Trees of Life

What's the difference between a pile of wet dirt steaming in the sun, and a tree?

I've asked people this question before and have gotten that is-he-off-his-meds look from them. But it's simple enough: a tree and a pile of wet dirt are composed of the same stuff. The difference is that the tree is alive, has life, is a life. That means it takes the moisture and dirt and air and sunlight and transforms it through self-sustained processes into a structure, a form. In effect, the life of the tree takes the raw materials - literally earth, water, air and fire - and uses them to assemble a form to realize or manifest itself.

The form it takes is a branching fractal, and in fact a tree is the paradigm for all such geometric shapes; for example, a chart that shows the branching of lines of descent from an ancestor is known as a family "tree."

Which brings me to the next question that tends to elicit "that look" from people: Where does life come from?

I hasten to add that I'm not asking about the origin or ultimate source of all life; rather, simply this: If we look at a specific living thing, where did its life come from? And the simple answer is: from another living thing. Life comes from life.

What a family tree shows, from this point of view, is the history of transmission of life through successive generations, as it branches, re-branches and multiplies.

Trying to trace these lines of transmission, as I indicated in my last post, can get to be a pretty complex task. And it gets even more complex if you consider that your personal family tree is just one of billions of sub-branches of the overall human family tree, which in turn is just a sub-branch of the mammalian family tree, which again is a sub-branch of a yet-larger "tree of life."

Here's one attempt to represent this situation graphically (click to enlarge; right-click to open in a new browser window):


(Source: Wikipedia)


Drastically simplified as this picture is, it does get the basic idea across, with special emphasis on the tree-like nature of the relationships.

This next one is much more scientifically up-to-date and gives a better picture of how complicated these life-connections have become over time:

(Source: Cold Spring Harbor Laboratory Press)

Even this diagram, however, exhibits a tree-like branching structure that fans out from a single point of origin. Now, there's obviously a lot of room for debate about the exact nature of that point of origin - was it an act of divine creation, or a chance combination of organic chemicals, or the arrival on earth of some existing simple organism from the far reaches of space? - but we can safely ignore that question for now. The point is that all subsequent life consists of an uninterrupted transmission from that one original source.

Here's one more example of a tree-like branching fractal structure:



(Source: U.S. Geological Survey; photo of Selenga River delta on the southeast shore of Lake Baikal, Russia.)

What does this river delta have in common with a tree, apart from a branching structure? I would argue that both can be thought of as objects created by a type of outflow. That's obvious in the case of the river, but perhaps not so obvious with regard to a tree. But I think it's a true way of looking at a tree's growth: The life within the tree is creating a flow up into the sky by assembling its outstretching branching structure, just as the gravitational energy of the river causes it to flow into the sea, depositing a similar structure as it does so.

In the very same way, the tree-of-life diagrams above chart the outflow over the eons of life itself. What we see in these diagrams, in other words, is the history of the flow of a single stream with many branches, just like the one in the satellite photo.

In short, all life on earth is one life flowing from a single wellspring through myriad branches. From that perspective, each individual living thing is related to every other living thing in the same way as the separate leaves on a gigantic tree, or as the fingers of one individual human's hands: distinguishable as objects of a kind in themselves, but impossible and meaningless without their connection to a larger life.

I suggested last time that when we stand in line at the grocery store, there's a fair chance that the cashier or some of the other customers may be our cousins. But clearly, our relatedness is ultimately much closer, much more intimate: There is only one life, a single self-same life, in all of us. It enlivens each of us for a time as it flows through us from its unknown past toward its unguessable future.

Knowing that, how can I possibly regard you or any other living being with ill-will?

Howdy, Cousin

Our culture is so conditioned to the idea that a society is formed by the voluntary association of individuals that it may come as an actual shock to some people to learn that there are alternative models of social formation. In fact, as I think everyone realizes deep down, the original mode of social organization was kinship. And this remained the dominant mode until very recent times, by way of a series of extensions or expansions: from family to clan to tribe to nation, with accompanying formalizations of relationship and status, reaching a peak of elaboration in the kind of hierarchical society exemplified by, say, the court of Louis XVI.

Now, I'm not going to argue that humanity's needs would best be met by a return to monarchy and hierarchy. But I am going to suggest that something of real value is lost in the current atomistic-individualistic view of things. In the understandable rejection of tyrannical absolutism, we’ve gone a bit too far in the opposite direction. One way of looking at it: In the famous revolutionary triad of "Liberté, Égalité, Fraternité," the present-day view seems to regard them as listed in descending order of value; indeed, "fraternité" seems largely to have gone off the radar in our hyper-competitive, social-Darwinist era.

The fact that we humans really are all members of one big family can be illustrated by something I’ve been mulling over recently:

Every human being has two parents. You have two parents, your parents had two parents each, giving you four grandparents, each of whom had two parents, giving you eight great-grandparents, and so on. So in looking back at your ancestry, the number of your ancestors doubles with each generation further back you look.

There's a conundrum here. At this geometric rate of expansion, by the time you get back to your 28-times-great grandparents, you've got a billion ancestors in that one generation. Allowing 20-30 years per generation, that would have been the situation somewhere between 600 and 900 years ago, i.e., sometime between the years 1100 and 1400. But according to experts' best estimates, the total human population didn't reach 1 billion until the early 1800s. And the disparity just gets bigger as you keep counting backwards: If you go back a further 30 generations, the number of your ancestors in that one generation rises to a staggering 1.2 quintillion; meanwhile, the actual population on Earth has shrunk to an estimated 200 million.

So how can we reconcile the obvious truth that everyone has two parents with the equally obvious truth that the human population gets smaller the further back in time we look? I think there's only one explanation: Among those theoretical 1 billion or 1.2 quintillion people, there's a lot of duplication. In other words, the same couples appear multiple times in a given generation, making them your ancestors along multiple lines of descent.

Suppose, for instance, you lived in the 15th-century and your father hiked 20 miles to a (to him) distant village to find his bride. Well, there's a fair chance that his great-great-great grandfather did the same thing in the opposite direction. So your father might have ended up marrying his fourth cousin, and you would have the same 4-times-great grandparents on both your mother's and your father's side – which, incidentally, would make you your own fifth cousin.

What this boils down to is that when you're standing in line at the grocery store, there's a pretty good chance that the cashier or some of the other people in line are your not-terribly-distant cousins. And if you don't believe a more or less random selection of people can turn up these kinds of family connections, recall that during the 2008 presidential campaign, the genealogical experts at Burke's Peerage informed the world that Barack Obama is an 11th cousin of George W. Bush and a ninth cousin of Dick Cheney.

Everyone is aware that all humans are related on the basis of the so-called "mitochondrial Eve" or whatever, but that kind of connection goes back tens of thousands or hundreds of thousands of years, so it may seem pretty remote and not very relevant to our lives today. But it turns out not to be necessary to look back anywhere near that far to see how connected we are, how closely related we all are.

Regrettably, in an age when social atomism has reached such an extreme that even the nuclear family seems increasingly fissile, it may not matter much to a lot of people to be reminded of their kinship with strangers; they’re already used to treating members of their immediate family like strangers. One way of looking at this spreading alienation is as an increasing narrowing of our horizon of interest or concern: from all humankind to our close kin to, finally, our singular personal selves.

It's an even more drastic narrowing of horizons if one looks at it from an even wider perspective than the merely human, as I want to do next time.