothesis," published in the journal Evolution, showed that increased sociality was linked to steadily bigger brains in at least three orders of mammals: primates like us, carnivores like lions and ungulates like zebras and bison. (Watch TIME's video "Chimps & People: Dangerous Bedfellows...
Finarelli and Flynn did not study as broad a collection of animals as the authors of the earlier paper. They studied just one order, the carnivores, but they did so in depth. Sampling both living terrestrial carnivores and the fossils of extinct ones, they analyzed overall brain volume relative to body mass in fully 289 species. They also factored in what is known (or, in the case of fossils, theorized) about each species' social behavior. What they got was a surprising mix of findings. (See pictures of 10 species near extinction...
...general, carnivore brains followed one of several developmental arcs, some growing larger over time, some fluctuating up and down, some remaining relatively steady, some actually growing smaller. Most of the larger members of the feliform suborder - which includes large cats as well as hyenas and mongooses - pretty much stuck with the brain size they had from the start. The extinct bear-dog - a family of animals that died out 9 million years ago and were, as their name suggests, related to both bears and dogs - actually became more pea-brained over time. Common dogs, like humans, have enjoyed a comparatively...
What doesn't seem to track, however, is a consistent connection between these measures and the complexity of the animals' communities. "The universality of the social-brain hypothesis does not apply," says Finarelli...
Doctors still don't know what causes vestibular dysfunction or why it is so common. The vestibular system in the inner ear is made up of three semicircular canals and two otolith organs that continuously send messages to the brain about the head's rotation and motion as well as its orientation relative to gravity. Humans keep their balance using the vestibular system's signals, along with visual cues and touch sensations. When the inner-ear signaling process is disrupted, it directly affects a person's ability to maintain equilibrium...