Nevertheless, there are significant morphological differences during early development, and to understand human developmental processes fully it is necessary at some point to study human material. At the moment human development is not well understood, partly because of a lack of biological material with which to work. Moreover, the completion of the Human Genome Project, the first draft of which is due next year, will open up many new avenues of research. Yet, while it will provide an inventory of all human genes, it will say little about their function. Studies of gene expression in early embryos will provide valuable clues to their function in this key period of human life.
Many clinical benefits are likely to arise from a better understanding of human development.
Currently, one in 30 babies is born with a major malformation. The developmental basis of some of these malformations is understood, but the causes of many remain unclear. Studying early human development, when most malformations arise, will be an important step towards understanding and, in the longer term, preventing abnormalities. Research on early embryos is beginning to explain how the developmental processes are affected by folic acid deficiency.