Saturday, October 24, 2009

Extinction and Adaptability

Some Permian (299-251 million years ago) fossil shark teeth came my way recently. These teeth from Xenacanthus texensis, a fresh water shark, are tiny (usually under 2 mm in height) and very weird, with a two-bladed crown and a little cusplet between the blades. Curiously, these sharks managed to trickle through the End-Permian Extinction – the Big Kahuna of extinctions (so far) – only to disappear during the succeeding period, the Triassic. [Later edit: I need to clarify that I'm not sure this particular species X. texensis outlasted the Permian. The order Xenacanthiformes as a whole did, but then the order went extinct in the Triassic.]

Surviving a mass extinction . . . . Interesting thought. I blame evolutionary ecologist Clive Finlayson for the extinction pall I currently find myself under. His recent Wall Street Journal piece (October 10-11, 2009, link here) identifying the five best books on extinction(s) was what really started me thinking about this. (I describe the article in more detail in the column at the right – at least, it is true as of the date of this posting.)

Finlayson has been studying the fate of Homo neanderthalensis. There isn’t a consensus theory on the cause or causes of their extinction after they enjoyed a 200,000 year period of dominance in Europe and western Asia. The competing theories range widely, from H. sapiens having a more energy efficient body structure to H. sapiens acting like we always do when we invade. I haven’t read Clive Finlayson’s new book, The Humans Who Went Extinct: Why Neanderthals Died Out and We Survived, but a recent Scientific American article (Twilight of the Neandertals, Kate Wong, August 2009) describes his thinking which centers, in part, on adaptability. The Neanderthals, according to this theory, had survived many climates changes during their period of dominance but, unlike modern humans, were unable to adapt to a string of rapid swings in climate that punctuated the end of their time on Earth.

Adaptability . . . . I was fuming earlier this week about unwelcome changes. Minor but upsetting nonetheless. A new format for my local newspaper (including little, ersatz pen and ink sketches of the columnists at the top of their columns – do I need to know that a favorite columnist has a double chin? should it make a difference? does it?); my first glimpse of an issue of Natural History magazine in many years (sadly, a pale reflection of its former robust self); and the introduction of Windows 7 (no further comment on that last). If these things are enough to upset my equilibrium in an epoch of war, pestilence, climate change, . . . .

The history of life on Earth is as much a history of extinctions as it is of survival. Faced with the reality that 99.9 percent of all species that ever were are no longer, writer Christopher Cokinos concludes, “Civilization is not a given. Extinction is.” (The Consolations of Extinction, Orion, May/June, 2007 – link here) Come on, give me those consolations. That some do survive is one he offers (but seems to take it away later). He counsels equanimity in the face of the inevitable. In the midst of the woeful Holocene (our current epoch) extinction, accelerated by human action, his advice is do what you can to ameliorate H. sapiens’ impact. Stay calm even when you realize that ultimately even the planet is toast. He writes, “I’m saying too much grief for the world means less energy to help it along.” In essence, there’s no point to the grief.

Perhaps that’s a perspective that comes from age, from long experience with natural cycles. To the 19th century (but deeply contemporary) poet Gerard Manley Hopkins (perhaps my favorite poet), grief in the face of the inevitable end of life is perhaps felt most sharply by the young. In his poem Spring and Fall: to a young child, he offers no consolation to Margaret for her sorrow over the “unleaving” (falling leaves) of Goldengrove. Not surprisingly, the Fall season represents the end of many things, including life. Of course, there’s also the Christian concept of the “Fall of Man” and what presumably flowed from that. (What I took away from all those undergraduate English courses – any great poem in the Western canon can be analyzed with at least one of the Big Trinity – sex, death, or Christianity, and, in Hopkins’ case, usually all three.)

At the poem’s conclusion, Hopkins asserts that Margaret’s grief is really over her own shared fate, telling her:
It ís the blight man was born for,
It is Margaret you mourn for.

Speaking to me, earlier in the poem, he makes it clear that he thinks it is different (though not better) for those with some life experience:
Áh! ás the heart grows older
It will come to such sights colder
By and by, nor spare a sigh
Though worlds of wanwood leafmeal lie;

Sadly, no consolation that. Perhaps, in a strange way, wishful thinking, because I still don’t “come to such sights colder.”

1 comment:

  1. "It is the blight man was born for,
    It is Margaret you mourn for."

    Well, that went straight to my facebook status. Thanks for posting this.


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