AGAIN, dear reader, it is your Curmudgeon’s pleasure to bring you another column by the splendidly-evolved Olivia Judson, an evolutionary biologist and a research fellow in biology at Imperial College London.
This article, part of Dr. Judson’s series in the New York Times, is titled Reflections on an Oyster, in which Olivia explains the rarity of fossils. Here are some excerpts, with bold added by us.
Olivia begins rather provocatively:
An oyster shell sits on the table in front of me. But I’m not about to have an oyster feast: I won’t be squeezing a lemon, grinding pepper and lifting the shell to my lips. This isn’t because I’d choke, though the animal from this shell would be far larger than one throatful. It’s because this oyster died more than 20 million years ago, and the shell is empty.
Oysters …squeezing … grinding … your lips … your throat … . Don’t do this to us, Olivia!
Let’s read on. Things will become more focused as we regain our Curmudgeonly composure:
It’s hard to become a fossil, to leave a tangible record of your presence on the Earth millions of years after you died. Most of us swiftly get recycled into other beings. After all, the competition for corpses is fierce. Species of bacteria, worms, ants, flies, beetles and even some butterflies have a taste for rotting flesh. And that’s without mentioning larger scavengers, like vultures, hyenas and mongooses.
The disappearance of a body can be rapid. To give one of my favorite examples, in the tropical forests of the Congo, an adult male gorilla — all 150 kg (330 lbs.) of him — will be reduced to a pile of bones and hair within 10 days of his death. Within three weeks, there will be nothing left but a few small bones. And this is without the help of creatures like hyenas, which pulverize and eat the bones of all but the largest animals. (That’s why hyena scat is white: it’s the remains of powdered bone.)
Thanks to Olivia, we have learned more about hyenas than we ever thought we’d know. Moving along:
But evading Nature’s undertakers is only the first step in becoming a fossil. If you want to be preserved for millions of years, you also have to choose the right place to die. If you’re lucky, you’ll have a quick burial in, say, the silts and sediments of a river bed, or under volcanic ash.
Are you taking notes, gentle reader? If you wish to be a fossil, choose your final location with care. We continue:
All this means that the fossil record of the Earth is inherently skewed. For instance, river deltas are great places to get buried and preserved. So animals that lived in or near them are much more likely to make it into the fossil record than most other creatures; as a result, we have river-delta fossils in much greater numbers than most other types. But during life, those animals were by no means the most numerous. As one friend put it, it’s like making an inventory of current North American wildlife based on what you find at the mouth of the Mississippi.
It seems that life is unfair even when it’s over. Here’s more:
In light of this, the fossil record we do have becomes the more amazing. Yes, it has limitations. Yes, there are many organisms that we can never know about, for we will never know they existed. They breathed, and changed the atmosphere; they preyed on other beings; their carcasses became food, and altered the composition of the soil; but they left no physical trace, no clues to what they looked like, to the lives they led, the mates they seduced, the songs they sang.
That’s almost poetry, and she’s writing about fossils! Another excerpt:
Yet it is not surprising that the fossil record is incomplete — how could it be otherwise? What is remarkable is that we know as much as we do about the lives of the organisms of the past. … And recent years have yielded up an astonishing wealth of “transitional forms” — organisms with bodies that are in between those of, say, dinosaurs and birds, fish and amphibians, or even whales and their nearest living relations, the hippos.
There’s more. Much more. Click over to the New York Times and read the entire essay. You can’t go wrong with Olivia.
But right at the end, Olivia gives us a bit of bad news:
From today, I’m taking a six-month sabbatical to work on a new book; I’ll be back at the beginning of July. But don’t go away: while I’m off, several guest columnists will be writing, starting in a couple of weeks. They’re an interesting and lively group, and I think you’ll enjoy their contributions.
Gone until July? We’ll be looking at the guest columns, but it won’t be the same without you, Olivia.
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