德國馬克斯·普朗克進(jìn)化人類學(xué)研究所的科學(xué)家近日在《英國皇家學(xué)會(huì)會(huì)志B輯：生物科學(xué)》（Proceedings of the Royal Society B：Biological Sciences）上發(fā)表了他們的最新研究成果：催產(chǎn)素與野生黑猩猩維護(hù)彼此合作關(guān)系密切相關(guān),。
會(huì)相互合作的動(dòng)物活得更久,，并且它們的后代有更好的生存機(jī)會(huì)。人們發(fā)現(xiàn),，在非人靈長類動(dòng)物和其它合作動(dòng)物中,，密集和持久的社會(huì)關(guān)系主要存在于相互有遺傳關(guān)系的動(dòng)物之間。但有時(shí)候,，這樣的合作也出現(xiàn)在相互之間沒有親屬關(guān)系或同一性別之間,。
在人類和其它合作的哺乳動(dòng)物中，神經(jīng)肽激素催產(chǎn)素（腦下垂體后葉荷爾蒙的一種）在促進(jìn)家庭成員和性伴侶之間的個(gè)人關(guān)系中起著關(guān)鍵作用,。因此,，馬克斯·普朗克進(jìn)化人類學(xué)研究所的凱瑟琳·克羅克福德、羅曼·維提希和同事對這一激素在野生黑猩猩之間合作關(guān)系中的作用進(jìn)行了研究,。
他們選擇了一群生活在烏干達(dá)布頓哥森林中的野生黑猩猩作為研究對象,。結(jié)果發(fā)現(xiàn)，催產(chǎn)素與黑猩猩維護(hù)合作關(guān)系密切相關(guān),。黑猩猩在與合作伙伴相互梳理毛發(fā)后,，其尿液中的催產(chǎn)素較高，這其中遺傳親屬關(guān)系或性興趣沒有起任何作用,。
科學(xué)家們通過塑料袋和樹葉收集了33個(gè)雄性和雌性成年黑猩猩的尿液樣本,，測量了這些動(dòng)物在互助梳理毛發(fā)前后的催產(chǎn)素含量。結(jié)果表明,，那些與合作伙伴進(jìn)行互助毛發(fā)梳理后的黑猩猩催產(chǎn)素水平特別高,，而這與兩個(gè)動(dòng)物之間是否是親屬?zèng)]有關(guān)系。反之,，同樣一只黑猩猩和群里沒有合作關(guān)系的黑猩猩進(jìn)行了毛發(fā)梳理,，或者根本就沒進(jìn)行毛發(fā)梳理，它的尿液中催產(chǎn)素水平就比較低,。此外,，研究表明，動(dòng)物的性別和年齡,、毛發(fā)梳理的時(shí)間以及其他因素并沒有顯著影響尿中催產(chǎn)素含量,。
克羅克福德說：“我們的研究結(jié)果顯示，催產(chǎn)素含量的增長與兩個(gè)因素的組合有關(guān),，互助毛發(fā)梳理和合作伙伴關(guān)系,。特別需要強(qiáng)調(diào)的是,，親屬和非親屬合作伙伴進(jìn)行互助毛發(fā)梳理后催產(chǎn)素含量一樣高。在黑猩猩中,，催產(chǎn)素似乎在維護(hù)合作關(guān)系上發(fā)揮了超越遺傳關(guān)系的關(guān)鍵作用,。”
維提希稱：“這是首個(gè)不抽取血液測量野生動(dòng)物催產(chǎn)素的研究。我們開發(fā)出一種方法,，可以檢測自然棲息地不同類型合作生活的野生哺乳動(dòng)物的行為對生理測量值的影響,。”通過新的方法，科學(xué)家們將來在實(shí)地調(diào)查研究中,，可對個(gè)別行為,，如合作或攻擊，在同一荷爾蒙水平上進(jìn)行相互比較,。（生物谷Bioon.com）
doi:10.1098/rspb.2012.2765
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Urinary oxytocin and social bonding in related and unrelated wild chimpanzees
C. Crockford1,2,3,†⇓, R. M. Wittig1,2,3,†⇓, K. Langergraber3,4, T. E. Ziegler5, K. Zuberbühler1,2,6 and T. Deschner3
Animals that maintain cooperative relationships show gains in longevity and offspring survival. However, little is known about the cognitive or hormonal mechanisms involved in cooperation. Indeed, there is little support for a main hypothesis that non-human animals have the cognitive capacities required for bookkeeping of cooperative exchanges. We tested an alternative hypothesis that cooperative relationships are facilitated by an endocrinological mechanism involving oxytocin, a hormone required for bonding in parental and sexual relationships across mammals. We measured urinary oxytocin after single bouts of grooming in wild chimpanzees. Oxytocin levels were higher after grooming with bond partners compared with non-bond partners or after no grooming, regardless of genetic relatedness or sexual interest. We ruled out other possible confounds, such as grooming duration, grooming direction or sampling regime issues, indicating that changes in oxytocin levels were mediated by social bond strength. Oxytocin, which is thought to act directly on neural reward and social memory systems, is likely to play a key role in keeping track of social interactions with multiple individuals over time. The evolutionary linkage of an ancestral hormonal system with complex social cognition may be the primary mechanism through which long-term cooperative relationships develop between both kin and non-kin in mammals.
