Developmental biology is poised to discover altogether new principles in biology in the 21st century.

In the 20th century, developmental biology spearheaded a revolution in our understanding of complex biological problems. Its success rests in great part on a truly unique approach that has recruited a diversity of systems and research organisms rather than focusing on isolated cells or molecules, while also employing a wide variety of technological and intellectual approaches. But what will developmental biology contribute to this century? Advances in technology and instrumentation are presently moving at neck-breaking speed and herald the advent of an age of technological wonders in which previously inaccessible biology is now tangibly within our grasps. For instance, single-cell RNAseq has revealed novel, transient cell states in both stem and differentiated cells that are specified by defined changes in gene expression frequency during regeneration. Additionally, genome-wide epigenetic analyses combined with gene editing and transgenic methodologies have identified the existence of regeneration responsive enhancers in adult vertebrate tissues. These circumstances combined with our discipline's diversity of experimental and intellectual approaches offer unimaginable opportunities for developmental biologists not only to discover new biology but also to reveal entirely new principles of biology.