Williams Adrian C, Hill Lisa J
Department of Neurology, University Hospitals Birmingham NHS Foundation Trust, Birmingham, UK.
School of Biomedical Sciences, Institute of Clinical Sciences, University of Birmingham, Birmingham, UK.
Int J Tryptophan Res. 2019 Jun 19;12:1178646919855944. doi: 10.1177/1178646919855944. eCollection 2019.
Meat and nicotinamide acquisition was a defining force during the 2-million-year evolution of the big brains necessary for, anatomically modern, to survive. Our next move was down the food chain during the Mesolithic 'broad spectrum', then horticultural, followed by the Neolithic agricultural revolutions and progressively lower average 'doses' of nicotinamide. We speculate that a fertility crisis and population bottleneck around 40 000 years ago, at the time of the Last Glacial Maximum, was overcome by (but not the ) by concerted dietary change plus profertility genes and intense sexual selection culminating in behaviourally modern . Increased reliance on the 'de novo' synthesis of nicotinamide from tryptophan conditioned the immune system to welcome symbionts, such as TB (that excrete nicotinamide), and to increase tolerance of the foetus and thereby fertility. The trade-offs during the warmer Holocene were physical and mental stunting and more infectious diseases and population booms and busts. Higher nicotinamide exposure could be responsible for recent demographic and epidemiological transitions to lower fertility and higher longevity, but with more degenerative and auto-immune disease.
在解剖学上现代人类得以生存所必需的大脑两百万年的进化过程中，获取肉类和烟酰胺是一种决定性力量。在中石器时代的“广谱”时期，我们接下来转向食物链下游，之后是园艺时期，再接着是新石器时代的农业革命，烟酰胺的平均“摄入量”逐渐降低。我们推测，大约4万年前末次盛冰期时的生育危机和人口瓶颈，是通过协同的饮食变化、促生育基因和强烈的性选择（但不是通过[此处原文有误，推测应为“不是通过……而是通过”之类表述]）得以克服的，最终形成行为上现代的人类。对从色氨酸“从头”合成烟酰胺的日益依赖，使免疫系统能够接纳共生体，比如结核杆菌（它能分泌烟酰胺），并提高对胎儿的耐受性，从而提高生育能力。在温暖的全新世期间的权衡取舍是身体和智力发育迟缓、更多传染病以及人口的兴衰起伏。更高的烟酰胺暴露可能是近期人口结构和流行病学转变为低生育率和高寿命的原因，但同时伴有更多退行性和自身免疫性疾病。
