Blockbuster Science

by David Siegel Bernstein

  WHOA! SLOW DOWN AND KEEP IT REAL

  In science fiction, evolution into our future tends to occur much quicker than it did in our history. In the classic 1968 movie Planet of the Apes, somehow by 3978 CE intelligent apes rule devolved humans. The premise is fun, but the science is shaky. If you take the difference between 3978 and 1971 (the year Charlton Heston's character George Taylor's rocket first launched), you get 2007 years. Not much time for traditional evolution.

  As long as we are looking at a two-thousand-year window for drastic evolutionary changes, I should mention the Wayward Pines trilogy. In the books, aberrations (called abbies) evolved from baseline humans in less than two thousand years.9 The next time you hear about the next phase in human evolution (think X-Men), be suspicious. It's probably just funky genetics (comic book meta-genes?) causing stuff and not natural selection.

  HOW DID LIFE BEGIN ON EARTH?

  Obviously, before life can evolve, it must exist. All preexisting life comes from earlier preexisting life, except when it does not. At some point, abiogenesis, meaning life from nonliving matter, occurred. Both philosophically and scientifically, this is a pretty big deal.

  Let's start at the beginning. Not the beginning of everything, but I'm talking about the origin of life on Earth. For clarity, I will use NASA's definition of life: a self-sustaining chemical system capable of Darwinian evolution.10 The chemical reaction part refers to the metabolic process, or obtaining energy from organic sources, that supports life.

  Life most likely began on Earth about four billion years ago. During the Hadean eon, Earth was a young and rambunctious five-hundred-million-year-old, the sun wasn't as bright, the moon was closer, and Earth spun faster. It spun so fast that a day lasted a mere ten hours.11 Oxygen wasn't present because there weren't any flora to produce photosynthesis waste. Meteorites pummeled the planet, providing it with some of our metals.

  Against this chaotic backdrop, scientists might be able to trace back to the origin of earthly life. The theory is still murky, so the tale I'll tell is one of scientific possibility. Obviously this will be a rough draft because we are all waiting for biologists and chemists to confirm these events and further flesh out details.

  Somewhere in Earth's history, chemicals (probably simple chemical polymers) developed a handful of biological properties such as self-replication and cooperation with other molecules.12 This is the era of chemical evolution when simple chemicals began making copies of themselves. Over billions of generations, more complex variations emerged.

  Eventually (let's say about 3.5 billion years ago), some variations were enclosed in a membrane, possibly from a fatlike substance that surrounded the molecules with a bubble. The first biological chemicals might have occurred after millions of years of chemical reactions assisted by ultraviolet light, lightning strikes, or deep-sea vents. These became the first microbial cells from which life evolved—abiogenesis. Each generation of these protocells produced new versions of themselves until eventually they split into bacteria and archaea.

  Quick fact: The you who is reading this isn't completely human. Your body contains about the same number of microbial cells as human ones.13 And because of evolution, that's okay. They coevolved with us.

  About 2.4 billion years ago, things got interesting. Simple organisms called cyanobacteria (a phylum of bacteria) evolved the ability to convert sunlight into energy, and photosynthesis was born. During this era, the buildup of oxygen led to the ozone that later would protect life from the sun's ultraviolet rays.

  Members from each family (bacteria and archaea) started dating and gave birth to more complex organisms. At some point, an archaea cell was taken hostage by a bacteria cell. Instead of killing the archaea, the bacteria enslaved it within itself. This was the first eukaryotic cell. A eukaryote cell contains a nucleus and other goodies like mitochondria, a power plant that provides energy to the cell and allows for complex organisms to arise.

  Fast forward to about six hundred million years ago when multicellular life began to flourish. Boom: the Cambrian Explosion.14 During the next thirty million years, complex organisms popped up all over the place. Most of the major animal phyla appeared. The Cambrian period corresponds directly to the rise in oxygen levels that was probably caused by algae and moss fixing carbon in the soil.

  WHAT IS DNA?

  Cells contain self-replicating material—deoxyribonucleic acid, aka, DNA. This molecule is composed of two coiling strands of phosphates and sugars that form a double helix. It contains the blueprint for the proteins and molecules used by human cells for growth and reproduction.

  Fig. 8.1. Illustration of DNA. (iStock Photo/Rost-9D.)

  Nearly every cell in one person's body has the same DNA. If you've watched even one episode of CSI, you know that one person's DNA is different from everybody else's DNA. Almost. My mother and father's DNA is the most like mine, unless I have an identical twin. I don't, but if I did he would be the exception. Our DNA would be the same.

  Quick fact: Not all “sames” are created equal. Although twins might have the same genome, it might still be possible to tell twins apart by their DNA, especially if they have been exposed to different environments or are living different lifestyles. These differences cause epigenetic differences between their DNA. Researchers have found that different epigenetics lead to different melting points for the DNA.15 This can be used for identification. See bonus 2 to learn more about the genome and epigenome.

  We can go deeper and ask, how did DNA originate? It is extremely unlikely to have been formed by a chemical accident. In order to make DNA, you need specific enzymes (proteins that cause reactions). To make those enzymes, you need precise instructions carried within DNA.

