"Human milk is universally considered as the best nutrition for the new born infant and recent research has revealed that, in addition to its nutritional value, it represents a constant supply of commensal, non-pathogenic and potential probiotic bacteria to the infant gastrointestinal tract. Milk is also a rich source of human milk oligosaccharides (HMOs), which have been shown to interrupt the attachment of enteric pathogens to the intestinal mucosa and to act as prebiotic substrates within the infant intestine, where they can promote the growth of certain beneficial bacteria. Therefore human milk may strongly influence the composition of the new born intestinal microbiota, known to be closely related to survivorship. The rationale behind this multidisciplinary and cooperative project is that human milk composition may have evolved differentially under various environmental pressures. Thus, a single “normal” or healthy milk composition would not exist, but instead it would be conditioned by a combination of evolutionary and socio-ecological factors. The applicant will investigate how selected population-specific factors can contribute to variation of two main human milk components, i.e. HMOs and milk microbiota. In addition, this project will provide further insights on the consequences that these variations may pose to the infant fecal microbiota. To achieve these goals the applicant will use conventional HMOs determination methodologies and will develop a new high-throughput variant of traditional molecular fingerprinting methods, which will significantly improve the existing ability to characterize complex microbial communities. Finally, socioecological data will be collected and analyzed on the studied populations, in order to gain insight on the environmental and evolutionary factors conditioning milk variation. Results obtained will be of great value to the European scientific community and will influence the way “normal” human milk composition is regarded."