THERE ARE NO SHARP DIVIDES WITHIN THE TREE OF LIFE, BUT EVENTUALLY MORE DISTINCTIONS DO APPEAR
In The Tree of Life all distinctions are fuzzy. There are no sharp lines between Nature’s products. All is continuous and without rupture. “Natura non facit saltum,” (Nature makes no leaps) is a biological principle embraced by Darwin whole-heartedly; it goes back to the Middle Ages but was more recently advocated in Darwin’s era by taxonomist Carl Linnaeus (1758) in his first major classification (since Aristotle) of all living things.
But what is important Philosophically and Ethically is that Distinct and Valuable Individuals only exist within The Vaguely Differentiated Whole of Life, a Whole that is itself the only True Unit.
These are the points that have been made in the preceding “Wonders in The Tree of Life” in support of the conclusion that Living Nature Is Continuous and Without Rupture. “Life” is a massive Unity of productive Processes and Products. A brief review follows.
WONDER ONE: The bloodline of each currently living thing (and every living thing at any time) runs unbroken into the past to the original living things some 3,500 millions of years ago. And let us not forget that a million is 1,000 thousands, and that you or I will be lucky to live to 100 years, which really does not come to that much. So really, we each go a long way back in a chain of ancestry. (Why is it these days that we talk about millions and even billions in such a cavalier fashion?)
Individual living things are individual, but their connection to the recent past, the far distant past and even to the future (a next generation) is essential to them. The Tree of Life is continuous from its root to the tip of its furthest branches.
WONDER TWO: Life is a competition that is “red in tooth and claw” (Tennyson), but it is organized to ensure its longevity; there are always “winners” to participate in the next round of the ‘tournament.’ Similar to an elimination tournament with brackets, The Tree of Life is also different in that many “forms” (as Darwin called them) do not always participate in the competition; they are ‘happy’ to remain (largely) as they are and many continue in that form indefinitely.
Yet some lineages of living things did ‘stumble into’ Adaptations of their structure and abilities and now obviously display An Evolved and Progressive set of characteristics. For these creatures, Nature Selected ‘winning’ Adaptations that accumulated into creatures more able to survive and reproduce in greater and greater varieties of ways.
WONDER THREE: The Tree of Life continues to display its Unity through various Values and Qualities among its many products. It is a Whole of Contrastive Structures and Abilities, each only with significance in relation to the others! Our “Values” and “Qualities” are most meaningful only within this Unit, this Tree of Life on Our Planet. Quantitatively, or more ‘objectively,’ these ideas of Quality and Value can be somewhat understood in terms of numbers of chromosomes and lengths of DNA and sequential variation in DNA seen within the many varieties of living creatures. Dennett spends much effort in his book arguing that Our Tree of Life is Possibility that has been Actualized and Naturalized. And what is possible for “Life,” now, has its limits set by the forms so far in existence!
It is The Tree of Life that is the true individual thing; all its individual creatures are its component parts. It is the Whole of which we are a part.
WONDER FOUR: At the core of the broad processes that we call “Evolution by Natural Selection” is a more abstract form of process that is now called “Algorithmic.” These processes build up more complex wholes from smaller and simpler parts—as in one, two, and three digit multiplication; or break down more complex wholes into a simpler unit—as in long division; or guide a process through a series of simple steps—as in a recipe or a computer program. Algorithmic processes often “run” over and over again with the same similar and simple process to achieve outcomes, and often these outcomes can have surprising characteristics. They can build up a simple unit into complex and surprising variations, or they can break down a seemingly unitary thing into surprisingly simple components.
In this way, Our Tree of Life is a massive network of cells built into more and more complex organisms or organic “forms,” or even into biological “machines,” as Dennett and some biologist (like Richard Dawkins) contend. Also, and very importantly, Our Tree of Life is a “River of Genetic Material” (Dawkins) flowing out of the past and into the present. It is a network of strands of genetic units (information stored in a chemical structure) of often growing lengths and sophistications.