  Guess what? You are trapped in a circular conundrum similar to the classic question over whether the chicken or the egg came first. By the way, the answer is the egg. Whatever laid it wasn't a chicken, but it was genetically close.

  Here are two leading theories that break the circle on how DNA evolved.

  Homegrown DNA DNA wasn't the first chemical to come to life. A lot of biologists believe the honor belongs to ribonucleic acid (RNA), the half-dressed version of DNA. Yes, this risqué molecule wears only a single biopolymer strand.

  RNA is like a construction worker who carries out the instructions in the DNA blueprint. On a planet of opportunities such as ours, it should be possible for construction workers to also be their own blueprint. Scientists have shown that RNA can spontaneously fold itself into structures that form self-replicating molecules. Therefore, in theory, RNA could act as both as information carrier and a catalyst (both worker and blueprint). It is very possible that RNA first evolved from the chemistry of early Earth. At some point, RNA life transitioned into the more complex DNA life we see today.

  Imported DNA Another idea is that life might not have originated on Earth but rather was seeded with ancient microbes that bombarded the planet billions of years ago. This idea is called Panspermia, the Greek word for “seeds everywhere.” If true, this would mean that the chemical evolution happened elsewhere and spread to Earth by piggybacking on the backs of asteroids or by swishing around in the water-ice of comets.

  A cool title for a book might be Ribose from Outer Space. And there is a possibility it would be nonfiction. Ribose (of RNA fame) might form on dusty ice that had been irradiated by ultraviolet radiation. Comets are made of ice, and they have been known to strike the earth. So make of that what you will.

  The seeding of biological matter doesn't have to be at the interstellar level. We could look closer to home. Our neighbor Mars has water. In the deep past, it might even have hosted oceans where organic matter could have formed. The early Earth lacked some of the elements necessary for life such as boron, which is needed to form RNA. While boron was rare on early Earth, it was less so on Mars. Meteorites from the Red Planet might have come loaded with the element. It might not be science fiction that Martian RNA led to Earth DNA.

  I know what you a
re thinking. The seeding could have been a bit more intentional, something planned by an alien civilization. Science fiction often agrees. In the 1993 Star Trek: The Next Generation episode called “The Chase,” we learn that the Star Trek galaxy was seeded by ancient aliens with DNA codes similar to the characters’ life-forms.16

  Thus the Star Trek galaxy is full of two-legged, two-armed, two-eyed races that, except for a little face makeup, look very similar. This also might explain why humans and Vulcans are able to interbreed. There is a distinct lack of speciation in the Star Trek universe. Speciation is the evolutionary process by which isolated populations from the same originator species eventually become so distinct that if they bump into each other again, they will no longer be able to breed.

  42

  —Douglas Adams

  Let's not forget Douglas Adams's wonderful The Hitchhiker's Guide to the Galaxy. The earth was built as a computer program, seeded with human life, and supervised by mice. Why? To determine the question to life, the universe, and everything…the one that might or might not go with the answer to life, the universe, and everything.

  PARTING COMMENTS

  Life began from those chemicals that developed biological properties like self-replication and cooperation with other molecules. These protocells branched into bacteria and archaea. Then one day, along came the eukaryote cell with its fancy nucleus, mitochondria, and DNA. From then on, life could not be stopped.

  To get to us it took a bit more evolution. Evolution is the slow process of inheritable changes of populations over time. Natural selection is an explanation of how these changes are passed down to successive generations. The variations are caused by random changes in DNA. Okay, cue up the ominous music because natural selection decides which mutations live and which die in the gene pool.

  Scientists no longer use fossils alone to reconstruct human evolutionary history. They now have DNA mapping. They have learned that hominins had many evolutionary branches. Almost all of those extras were cut off because the subspecies couldn't adapt to changing environmental conditions or competition from other subspecies. In the end, only one type of hominin was left: Homo sapiens sapiens.

  CHAPTER 8 BONUS MATERIALS

  BONUS 1: EVOLUTION IS SMART

  Evolution doesn't guarantee that every mutation will be a long-run improvement. But a mutation that doesn't necessarily look so great at first might prove to be pretty good. Take our inability to make vitamin C (ascorbic acid). This vitamin is necessary to produce collagen and to prevent connective tissues and blood vessels from breaking down. Almost all animals and plants produce their own vitamin C. Why not us?

  An intriguing theory is that our ancestors had a vitamin C–rich diet, so it was more efficient to eat it than to produce it. This redirected our bioenergy to building a more resourceful (and bigger) brain. An alternate theory is that our ancestors’ vitamin C deficiency damaged their DNA. Mutation rates increased, and our evolution sped up.

  BONUS 2: THE “OME” HOME

  Let's take a ride up the taxonomy elevator of your genetics. The first floor is the genome represented by DNA. This is where your genes come from. The next floor up is the transcriptome level where you are greeted by RNA, which is busy switching genes on and off. Up another floor, you reach the proteome level where you can say hi to the proteins.

