Strong, Fertile Hands Flickr/Nationaal Archief
強壯，能生的雙手 來源：Flickr/Nationaal Archief

Recent research tells us that the sound of our voices betrays clues about our age, whether we’re menstruating (if we’re female), our sexual behavior and our physical strength. All of these factors, evolutionary psychologists say, are indicators of her reproductive potential. Voice pitch, in particular, has been associated with indirect measures of reproductive fitness in both men and women—men with “masculine” low-pitched voices and women with “feminine” high-pitched voices tend to be rated more attractive and have more sexual partners, for example, and they have higher levels of sex hormones (testosterone in men and estrogen in women).
最新的研究顯示，我們聲音的音色會出賣有關我們身體的蛛絲馬迹，包括年齡、我們是否在經期、性行爲和體力。所有這些，根據進化論心理學家的說法，是女性生育能力的體現。特別是聲調，可以間接測量男性和女性的生育能力，比如，有“磁性”的男低音和“嬌柔”的女高音被認爲更有吸引力，有更多性伴侶，他們有更高水平的性荷爾蒙（對男性來說是睾酮，女性是雌性激素）。

But there’s been very little research so far on whether the way we speak actually relates to higher fertility, in part because most of this work is done on college students who haven’t started having children yet. In 2007, researchers finally left campus and travelled to Tanzania to study how voice pitch relates to fertility. The Harvard-lead team found that among the indigenous Hadza people, men with low-pitched voices reported having more offspring. This study was a step in the right direction, but it was limited by the fact that without a paternity test, men can’t be sure that the children they’re raising are their biological offspring. In fact, depending on where in the world you look, between 2 and 30 percent of men are—unbeknownst to them—raising children that they didn’t sire.
但到目前爲止關于說話的聲音是否與更高生育能力相關還沒有很多研究，部分是由于這項研究中大部分的研究對象是還沒有生孩子的大學學生。在2007年，研究人員終于離開了校園到坦桑尼亞去研究聲調與生育能力有多大的關聯性。這支由哈佛大學領導的研究團隊發現，在土著的哈扎人中，聲調低的男子會有更多的后代。這個研究是在正確的方向上邁出了一步，但研究也因爲沒有進行親子鑒定的事實而受到限制，這些男子不能確信他們所撫養的孩子就是他們生物學上的后代。事實上，取決于你看到的是世界的哪一個地方，百分之二到百分之三十的男子是在不知情的狀況下撫養不是他們所生的孩子。

Outside of the rare maternity-ward mix-up, this isn’t a problem for women, so an international team of researchers decided to shore up the Hadza study findings by looking at voice pitch and female fertility rates in another indigenous African population, the Himba of northwest Namibia. This group has very little contact with western society, which means they don’t use contraceptionand they still live off the land (more later on why this indigenous lifestyle was particularly important in this study).
排除非常少見的産科病房孩子抱錯的狀況，這對于女人來說並不是一個問題。因此一組國際研究人員決定在另外一個非洲土著人群，納米比亞西北部的辛巴族中，研究音調和女性生育能力的關系，來支撐他們對哈扎人的研究結果。這個族群與西方社會罕有聯系，這意味著他們不采取避孕措施，而且他們仍然靠土地爲生（越到后來越顯出爲什麽這種原始的生活方式在這項研究中特別重要）。

