Population genetic studies have clearly indicated that immunity and host defense are among the functions most frequently subject to natural selection, and increased our understanding of the biological relevance of the corresponding genes and their contribution to variable immune traits and diseases. Herein, we will focus on some recently studied forms of human adaptation to infectious agents, including hybridization with now-extinct hominins, such as Neanderthals and Denisovans, and admixture between modern human populations. These studies, which are partly enabled by the technological advances in the sequencing of DNA from ancient remains, provide new insight into the sources of immune response variation in contemporary humans, such as the recently reported link between Neanderthal heritage and susceptibility to severe COVID-19 disease. Furthermore, ancient DNA analyses, in both humans and pathogens, allow to measure the action of natural selection on immune genes across time and to reconstruct the impact of past epidemics on the evolution of human immunity.

群体遗传学研究清楚地表明，免疫和宿主防御是最常受自然选择影响的功能之一，并增加了我们对相应基因的生物学相关性及其对可变免疫特性和疾病的贡献的理解。在此，我们将关注一些最近研究的人类对传染源的适应形式，包括与现已灭绝的古人类（如尼安德特人和丹尼索瓦人）的杂交，以及现代人类种群之间的杂交。这些研究部分得益于古代遗骸 DNA 测序技术的进步，为当代人类免疫反应变异的来源提供了新的见解，例如最近报道的尼安德特人遗传与严重 COVID-19 易感性之间的联系疾病。