Calcium isotopes: a new tool to study the spread of dairying in prehistory

这个项目是应用一种分析骨骼的新方法，以了解牛奶和乳制品是如何在西方人类饮食中变得如此重要的。我们的食物经历了两次“革命”，一次是大约10,000年前开始的农业发明，另一次是大约100年前开始的工业化规模的食品生产。牛奶及其产品仍然是我们饮食中非常重要的一部分，也是我们钙的主要来源，但这只适用于史前时期开发的人和地区（在欧洲，印度和非洲部分地区，但不是，例如在中国，美洲或大洋洲）。因此，我们关注的是新石器时代，这是农业在欧洲发现和传播的文化时代。在新石器时代，已经有一些证据表明乳品业存在（来自陶器遗骸和动物骨骼），但我们不知道它在营养或经济上的重要性。我们确实知道，随着农业的发展，新石器时代的人口增长迅速，导致了社会变革和城镇的兴起;我们还知道，牛奶消费在生物学上的重要性足以让欧洲人在婴儿期后通过基因选择消化乳糖的能力。我们的方法依赖于测量自然界中发现的钙同位素的丰度比。当钙在食物链中流动时，其独特的同位素比例可以用作示踪剂。我们最近发现，牛奶中的钙与当地其他饮食来源的钙（主要来自植物）有很小但明显不同的同位素比;我们对少量考古骨骼的研究结果证实，这种差异出现在新石器时代和后来的人类骨骼中，这些骨骼似乎很可能是乳制品，但不是早期的骨骼。下一步是更广泛地测试该方法，了解其优势和局限性，并学习如何最好地将其应用于量化史前时期乳品业对人类饮食和营养的影响。然后，我们可以在几个网站上对牛奶消费进行适当的研究，并将其与其他类型的饮食信息（例如蛋白质消费类型）联系起来。我们还想研究将钙同位素测量应用于这项主要研究之外的相关问题的潜力，例如了解哺乳和断奶的时间（该方法适用于母乳和养殖动物乳汁），因为这也可以告诉我们对人口增长的影响。一个令人兴奋的前景是，它可能适用于研究非洲早期人类的发展。其他计划包括看看这种方法是否适用于火化的骨头，因为这些是某些时期的主要遗骸。

This project is to apply a new way of analysing bone, in order to learn how milk, and dairying generally, became so important in Western human diet. Our food has been profoundly changed by two 'revolutions'; the invention of agriculture starting about 10,000 years ago, and of industrial scale food production, starting about 100 years ago. Milk and its products remains a very important part of our diet, and also provides our major source of calcium, but this is true only for the people and areas where it was developed in prehistoric times (in Europe, India, and parts of Africa, but not, e.g. in China, America, or Oceania). So we are focussing on the Neolithic period, the cultural epoch of the discovery and spread of agriculture in Europe. Some evidence already exists for dairying during the Neolithic (from pottery remains and from animal bones), but we do not know how nutritionally or economically important it was or became. We do know that with agriculture, the Neolithic saw great demographic growth, leading to social change and the rise of towns; and we also know that milk consumption was biologically important enough for Europeans to become genetically selected for the ability to digest lactose after infancy. Our method depends on measuring the abundance ratio of the calcium isotopes found in nature. As calcium flows through food chains, its distinctive isotope ratio can be used as a tracer. We have very recently shown that calcium in milk has a small but clearly different isotope ratio from other local dietary sources of calcium (mainly from plants); and our results on a small number of archaeological bones confirms that this difference shows up in Neolithic and later human bones where dairying seems likely, but not in earlier bones. The next step is to test the method very much more widely, understand its strengths and limitations, and learn how best to apply it to quantifying how dairying impacted on human diet and nutrition during prehistory. We then can make a proper study of milk consumption on several sites, and relate this to other types of dietary information from them (e.g. of types of protein consumption). We also want to investigate the potential of applying calcium isotope measurements beyond this main study, to such related issues as learning about the timing of nursing and weaning (the method applies to taking in maternal milk as well as farmed animal milk), as this also can tell us about the influences for human population growth. An exciting prospect is that it might be applicable to studying the development of Early Man in Africa . Other plans include seeing if the method works for cremated bone, as these are the main remains at some periods.