49 Essays on Infinite Lifespans   João Pedro de Magalhães possible to reverse the genetic program of adult cells back to youthfulness by cloning techniques. [3] There is no law of nature to prevent us from instructing the cells of an adult human being to avoid aging by, for example, changing the genetic program at a DNA or epigenetic level. Since, like any disease, aging results from disrupted or unbalanced molecules it is also theoretically possible to reverse age-related changes by precise molecular and cellular therapies. [4;5] To  slow,  stop,  and  reverse  human  aging  we  will  likely require three steps: (1) remove damaged or inactive molecules and cells; (2) restore function to several molecules and cells by repair or replacement; (3) modify the genetic program to prevent the aging process from repeating itself. These inter- ventions  are  what  we  will  most  likely  need  to  balance  the body’s chemical reactions and molecular structural changes that become disrupted as we age. Yet how can we transmit such massive amounts of information to our body? INSTRUCTING THE HUMAN BODY Most pharmaceutical interventions are composed of chem- icals or biomolecules usually transmitting a single signal to the body: acetyl-salicylic acid, also known as aspirin, the anti- depressantfluxetine,hormones,etc.Novelfindingsinchemical genetics may allow the development of small molecules that target specific genes and pathways. [6] Yet the simple instruc- tions these deliver to our cells are unlikely to be enough to cure aging. Assuming that aging is, to a large degree, programmed in our genes [7], curing aging will require technologies that are not yet available. To give an example, there are dozens of inherited diseases originating in single genes for which there is no cure simply because we lack the technologies to turn on and off human genes. Since curing aging will require us