by Jamie Metzl
You hardly answer. Your mind is already transfixed in the range of possible futures playing out on the wall. You take in a deep breath.
“Shall we begin?”
Your mind reaches back to the choices our species has already made.
To understand how far selective breeding can take us, we only need to look in our refrigerators.
A wild chicken lays only about one egg a month for some very good reasons. As a species that, unlike salmon, actually raises its young, wild chickens can’t produce many more offspring than they are able to rear. Reproduction takes a lot of energy, so laying more eggs would also place more pressure on wild chickens to secure a steady stream of food. And laying a lot of eggs would make wild chickens even more susceptible to lurking predators. For fertile wild females, laying about an egg a month represents a balancing act of evolutionary imperatives played out over millions of years.
Around eight thousand years ago, humans first domesticated chickens from an Asian red jungle fowl called the Gallus Gallus. It didn’t take Gregor Mendel’s meticulous mind or PhDs in genetics for our ancestors to observe which of their newly domesticated chickens were laying the most eggs. It didn’t take an IVF clinic or even a galline dating app for farmers to breed the chickens laying the most eggs. Using little science to speak of, our ancestors used selective breeding to amplify a chicken trait that had emerged over millions of years of evolution.
Today, each American consumes an average of 268 eggs per year, amounting to a total U.S. egg consumption of nearly 87 billion a year, produced by around 270 million hens hatching on average one egg a day. Nearly 1.2 trillion eggs are consumed globally each year, produced by a worldwide army of 50 billion domesticated chickens. Many have come to see the large numbers of chicken farms around the world producing these eggs as a dangerous and dirty nuisance.
Imagine what would happen if these domesticated chickens were laying eggs at the same rate as their wild forebears. Instead of 50 billion chickens in farms around world, we’d need around 775 billion chickens. Imagine how people would feel? Earth would become a planet of chickens.
Because the Gallus Gallus still runs wild in Southeast Asian forests, it is easy to compare domesticated chickens with their wild ancestors, just as it is easy to compare domesticated dogs and the wolves from which they came. In addition to laying more eggs, domesticated chickens are less aggressive and more social, active, and mobile. As with our other domesticated animals and plants, humans have successfully hacked the chicken.
If we got in our time machine and went back eight thousand years to visit those first chicken-domesticating humans and asked them how many eggs a chicken might lay, they would have been hard-pressed to envision thirty a month. Thirty eggs a month would have sounded then as crazy as a woman today having thirty babies in nine months.
The point here is that biology is significantly more susceptible to hacking than initially meets the eye. We know this intuitively because all of the complex life forms around us evolved from the same origin. But the chicken example suggests that even our own biology might potentially be more manipulable by selective breeding than we are often inclined to believe.
With chickens as a backdrop, now let’s look at another organism we will want to hack so it can live longer, healthier, or however we might define it, better.
Homo sapiens like you and me come with time-limited hardware and some very buggy software. Most of the cells in our body turn over, on average, every two years. As we continually copy and recreate ourselves through the magic of our stem cells, small errors start showing up in the genetic code of our new cells. At first this doesn’t hurt us much, because we have the machinery inside our cells to fix the errors or keep them from causing damage. But as we get older the number of these errors increases and our ability to fight them declines. We call some of these bugs aging and others cancer.
As we’ve come to understand these bugs over the past 150 years, we’ve also developed some preliminary hacks that allow us to fight back. That’s what we’re doing every time we treat a genetic disease. When someone gets a bone-marrow transplant, for example, doctors destroy their faulty hematopoietic (blood-forming) cells using radiation and then repopulate the patient with healthy cells from a donor. But if the underlying problem is a heritable genetic disease, the children of even a person cured by a bone-marrow transplant could inherit the same problem.
But what if we wanted to push genetic change like eliminating genetic diseases or enhancing certain traits through our own species as thoroughly as we’ve pushed increased egg production through chickens? What if we come to see our current biology like our ancestors once saw chickens laying an egg a month—a challenge to be overcome by human ingenuity and selective breeding? The first problem we’d need to overcome would be time, because we humans are just a slow-breeding species.
We enter the world completely helpless and unable to care for ourselves and spend years learning which way is up. At some point in our early teens, some of us begin to recognize there’s something different about members of the opposite sex, but we’re not quite sure what it is. Terror sets in when some of us realize in our early teens that we need to figure out how the opposite sex works because some day we may need, OMG, to have children with them. We start the process of dating with pimpled awkwardness but then, in our later teens and early twenties, tend to get the hang of it. Having so much fun, we then don’t want to end the run prematurely and often aspire to meet enough people to make a smart choice. Finally, at an average age of 27.5 for women and 29.5 for men in the United States and a bit lower worldwide, humans get married. At an average of around twenty-eight in the United States and twenty-six globally, women have their first child, and the process starts again.10 Twenty-eight years for humans to pass a generation, six months for chickens. That’s a big reason why pushing genetic change in chickens can be far quicker than in slow-breeding animals like us.
