Disclaimer: I am not a biologist or a trained scientist. I am writing this as a science enthusiast.
In 1976, Richard Dawkins published The Selfish Gene in which he laid out the already recognized case for personifying the role of genes in evolution as being selfish or self-centered. It’s a humbling view of life, one that examines nature on a timescale of billions of years: that genes exist in competition to perpetuate themselves through whatever torturous, indirect means they can.
“We are survival machines – robot vehicles blindly programmed to preserve the selfish molecules known as genes. This is a truth which still fills me with astonishment.”
At first, the concept of the selfish gene might seem to be an extreme view, as we tend to see our bodies as serving us rather than thinking of ourselves as an elaborate extension of genetic material, and yet that’s the truth.
“Different sorts of survival machine appear very varied on the outside and in their internal organs. An octopus is nothing like a mouse, and both are quite different from an oak tree. Yet in their fundamental chemistry they are rather uniform, and, in particular, the replicators that they bear, the genes, are basically the same kind of molecule in all of us—from bacteria to elephants. We are all survival machines for the same kind of replicator—molecules called DNA— but there are many different ways of making a living in the world, and the replicators have built a vast range of machines to exploit them. A monkey is a machine that preserves genes up trees, a fish is a machine that preserves genes in the water; there is even a small worm that preserves genes in German beer mats. DNA works in mysterious ways.”
Evolution is the natural, predictable outcome of the geometric expansion of living organisms. Too many seeds fall, too many pups are born, too many eggs are laid to ever survive to adulthood and reproduce.
- A single, female salmon produces 7,500 eggs when spawning
- A single oyster produces 114,000,000 eggs a season
- Charles Darwin realised that elephants are the slowest breeding land mammals. Yet if the generations that stem from a single litter could all survive and breed down through numerous generations, there would be 19,000,000 elephants in roughly 750 years
Something has to be preventing the world from being overrun with elephants, salmon and oysters! Darwin realized the intense competition between individuals for limited resources would winnow out the majority of offspring. In addition, the presence of predators and disease and sexual selection also act as a filtering mechanism. Darwin’s great insight was to realize that those animals that survive do so because of a subtle advantage they have over their peers, and in this manner Natural Selection gives rise to the astonishing diversity of life we see around us today.
Much to the surprise of naturalists in Victorian England, Charles Darwin noted that the greatest competition comes from within a species or from closely allied species. He understood that those organisms that survive these intense pressures into adulthood to breed have inherited some slight advantage from their parents. Richard Dawkins clarified this subtle advantage as the triumph of the selfish gene, being a genetic difference that gave one organism an edge over its competitors.
In this way, evolution has led to increasing complexity not dissimilar to a Rube-Goldberg machine. The eccentric, convoluted interactions are secondary to reaching a certain goal. In the case of life, that goal is the propagation of genes to the next generation.
OK, I admit it, this entire post was an excuse to insert that video. OK Go are awesome!
Seriously, at the end of the video there’s a shot of all the people that set up the Rube-Goldberg machine on the mezzanine level. They’re the genes! They’re the ones that ensured this level of complexity was possible and would come to pass.
Perhaps the best example of selfish genes at work is the sloth. Although they’re not directly related in a linear sense, the Megatherium (ground sloth) and the current tree sloth are very closely related, being part of the same branch within the evolutionary tree of life.
In the age of the megafauna, Megatherium was a four-ton, elephant-sized herbivore that was anything but slothful. Some researchers suggests Megatherium could scavenge the kill of a Smilodon saber-tooth cat, and yet today both Megatherium and Smilodon are extinct. The only sloths still carrying the Xenarthra Pilosa Folivora genetic line forward are tree sloths, a poor imitations of Megatherium. If this video is any representation of their survivability, they may not be around much longer.
Nope, this sloth hasn’t been hit by a car. He’s not road-kill. That’s his normal speed. How could such a magnificent genetic line such as Xenarthra Pilosa Folivora be humbled in this manner? By selfish genes, genes that alter without regard to their host.
Genes change randomly, but they only propagate to another generation if their host is successful in breeding. Genetic change is random, survival is not, as it’s governed by Natural Selection, a distinctly non-random process. From the perspective of genes, adaptation is a blind experiment to find the best genetic combination to survive into the future, regardless of how bizarre such variations may be.
Animals such as Smilodon and Megatherium were driven to extinction by a combination of factors, including aggressive human hunters (who would be considered predators) and climate change. As strangely inefficient and ungainly as the current tree sloth may seem to us, it was better suited to surviving these changes. There’s little doubt, however, that it is evolving into a genetic dead-end. Without human intervention, the sloth will go extinct.
Another example of the counterintuitive results of selfish genes at work is the sea squirt.
These beautiful sea creatures have a distinctly different larval stage in their infancy, during which they can swim around seeking an outcrop for their adult phase of life. After roughly three days, they settle and transform from a juvenile into an adult, only that transformation includes absorbing body parts such as their gills, tail, spine-like notocord, eye and brain ganglia. Yep, these guys “eat” their own brains! The pathway scribed by their selfish genes have determined that as adults they no longer need eyes or brains to succeed as an organism.
99.9% of all species that have ever existed have gone extinct. Why? With the exception of the occasional asteroid, they’ve all been driven to extinction by competition with other species. As genes continue to evolve by means of Natural Selection, they cause species to adapt better to compete with each other. Those parent species that fail to keep pace in this genetic arms race fall to extinction.
