Ben Stanger (W. W. Norton)
鈥淲HERE do babies come from?鈥� isn鈥檛 just a question some parents dread hearing from their children, but also one that has perplexed philosophers since the time of Ancient Greece. For anyone today, armed with the grasp of basic biology that was lacking in our forebears, it is hard to imagine how they could have even framed the problem. Once you know something, it is hard to unknow it.
To get around that conceptual obstacle, Ben Stanger, a developmental biologist at the University of Pennsylvania, posed the question to his 6-year-old daughter, Sarah. She thought that the answer was obvious: a baby starts out as a 鈥渢iny tiny tiny baby鈥�.
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Interestingly, this idea of preformationism 鈥� that we develop from miniature, squished-up versions of our later selves 鈥� was popular for many centuries. The 17th-century Dutch microscopist Nicolaas Hartsoeker even produced a now iconic sketch of how a preformed human might be squashed into every sperm, with an outsized head tucked into diminutive knees.
Preformationism died out in the 1800s, partly thanks to a key scientific leap: cell theory, the principle that the cell is the basic unit of life, much as atoms are the building blocks of matter. Babies start life from a single cell 鈥� as do nearly all multicellular organisms, from meerkats to marigolds to mushrooms.
But that discovery only ended up creating a deeper mystery. As Stanger puts it: 鈥淗ow does all the information necessary to make something so complex get compressed into something so apparently simple? How do the trillions of cells generated from this peculiar unit know what to become and where to go?鈥�
These are the questions that Stanger explores in his book From One Cell: A journey into life鈥檚 origins and the future of medicine. There, he covers not just our current understanding of embryology, but also the past and future of this science.
This turns out to be a fascinating tour of the major landmarks in the history of biology, including the discovery of genes, the structure of DNA and the concept of messenger RNA (mRNA) 鈥� the intracellular mediator between DNA and ribosomes, the cell鈥檚 protein-making machinery.
The idea that nothing in biology makes sense except in the light of evolution has long been commonplace. But Stanger makes the case that little about the structure and functioning of adult life forms makes sense except in light of their embryonic development.
For instance, many medical conditions such as cancer, autoimmune diseases and neurodegenerative conditions are better understood thanks to a knowledge of their embryological underpinnings. As Stanger explains: 鈥淭he same processes nature uses to construct the body are all too often the means of its undoing.鈥�
Embryology is also a potential source of new kinds of medicine, most obviously thanks to the nascent science of stem cells, which have the ability to multiply almost indefinitely and to turn into different bodily tissues.
The early embryo can be thought of as a ball of stem cells, and this is, in fact, where these wonder cells were discovered. If we can take control of stem cells and manipulate them in the lab, we could grow new tissues and organs to help people with a wide range of medical conditions.
Stanger has a gift for original metaphors. For instance, cells 鈥渒now鈥� their position in the embryo by detecting the levels of certain chemicals, whose concentration drops off with greater distance from their source 鈥� a process he compares to the way we can tell how far we are from a mobile phone tower based on the number of bars of signal that we receive.
And then there is the impressive power of stem cells to give rise to cells of specialised tissues while also duplicating themselves, which Stanger likens to the trick of someone who is granted three wishes using their last request to ask for another three wishes.
We are a long way from understanding all the mysteries of embryonic development: in fact, you might say that we have only taken our first baby steps down this road. But in this book, the original origin story, Stanger makes a convincing case that it is a journey worth taking.
