by Bor, Daniel
There are many practical examples of the extent of this staggering uniformity. For instance, scientists have countless times successfully spliced genes from one species into a completely different one and changed its characteristics. This includes human genes introduced into mice, and mouse genes into flies. You might think that such gene swaps are unnatural, the Frankenstein-like artifacts of biology labs. This couldn’t be further from the truth. For instance, in the wild it is now assumed that about 13 percent of all plant species were formed by the melding together of two or more distinct lineages. And there are also well-documented examples of useful gene swaps between humans and viruses or bacteria.
Part of the reason for the rapid rise of this DNA-RNA-protein system, and its consequent total dominance, may well be the fact that it is very close to an ideal biological system for storing and processing information. DNA is a tremendously safe, reliable holder for vast numbers of genetic ideas, while the machinery in the cell can efficiently retrieve those ideas and express them as proteins. There is also a simple way of making copies of the entire organism: by unzipping the twin strands of DNA code, each strand making a single copy of itself, and then rejoining these into two double strands for the new cells.
With this ideal ability to store information and easily convert it into useful protein tools, the standard DNA-based mechanism we know today must have trounced the alternatives 4 billion years ago, and once this recipe for life took hold in the world, there was no going back.
EXTRA INNOVATION IN DESPERATE TIMES
Now, though, with DNA-based life carefully designed to preserve large sets of ideas, it seems the scales have been aggressively tipped toward the boring, stable side of information processing, with little chance to adapt the DNA code when circumstances change.
To compound this problem, there are various biological mechanisms that make every effort to ensure that organisms avoid the chaotic route. For instance, the DNA words that code for individual amino acids can sometimes still be read correctly, even if they are slightly misspelled, because there are in many cases a few spelling variations for each word. There are also more active and sophisticated mechanisms in play in some organisms by which a careful proofreading of the code is done to detect and correct any errors as they arise.
But to even the score against DNA inflexibility, there is a second set of biological tricks. For example, whole sections of DNA can be mixed up to inject measured levels of chaos into the ordered DNA code, allowing a family of organisms over the generations to soak up new ideas.
Some fixed, equal balance between stability and chaos is an effective learning system: Now you can both maintain your DNA ideas and modify the code across the generations, so that new concepts can be gleaned from the world. But never deviating from this informational midpoint introduces its own inefficient, unintelligent stubbornness. In one extreme, possibly applying to a handful of bacterial species on the planet, if you are living relatively easily in a place that never changes over the millennia, with no enemies to speak of, then doing everything you can to keep your current successful ideas just as they are across the generations makes perfect sense. At the other end of the spectrum, if a species’ genetic set of ideas are obviously unsuccessful, and many creatures are dying in droves, possibly because of a violently changing environment or many forms of competitors, then a mode of maximal innovation is the only likely road to safety. This is true despite the fact that the chaotic route itself will also introduce poor ideas that lead to even more deaths, since as long as new accurate genetic ideas are found, some members of the species will definitely be saved. In both cases, the middle ground is far from ideal.
In the usual niches that life inhabits, there is a mixture of good times and bad. Here, the ideal computational solution is to be able to tweak the ratio between existing beliefs and new ideas according to the circumstances. So, ideally, an organism should suppress any chaotic changes to its DNA in successful times, but then positively encourage such dangerous innovations when previous beliefs no longer work in a new, life-threatening world.
In a close analogy to this, the distinction between heavily grooved beliefs and innovation is one of the most prominent psychological features of human experience. We all have habits we’ve carried out a thousand times before, such as having that morning shower. I for one tend to spend the vast majority of each shower daydreaming, as my muscles unconsciously take over the tedious task of sponging myself clean. But if the water would suddenly turn stone cold, I’d come back to myself, know that something is wrong, and explore how to fix the faulty plumbing. This acknowledgment that an error has crept in, and that innovation is required to fix it, makes me feel more conscious, more energized, and certainly cuts out any daydreaming. In fact, it’s no coincidence that moments like these initiate a spike in my awareness. I will elaborate throughout this book that this drive to innovate your way out of a problem is a crucial feature of consciousness, whereas, in contrast, an important role of unconscious, habitual plans is to implement those fully learned products of the initially conscious innovations.
Although simpler DNA-based life, such as bacteria, do not have any form of consciousness by which to modify their levels of innovation from dogmatic autopilot to desperate creativity, they nevertheless have an impressive suite of mechanisms by which to slide the level of creativity back and forth as they track the level of dangers in the environment. This provides striking evidence that sophisticated learning strategies, mirroring those that distinguish between conscious and unconscious thoughts, occur even at the humble level of single-celled organisms.
