When we use a computer programming language, we are directing an abstract machine to interpret and manipulate data to get a result that we want.  We have all the knowledge we need about the machine because we conceived and designed it ourselves.<p>DNA is like a programming language for a biological computer, a living cell.  However, we don&#x27;t know nearly everything there is to know about a living cell.  We can&#x27;t predict its mechanisms.  There is no debugger.  The compiler didn&#x27;t come with an instruction manual.  The code bootstraps itself into its own machine and runs in an environment we can&#x27;t predict.  And the syntax has been obfuscated and optimized by a genetic algorithm that&#x27;s been running in parallel on quintillions of cores for a billion years.<p>Because the code executes on an unknown machine in an unpredictable physical environment, many features we might expect to see in a programming language are missing.  This might be what he meant by &quot;shallow&quot;.