But what if we could speed up that process to reduce the human generational turnover to about the same six months as a chicken—not by making babies mature faster but by breeding preimplanted embryos with each other? The idea sounds straight out of dystopian science fiction but could someday in the not-too-distant future will be possible.
Imagine we start by taking the mother’s blood sample and then induce her peripheral blood mononuclear cells into stem cells, and then into hundreds of eggs. We then fertilize the eggs with the father’s sperm and select one embryo (based on whatever criteria). But now, rather than implanting that early-stage embryo in the mother, we instead extract a few cells from it to generate new sex cells. Let’s make these new sex cells eggs for the purposes of this hypothetical.
Now imagine that another mother and father went through the exact same process, but instead of inducing eggs from the cells extracted from their preimplanted embryo, they create sperm. If we use this second embryo’s sperm to fertilize the first embryo’s eggs, then the embryos become the biological parents of their offspring, and the original two sets of mothers and fathers become the grandparents. This grandchild embryo could then be mated with another embryo with an entirely different set of parents and grandparents, now making the original mothers and father great-grandparents (and the original preimplanted embryos grand-parents). This process could, theoretically at least, go on forever.
Here’s a visual depiction of how this might work:
Of course, finding the right embryo to mate with yours and avoiding inbreeding would require a process for preimplanted embryos equivalent to that used by mate-seeking adults today. Perhaps someday an app could be created to help parents find the perfect mate for their precious little preimplanted embryo.
For technical reasons, this process would take about six months per generation and conceivably could go one forever. Six-month-old embryos could become genetic parents. Year-old frozen embryos (or three-month-old babies) could become grandparents. Using this process would mean we could pass fifty-six human generations over the same tw
enty-eight years it now takes for one—equivalent of the generational distance between us and Kublai Khan. Rather than three-and-a-half human generations in a century, we could go through two hundred—that number of current human generations would bring us back to just when the wheel was being invented. Sped up by genome sequencing and biological systems analysis driving decisions instead of old-fashioned trial and error, generation change through selective breeding in humans might start seeming as malleable for us as it’s been for chickens.
But why might people in the future even consider something as frightening and dehumanizing as breeding human embryos to push genetic changes as we have chickens?
They might not, and this potentially feasible process might remain just a thought experiment. But future generations also might look at the numbers.
We’ve already seen that IQ is influenced by hundreds or even thousands of genes, in most cases each with a relatively small effect. We’ve also seen that people with higher IQs tend to live longer, earn more, and have more fulfilling relationships than their lower IQ peers, so we know that some parents would conceivably have an incentive to endow their children with the greatest IQ potential possible if they had the choice and believed it was safe.
In their thought-provoking paper, Embryo Selection for Cognitive Enhancement: Curiosity or Game Changer?, Oxford professors Carl Shulman and Nick Bostrom attempt to quantify what increase in IQ might be possible based on mating unimplanted embryos with each other.11
The IQ of a traditionally conceived child, an n of 1, simply has the genetic component of IQ he or she is born with. Because the genetic component of IQ varies among embryos created by the same parents, other than identical twins, we can safely assume the range of IQ options would be greater the larger the number of embryos that might be generated. This means that we would have a greater chance of selecting an unimplanted embryo with a higher IQ if the number of options was larger.
According to Shulman and Bostrom’s calculations, the average IQ difference between the highest and lowest IQ of the fifteen or so embryos conceived in IVF, as practiced today, from the same parents would be about twelve points. But if we use the induced stem-cell procedure to start with a hundred fertilized eggs, rather than just ten or fifteen, the average difference between the highest and lowest genetic IQ potentials between these hundred options is estimated at about twenty points. Making a thousand embryos could increase the average differential between the highest and lowest IQ of all the embryos to about twenty-five points.
Twenty-five IQ points may seem like a small return from generating and testing a thousand preimplanted embryos, but that difference would, on average, lead to vastly different life experiences. Einstein was estimated to have an IQ of 160. Arnold Schwarzenegger, not an Einstein but no dummy himself, has an estimated IQ of 135. Enough said.
When we explore the mathematics of mating these already highly selected embryos with each other, the numbers start to look astounding. Shulman and Bostrom estimate that breeding five generations of embryos picked for having the highest IQ among their ten cohorts could create a bump up of sixty-five points in IQ, and a 130-point bump after ten generations. One hundred and thirty IQ points is the difference between an Einstein and a person with severe intellectual disabilities who requires constant care. In the other direction, it’s the difference between an Einstein and someone with, by far, the highest IQ ever recorded.
Stephen Hsu is even more optimistic about how much of a bump might be possible. Normally, some human genes have either a positive or a negative effect on intelligence, resulting in a normal curve of intelligence. If each of these genes is tweaked to have a positive effect, then the aggregate effect could be a human with a much higher level of intelligence than the 100 standard deviation IQ average. Hsu believes that because we will likely be able to identify most of the genes associated with intelligence within a decade, parents in the future might be able to select between preimplanted embryos based on the expression of genes associated with intelligence to create a super-intelligent person with an IQ of 1,000.
