Editor's Note

Redefining What It Means to Be Human

Genomic science is getting eerily close to becoming a sci-fi thriller.

By Jeanette McCarthy, MPH, PhD

The British television series Humans takes place in a fictional present where synthetic human beings, “synths,” coexist alongside natural-born humans. In the show, the synths look just like humans, but they are actually androids. They are, in many respects, superior to humans. They have a full neural processor built into their brains, superhuman strength, lightning fast reflexes, an all-day battery, and no emotions to cloud their judgment. Moreover, they are completely subservient to their human masters. These mechanical maids can do everything from cooking, babysitting, driving, and cleaning (Sign me up!). They can perform skilled jobs and even offer companionship. Everything is fine until a few of the synths, which are revealed to be human-synth hybrids, go rogue.

A closed-door, invitation-only meeting of scientists in Boston earlier this year made me think synths are not that far off. These scientists, including Harvard genome scientist George Church, were discussing a proposed extension of the Human Genome Project (HGP) or HGP-read, the first sequence of the 3.2-billion-letter DNA code that provides instructions for making a human. The new project, dubbed HGP-write, wants to leverage that information to create a completely synthetic human genome in a cell line within the next 10 years.

“While not as useful around the house as the android synths in the television series, the synthetic cells will help scientists interpret the biological function of the human genome with applications for human health.”

While not as useful around the house as the android synths in the television series, the synthetic cells will help scientists interpret the biological function of the human genome, with applications for human health. Yet the prospect of synthesizing human life leaves me unsettled. Although initially confined to a petri dish, these efforts naturally take my mind uncomfortably close to the prospect of human synths wandering the streets in my neighborhood.

Imagine a menu where you could select the features of your made-to-order synth.

How would you engineer the perfect human from their genome? Would you tinker with the genes for autism, knowing that those very same genes are related to typical variation in social behavior? How would you determine which skin color to give it? Would you choose the lighter skin color, knowing that it increases risk of melanoma? Would you select a gene variant that protects from infectious disease, knowing that this same variant increases the risk of a potentially life-threatening genetic disease?

We’ve spent more time thinking about disease-causing mutations that we would want to cut out of our genomes, but relatively little about what desirable genetic traits we would choose, if we could, and if we should. Regarding synthetic life, there is no shortage of material to keep ethicists busy for years to come.

“We’ve spent more time thinking about disease-causing mutations that we would want to cut out of our genomes, but relatively little about which desirable genetic traits we would choose, if we could, and if we should.”

More immediately, genomics is slowly changing our definitions of diseases, the concept of race, and the distinction between self and non-self. The lines are becoming blurred. For example, where does one disease end and the other start? In this issue of Genome, we learn about genomic research in schizophrenia, a mental health disorder that, at the genetic level, shares more determinants than expected with depression, autism, and general social behaviors. Another example is the constellation of microorganisms that live in and on our bodies. Are they autonomous, or an integral part of what keeps us alive and healthy? In “Rite of Passage,” on page 28, you’ll read about how C-section babies are being swabbed at birth with vaginal microbes from their mothers to give them the best shot at a healthy life. Or consider the question of whether the races are truly separate. If they aren’t, why do we keep treating them that way for scientific research? “A Piece of the Puzzle,” on page 32, explores the implications of considering race in genomic research.

Meanwhile, our journey into synthetic life has already begun. Genome maverick Craig Venter created from scratch the first custom bacteria this year. Through a trial and error process, he determined the minimal set of genes essential to the viability of the bacteria and built it. This work is a natural extension of the genetic engineering used by scientists for decades on a much more limited scale. It differs from newer engineering techniques that edit existing genomes, like CRISPR, in that it creates from scratch versus editing existing DNA sequence.

You’ll learn more about synthetic biology in future issues of Genome. In the meantime, you can binge watch seasons 1 and 2 of Humans on AMC. In this show, synths are able to function on fewer than six hours of sleep. I wonder if there’s a gene for that.