As I See It: The Challenge To Selfhood
January 21, 2019 Victor Rozek
By almost any measure, it was one of the biggest news stories in last hundred years. And I’ll bet you missed it. In fairness, almost everyone did. After all, there was nothing entertaining or scandalous about it, so it failed to meet the current criteria of news worthiness. Plus, it dealt with concepts not easily collapsed into sound bites. It was loaded with strange, off-putting words like Prokaryotes and Eukaryotes, and alien goings-on such as Endosymbiosis, and Molecular Phylogenetics.
Too complex for Twitter, too impersonal for Facebook. So, almost everyone missed it – at least those of us outside the rarified world of molecular biology.
There were actually three separate but related discoveries that in aggregate will have you looking questionably at your colleagues and, who knows, perhaps even yourself. They are brilliantly documented by David Quammen in a thick, dense, and superbly-written tome called The Tangled Tree: A Radical New History Of Life. The first of these was the discovery of Archaea, a life form that was not known to exist just a few decades ago.
Archaea are similar to bacteria, except they’re not. They’re single-celled organisms whose cells lack a defined nucleus. But they have genes, and a bunch of other characteristics that mean a lot to people in lab coats, but not so much to the rest of us. Suffice it to say that, as microbes go, they are unique enough to comprise a third, separate domain of life, the other two being the aforementioned Bacteria and Eukaryotes, which include fungi, plants, animals and, yes, us.
While discoveries on a microscopic scale may fail to elicit handsprings from the average reader, the unearthing of a new life form is of greater import and rarity (though far less media frenzy) than, say, discovering that Bigfoot actually exists.
The second discovery was HGT, which sounds like a human growth hormone, but actually stands for Horizontal Gene Transfer. HGT was a game changer, although its full implications are still not wholly understood.
It was previously thought that genes could only be inherited upward, from one generation of any given species to its offspring. From that perspective, Darwin theorized that genetic changes occurred over long periods of time driven by successful adaptation or, in some cases, random mutation. Thus, giraffes with longer necks had more access to food and passed that trait on to their young, while during times of food scarcity short-necked giraffes died in greater numbers and passed on nothing at all.
But what if useful characteristics could be inherited from other species? The concept is called Endosymbiosis – a two-dollar word that describes the cooperative integration of living creatures within living creatures. For example, researchers discovered that different types of bacteria can in fact share bits of useful genetic code, which may account for why bacteria so frequently appear to “change overnight.” One of the more disturbing characteristics thought to be transferred horizontally is immunity to antibiotics, which is rampant globally and occurring with unprecedented speed.
But if genes are horizontally transferrable between species, are they also inheritable from other life forms? Can humans possibly inherit genetic material from non-primate sources? The third discovery answers that question and it’s a resounding, “Yes!” It turns out that Archaea, the previously undiscovered life form, accounts for about 8 percent of our genetic code. We humans apparently “come from creatures that, as recently as 40 years ago, were unknown to exist.”
Imagine the implications. Some free-riding organism living on our skin or in our gut was able to splice its genetic code to ours. In some way it made itself useful, and that usefulness was passed on through countless human generations. Such infective heredity was never imagined by Darwin, or by creationists for that matter, and what it says about human nature is open to speculation. This much we know: There are, on average, about 37.2 trillion cells in the human body, and while that number is impressive, it pales in comparison to the number of bacteria we transport, which is estimated to be ten times greater than the number of human cells. We are, in effect, Uber for bacteria.
The acquisition of much of this knowledge would not have been possible were it not for the advent of computers able to process vast amounts of data. Gene sequencing, much less comparing the human genome to that of other species, was dauntingly problematic. Although humans possess only about 24,000 genes, there are some 2.9 billion base pairs in the haploid human genome alone. The process was lugubrious and expensive. Computers changed all that. Sequencing the first human genome cost about $1 billion and took 13 years to complete; today it costs about $3,000 to $5,000 and takes just one to two days. The Internet also plays its part: as genomes of various organisms are charted, they are posted on-line kick-starting the research efforts of other scientists.
The full role of Archaea DNA in our overall makeup is not certain, although there is conjecture that it might either cure or cause disease, or both. Regardless, we are all – at least in part – the product of something akin to a bacterial infection.
If nothing else, the discovery of this primal bonding offered humans an opportunity to rethink the way we view ourselves and our place in the tangle of life. If only we hadn’t missed the story.
The thing that struck me most about reading Quammen’s book is that life appears to be organized around the principle of sharing. Chimps share well over 90 percent of their DNA with us. Bananas share 60 percent. And if our distant ancestors migrated out of Africa, we carry a bit of Neanderthal DNA as well. We in fact share genetic spit with about 100 other organisms. And these organisms come from at least three known branches of life that are intertwined vertically and horizontally. Like different-looking cars built on the same chassis, the fundamental structures of life are widely distributed but closely linked.
In spite of our devotion to individuality, we appear to be neither self-contained nor sovereign creatures. So, as we continue to cling to beliefs about our uniqueness and exceptionality, it may be useful to ponder that we are part chimp, part Neanderthal, part banana, part Archaea, and part God knows what. At the very least it’s an argument for graciousness and humility.
But those, as far as we know, are not inheritable traits.