A ninth installment of Cosmos aired on Sunday night — see Jay Richards’s comments yesterday — and it covered one of my favorite topics, plate tectonics, which is also one of the best supported theories in geology. The episode explained how crust is created at mid-ocean ridges, and then gets subducted back into the mantle. The animations and other visual explanations were great, as usual.
Tyson, however, couldn’t resist throwing in his usual dose of theology. Earthquakes, he explained, are caused by tectonic forces “not because somebody misbehaved and is being punished. It’s due to random forces that are governed by the laws of nature.” The interjection seemed totally out of place if all you were trying to do is teach the public about science, as opposed to promoting a materialist worldview. But as we’ve seen, and were reminded again on Sunday, teaching materialism is indeed a large part of Tyson’s agenda.
In discussing plate tectonics, Cosmos offered a nice retelling of the stories of Abraham Ortelius, and later Alfred Wegener and Marie Tharp, who proposed early ideas about continental drift. Wegener, the famous German meteorologist, was harshly ridiculed for advocating such a theory. Neil Tyson explained that Wegener cited as evidence not only the way continents look as if they could fit together like a jigsaw puzzle, but also matching fossils on both sides of the Atlantic. I discussed some of this same evidence in my response to last week’s episode.
Tyson observed, “Most geologists ridiculed Wegner’s hypothesis of continental drift” and preferred “imaginary land bridges to explain away Wegener’s evidence.” But since Wegener could offer no mechanism to explain how the continents might have plowed through the ocean floor, his theory was not accepted. Last week I explained what happened:
Obviously the case for continental drift [in Wegener’s day, the early 1900s] wasn’t nearly as strong as it was after paleomagnetic data was discovered decades later, but that doesn’t mean there was zero good evidence in Wegener’s time, and it doesn’t mean Wegener deserved the nasty dismissal or the ridicule he received. It also doesn’t mean scientists behaved objectively about the situation — that’s an important point because Tyson in Cosmos promotes a na�ve view of science that scientists are like perfectly objective robots.
In this week’s episode, it’s almost as if Tyson heard my concerns — which of course is impossible since these programs were undoubtedly all produced long before the first one aired. Immediately after discussing Wegener, Tyson offered the following wonderful statement acknowledging the fallibility of scientists:
Scientists are human. We have our blind spots and prejudices. Science is a mechanism designed to ferret them out. The problem is we aren’t always faithful to the core values of science.
Exactly. It’s heartening to hear Tyson acknowledge this point. In light of it, I would like to soften my prior statement about Tyson’s “na�ve view.” Yet despite his concession, something still bothered me about Cosmos‘s presentation of how science works. It wasn’t until a few hours after episode 9 ended that I put my finger on it.
Yes, Tyson should be commended for recognizing many past instances where the scientific consensus turned out to be wrong. But his discussions of past scientific errors are always just that — in the past.
Cosmos has done a wonderful job of recalling how old mistaken ideas were overturned — ideas about geocentrism, stellar composition, continental drift, whether lead is dangerous to human health, and more. However, these are all tales from the annals of scientific history. Cosmos presents current scientific thinking as if it were all correct, with everything figured out, never recognizing that today too there are serious questions about dominant scientific ideas. Certainly Tyson never discusses evidence that challenges the prevailing evolutionary view.
In this Sunday’s episode, for example, he spent quite a bit of time discussing the Permian extinction, the largest such event in the history of life on Earth. He is right that many different kinds of animals died out at the end of the Permian. Why did it happen? Tyson tells a convoluted tale involving highly complex causes. He presents these without qualification, as if scientists have solved the mystery and all agree on the same story. Not true. In reality, the triggers of the Permian extinction are still very much an unsolved enigma. Tyson never acknowledges that its causes are very difficult even for modern scientists to decide. That is because of the mysterious grab-bag diversity of the organisms that perished, from deep sea to terrestrial.
