摘要：2017年5月17日，*學(xué)術(shù)期刊《Science》旗下《Science Advances》雜志上在線發(fā)表了澳大利亞格里菲斯大學(xué)Tanya M. Smith研究員的一篇研究論文，論文通過(guò)研究猩猩的牙齒，揭示了猩猩長(zhǎng)時(shí)間吸奶的情況。

2017年5月17日，*學(xué)術(shù)期刊《Science》旗下《Science Advances》雜志上在線發(fā)表了澳大利亞格里菲斯大學(xué)Tanya M. Smith研究員的一篇研究論文，論文通過(guò)研究猩猩的牙齒，揭示了猩猩長(zhǎng)時(shí)間吸奶的情況。

研究人員研發(fā)了一種方法，它能對(duì)靈長(zhǎng)類中特別難以捉摸的喂奶方式進(jìn)行了追蹤，他們用它發(fā)現(xiàn)，某些發(fā)育未全的猩猩吸奶時(shí)間長(zhǎng)達(dá)8年或以上--這超過(guò)了其它非人類靈長(zhǎng)動(dòng)物中所報(bào)告的zui長(zhǎng)斷奶年齡。這些發(fā)現(xiàn)對(duì)管理生殖率緩慢低下的瀕危靈長(zhǎng)動(dòng)物(如蘇門答臘和婆羅洲猩猩)頗具意義，因?yàn)槿藗儗?duì)這些動(dòng)物的生活史了解甚少。對(duì)野生猩猩的斷奶年齡幾無(wú)所知，但有些科學(xué)家提出，它們?cè)诔錾蟮臄嗄趟钑r(shí)間會(huì)持續(xù)6年之久(或更長(zhǎng))。鋇是一種非必需元素，它在體內(nèi)的代謝通路常常類似于鈣;當(dāng)鋇隨母乳一同被攝取后，它很容易進(jìn)入像牙齒等骨骼組織之中。因此，對(duì)這一元素進(jìn)行測(cè)試會(huì)是一種提示嬰兒或發(fā)育不成熟幼兒是否還在吸奶的有效方法。

在本研究中，Tanya M. Smith和同事對(duì)4個(gè)猩猩從其出生頭一年便開(kāi)始分析其牙齒中的鋇含量，從而提供了*如此詳盡的野猩猩吸奶史。他們發(fā)現(xiàn)，在出生*年后，牙齒中的鋇濃度通常會(huì)降低，但在其8歲和9歲時(shí)鋇會(huì)一直存在于牙齒之中。此外，作者發(fā)現(xiàn)，牙齒中鋇濃度會(huì)年復(fù)一年地出現(xiàn)高低周期性變化。他們指出，牙齒中鋇濃度下降時(shí)期可能對(duì)應(yīng)于水果獲取量大的時(shí)候，這時(shí)，正在生長(zhǎng)的猩猩對(duì)奶汁的依賴度較小，而牙齒中鋇濃度的增加則是因?yàn)槟虜z取量增加的結(jié)果，它發(fā)生在食物時(shí)，那時(shí)正在長(zhǎng)身體的猩猩需要多吸奶才能維持生長(zhǎng)。對(duì)猩猩的喂奶和斷奶模式有所了解是有價(jià)值的，因?yàn)橐^察生活在樹(shù)上且不顯眼的猩猩的吸奶情況總是具有挑戰(zhàn)性的。

原文摘要：Nursing behavior is notoriously difficult to study in arboreal primates, particularly when offspring suckle inconspicuously in nests. Orangutans have the most prolonged nursing period of any mammal, with the cessation of suckling (weaning) estimated to occur at 6 to 8 years of age in the wild. Milk consumption is hypothesized to be relatively constant over this period, but direct evidence is limited. We previously demonstrated that trace element analysis of bioavailable elements from milk, such as barium, provides accurate estimates of early-life diet transitions and developmental stress when coupled with growth lines in the teeth of humans and nonhuman primates. We provide the first detailed nursing histories of wild, unprovisioned orangutans (Pongo abelii and Pongo pygmaeus) using chemical and histological analyses. Laser ablation inductively coupled plasma mass spectrometry was used to determine barium distributions across the teeth of four wild-shot individuals aged from postnatal biological rhythms. Barium levels rose during the first year of life in all individuals and began to decline shortly after, consistent with behavioral observations of intensive nursing followed by solid food supplementation. Subsequent barium levels show large sustained fluctuations on an approximay annual basis. These patterns appear to be due to cycles of varying milk consumption, continuing until death in an 8.8-year-old Sumatran individual. A female Bornean orangutan ceased suckling at 8.1 years of age. These individuals exceed the maximum weaning age reported for any nonhuman primate. Orangutan nursing may reflect cycles of infant demand that relate to fluctuating resource availability.