Fossil Flaw Tosses Years of Evolutionary Research

Fossils may be real, but the methods used to analyze them have come under fire, with implications for Darwinian theory.

It can ruin your whole day. Finding that, after years of work, your assumptions undermine everything you believed can be hard to take. But that’s exactly what scientists at the Universities of Bristol and Reading (UK) announced: “Flawed analysis casts doubt on years of evolutionary research.” What went wrong?

Years of research on the evolution of ancient life including the dinosaurs have been questioned after a fatal flaw in the way fossil data is analysed was exposed.

Studies based on the apparently flawed method have suggested Earth’s biodiversity remained relatively stable – close to maximum carrying capacity – and hinted many signs of species becoming rapidly extinct are merely reflections on the poor quality of the fossil record at that time.

However, new research by scientists at the University of Reading suggests the history of the planet’s biodiversity may have been more dynamic than recently suggested, with bursts of new species appearing, along with crashes and more stable periods.

The new study, published in Methods in Ecology and Evolution by Dr Manabu Sakamoto and Dr Chris Venditti, from Reading, and Professor Michael Benton, from Bristol, says a technique used to ‘correct’ records of diversity in fossils is actually giving misleading results. 

It means almost a decade’s worth of work aimed at providing an insight into evolution may be misleading as it was based on this fundamental error.

The ‘residual diversity method’ for correcting sampling bias in the fossil record was first used in 2007. According to the paper’s summary, “the unorthodox way in which these residuals are generated presents serious statistical problems; the response and predictor variables are decoupled through independent sorting, rendering the new bivariate relationship meaningless.” Some studies can be up to 100% wrong, the press release says.

The researchers ran thousands of simulations to test the data correction method, but found it failed to return correct results in as much as 100% of the simulated cases.

Professor Mike Benton, Earth Scientist at University of Bristol, said: “The core assumption is that any portion of fossil diversity that can be explained by variations in rock volume should be explained by variations in rock volume. This assumption is based on no evidence.

“At the extreme, if you have no rock you get no fossils. However, there are many cases where two time intervals are represented by the same amount of rock worldwide, and yet fossil diversity varies massively. Explain that.“

According to the summary, “The large number of recent papers that used the method are likely to have produced misleading results and their implications should be reassessed.” One of the authors argued earlier this year that dinosaurs were already going extinct before the asteroid hit.

But will the paper’s suggestions improve things? The authors say that “Evolutionary dynamics such as speciation are inherently a phylogenetic process, and only an explicitly phylogenetic approach will correctly model this process.” This means that to interpret rocks in an evolutionary way, you have to start by believing in evolution. That’s circular reasoning. If the fossils are not a record of Darwinian common descent over millions of years, any phylogenetic approach could also “fail to return correct results in as much as 100% of simulated cases.”

A case of the blind leading the blind into the ditch. Time to ditch natural selection (see 10/03/15).