Though this mass extinction very likely involved the acidification of the oceans and atmosphere, the precise reasons for it are still unclear to biologists. Proposals range from asteroid impacts, to mass earthquakes, tsunamis, and flood basalt volcanism, to a global freeze, to a runaway greenhouse situation, to methane being released from undersea gas hydrates. Many other hypotheticals are cited. They all may be possible, but if the the entire event took place in a window of just 60,000 years, as seems to be the case, what are the odds of all these factors conspiring to happen around the same time?
Try doing a Google search for “Permian extinction debate” and you’ll see just how much controversy remains. A chapter in a 2012 book, Earth and Life: Global Biodiversity, Extinction Intervals and Biogeographic (Springer-Verlag), explains:
The quasi-perennial debate on the causes of the end-Permian extinction is shifting from a simple uni-parameter to a multi-parameter cause in which short-term and long-term changes of each factor concurred to disrupt the global disequilibrium of Late Permian life. The debate has given rise to a thousand papers or more, often based on several datasets of differing nature (litho-, bio-, chrono-, chemo- and magnetostratigraphy), leading to contrasting or partly overlapping solutions for this enigma. Moreover, it is not unusual to find a set of data collected in one stratigraphic section contrasting with data of the same nature collected from the same section by different researchers. This puts geologists at risk of shifting towards a “nihilistic” scientific position… (emphases added)
Likewise, a 2012 paper in Annual Reviews of Earth and Planetary Science says this:
Few events in the history of life pose greater challenges or have prompted more varied speculation than the end-Permian mass extinction [?252 million years ago (Mya)], the greatest biodiversity crisis in the history of animal life. … During the past decade, debate over the causes of the end-Permian mass extinction has focused on three geological triggers. These are (a) bolide impact; (b) overturn or upwelling of deep water in a stratified, anoxic ocean; and (c) flood basalt volcanism.
Cosmos mentions many of these potential triggers, but gives no hint of how much disagreement there is. Clearly, the Permian extinction happened — the fossil record attests to that — and it’s not unreasonable to think that some of the causes that have been offered could be correct. However when Cosmos confidently tells a story like this, without qualification, it paints an inaccurate picture of what scientists actually say, and whitewashes all the disagreement on this topic.
As a second example, Sunday’s episode presents as solid fact the notion the ancestor of all mammals was a small weasel-like creature that lived in what would later be Newark, New Jersey. It’s a cute story, but the history of mammals is a more complicated subject than Cosmos lets on. Tyson later notes that mammals diversified at the end of the Cretaceous after the dinosaurs died out. But there’s no mention of the abrupt diversification of mammals in what has been called by some a “mammal explosion.” As Niles Eldredge wrote in the 1980s: “There are all sorts of gaps: absence of gradationally intermediate ‘transitional’ forms between species, but also between larger groups — between, say, families of carnivores, or the orders of mammals.” A 2000 paper in Nature describes another conundrum facing researchers who study the origin of mammals:
[M]any orders of mammals and birds are now thought to have originated long before the end-Cretaceous extinction, which occurred 65 Myr ago and which was thought previously to have been the signal for their radiation. If the new timescale can be trusted, these findings present a puzzle and a warning. The puzzle is the absence of fossils. Why have we not found traces of these lineages in their first tens or even hundreds of millions of years?
Now you might respond that Cosmos has limited airtime and can’t get into every unresolved question. That’s true, but nearly every episode does devote a lot of time to discussing scientific controveries. The problem is, it only discusses controversies that were resolved many decades (if not multiple centuries) ago, and never mentions current debates with the scientific community. Contemporary scientific debates — especially when they pertain to the evolution of life — are left entirely unmentioned.
A further example: Tyson repeats the old savannah hypothesis of humans origins. According to this idea, when Central America formed tectonically, it separated the Pacific and Atlantic Oceans, changing ocean currents, and ultimately creating a drier climate in Africa. As the story goes, the drier climate in Africa diminished the woodlands and the forest, forcing our forebears out of their trees. According to Tyson, this is what drove human evolution. Showing an animated scene of an australopithocene-like creature standing in a dead tree amid a dry landscape, Tyson explains at length:
But then it got colder, and the trees thinned out. Broad grasslands sprang up. And our ancestors were forced to traverse them in search of food. You needed a totally different skillset to make it on the savannah.
