A major transition occurred during the first part of the Holocene: Humans entered a new adaptive niche by settling in favored environment and by domesticating species of plants and animals. From primary "centers of domestication", it is frequently considered that Neolithic farmers - as well as the idea of agriculture - spread to some "marginal" areas. Simultaneously, a main event of demographic expansion occurred, and it seems that this process impacted at various degrees both the human health and the human biology. Focusing on the analysis of the remains of more than 500 humans discovered in several regions of the Balkans (the Danube Gorges; the territory of the Central Balkans; the Great Pannonian Plain), and covering the Mesolithic (9500 BC - 6200 BC) and the Early Neolithic (6200 - 5500 BC), we discuss this usual perception of Neolithization as "an episode of ecological niche colonization" by addressing simple questions: who were the earliest famers in the Central Balkans? what were they looking like? and what about their living conditions? To better understand the behavioral mechanisms and the biological outcomes of the Neolithization process, we tackle the issues of migrations, diet, health and bodily adaptations by synthesizing data coming from recent analyses: physical anthropology, 3D morphometric, stable isotopes, aDNA. Taken as a whole, results suggest that Neolithization should be understood as a complex phenomenon combining both foragers innovations and farmers migrations, foragers and farmers interactions in some specific spots, local behavioral adaptations - particularly in term of subsistence patterns - to environmental conditions, a global health decline and a specific pattern of body adaptation to the new sedentary lifestyle. By offering a glimpse into the life of the first farming communities this study also emphasizes the contributions of Human Behavioral Ecology to our understanding of the mechanisms of bio-cultural adaptations.