How xenobots reshape our understanding of genetics

Where in the embryo does the person reside? Morphogenesis – the formation of the body from an embryo – once seemed so mystifying that scholars presumed the body must somehow already exist in tiny form at conception. In the 17th century, the Dutch microscopist Nicolaas Hartsoeker illustrated this'preformationist' theory by drawing a foetal homunculus tucked into the head of a sperm. This idea finds modern expression in the notion that the body plan is encoded in our DNA. But the more we come to understand how cells produce shape and form, the more inadequate the idea of a genomic blueprint looks, too. What cells follow is not a blueprint; if they can be considered programmed at all, it's not with a plan of what to make, but with a set of rules to guide construction. One implication is that humans and other complex organisms are not the unique result of cells' behaviour, but only one of many possible outcomes.