In the old days you could sit perched on your tree branch and watch the big cats from a safe distance. Now you were playing on the same dangerous field.
The survivors were those who evolved the ability to walk great distances on their hind legs and to run when necessary. This changed the way they looked at the world. Hands and arms were no longer tied up with walking. They were free to gather food, and pick up sticks and bones. These could be used as weapons and tools.
Think of it: A change in the topography of a small piece of land half a world away reroutes ocean currents. Africa grows colder and drier. Most of the trees can’t withstand the new climate. The primates who lived in them have to seek other homes. And before you know it, they’re using tools to remake the planet. The Earth has shaped the course of human destiny.
So the climate got drier in Africa, and “before you know it” human intelligence evolved. Is this compelling? Of course not. Tyson leaves entirely unmentioned any biological explanation of what had to change for the chimp-like brains of our supposed australopithecine ancestors to achieve human intelligence. That’s a gargantuan omission. Nor does he mention that the savannah hypothesis has prominent detractors among evolutionary paleoanthropologists.
As my co-authors and I explained in the book Science and Human Origins, back in 2001 the species Orrorin tugensis was being promoted as possibly the “earliest human link.” It was called potentially “the earliest known ancestor of the human family.” It was also thought that this creature might have walked upright. But because the fossil was deposited in a wooded environment, it threatened the savannah hypothesis, according to which upright walking evolved so our supposed ancestors could stand tall and see over the grass. Martin Pickford, one of the investigators who studied Orrorin, explained:
The fact that Orrorin is found with other fauna that indicates a wooded to forested environment, tends to refute the “savannah” hypothesis of human origins. It seems more likely now that bipedalism originated from an arboreal ancestor, rather than via a knuckle-walking ground dweller similar to chimpanzees. Thus, previous palaeoecological and palaeoenvironmental scenarios of human origins will need to be reconsidered in light of the new data.
Then, when “Ardi” was unveiled in 2009, she became the new human-ancestor du jour, and again the savannah hypothesis was ready to be discarded. Because the data suggest she walked upright in a wooded, forest environment, Time Magazine explained that the savannah hypothesis could no longer be considered correct:
This tableau demolishes one aspect of what had been conventional evolutionary wisdom. Paleoanthropologists once thought that what got our ancestors walking on two legs in the first place was a change in climate that transformed African forest into savanna. In such an environment, goes the reasoning, upright-standing primates would have had the advantage over knuckle walkers because they could see over tall grasses to find food and avoid predators. The fact that Lucy’s species sometimes lived in a more wooded environment began to undermine that theory. The fact that Ardi walked upright in a similar environment many hundreds of thousands of years earlier makes it clear that there must have been another reason.
Writing in Science, prominent paleoanthropologists including Tim White observed that Ardi’s depositional environment “is not easily accommodated by an environmentally deterministic view that involves globally shrinking forests spawning savanna-striding hominids. We contend that this narrative is now undermined by the totality of data from [the location Ardi was discovered].”
Other technical papers have challenged the savannah hypothesis. A 2012 paper in Philosophical Transactions of the Royal Society B observes that the appearance of Homo — which marks the crucial point where big brains first appear — didn’t even take place on the African savannah:
The appearance of the genus Homo, and subsequently of H. erectus (or ergaster), was historically associated with the expansion of the savannah. However, recent reinterpretations of the palaeoclimate record have questioned this hypothesis. Recent re-evaluations of the African palaeoclimate data suggest that pulsed changes may be more important than long-term trends. Moreover, these analyses suggest that the periods associated with this step-change in encephalization may have occurred during a wet rather than a dry period.
