Are Human Genes Changing As Fast As Culture and Technology?
On the Rise of Epigenetics in the Anthropocene
A staple of cinema, even from its earliest incarnations, has been the portrayal of the future and humanity’s place in it, either overtly or allegorically, and quite often that vision has been dystopian. For example, consider the polluted cityscapes portrayed in the 1982 film Blade Runner, where it is small mom-and-pop stores that produce organs and whole creatures synthetically, while larger corporations produce artificial humans, or “replicants.” The 21st-century movie sequel continued visions of the environmental and technological future where a technological elite equipped with godlike powers of invention produces products that eventually turn on their inventors (just as they did in Blade Runner, in the many Jurassic Park movies, and most recently in the television series Westworld).
We are still a long way (if ever) from building Turing-tested AIs so “human” that neither they nor we can tell that they are artificial, or from bringing dinosaurs back to life from the long dead. Yet the distant future often has a tricky way of arriving sooner than is comfortable. In one sense a “far future” that was technologically impossible prior to this new century has indeed arrived. We are building the laboratories and instruments now bringing to life new kinds of organisms that evolution never produced, and using these tools to concoct a welter of genetically altered or grown-in-test-tube animals and plants. We are now fully capable of artificially producing humans with attributes making them more efficient killing machines than any brought to life by natural selection. Superorganisms. The means to build them comes from a theory first espoused almost a quarter of a millennium ago by the French naturalist Jean-Baptiste Lamarck, using a new term for that science: heritable epigenetics.
Beyond imagining what the future might hold, television and cinema have two prime motives: to make money for large corporations and to entertain the masses. Yet beyond all of our wishes to be entertained is a third role of big-budget screen entertainment: as a refuge from stress. There is a palpable sense of fear that the near future evokes, because never before has technology been so frightening to so many people. It is no longer simply the possibility of nuclear Armageddon that can keep children fearful in the night. Biology is now more threatening and at the same time more promising for our next generations. Designer soldiers can be faster, stronger, deadlier. Designer children can be smarter, healthier, more beautiful, more long-lived. Biology is the curse and the blessing, and as a main purveyor of our species’ emotions, cinema knows this. Now cinema is economically dominated by humans that are “super.” Some are good, some are evil. All are more powerful than we “ordinary” (i.e., produced by evolution) members of Homo sapiens. They are also subtly portrayed as what we need to become to survive this increasingly violent, crowded, toxic world. And watching them on-screen can keep the nightmares at bay, at least in two-hour shots.
We want to be entertained, which is often synonymous with escape, because outside of the multiplex or our various screens at home as well as at work, the world is getting scarier. Going outside is more dangerous. Staying home is safer. Our screened world is the safest place of all for many of us. The screened world, be it in the multiplex, the home TV, the iPad, or the cell phone, is also a place where our species evolves culturally—and, according to many scientific seers, probably biologically as well. The average American spends a minimum of ten hours on one kind of screen or another each day. Now the same movies can be delivered to us at the touch of a button, and that touch can serve as a means of isolating ourselves from the human community. Where once there were suits of armor to defend ourselves, now we are armed with cell phones, and this transition may be rapidly evolving the human race.
Are our genes changing as fast as culture and technology? More important, does anything we experience during our lifetimes have any effect on our own genomes, our inherited genes, the information locked in our DNA that has been uniquely ours since birth? Based on Darwinian evolution, now called the “new synthesis,” the answer is a reassuring and resounding “No!” It is an answer megaphoned by leading scientists who keep the flame of the Darwinian paradigm alive, and backed by the major scientific funding agencies. Yet epigenetics argues otherwise.
Darwin and his great theory have always seemed to give a grace note of safety: that our genes are impervious to change during our lifetimes. Biologically, this meant that no matter how badly you screw up via bad choices, such as the use of drugs, cigarettes, or alcohol, or exposure to toxins, violence, religion, or love, none of it will affect the genes you pass along to your children.
Thus according to current evolutionary theory, events in our lives, both the good (achieving happiness, religious contentment) and the bad (acquiring post-traumatic stress disorder from exposure to inhuman violence, or having been abused as a child, or growing up near a factory releasing polychlorinated biphenyl [PCB]-like poisonous chemicals into the nearby environment), are meaningless to the children we might produce. Darwin gave us this solace: Nothing that happens in our lives can affect what we pass down to our children through heredity. The revolution that is epigenetics demonstrates that this is not true.“What if we could take a sample of global human stress in the same way that paleontologists take a sample of global organismal diversity?”
Charles Darwin espoused evolution as driven by natural selection. However, an earlier theory, proposed more than a half century before the first publication of Darwin’s greatest work, came from a naturalist whose life and work were limned by the flames of the French Revolution.
Jean-Baptiste-Pierre-Antoine de Monet, Chevalier de Lamarck, had a different view about heredity and why animals changed through time. His scientific beliefs were that things that happen to us during our lives can change what we pass on to our next generation, and perhaps into even further generations. Darwin knew well what Lamarck theorized. Darwin believed that his own theories about evolution could not coexist with any aspect of what Lamarck postulated. We now know this is no longer the case.