  Shall we continue up? Good. The metabolome level is waiting to show you all the small molecules in the cells. Up again to discover the epigenome level where the environment plays a role in gene expression. Finally you arrive at your destination, the phenome level, where your traits (physical and behavioral) are determined from the activities on all the floors beneath.

  The genome is the most stable over time. The other levels are a bit more flighty and switch genes on or off at particular moments. The genome describes what can happen, while the proteome and the metabolome reveal what is actually happening. Two people with the same genome can have very different phenomes.

  There are ways to influence the way genes function without changing the underlying DNA sequence. Stress, poverty, and pollution can accelerate aging. These genetic expressions occur at the epigenome level and are called epigenetic traits.

  I teach you the overman. Man is something that is to be overcome. What have you done to overcome him?

  —Friedrich Nietzsche, Thus Spake Zarathustra

  Is aging a disease? Should extending life and increasing happiness through biological hacking or by harnessing technology be a goal? Is there any reason you can't choose your gender on demand? Is there even a reason for gender?

  Someday (soon?) we will be able to make ourselves smarter, stronger, and more attractive. Improved people are another staple of science fiction. But predicting what humans will self-evolve into is tricky (and fun). We might enact biological improvements down to the DNA level, or we might blend our bodies with machine (cyborgs), or become completely synthetic, or do away with bodies entirely and become enhanced uploads.

  The road to improved people is often bumpy, and no speed limit has been posted. This truth of science is exploited in good science fiction. For example, consider a fictional Earth where at some time in its (future) history, it will be popular to experiment with memory enhancing drugs and antiaging treatments. Plausible.

  Now, I trust the readers of science fiction to know that small changes become cumulative over time, so allow me to continue. As more time passes, perhaps my fictional population begins to add nanotechnology (technology nearly at the atomic level) and bioengineering to the mix. How about neural interfaces to connect their brains to information webs? After all these changes, are they still human?

  What I described above is called transhumanism—the human in transition. It is a stage in human development where human beings use technology rather than evolution to improve the race. Genetic modification, gender reassignment, upgrading with prosthetics, implants, and/or various chemical enhancements are all on offer. We already conduct biological hacking by replacing knees and hips. Why not cheat death by replacing aging or damaged organs with ones grown from the body's cells?

  If these cumulative changes keep occurring, the mental and physical capabilities of augmented beings will at some point so radically exceed those of baseline humans that they might no longer be considered human. Posthumanism (when the body becomes irrelevant) might come after that. In fact, posthuman thinking and experiences might be so profoundly different from ours that we can't conceive it. Posthumans will shape themselves as well as their environment.

  A lot of arguments blaze about modern ideas to improve humanity. The following chapters reveal that evolution doesn't have to be random. Humans can take over the human condition with science and technology. Chapter 9 covers how we can use technology to modify our bodies on the road to transhumanism. Chapter 10 describes how we might add technology directly to our bodies, merging us with machine.

  Death is an existential threat. It is the end of consciousness, and yet we cannot consciously imagine not being conscious. All we have to do to bypass this paradox is to live forever. Simple. Using technology externally and internally is a way to stall death until we can download our minds into a virtual (posthuman) world housed in an indestructible data storage device floating safely in deep space.

  Concerns about the sun dying out or Earth being overtaken by hostile aliens become moot. You or your progeny will be able to exist indefinitely, or at least until you read the bad news in chapter 21 (how everything ends).

  How I, then a young girl, came to think of, and to dilate upon, so very hideous an idea?

  —Mary Shelley

  In Mary Shelley's story, Dr. Victor Frankenstein is so wracked by grief he buries himself in an experiment to give something nonliving a life. He creates a large humanoid using repurposed parts (from corpses). Eventually, he abandons his creation and mayhem ensues.

  This chapter is less about creating life and more about hacking it.

  GENETIC ENGINEERING AND EVOLUTION


  Passing down favorable traits using good, old classical evolution (via breeding) is so yesterday. I think all we hominins can agree that natural selection/random mutation evolution has had a good four-million-year run, but, as Bob Dylan might say, times are a-changin’.

  We no longer need this low-tech type of genetic engineering. Today we can go a lot less natural with our selections. We can identify specific genes and insert them directly into the DNA of an embryo, passing down a trait in a single generation. A trait not already mainstreamed in the population.

  To avoid future disease, doctors have been tinkering with the human genome through gene therapy for some time now. They also use gene-editing technology to discover which DNA sequences are present in diseases. Humans can be edited. Instead of just removing negative traits, this same technology can be used to engineer more positive ones. The question is, should we? The answer for a lot of people is yes. If enough people agree then we might be past the age of random mutation and into the era of intelligent human design.

  Here is something outside of science to consider: is it ethical to impose eye color, intelligence level, or sexual orientation of your choice on the next generation?

  HOW IS GENETIC MODIFICATION DONE?

  In the field of biology, humans now can “cut and paste” using the newest and hottest gene editor called the CRISPR/Cas9.1 CRISPR stands for clustered regularly interspaced short palindromic repeats. The CRISPR can be used to fight viruses, eliminate genetic diseases, prevent HIV infection in human cells, and for the contentious idea of creating designer babies.