Over the weekend I stumbled across this link to a story about evolution on the FOX news web site. Surprisingly it was not an anti-evolution diatribe (or perhaps not, most of my knowledge of FOX news is based on second hand info - I don't think I've ever watched it for more than a couple of minutes straight) but rather a story about a possible new explanation for the Cambrian explosion. If you haven't heard of the Cambrian explosion it refers to the beginning of Cambrian era and the rather 'sudden' start to an extensive fossil record of multicellular life. This occurred 530-540 million years ago. This means that most of the earth's fossil record occurs in only slightly more than 10% of the earth's history.
What caught my eye was the title which referred to a solution to Darwin's dilemma. This triggered my interest. A lot of science reporting tends to overdramatize the importance of new research findings, sometimes to the point of completely misconstruing its actual importance. Secondly a lot of reporting on evolution in particular jumps back to Darwin as a reference point completely ignoring a century and a half of intervening research which has improved our understanding of evolution considerably since the publication of the Origin of Species.
Reading the FOX article confirmed my suspicions (more about that in a minute) but also revealed that the article was a slightly abbreviated version of one originally published at some site called newser. The newser article is, in turn, based on one from ABC news a week ago. The newser article also cited this Live Science article and a press release by the University of Texas to give a bit more background.
The original ABC story is a pretty nice piece of journalistic synthesis. The main focus is on work by geologist Ian Dalziel at UT Austin who has apparently discovered that the tectonic plates were moving in ways differently than previously understood and possibly resulted in the formation of shallow seas and massive nutrient upwelling at the time of the Cambrian explosion. The ABC report tied this in with the following.
A paper published last week in Science by Noah Planavsky of Yale University and Christopher Reinhard of Georgia Institute of Technology, based on ancient sediments from China, Australia, Canada and the United States, suggests that scientists have long overestimated the amount of oxygen in the earth's atmosphere in the pre-Cambrian era just before the "explosion."
Dalziel's findings may explain the reason for the increased oxygen although he is, to his credit, very clear that he has not demonstrated that the geological changes he discovered caused the Cambrian explosion but that it is an interesting line of thought for further study. I should also note that I am not a geologist and have not read the original paper. My issue is not with the reporting of the current research but rather with the context in which it is placed by the various news sources.
Certainly Darwin, like any other natural historian of his era would have found the Cambrian explosion rather baffling and it is probably one of the most intriguing events in the history of life. However a lot more is known about the history of life now. Which is why statements like the following close to the start of the ABC article are kind of irritating.
Some estimates indicate the earth was only a few tens of millions of years old when the first simple organisms appeared. There was a little evolution over the first billion years when single-celled organisms morphed into bacteria, slimy algae and other simple kinfolk, but it was still pretty dull.
It didn't get much better until nearly 600 million years ago when the most dramatic period in the biological history of the planet erupted in what has become known as the "Cambrian Explosion."
I don't really have a problem with the cutesy language except that it is vague and turns into what's below by the time it gets to newser.
For about a billion years after the dawn of life on Earth, organisms didn't evolve all that much. Then about 600 million years ago came the "Cambrian explosion."
Given that life on earth is over 3.5 billion years old those two sentences just wiped out over half of it. So there's a pretty major factual error right there. But here is some background that they left out.
1) Darwin did think evolution proceeded very slowly and gradually. It has been appreciated for some time that he over emphasized this in his writing and that evolution can occur quite rapidly. The fossil record, studies of molecular evolution, and studies of evolution in wild organisms all indicate that rapid evolution is quite possible under the right conditions. This may not explain the Cambrian explosion but it does make it less surprising.
2) Detailed studies of the fossil record have shown that multicellular life evolved well before the Cambrian explosion. Although still a dramatic event it has been shown to be a less 'out of nowhere' event than would have been thought in the 1800s.
3) This idea that nothing happened and evolution was dull prior to multicellular life shows an astonishing lack of perspective for anyone with even a modest amount of training in modern biology. The freaking cell had to evolve with all of its incredibly complex and interlocking mechanisms to maintain itself. And then the even more complex freaking eukaryotic cell had to evolve. That is a huge amount of evolutionary heavy lifting.
I also heard of the low oxygen concentration idea many years ago but it just may not have been documented until now. Again, not a geologist.
I realize that this may sound pretty trivial to the general public but I do feel that a lack of context in science reporting (and in fact any reporting) leads to quite a bit of misinterpretation.