Another paper in Palaeogeography, Palaeoclimatology, Palaeoecology found that there have been four dry periods in Africa over the past four million years, meaning that if climate change did drive the evolution of human intelligence, then “any such link is complex,” and not nearly as tidy as Tyson presents it. Another paleoclimate paper (ultimately published in Quaternary Science Reviews) states:
We analyzed published records of terrigenous dust flux from marine sediments off subtropical West Africa, the eastern Mediterranean Sea, and the Arabian Sea, and lake records from East Africa using statistical methods to detect trends, rhythms and events in Plio-Pleistocene African climate. The critical reassessment of the environmental significance of dust flux and lake records removes the apparent inconsistencies between marine vs. terrestrial records of African climate variability. Based on these results, major steps in mammalian and hominin evolution occurred during episodes of a wetter, but highly variable climate largely controlled by orbitally-induced insolation changes in the low latitudes.
Again, my concern isn’t that Cosmos discusses the savannah hypothesis, but that it promotes this disputed theory uncritically, wrongly suggesting that scientists all agree on the causes of one of the most profound questions science can tackle — the origin of the human mind. Cosmos would do better to admit where ideas about human evolution in fact are lacking in evidence, or are controversial.
Missing: More Fine-Tuning
Speaking of trees, Tyson might even mention that alternative hypotheses like intelligent design explain some of the very data that has puzzled evolutionary biologists.
“Trees evolved a way to defy gravity. A plant molecule evolved that was both strong and flexible. A material that could support a lot of weight, but could bend in the wind,” Tyson asserted during Sunday’s episode. That material, of course, is lignin. Tyson explained that “lignin had a downside. It was hard to swallow.” More precisely, lignin is notoriously difficult for organisms to break down and metabolize. If Darwinian processes are so adept at evolving new traits, why has this problem been so hard for evolution to solve? Cosmos doesn’t mention this, but the hypothesis of pro-intelligent design scientists may hold the answer.
Matti Leisola (a specialist in enzymology and enzyme engineering, formerly at Aalto University School of Chemical Technology, Finland), Ossi Pastinen (also at Aalto University in the School of Chemical Technology), and Douglas Axe (Biologic Institute) authored a 2012 peer-reviewed paper in BIO-Complexity, “Lignin: Designed Randomness.” They argue that the reason no organisms can digest lignin is to allow the buildup of humus in the soil, which in turn permits plant growth, all resulting in life that depends on plants. Lignin forms the basis of an ecological fine-tuning argument, pointing to a designed ecosystem. But since Cosmos has thus far refused to mention fine-tuning, it’s probably not interested in discussing this hypothesis.
In their paper, Leisola, Pastinen, and Axe recognize that lignin poses a conundrum for Darwinian theory, which tends to suppose that new molecular functions readily evolve. Instead, they find:
The Darwinian account must somehow reconcile 400 million years of failure to evolve a relatively modest innovation — growth on lignin — with a long list of spectacular innovations thought to have evolved in a fraction of that time.
They thus ask: “How can microorganisms have failed to exploit lignin as an energy source while much less evolvable species have, on innumerable occasions, acquired solutions to problems that appear to be considerably harder?” In their view:
That tension vanishes completely when the design perspective is adopted. Terrestrial animal life is crucially dependent on terrestrial plant life, which is crucially dependent on soil, which is crucially dependent on the gradual photo- and biodegradation of lignin. Fungi accomplish the biodegradation, and the surprising fact that it costs them energy to do so keeps the process gradual. The peculiar properties of lignin therefore make perfect sense when seen as part of a coherent design for the entire ecosystem of our planet.
They conclude that lignin makes an argument for design not just in microbiology, but also in ecology:
Perhaps the oddest aspect of this is that Darwin’s theory is unable to make sense of a situation that otherwise makes perfect sense. If life is the product of intelligent design, it stands to reason that the whole design must be considered — not just the functions of molecules and cells and tissues and organs and organisms, but also the functions of entire ecosystems, all the way up to the global ecosystem.
Whatever you believe about evolution and intelligent design, the origin of humans or the future of climate change, dissent deserves to be heard. It’s a shame that Cosmos presents current science as a monolithic enterprise, where the current “consensus” on basic ideas is fully correct. It scuttles debate. Indeed, debate is hardly acknowledged to occur at all anymore.