WONDER FIVE: The Tree of Life displays an amazing Fullness! There are vast quantities of Individual living creatures arrayed in a vast quantity of Kinds of creatures. To add to this Darwin asks us, in his Origin of Species, to imagine all the kinds of creatures (species) that have ever existed returning and added to all those that now exist. He contends that all of life’s kinds would then form an array as finely distinguished as that of the most luxuriant of varieties that exist today. These kinds would be so finely meshed that no formal definitions would be possible to distinguish them! A Tree without gaps!
To acknowledge the fullness of The Tree allows us to understand Gradualism as the core of Evolution. Darwin realized—and Dennett emphasizes—that the great complexity, diversity, and intricate organization of living things was not possible without a God-like Designer, unless it developed slowly and gradually through minute incremental additions and improvements. Something as complex as an elephant or daffodil could not naturally come into existence in one fell swoop, that would be Vastly Improbable.
As stated in Post III (see it for additional detail), Darwin realized that the world of living things and the fossil record suggested (was evidence of) a tree-like relationship of kinds and its gradual historical development. Large improbable leaps were replaced in his thinking by very small developments! And each of these tested in the Competition of Life and built up through eons of time.
The Tree of Life has Gradually built upon itself and displays a marvelous fullness among its different forms!
WONDER SIX: There are not “Firsts!”
Talk about continuity. Talk about counter-intuitive notions! With all the different kinds of creatures in The Tree, it is mistaken to think that at some exact point the original mammal appeared, or fish, or even the original living thing. “There are no firsts” is a corollary of the reality of Gradualism.
Dennett phrases it: new kinds of living things “must grow out of something less, something quasi-, something merely as if.” The ‘first’ mammals, for example, were merely a quasi-mammal and a quasi-reptile. Mammals became less and less reptilian and more and more mammalian, but there is No Place To Truly Draw “A Line,” as the title of this post series contends.
Biologist Dawkins puts it: In our line of human descent, if we go back into our past in “the range of 185 million generations of parents and grandparents and great grandparents…we come face to face with a fish.…[then] your fish ancestor had a fishy child, who had a fishy child, who had a child…who 185 million (gradually less fishy) generations later, turned out to be you” (my emphasis). Dawkins resists drawing any firm line; some fish became more amphibian-like, then less amphibian and more reptilian, and so forth to mammals and humans. Mother Nature draws no lines nor makes no leaps: Natura non facit saltum.
An interesting case of “no firsts” that was not mentioned in the initial presentation of Wonder Six involves Prokaryotic Creatures (no nucleus, just a small strand of free floating DNA) and a variety of single-celled nucleated organisms. But this case might be called, “No Seconds!”
All these creatures reproduce Asexually through “binary fission.” They double their size by duplicating the relatively little internal machinery they have, including their DNA, and then splitting in two. Biologists call the two new cells “daughter cells,” but what happened to the “parent,” so to speak?
Dawkins rightly points out an issue here. The ‘daughter’ organisms are identical to each other but also identical to ‘the parent’ and that includes its genetic material! Further, the parent’s doubling occurs through mitosis, the normal means for cell Growth in sexually reproducing organisms. Dawkins contends we could say that an Amoeba, for example, grows from one to two to four to eight.. Amoebas, and all copies of itself. Its Reproduction is not much different from what is often called Growth! It grows more copies of itself.
Biologist Ralph Buchsbaum, in his 1948 text on invertebrate animals (that I picked up at a garage sale decades ago), contends, “since an ameba (old spelling) continues to exist in its offspring, it may be said to be “immortal”; and every ameba which now exists is directly continuous through the ages with the first ameba” (my emphasis). Now there is Continuity! Is it One or is it Many?
So here in WONDER SEVEN, I hope we can Convincingly Conclude, that THE TREE OF LIFE IS AS MUCH ONE AS IT IS MANY. The DISTINCTIONS it contains are GRADUAL AND CONSEQUTIVE and are based upon Each Other TO FORM A SINGLE ARRAY OF LIFE.
More kinds of kinds:
Next week, The Conclusion concludes with the recognition that Distinctions—gaps—do appear in The Tree, and the sources of those differences will be outlined. After all, a Daylily is not an Elephant (see Part I), and it would be very hard to mistake the two.