Evolution of Species

For those of you who followed YAG's and my long discussion of whether there really is such a thing as "species" outside the human mind, an article on translating Darwin into Arabic, which lacks a word for species. How do you begin to convey the concept?
There rolls the deep where grew the tree.
O earth what changes hast thou seen!
There where the long street roars, hath been
The stillness of the central sea.
And:
Are God and Nature then at strife,
That Nature lends such evil dreams?
So careful of the type she seems,
So careless of the single life.
It's strange to think that Tennyson was wrong, but perhaps -- at least in animals -- the single life is all there is. It is different in plants. You can take a cutting off a tree and graft it to another, often even one of a very different 'type.' You can pluck a green twig and put it in the right compound, and it will grow a new tree.

Perhaps we could do that with adequately advanced technology even with people. Presumably if I took your right arm and made a new you, it would not be the same person. The seat of consciousness would differ, and that alone means you are not the same. Do trees have consciousness? Somehow they know the sun.

2 comments:

MikeD said...

Taxonomy in general is a strictly theoretical concept. It is our attempt to structure and codify the inherently chaotic and free flowing nature of life into distinct and separate categories and classifications. As such, it will never work. The difference between horse, mule and donkey is on of spectrum, not of rigid differences. According to classic taxonomy, the difference between species is so vast, they cannot interbreed (or an early exception was they could interbreed, but the offspring would be sterile).

But dogs can interbreed with wolves (as one would imagine, given that they are descended from them) and indeed their genus and species are both canis lupis (with domesticated dogs having the "subspecies", a category that did not exist when I was in high school, of familiaris). And yet, both can, and do interbreed with coyotes (canis latrans) even in the wild. This should lead one to believe that the species latrans is a human construct, and that coyotes are actually canis lupus. And of course, the former is absolutely correct, it IS a purely human construct. Nature routinely puts the lie to the concept of distinct species routinely.

We have such examples as the liger (or tigon, depending on what the father was), or the zedonk (zebra-donkey hybrid), or the grolar (or pizzly bear), the list goes on. Many of these crossbreeds only occur in captivity, but some (such as the grolar bear) also occur in the wild. Nor are these crossbreeds necessarily sterile. I was reading an article recently about a grolar bear shot in the wild that according to DNA tests was actually three quarters grizzly. But by every standard short of the capability to interbreed, the differences between grizzly bears and polar bears is vast enough to classify them as seperate species. Behavior, body morphology, hair structure, habitat... all these things are vastly different, and yet, they can interbreed in nature and produce viable offspring.

Taxonomy is useful insofar as it allows us to say that these types of plants or animals have these common traits. But when it comes to the very specific species, I think taxonomy will always break down, and life will make fools of attempts to put it into a neatly ordered box.

Grim said...

Quite right.

(Except that wolves and dogs, according to new evidence, turn out not to be in a parent/child relationship, but rather are both children of an earlier independent 'species.' But that's a minor point.)