Hidden in these calculations of multiples and averages is the increasing possibility that future children with truly outstanding outlier capabilities—such as a genius for math, making music, or writing advanced computer code—might revolutionize our ways of thinking even more than our greatest geniuses like Einstein, Confucius, Marie Curie, Isaac Newton, Shakespeare, and David Hasselhoff. “We can imagine savant-like capabilities,” Hsu writes, “that in a maximal type, might be present all at once: nearly perfect recall of images and language; super-fast thinking and calculation; powerful geometric visualization, even in higher dimensions; the ability to execute multiple analyses or trains of thought in parallel at the same time; the list goes on.”12
Of course, we have no idea what an IQ of 1,000 would mean for a person. Evolution is full of redundancies, protections, and trade-offs. It is very possible, perhaps even likely, that a person engineered to have a 1,000 IQ might be driven crazy, become a dangerous sociopath, or develop some type of neurological malady we’ve never seen. It would be extremely difficult to know what harmful mutations were being pushed across multiple generations of embryos mated before an actual human child was born. Creating super-intelligent humans would, of course, also have massive social and ethical implications.
It certainly sounds crazy and frightens many people to imagine that future humans could have IQs so far beyond history’s greatest geniuses, but is it not crazy to believe our current IQ range makes us kind of like the wild chickens popping out a humble egg a month. It may be that our evolution to date has been so optimized for intelligence in balance with our other survival imperatives that such big IQ gains would require physically larger brains not possible within the space constraints of the craniums we now have.*
If so, one solution to this hypothetical problem would be to optimize future children for larger craniums. Futurists like Ray Kurzweil predict this limitation on what our biological brains can do will force us to merge with our machines, so our mental capacities can expand exponentially, perhaps in a computing cloud, without bumping into any physical space constraints. Even then, our species might need some super-biological geniuses with IQs far beyond today’s normal to write the code that guides our AI (at least until the AI starts writing its own code) or helps make this expansion of understanding and consciousness available to everyone.†
Human women will not be selecting from among hundreds of preimplanted embryos for at least a couple of decades, and human embryos will not be mating for significantly longer. But if and when this becomes possible, we’ll face a host of incredibly thorny ethical questions. Would the responsibility of a mother giving birth to her great-great-great-great-grandson be any different than to a direct biological child? Are unimplanted embryos in a dish entitled to any rights? Is mating embryos without their consent a form of slavery?
But as strange as these types of hacking human reproduction seem today, any child born from this process would have 100 percent unadulterated human DNA. If that doesn’t seem like much of a consolation, it’s because we haven’t yet begun to discuss the gene-editing technologies with an even greater potential to fundamentally transform our species.
*My apologies to any odontophiliacs reading this book!
*This is why the advanced space people in so many sci-fi films have such big heads.
†These people could also become arrogant pricks oppressing us.
Chapter 5
Divine Sparks and Pixie Dust
Revolutionary ideas and revolutionary technologies often advance together.
Experimenting with his pea plants, Gregor Mendel could hardly have imagined the complexity of calculations computers would make possible a century later. Watson, Crick, Franklin, and Wilkins could never have uncovered the double-helix structure of DNA without X-ray photography and the microscope. Fred Sanger, Alan Coulson, Leroy Hood, and others could never have invented genome sequencing without the microproces
sor. The army of researchers around the world striving to better understand the human genome would be nowhere without their complex algorithms and advanced processing chips.
This tango between our coevolving tools and ideas is also forever shifting our sense of ourselves as a species. While our ancestors may have seen themselves as the love children of divine sparks and pixie dust, many of us today see ourselves as the output of code. We have given a language to our machines that’s become a metaphor for the inner workings of ourselves. It’s not just a scientific leap but also a conceptual one. After billions of years of Darwinian evolution by random mutation and natural selection, this shift enables us to envision a future when we will start not only selecting our future children but also hacking and writing their genetic code.
As soon as scientists began unlocking the mysteries of the genome they began imagining how changes could be made. In the 1960s, they started using radiation to spur random genetic mutations in simple organisms and plants, a slow, expensive, imprecise, and painstaking process. For every desired mutation found there could be hundreds, thousands, or even millions of inconsequential or harmful ones. Figuring out in the 1980s and ’90s how to more precisely splice genes from one organism to another was a big step forward, but the hunt was still on for a better, faster, and more targeted way of altering genes. More recently, this process has shifted into overdrive.
In an important 2009 study, American geneticists Aron Geurts and Howard Jacob detailed how a class of proteins called zinc-finger nucleases, or ZFN, designed to bind to DNA, could be used to precisely edit genomes. With ZFN, proteins are painstakingly engineered to bind and create double-strand breaks to DNA in a specific place. If we imagine the DNA helix as a twisting ladder, ZFN cuts the part where you hold your hands when climbing.