This paper discusses the role of ecological systems and manmade physical infrastructure in provisioning services and human welfare. The first section discusses concepts of human welfare, human development, environmental security, quality of life, and ecosystem services. The author discusses how these concepts interact and integrates them to lay the foundation for further analysis. The paper reviews ecosystems and manmade infrastructure characteristics, as well as characteristics of their services. Further analysis reveals a general trend that manmade infrastructure substitutes ecosystem services in line with human development and technological progress. The author draws on some examples, which show ecosystem deterioration and inability to provide as many services as needed, dense consumption of infrastructure services in urban areas, and an emerging trend of artificial development of ecosystems to provide services of a better quality. The author thinks that comparative analysis of efficiency in services provision by ecosystems and infrastructure remains an important open research question.