Toktok Talkie
by Joh Henschel
Messenger cast in stone
As I write, in front of me squats a little creature, the size of a big toktokkie with pearly eyes perched
on puffed cheeks flanking a globular forehead, its face resembling a quaint caricature of an absentminded professor. It is a phacopid trilobite, an arthropod with three lobes along the length of its
body and many segments along its body, like three pillbugs merged side by side. Way back when, it
had evidently crawled across its shallow sea until it turned to stone, seemingly in mid-crawl, a fossil
with wrinkles, pimples, suspended action and all. It made its way from its bed in rock via a curio shop
to me. It comes as shrapnel from an explosive era, now serving as messenger cast in stone.
As every Namib toktokkie knows, trilobites came into their stride during the Cambrian, the grandest
explosion of biodiversity ever on earth. This took place some 540 million years ago and was not an
explosion of the destructive kind, but the opposite, a time of origins. For three billion years prior to
the Cambrian, life consisted mostly of relatively simple single-celled creatures with only gradually
increasing complexity over time. Then for some 80 million years, the rate of diversification of life
forms increased about five times faster than normal rate, according to a recent study examining the
speed of genetic clocks of living species. Most modern life forms at level of phyla can trace their
origins back to that era, though the bearers of these forms changed species over the course of time.
Trilobites were the most successful animals for over 200 million years starting in the Cambrian, but
lost their stride somewhere along the line. They nearly all bit the dust when Devonian trilobites, such
as my little phacopid, could not face the tumultuous environmental changes some 350 years ago. The
last surviving trilobites then crashed to extinction a hundred million years later. For the past 250
million years Earth has been trilobite-free, except in fossil form, such as my lithic messenger. Horseshoe crabs and horse-shoe shrimps are their closest living relatives.
My Professor Trilobite projects into the era in which beetles, including toktokkies, are the most
successful animals, at least in terms of biodiversity. Like the trilobites, but in different ways, beetles
now face innumerable challenges and pressures of environmental change, of which the humaninduced changes may represent considerably stronger pressures than the long-term, complex, subtle
environmental changes in the Devonian which caused the demise of most trilobites, including my
phacopid: expanding forests caused carbon dioxide to drop and global cooling set in. The current
climate change is in the opposite direction – deforestation, carbon dioxide increase, global warming,
land conversion. Another difference is that humans can now choose to reduce or reverse the causes.
Zophosis moralesi notes that current changes, if left unattended, could approach the hot conditions
Professor Trilobite might have liked. But he cannot return, as all that is left of him serves as
messenger cast in stone.
©Joh Henschel, EnviroMEND, [email protected]
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The Namibian, 26 September 2013