Lamarck’s Revenge looks anew at what are, perhaps, humanity’s most basic questions: the “where,” “when,” and “why” of getting to the present-day biota on this planet. But the vehicle to do this is by asking specifically about the “how.” What were the evolutionary mechanisms, the balance between Darwinian and neo-Lamarckian (aka heritable epigenetics), that produced not only our physical biology but some aspects of our heritable behavior as well?
Here are some possibilities. First, that the process known as epigenetics combined with periods of extraordinary environmental change has played a far greater role in what is called the “history of life” than is accepted by all but a small cadre of revolutionary biologists. This is perhaps most decisively shown through the epigenetic process of “lateral gene transfer,” where on a given day, in a given minute, some organism is invaded by another and a product of that invasion is the incorporation of vast numbers of new genes, making the invaded creature something else again, neither the invader nor the invaded. This is known.
Second, new evidence points to a probable role of epigenetics in producing rapid species transitions by mechanisms other than lateral gene transfer. Science has discovered that major evolutionary change of a species can happen a thousand times faster by epigenetics than by the process demanded by the Darwinian theory of single, random mutations along a creature’s genome or DNA (or, in some cases, RNA). This is most likely to occur during and immediately after rare, major environmental perturbations (such as mass extinctions and their aftermath).
Many scientists believe we are in such a period again, and that humanity itself is surrounded by genomes undergoing “epi-mutations,” the extremely rapid change of genomes by the major epigenetic processes, themselves triggered by environmental crises during random day-to-day existence. It makes sense that we are not only surrounded by such change but that our own genes are equally malleable and now equally affected. In humans, such crises work through the effects of our mammalian stress systems, which are coupled to human gut biomes. It has been our response to cancer-causing environmental toxins and our responses to war, famine, disease, and strident religion; to the poisons we eat; the poisons we hear on partisan media; the poisons we bear through racism, sexism, and any form of abuse, from child to spousal to bullying in general. Stress hurts us. Stress also changes us epigenetically. We evolve from stress, and we pass on new characteristics acquired during our lifetimes.
The many physical environments or habitats colonized by life are obviously not the same, with some being more rigorous than others. But in exploring many of the veritable libraries written about evolutionary theory, what seems to often be missing concerns the intersection of time and environment.
Yes, there are genuine paradises for Earth life, places like the rain forests and corals reefs so filled with the ingredients that support life that they are packed with species, and have been since the time of the first animals on Earth. At the opposite ends, in the most inhospitable places on land and in the greatest depths of the oceans, there are far fewer species. In similar fashion, some time periods have been more challenging to life than others, even in the most supportive of environments. There are good times and bad on Earth, and that dichotomy has fueled a coupling of times when evolution has been mainly through Darwinian evolution and others when Lamarckian evolution has been dominant. Darwinian in good times, Lamarckian in bad, when bad can be defined as those times when our environments turn topsy-turvy, and do so quickly. When an asteroid hits the planet. When giant volcanic episodes create stagnant oceans. When a parent becomes a sexual predator. When our industrial output warms the world. When there are six billion humans and counting.
The history of humanity also has witnessed fluctuations in “environmental” conditions through time. Such stress might be quantified in some respects—theoretically, in the average level of stress hormones of a human at a given moment in time. Environmental changes range from the coming and going of the repetitive ice age advances of the last 2.5 million years to the times of global disease and pestilence, or global hunger, or global war, or even heightened level of violence. Have these ebbs and flows caused variance in the rate of evolutionary change of our own species by triggering rapid epigenetic evolution, compared to the more tranquil periods, when change—if it took place at all—was the slower, more Darwinian kind? What if we could take a sample of global human stress in the same way that paleontologists take a sample of global organismal diversity (number of species) and disparity (number of body plans) at some interval of geologic time? In this experiment we would compare stress levels continent by continent, race by race, gender by gender, age by age. What is the level of stress molecules in descendants of enslaved people or survivors of the Holocaust or genocide? What is the level of stress in the rich compared to the poor? Which groups are evolving more quickly at least partially by heritable epigenetics? And most important: If stress in our modern world is causing human evolutionary change, what are we evolving into?
These are uncomfortable questions. But comfort is not something science cares about. Scientists have actually posed these questions, and by sampling both human and animal bones from the last several millennia we can measure the level of epigenetic change for given times. Scientists in the emerging field of paleophysiology are searching the entire archeological record, sampling the bones of man and beast in search of answers. How much epigenetic change will be visible from the extracted DNA?
There is far more to evolution than simple morphological or physiological change. Behavior—violence, religion, sexism, love, tolerance, racism, intolerance—can be hereditary in at least having the capability to change genomes. All of these might be changing our species. The balance of hormones in each of us is affected by our exterior experiences; all that we experience during our lives can affect the generations we contribute to. Lamarck first suggested this. That it is not just whether we survive our environment, but what our environment does to us. Now we know that this is indeed the case. Our DNA is changed not by subtraction or addition of new code, but by adding on tiny molecules that act like on-off switches. Genes that once worked no longer do. Genes that were switched off by natural selection get switched back on.
From Lamarck’s Revenge by Peter Ward, courtesy Bloomsbury. Copyright 2018 by Peter Ward.