Species go extinct at a regular rate, known as the background extinction rate, although this has accelerated with human activities. On average, marine species fall extinct every 4-5 million years, while land mammals have an average species lifespan of just over a million years. As alarming as that may seem, extinction often aligns with the emergence of new species. In essence, the child species displaces its parent species.
The genetic relationships between life on Earth have been described by Charles Darwin and others as a tree. But Darwin saw the fallacy in this analogy himself, as the branches and connections within a tree are alive. In light of this, Darwin also likened the evolutionary tree of life to a coral, where living polyps thrive on the dead branches.
The tree of life should perhaps be called the coral of life, [its] base of branches dead; so that passages cannot be seen.
Life and Letters of Charles Darwin – Volume 1, pg 368
What is the selfish gene? In a nutshell, it’s a metaphor to that describes the self-serving agency of genetic material as it propagates itself into the future. The selfish gene is constantly adapting to natural pressures so as to survive the fierce competition of life. In this way, new species branch off from old species, often condemning them to extinction.
Because the title is so arresting, it is easy to assume Dawkins was promoting selfishness when he wrote The Selfish Gene, but he wasn’t. Far from considering the selfish gene as an ideal, Dawkins sought to expose the self-indulgent nature of genes and promote our ability to live above and beyond their pernicious influence.
“We, alone on earth, can rebel against the tyranny of the selfish replicators.”
“Let us try to teach generosity and altruism, because we are all born selfish.”
Fast forward to 2013 and science writer David Dobbs published an article called Die, Selfish Gene, Die. In essence, his argument is that other factors, such as gene expression in different environments, epigenetics and genetic assimilation make the gene-centric view of evolution out-moded. It’s an extremely well written article, but Dobbs overplays his hand.
At the core of Dobbs’ examples is the plasticity and versatility of the gene! Ultimately, there is no other hereditary component being passed from generation to generation. Like our Rube-Goldberg machine, the process may have an astonishing degree of complexity, but someone (genes) had to establish that in the first instance and carry it forward to subsequent generations.
The example Dobbs provides is of the Schistocerca gregaria locust (left) and Schistocerca gregaria grasshopper (right). The differences between these two insects reaches well beyond their coloration. The hind legs of the locust are set at a different pitch. The wings are smaller while the brain is larger, and yet these two insects are the same species. In fact, the grasshopper can transform into a locust in a matter of hours with the right hormones (normally triggered by environmental factors).
As spectacular as this is, it is entirely dependent on the plasticity of the Schistocerca gregaria genes. In the same way, a caterpillar and a butterfly share the exact same genes, but they’re expressed in different manners at different stages of life.
Genes may be more remote in these examples, but they’re still the foundation of the transformation of a grasshopper to a locust. This transformation is only possible because the genes allow for it.
As far as we know, genes are the only way for biological information to be passed from one generation to the next.
One of Dobbs’ claims is that the gene follows, it doesn’t lead. But this is only the case in a handful of examples and if the gene follows then it is following other genes!
Perhaps the clearest example of how genes lead is in Richard Lenski’s 50,000+ generational experiment into the controlled evolution of E. Coli under laboratory conditions. Lenski was able to observe one of his twelve colonies of E. Coli evolve to consume citrate, something E.Coli cannot do in the wild. In a stroke of brilliance, Lenski kept frozen samples of bacteria every 500 generations. This gave Lenski the ability to “replay” evolution from different depths of generations. What he found was astonishing.
E.Coli originally evolved the ability to consume citrate around generation 33,127. If Lenski revived bacteria within that colony from generation 25,000 the ability to consume citrate evolved again, albeit in a different generation. Now, here’s the clincher. If Lenski revived a generation from prior to 20,000 that colony never evolved to consume citrate! What that tells us is that some other correlated adaptation that later supported citrate consumption occurred around the 20,000th generation, roughly 13,000 generations before the bacteria adapted to consume citrate. In other words, Lenski demonstrated that genes lead, they don’t follow!
Genes are a Rube-Goldberg machine. They not only affect the development of an organism, they can act on other genes, they can lie dormant until activated at later stages of life (as in the caterpillar and butterfly), or in response to environmental changes (as in the grasshopper and locust), but their motive (if a gene’s function can be personified in that way) remains the same: to survive and propagate by any means possible.
And this brings us to the Selfish Meme, the title of this article. Memes are ideas. The word itself is a play on the word gene, and describes how information can take on similar characteristics to genes, slowly accumulating from one generation to the next as an idea spreads within a population.
In practice, genes are memes. They’re biological information that replicates and becomes more refined over time.
Ever since life first arose roughly 3.8 billion years ago, it has been spreading its message. We think of animals and plants as distinctly different species, but they are interrelated in a way that is astonishing. All of life on Earth is related at a genetic level. And it’s not just that all life uses DNA. All life uses a variation on the original pattern of life that emerged some 3.8 billion years ago!
Life has adapted and diverged, filling various niches, in constant competition for limited resources in an ongoing struggle to survive and propagate. The selfish gene is merely a manifestation of the selfish meme, Life!
Life is an idea, an ideal that has thrived and survived on Earth against the odds. Rather than being selfish in the arrogant, narcissistic sense of the word, life is selfish in that it seeks to survive in whatever form it can.
Life is the selfish meme.