MUTANTS, SEX, AND DEATH
The first, most obvious means of injecting new ideas into DNA code is through mutations. Although DNA is an immensely robust molecule, DNA machinery isn’t perfect, and occasionally errors do arise. For instance, for bacteria, one mistake occurs every 10 million letters. If you only have 100,000 letters to spell your entire recipe, that means there will only be a single mistake in a single letter for every 100 bacteria. Some of these misspellings won’t even make any difference, as they will just be a new spelling of the same word. Others could radically alter the protein made—probably causing serious problems for the cell’s functions. But there’s also a slim chance that it will be an improvement, a better idea for how to survive and reproduce in the current environment.
With mutations being the mainstay of innovation in all organisms, manipulating this mutation rate is one way that creatures can increase the frequency of potential new ideas in order to match a more volatile world. Some species do indeed utilize this trick: When the situation looks grim, and survival is strained, random mutation rates are increased in some bacteria. Yeast react to stress not by reshuffling letters, but entire chromosomes, for the same inventive result.
An interesting analogy to this is in primate innovation. Those primates with the lowest social standing tend to exhibit innovative behaviors far more often than their higher-ranking compatriots, in the hopes of chancing upon some strategy that will raise them up the social ladder. There are many human analogues to this, such as the technological leaps that tend to occur in or around wartime.
Animals, however, with similar mutation rates to bacteria, but a far greater investment in complexity and size, have a serious problem: Since they reproduce up to half a million times slower than bacteria, their genetic creativity has taken a massive hit. This makes many animals terribly vulnerable to certain changes. The 10-kilometer-wide asteroid that crashed into the earth 65 million years ago was devastating for many animals, especially the dinosaurs, partly because they couldn’t adapt fast enough to the climate changes it brought. Seventy-five percent of all animal species were made extinct by this event. Although it’s impossible to collect such ancient data for bacteria, their extinction rate would very likely have been a very tiny fraction of this. Evolution would have been spoiled for choice to pick new forms of bacteria within most species, as they would have quickly adapted to thrive in the helli
sh conditions that arose after the asteroid’s catastrophic arrival.
To attempt to compensate for this serious limitation (slow replication), animals reproduce sexually. Sex is in many ways the first port of call for new strategies. Although bacteria normally simply divide, preserving every gene in the process, they can also perform an analogy to sexual reproduction by combining with another bacterium, even of another species, and swapping a section of genetic code with their ephemeral lover. But for animals, sexual reproduction has to be very much the rule, rather than the exception.
From a “selfish gene” point of view, indulging in sexual reproduction, instead of simply cloning oneself, is a minor disaster, since only half of an animal’s genetic identity is passed to the next generation. But the reward—genetic creativity—is very much worth it. Heavily mixing an animal’s genes with its partner’s throws up new genetic ideas in their offspring, helping them cope with the world’s many threats. This compensation for slow reproduction is so useful that almost all animals exploit it.
One animal has been definitive in demonstrating the utility of sexual reproduction, the lowly nematode worm. One nematode species, Caenorhabditis elegans, is a favorite model of genetic research. Because these worms are very simple animals that rapidly create offspring (every four days or so), the case for sexual reproduction is marginal. C. elegans’ response to this is to keep their options open, so they can either reproduce on their own or have sex with others.
From an information-processing point of view, if the worm’s world is a safe paradise, replete with abundant, choice morsels, it may as well reproduce asexually, since its genetic ideas about how to survive in the world are accurate and successful. But if there are mortal dangers, then its DNA could do with a shake-up for the next generation, of the kind that sexual reproduction can offer, to see if its rather different children will chance upon a better genetic recipe to cope with this harsh world. In fact, this is exactly how C. elegans behaves. Patrick Phillips and colleagues have shown that, when faced with some threat, such as a bacterial infestation, these worms are more likely to forgo the default of self-fertilization and instead have sex with others, and because of this, the family line is more likely to survive. The cauldron of sexually induced genetic diversity is beneficial at those times. In contrast, any that are forced to self-fertilize, despite the same threats, simply cannot cope, and they are soon wiped out after only a handful of generations.
Another injection of creativity into evolutionary hypothesis testing may well be death itself. Some people believe that research departments benefit from forcing crusty old professors to retire at sensible ages, so that stubborn, old-fashioned theories and habits aren’t perpetuated so forcefully in the community, and new ideas from younger, more dynamic scientists have more space to flourish. Likewise, in nature it’s possible that the existence of death helps species to avoid the buildup of outdated hypotheses. It’s true that organisms just wear out. It’s also true that any fatal genetic illness that materializes after the creature has successfully had children is not something that evolution is particularly interested in removing. But this isn’t necessarily the whole story.
For instance, death can be held at bay, seemingly indefinitely, in some cases. Some bacteria can survive, in stasis, in the cold wasteland of the Antarctic, for hundreds of thousands of years, if necessary. What’s more, all organisms so far tested, from yeast to worms to humans, can, on average, have their lives extended by at least a third simply by eating less. It’s therefore quite possible that this is an important biological mechanism by which to hang around for longer, until food becomes plentiful again and the environment is ripe for babies once more. So death, to some extent, seems programmed and flexible, and possibly for good reason.
