ScienceDaily (Mar. 24, 2010) — Who's in charge? Who's got food? The brain region responsible for learning and memory is bigger in social bee queens who may have to address these questions than in solitary queens, report scientists at the Smithsonian Tropical Research Institute who study the tropical sweat bee species, Megalopta genalis in Panama. Their study is the first comparison of the brain sizes of social and non-social individuals of the same species. "The idea is that to maintain power and control in groups you need more information, so the bigger the group, the bigger individuals' brains need to be." says William Wcislo, Smithsonian staff scientist. "This is called the 'social brain hypothesis' also known as the 'Machiavelli hypothesis'." Previous studies compared brain sizes among social and non-social animals. However, different animal species may be different in so many ways that it's hard to make a direct connection between brain size and sociality. This study focuses on a single species in which some individuals are social and others are not. Megalopta bees exhibit a very primitive form of social behavior. Either a bee lives as a solitary queen, going out from her nest to forage for her own food or she can be a social queen--a stay-at-home mom. In that case, one of her daughters goes out to forage for her, so she rarely leaves the nest. Her daughter's ovaries don't develop, and she never leaves her mother to become a queen. "It was surprising to us that even thought the social queens don't have bigger brains overall, the fact that the area associated with learning and memory--the mushroom body-- was more developed in the social queens than in the solitary bees suggesting that social interactions are cognitively challenging, as predicted by the social brain hypothesis," said Adam Smith, postdoctoral fellow at STRI. "It's interesting to see that a characteristic like brain development changes so immediately, even with this simple mother-daughter division of labor." This study was done in STRI's new insect neurobiology laboratory, built to take advantage of diverse tropical insect groups with a variety of brain sizes to understand how brain size and behavior are related. These results, supported by Panama's National Secretariat for Science, Technology & Innovation, the Smithsonian Institution's Scholarly Studies Program, and the F.H. Levinson Fund are published online in the journal Proceedings of the Royal Society B. -- 原始網址： http://www.sciencedaily.com/releases/2010/03/100323212247.htm 蠻有趣的研究。 研究大意是Megalopta bees這種蜜蜂的女王蜂， 有一種是較為孤僻，另一種有較好得社交能力。 前者需要自己覓食，後者只要待在家裡等人家傳便便。 研究發現後者負責學習與記憶的腦容量較大。 是第一個在同物種之間，比較有社會性和沒社會性所造成腦容量差異的研究。 --

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