Husband-and-wife team Piotr and Agnieszka Sorokowscy, psychologists at the University of Wroclaw in Poland, recorded 54 Himba women counting from one to 10 in Herero, their native language. Each woman’s average voice pitch was measured across her vocal recording. Cross-referencing voice data with number of progeny confirmed the 2007 study linking pitch with fertility: Women with higher voices had more children and grandchildren. “The model predicts that by increasing voice pitch by 40 hertz (say from 180 to 220, a noticeable change in voice pitch for women), reproductive success goes up by 1, which is equivalent to having one child or two grandchildren,” explains co-lead author Nathan Pipitone, a psychologist at Adams State University in Colorado.
夫妻團隊皮奧特（Piotr）和阿格涅斯卡·斯洛科斯基（Agnieszka Sorokowscy）都是波蘭弗羅茨瓦夫大學的心理學家，他們錄下了54位辛巴族的女性用他們的母語赫雷羅語從數字一數到十。每位女性的平均音調都通過她的聲音錄制進行衡量。交叉引用的聲音數據和子孫數目確認了2007年的研究成果，把聲調和生育能力聯系了起來：聲調高的女性有更多的兒子和孫子。“根據這個模型推知，聲調增加40赫茲（比如從180到220，對于女性的音調來說是一個顯著的變化）生育能力就上升1，這意味著大約會多1個兒子或2個孫子，”聯合作者南森·皮皮托內 （Nathan Pipitone），一個在科羅拉多的亞當斯州立大學的心理學家如此解釋。

The common factor between female vocal pitch and fertility is estrogen, says Pipitone, who has previously studied voices as fertility cues. In addition to having higher-pitched voices, women with high estrogen levels have been shown to experience more regular periods, better rates of ovulation (since ovulating women don’t necessarily release an egg every month), healthier weights and body mass indexes, lower body-fat percentages and more favorable uterine and cervical environments for pregnancy. “We think that this association goes hand-in-hand: Traits that are linked to reproductive potential are also seen as attractive. High voice pitch is a consequence of higher estrogen levels—and men find this attractive,” Pipitone explains.
關聯女性音調和生育能力的共同的因素是雌性激素，皮皮托內說，他之前一直在把聲音作爲生育能力的線索進行研究。除了有較高的聲調，有較高雌性激素的女性表現出更有規律的經期，更高的排卵率（因爲排卵期的女人不一定每個月排出一個卵），更健康的體重和身體素質指數，更低的身體脂肪比例和更適宜懷孕的子宮和子宮頸環境。“我們認爲這種相關性非常緊密：與生育能力相關的這些特性也被視爲有魅力的特征。高音調是高水平雌性激素的結果——男人認爲這很有吸引力，”皮皮托內解釋說。

The male attraction to high estrogen levels is subconscious, he says—“at the level of our nervous system”—and passed down through countless generations of successful reproduction. “Throughout human evolutionary history, males who found higher-pitched voices more attractive probably left more descendants, since high-pitched women had higher levels of estrogen and had more offspring.” Over eons, subconsciously favoring high-pitched voices became the norm for men. (That preference has been scientifically documented; the affinity for the low, sultry female voice portrayed in the media is something we need to learn more about, Pipitone says.)
男性被高雌性激素所吸引是下意識的，他說，“存在于我們的神經系統中”——並經由無數代的成功的繁衍而傳遞下來。“在整個人類的進化曆史上，那些認爲高音調聲音更有吸引力的男性可能留下了更多的后代，既然高音調的女性有更高水平的雌性激素，生下了更多的后代。”數十億年來，潛意識中喜歡高音調聲音就變成了男性的標準。(這個喜好已經被科學的記錄下來；至于媒體描述的對低沈，悶悶的女性聲音的偏愛是我們需要更詳細去了解的現象，皮皮托內解釋說）

The team also looked at another proxy of reproductive success in the Himba, handgrip strength (HGS), which is considered a sign of phenotypic quality (i.e. health) in both modern and indigenous populations. On average, individuals with good HGS have healthier weights at birth, and they live longer and have lower risk of cognitive diseases in old age. In men, good HGS has been associated with higher testosterone levels, lean muscle mass and facial attractiveness. “If an individual's phenotype (traits expressed in the body from genes) is robust, that person has a healthy immune system to fight infection and can do strenuous work under harsh environments, all the while producing healthy offspring,” Pipitone says.
這個團隊同時研究了辛巴族的另外一種生育能力的表現，手握力（HGS），這在現代社會和土著人群都被認爲是表型品質（也就是健康）的表現。平均說來，有很強握力的人通常出生時體重更健康，他們會活得更長壽，年老時得認知疾病的風險更低。對于男性來說，強的手握力意味著高水平的雄性激素，瘦的肌肉質量和容貌有吸引力。“如果一個人的表型（也就是身體中由基因所表現出來的特性）很健康，那麽這個人會有健康的免疫系統，可以抵抗感染，能在惡劣的環境下從事體力勞動，始終能生出健康的后代，”皮皮托內說。

