Why should we engage in Developmental Biology?
Developmental Biology enquires about the fundamental processes that underpin the fertilisation of an egg cell and its step-by-step transformation into the fascinating complexity of a whole organism (Box 1).
At first sight, Developmental Biology could be viewed as an academic discipline driven by mere curiosity and, hence, to be of little relevance to the big challenges of population health or sustainability. On the contrary, Developmental Biology – shoulder-to-shoulder with Physiology – is arguably the most important biological discipline we have. Here we will explain this statement.
(1) Developmental defects in humans are very abundant (Box 2). Therefore, studying the underlying mechanisms and causes, as an essential remit of Developmental Biology, addresses the key challenge of population health. Sustainability of food resources is another major global challenge, and Developmental Biology can provide key strategies to improving crop and plant cultivation (see Mathan et al., 2016, Development 143, 3283ff. — LINK; further arguments will follow).
(2) Developmental Biology (like Physiology) is asking fundamental questions at the level of whole organisms, organs or tissues (Box 3). Notably, this is the level at which diseases become manifest. For this reason, Developmental Biology has been, and continues to be, most effective in delivering explanations for diseases or medically relevant processes including infertility, neonatal death, birth defects (e.g. deformation, body growth abnormalities, developmental brain disorders, blindness, deafness), cancer, wound healing, tissue regeneration (regenerative medicine including stem cell biology), etc.
(3) By asking fundamental questions at the level of organisms, organs and tissues, Developmental Biology-related research is a generator of new ideas and concepts (Box 4). These concepts essentially underpin the modern biomedical sciences and include cell signalling, tissue and body patterning, growth regulation, cell migration or morphogenesis; they form the basis for contemporary research into stem cells, cancer, wound healing, regeneration or ageing.
(4) Developmental Biology is exciting and powerful because it reaches across the different levels of biological complexity and explanation; phenomena at the level of organisms, organs or tissues can ultimately be understood only by tracing them back to events at the level of genes and cells. Consequently, Developmental Biology embraces disciplines such as genetics, molecular biology, (stem) cell biology, biochemistry, biophysics as well as evolutionary biology.
(5) Developmental Biology capitalises on the principle of evolutionary conservation of genes, mechanisms and concepts. Thus, it makes use of suitable model organisms, down to experimentally and genetically amenable invertebrates, which provide an efficient and powerful strategy to generate new ideas, concepts and understanding – before validating these in higher organisms including their medical application in humans (LINK). This discovery pipeline has been a central driver for the enormous contributions that Developmental Biology has made and continues to make to the biomedical sciences.
 In the sense used here, Physiology comprises disciplines like immunology or functional studies in the field of neurobiology
 Arguments and examples given so far concern studies of animal development, and those for plant development will follow soon