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Chicxulub Commentary - Impact factor

Prof. Gerta Keller and friend

Geoscientist Online 18 July 2007

Ted Nield with a cautionary tale of science, peer review, and Charlton Heston…

First, in 1980, came a Nobel Prize-winning physicist and his geologist son who found an end-Cretaceous iridium-rich layer in Italy that nobody else had noticed. They found it all over the world. Like stout Cortez and all his men, they made a truly wild surmise – and appeared to solve a great and abiding mystery. Dinosaurs had been killed off in a global apocalypse from outer space. Walter Alvarez described the theory in a popular book with a truly great title – T. rex and the Crater of Doom. Dinosaurs, amazingly, had got even sexier.

What was more, the public found it was being handed a "nuclear winter" scenario just as one was needed to counteract the Cold War, then re-igniting under Reagan and Thatcher. Carl Sagan, no less, made the connection. Nuclear war, amazingly, had become even deadlier.

Never was a science news story more exciting, better aimed, more timely, or backed by scientists and writers with higher credentials. Like all good stories, it kept moving on. Not long after the "nuclear winter" angle was played out, the crater of doom itself was, it seemed, finally located – at least 170km km across, and conveniently close to the USA, just offshore Yucatan in the Gulf of Mexico. Journalists and NSF fund managers learned how to spell Chicxulub.

A funding tsunami soon flooded in, driven by the possible dino-connection. CGI dinosaurs, looking furtively over their shoulders only to be blown away by shockwaves and broiling hypercanes, became a cliché of the documentary genre. Chicxulub even starred in a Hollywood film, Chuck Heston himself intoning his portentous voice-over for Armageddon (1998) - a disaster movie in every sense.

Not surprisingly, it stuck. Today, among the public, the "killer impact" theory is almost universally accepted as proven fact. It's something everyone knows, and everyone loves. And alas, like so many – perhaps all – those things that we believe because we want to, it's wrong.

That, at least, has been the contention of a small group of researchers led by Professor Gerta Keller (Princeton University), a stratigraphic palaeontologist and expert on the faunal changes at the K-T boundary. She, together with a small band of co-workers, has been doggedly throwing ugly little facts in the path of the Chicxulub juggernaut for years, and receiving, she says, scant thanks for her pains.

A proponent of the multi-cause hypothesis of end-Cretaceous extinction, she has never denied the reality of the Chicxulub impactor. Nor has she denied that it would have contributed towards making the late Maastrichtian a particularly nasty time to be alive. She merely challenged its status as the dino-nemesis – but that, for many, was the greater treason; for it was the dinosaur connection that constituted Chicx’s funding paydirt.

According to Keller, the impact happened too soon - one of a number of major hits that clustered about the K-T boundary, but 300,000 years too old to live up to the claims of those who believed they had found the “smoking gun”. Meanwhile, from more than 200 localities across the world, a database began to be built up that supported an alternate theory involving Deccan volcanism, climate change and (largely coincidental) impacts.

This was not, as we have come to say, “on message”.

“Eternal vigilance is the price of liberty—power is ever stealing from the many to the few…. The hand entrusted with power becomes … the necessary enemy of the people. Only by continual oversight can the democrat in office be prevented from hardening into a despot: only by unintermitted Agitation can a people be kept sufficiently awake to principle not to let liberty be smothered in material prosperity.”

Wendell Phillips (1811–84) Boston, Massachusetts, 28J anuary 1852. See “Speeches Before the Massachusetts Anti-Slavery Society”, p. 13 (1853).

Professor Keller puts her finger on the problem

Despite her distinguished credentials, Keller began to find difficulty in gaining a hearing at conferences; difficulty also in gaining access to certain peer-reviewed journals. Her uncomfortably off-message contributions, hitting the world of Chicxulub studies, turned its subject into an apt metaphor. That there were waves, goes without saying. The sulphur content of the academic atmosphere went up considerably. There was acid rain - and good deal of noxious falling-out.

The backwash even crossed the Atlantic and lapped around the feet of this reporter who, for having written about Keller’s work, attracted his small share of reflected glory. I knew things were serious when (at the end of a stabbing finger) I was told that I had done a disservice to science by giving the oxygen of publicity to “that bloody woman”. When a fellow member of the scientific sisterhood (for such it was) is moved to language of that sort, you know there’s something far more serious - or at least tangible - at stake than science. I got just a little whiff of the empire striking back. Apart from this, of course, the pursuit of science is always a completely disinterested and impartial quest, with nothing but nature as its yardstick and no concern for aught but truth.

Although I wrote that last sentence with an irony that I hope is evident, I do believe it is mostly true. But it can go wrong sometimes, and it is not a service to science to pretend it can’t. Peer review, the process that makes scientific publishing and funding “scientific”, is, like democracy, a “best worst” form of government; but no-one in their right minds would seriously suggest ditching it just because it has weaknesses. We should instead admit that sometimes, even the best organs of state can go bad. Eternal vigilance is supposed to be the price of liberty, and freedom of speech is the first casualty when we fail to exercise it. As in politics, so in life; and science is another part of life - something that people do.

And that, I am proud to say, is where the grey literature can come in (“grey literature” being what you are reading now). When peer review becomes oppressive because a dictatorial putsch has taken over not only the finance ministry but also state TV, only a fourth estate, free of official trammels, can still operate.

And then at last, the grubby grey knight gets his rare chance to ride to the rescue of his hero the white, tend his wounds, buff the mud from his greaves and set him back upon his noble steed…


  • Keller, G et al., 2007a Chicxulub impact predates K-T boundary: New evidence from Brazos, Texas. Earth & Planetary Science Letters 255, 339-356
  • Keller, G 2007b The Chicxulub Impact and K-T mass extinction in Texas. Bulletin of the South Texas Geological Society XLVII, no 9 pp1-26.
“The Great Chicxulub Debate”, a mediated online discussion between Gerta Keller and her opponents, took place on in 2003. It can now be accessed here. Ted Nield