I would speculate that without age-related death, genetic creativity across a species would become increasingly polluted by outdated ideas. If an older generation persists, then its offspring with genuinely useful innovations are less likely to flourish, as they have greater competition from their own family. If this situation continues for many generations, then the good ideas will increasingly become diluted and the species will be far more sluggish in response to changes. And when some crisis looms, for which the creatures with this excessive longevity have no solution, the species will be far more fragile than it would have been with a rapid turnover of creatures across the generations.
A similar reason exists for why we don’t, as a rule, remember everything we experience in our lives. Holding on to an increasingly irrelevant bank of information would drastically interfere with our daily functioning, and we would eventually be mentally crippled. One particularly striking case of near perfect memory is that of Solomon Sherashevski. Sherashevski was born around 1886 and grew up in a small Russian Jewish community, eventually, in his late twenties, ending up as a journalist.
It was as he began this profession that Sherashevski’s extraordinary mental skills were revealed to the outside world. His editor was having his usual morning meeting with the staff to portion out all the instructions necessary for the reporters to go about town to do their daily jobs. Everyone was industriously taking notes—except Sherashevski. He, in stark contrast, didn’t even have a pencil and paper at the ready. Assuming that Sherashevski was being lazy, the disgruntled editor called him up on his behavior. Sherashevski explained that he didn’t need to take notes, as he simply remembered absolutely everything, all the time. Disbelieving, the editor asked him forthwith to prove this wild assertion, which he duly did, by quoting back with perfect fidelity every word that the editor had said that morning.
In fact, to this remarkable man, it was incomprehensible that other people didn’t do exactly the same thing—why on earth would someone immediately forget these important facts? What’s the point of that? At this stage, it was clear to outsiders that Sherashevski was far from normal. He was soon sent to a famous Russian psychologist, Alexander Luria, who studied him extensively over a period of thirty years.
Sherashevski’s memory was indeed incredible. He seemed to remember almost everything he came across entirely naturally. One example involved him being read aloud some stanzas of Dante’s Divine Comedy in its original Italian—a language he had no knowledge of. When given a surprise test on this content fifteen years later, he could recall the stanzas so completely that he even repeated the words with the same stresses and pronunciation as they were originally spoken to him.
Although the ability for such vast, faithful recall seems a fantastic mental gift, there were prices to pay, both big and small. One drawback of his exceptional recall was an occasional inability to see the forest for the trees, to discover meaning, structure, or patterns in the stream of information he was busy encoding. For instance, while he could memorize long sequences of numbers, he would be completely oblivious to any simple structure within them, such as ascending numbers 1, 2, 3, 4.
But these unfortunate quirks of his mind were nothing compared to the emotional consequences of his superlative memory. For instance, his imagination was so vivid, so complete, that he often would mistake reality for a daydream. At the very least, imagination would corrupt reality so profoundly that he would struggle to get through something as mundane as a novel—every word in it would conjure up too many distracting images. For similar reasons, he struggled to overcome the crushing weight of his past. Sherashevski claimed to have near perfect memories from before he was one. These were so striking that he fought in vain to banish these carbon-copy recollections, since they also included the overwhelming intensity of these earliest feelings—the absolute terrors, or racking sobs of infancy.
As Sherashevski aged, the burden of this enormous memory became increasingly difficult to endure. He became desperate to find some effective strategy by which to forget things. He drifted from job to job, and unfortunately he died believing that he’d somehow wasted the mental opportunity he’d been given, and that he had never really amounted to much.
Examples like Sheras
hevski demonstrate that sometimes the fading and death of old information can help a person succeed. The person who forgets an optimal amount of old material can have a more accurate, organized view of what’s relevant in the world right now. Likewise, perhaps the death of older creatures can lead to a family or species with collective tools that are better honed for an ever-changing environment.
Replication has always been the driving force of evolution, with survival taking a back seat. But more than this, death as an evolutionary strategy might even be an example of how survival and replication can come to loggerheads, with replication not hesitating to abandon survival if there are gains to be made in terms of having a more accurate, up-to-date implicit picture of the relevant features of the world.
EVERY CREATIVE TRICK IN THE BIOLOGICAL BOOK
Mutations, death, and sex are by no means the only methods for potentially invigorating DNA sequences with useful new ideas, or tweaking the learning rate to reflect whether the microbe’s current world picture is successful or deeply flawed.
There is a large array of tricks that various simple organisms can exploit to discover new ways to successfully survive and reproduce, but one of the most intuitive is simply to try moving a sequence of code somewhere else in your recipe. After all, if much of this code is capturing something useful—perhaps it already creates a functional protein—then its shift to another part of the genome could create a similar protein that might be even more beneficial. So, compared to making changes in a painstaking way, letter by letter, this method is both more powerful and efficient: The potentially useful idea is already half-baked. Of course, mixing up code like this could be utterly disastrous, but there is also a chance that it might be not just a step, but a great leap in the right direction of advantageous innovation.
