Borries Carola, Lu Amy, Ossi-Lupo Kerry, Larney Eileen, Koenig Andreas
Department of Anthropology, Stony Brook University, Stony Brook, NY; Interdepartmental Doctoral Program in Anthropological Sciences, Stony Brook University, Stony Brook, NY.
Am J Phys Anthropol. 2014 Jun;154(2):291-301. doi: 10.1002/ajpa.22511. Epub 2014 Mar 11.
In primates and other mammals, weaning is an equivocal concept, as is reflected in the numerous ways it is measured: a) first intake of solid food, b) conflict over access to the nipple, c) ability to survive without mother, d) maternal resumption of cycling, or e) the cessation of nipple contact. The lack of a consistent definition means that weaning age, although it falls between gestation (fetal growth) and age at first reproduction (most energy diverted from growth), is currently not a reliable life history variable capturing offspring independence. Using data for wild Phayre's leaf monkeys (Trachypithecus phayrei crepusculus) at Phu Khieo Wildlife Sanctuary, Thailand (51 offspring, four groups), we asked whether the end of nipple contact indicates offspring independence as measured by survival to 3 years. To establish a baseline for the onset of independence, we assessed the youngest age at which individuals were orphaned (15-17 months) but then survived to 3 years. Next we determined that offspring age at last nipple contact (19.0 months) was comparable to two other independently calculated measures: offspring age at mother's first postpartum ovulation (11.5 months), and age at mother's re-conception (15.6 months). Using these separate "starting points," we arrived at similar ages for nipple contact cessation (18.4 and 19.2 months, respectively). Overall, in wild (but not in provisioned) Asian colobines, age at last nipple contact was allometrically related to adult female body mass, supporting its designation as a life history variable. Future comparisons need to show if this holds for other taxa.
在灵长类动物和其他哺乳动物中，断奶是一个模棱两可的概念，这一点体现在众多衡量断奶的方式中：a）首次摄入固体食物，b）争夺乳头的冲突，c）在没有母亲的情况下生存的能力，d）母亲恢复排卵周期，或e）停止乳头接触。缺乏一致的定义意味着断奶年龄虽然介于妊娠期（胎儿生长）和首次繁殖年龄（大部分能量从生长转移）之间，但目前并非一个可靠的生活史变量来衡量后代的独立性。利用泰国普基奥野生动物保护区野生菲氏叶猴（Trachypithecus phayrei crepusculus）的数据（51只后代，四个群体），我们研究了停止乳头接触是否表明后代达到了以活到3岁来衡量的独立性。为了确定独立开始的基线，我们评估了个体成为孤儿（15 - 17个月）但随后活到3岁的最小年龄。接下来我们确定后代最后一次乳头接触时的年龄（19.0个月）与另外两个独立计算的指标相当：母亲产后首次排卵时后代的年龄（11.5个月），以及母亲再次受孕时的年龄（15.6个月）。使用这些不同的“起始点”，我们得出了停止乳头接触的相似年龄（分别为18.4个月和19.2个月）。总体而言，在野生（而非人工喂养）的亚洲叶猴中，最后一次乳头接触时的年龄与成年雌性体重呈异速生长关系，这支持了将其指定为一个生活史变量。未来的比较需要表明这是否适用于其他分类群。
