New Study Has Scientists Reevaluating Relative Brain Size and Mammalian Intelligence 1
An anonymous reader quotes a report from Phys.Org: Scientists from Stony Brook University and the Max Planck Institute of Animal Behavior have pieced together a timeline of how brain and body size evolved in mammals over the last 150 million years. The findings, published in Science Advances, show that brain size relative to body size -- long considered an indicator of animal intelligence -- has not followed a stable scale over evolutionary time. The international team of 22 scientists, including biologists, evolutionary statisticians, and anthropologists, compared the brain mass of 1400 living and extinct mammals. For the 107 fossils examined -- among them ancient whales and the most ancient Old World monkey skull ever found -- they used endocranial volume data from skulls instead of brain mass data. The brain measurements were then analyzed along with body size to compare the scale of brain size to body size over deep evolutionary time.
According to the study, "big-brained" humans, dolphins, and elephants, for example, attained their proportions in different ways. Elephants increased in body size, but surprisingly, even more in brain size. Dolphins, on the other hand, generally decreased their body size while increasing brain size. Great apes showed a wide variety of body sizes, with a general trend towards increases in brain and body size. In comparison, ancestral hominins, which represent the human line, showed a relative decrease in body size and increase in brain size compared to great apes. The authors say that these complex patterns urge a re-evaluation of the deeply rooted paradigm that comparing brain size to body size for any species provides a measure of the species' intelligence. The study has been published in the journal Science Advances.
According to the study, "big-brained" humans, dolphins, and elephants, for example, attained their proportions in different ways. Elephants increased in body size, but surprisingly, even more in brain size. Dolphins, on the other hand, generally decreased their body size while increasing brain size. Great apes showed a wide variety of body sizes, with a general trend towards increases in brain and body size. In comparison, ancestral hominins, which represent the human line, showed a relative decrease in body size and increase in brain size compared to great apes. The authors say that these complex patterns urge a re-evaluation of the deeply rooted paradigm that comparing brain size to body size for any species provides a measure of the species' intelligence. The study has been published in the journal Science Advances.