Because HGS is associated with health, the researchers hypothesized that higher strength would predict better reproductive success. The so-called Grandmother Hypothesis, they believed, could explain the association. This idea suggests that living past their childbearing years is an adaptive trait that allows women to help provide for their grandchildren; strong grandmothers will be able to help more, and should therefore have more grandchildren.
因爲手握力與健康息息相關，研究者們假定握力越強預示著生育能力越強。所謂的“祖母假設”，他們相信，可以解釋這種關聯性。這個理論認爲，女性活過她們的生育年齡是一種自適應的的特征，這讓她們可以幫忙供養她們的孫輩；強壯的祖母們能夠幫助供養更多的孫輩，所以她們會有更多的孫輩孩子。

Team member Jeremy Atkinson, a psychologist at SUNY-Albany, found that women with higher HGS had more children and “genetic vectors,” the combination of children and grandchildren. When looking at grandchildren alone, they didn’t find the association, which Pipitone believes could be explained by the smaller number of grandchildren in the sample. The findings therefore only indirectly support the so-called Grandmother Hypothesis.
這個團隊中的研究成員杰瑞米·阿肯森（Jeremy Atkinson），一位紐約州立大學阿爾巴尼校區的心理學家，發現有較強手握力的女性有更多的孩子和“遺傳載體”，兒子和孫子的組合。當單獨研究孫子輩的時候，他們沒有發現這種關聯，皮皮托內認爲這是因爲樣本中的孫輩孩子數量較少的原因。研究結果由此只能間接支持所謂的“祖母假設”。

Still, the finding that stronger women have more children confirms that HGS is valid proxy of reproductive success, and it refutes the common assumption that strength is more important for reproductive success in men than in women, especially in an indigenous population, in which the ability to survive depends on physical labor. Among the Himba, men herd livestock while women take care of the day-to-day business of living. “Looking at what these women do is incredible,” Pipitone says. “Walking miles for water, having to dig up tubers in crappy soil, all with children strapped to them.”
盡管如此，研究結果——強壯的女性有更多孩子——確認了手握力是一個生育能力的有效表現，這也駁斥了一個常見的想法，即，力量對于男性的生育能力比女性更重要，特別是在土著族群中，他們生存的能力依靠體力勞動。在辛巴族中，男性蓄養家畜而女性照料日常生活。“看看這些女人干的，真是令人難以置信，”皮皮托內說，“行走數英里取水，在難墾的土壤上挖掘塊莖，而且還背著她們的孩子！”

“Totally ‘dainty’ females like we see today in modern society have feminine characteristics and most men find these traits attractive, but getting back to how humans have lived overevolutionary history probably tells a slightly different story,” he continues. “A combination of strength and femininity was probably more valuable among early humans.”
”像我們今天現代社會中看到的非常“優雅美麗”的女性有很女性化的特征，大多數男性覺得這些特征很有吸引力，但是回顧人類生活的進化曆史，會講述一個稍微不同的故事，“他繼續說，“力量和女性特征的結合也許在早期人類的生活中更有價值。”

Jennifer Abbasi is a science and health writer and editor living in Portland, OR. Follow Jen on Twitter (@jenabbasi) and email her at [email protected].
詹妮弗·阿巴斯（Jennifer Abbasi）是一個科技和健康作家與編輯，生活在俄勒岡州的波特蘭。你可以在Twitter上關注她 （@jenabbasi) 也可以給她寫信，地址是 [email protected].