The intense relationship between mother and child - at times harmonious, at other times rife with conflict - has repercussions for several levels of biological organisation, from individual development through to species diversification. My recent research has focused on developing theoretical models of how mothers and experiences in early life can impact health and behaviour in later life, and in subsequent generations. I am currently investigating the role of mothers in evolution using the tsetse fly as a model. More like mammals than most insects, female tsetse flies become pregnant, lactate to their young, and give birth to a larva even larger than the mother. The role of the tsetse fly as a vector of sleeping sickness means that its biology has been thoroughly studied, yet its potential as an evolutionary model of pregnancy has been underestimated. I will use a combined approach of field and laboratory observations, theoretical models and comparative analyses to investigate two main questions. First, do mothers strategically adjust their investment in their young during harsh conditions and what are the consequences for their offspring? Second, what role does mother-offspring conflict, particularly intense in viviparous organisms such as tsetse flies, play in the divergence of populations and the generation of new species?