人們普遍認(rèn)為昆蟲是沒有思維活動(dòng)的低等動(dòng)物,。然而,，別看昆蟲的大腦小如針尖，它們的智力卻一點(diǎn)不遜于體形龐大的高等動(dòng)物,。英國(guó)科學(xué)家最新研究發(fā)現(xiàn),，昆蟲不僅有思維活動(dòng)、會(huì)數(shù)數(shù),、懂得分門別類,，甚至可以識(shí)別人臉。
來自英國(guó)瑪麗女王學(xué)院,、倫敦大學(xué)和劍橋大學(xué)的科學(xué)家用計(jì)算機(jī)模擬昆蟲大腦開展實(shí)驗(yàn),。實(shí)驗(yàn)結(jié)果顯示,，昆蟲的大腦容量足以使它們擁有思維活動(dòng)。實(shí)際上,，數(shù)百個(gè)神經(jīng)細(xì)胞就可以支持動(dòng)物數(shù)數(shù),；數(shù)千個(gè)神經(jīng)細(xì)胞就可以使動(dòng)物擁有思維活動(dòng)。
蜜蜂的大腦重量約為1毫克,，包含近100萬(wàn)個(gè)神經(jīng)細(xì)胞,。這些神經(jīng)細(xì)胞足可以使蜜蜂擁有思維活動(dòng)和數(shù)數(shù)能力。此外,，它們可以區(qū)分出各種動(dòng)物,，判斷圖形是否對(duì)稱。
美國(guó)西弗吉尼亞大學(xué)神經(jīng)生物學(xué)家薩拉·法里斯說,，蝗蟲,、螞蟻、蜜蜂等腦容量較小的昆蟲實(shí)際上都比人們想像中聰明得多,，能夠根據(jù)外部環(huán)境改變自己的行為習(xí)慣。
眾所周知,，螞蟻,、蜜蜂等昆蟲擁有復(fù)雜的社會(huì)系統(tǒng)；蜜蜂可以通過特殊的舞姿與同伴展開交流,。這些小昆蟲的行為甚至比一些脊椎動(dòng)物還復(fù)雜,。
希特卡說：“它們聰明絕頂?；蛟S,，我們只是不敢相信如此微小的大腦竟能完成如此復(fù)雜的行為。它們的大腦雖然小,，但做這些事情已經(jīng)足夠,。”
“問題是，既然這些昆蟲憑借如此微小的大腦就可以做這些事情,，那么對(duì)腦容量大的動(dòng)物而言,，體積大的大腦又有什么用處呢，”希特卡提出并解決了這個(gè)問題,，“更大并不意味著更好,。有時(shí)候事實(shí)與人們想像的恰恰相反。”
他解釋說：“我們知道,，身材決定動(dòng)物的腦容量,，但腦容量并不決定動(dòng)物可以做出哪些行為。體積大的大腦并不一定復(fù)雜,，可能只是相同神經(jīng)元的無(wú)限重復(fù),。它能記住更多圖像和聲音,，但并沒有增加功能的復(fù)雜性。在計(jì)算機(jī)模擬實(shí)驗(yàn)中,，體積大的大腦意味著更大的硬盤驅(qū)動(dòng)器,，而不是更好的處理器。”
鯨魚大腦可重達(dá)9千克,，包含約2000億個(gè)神經(jīng)細(xì)胞,；人類大腦重量通常在1.25千克至1.45千克之間，包含約850億個(gè)神經(jīng)細(xì)胞,；蜜蜂大腦重量約為1毫克,，包含近100萬(wàn)個(gè)神經(jīng)細(xì)胞。
希特卡說,，龐大的腦容量可以提高行為的準(zhǔn)確性,，使動(dòng)物擁有更加發(fā)達(dá)的感官，例如視覺和聽覺,。此外,，體型大的動(dòng)物可能只是需要更多腦細(xì)胞去支配身體。（生物谷Bioon.com）
生物谷推薦原始出處：
Current Biology,17 November 2009 doi:10.1016/j.cub.2009.08.023
Are Bigger Brains Better?
Lars Chittka1, and Jeremy Niven2
1 Queen Mary University of London, Research Centre for Psychology, School of Biological and Chemical Sciences, Mile End Road, London E1 4NS, UK
2 University of Cambridge, Department of Zoology, Downing Street, Cambridge CB2 3EJ, UK
Attempts to relate brain size to behaviour and cognition have rarely integrated information from insects with that from vertebrates. Many insects, however, demonstrate that highly differentiated motor repertoires, extensive social structures and cognition are possible with very small brains, emphasising that we need to understand the neural circuits, not just the size of brain regions, which underlie these feats. Neural network analyses show that cognitive features found in insects, such as numerosity, attention and categorisation-like processes, may require only very limited neuron numbers. Thus, brain size may have less of a relationship with behavioural repertoire and cognitive capacity than generally assumed, prompting the question of what large brains are for. Larger brains are, at least partly, a consequence of larger neurons that are necessary in large animals due to basic biophysical constraints. They also contain greater replication of neuronal circuits, adding precision to sensory processes, detail to perception, more parallel processing and enlarged storage capacity. Yet, these advantages are unlikely to produce the qualitative shifts in behaviour that are often assumed to accompany increased brain size. Instead, modularity and interconnectivity may be more important.
