Darwin vs. the Fossils
What could be more iconic to evolution than dinosaurs and the horse series? Museums often display skeletons of these animals as proof of evolution. The real story told in scientific papers is often very different. Two recent studies present major, serious challenges to Darwin’s theory.
- Horse series: The old straight-line chart of horse evolution from a small dog-like animal to the modern thoroughbred is out. Othniel Charles Marsh and Thomas Henry Huxley in the 1870s were possessed of a vision of straight-line evolution known as orthogenesis. The iconic series presented in museums and textbooks has long been known to be erroneous. Most evolutionists today realize that Darwin’s theory does not call for a single progressive line of descent, but rather a branching tree or bush. Still, if Darwin’s theory is true, gradualism should prevail, with numerous intermediate forms progressing from ancestors to descendents. Darwin himself taught that “Natural selection acts only by taking advantage of slight successive variations; she can never take a great and sudden leap.” Then came a paper in PNAS this week.1
A team of 22 international researchers led by Ludovic Orlando of the University of Lyon in France did one of the first-ever comprehensive comparisons of ancient DNA (aDNA) from fossil equids (including horses, donkeys and zebras). These specimens came from 4 continents. The results were so shocking, they call for an almost complete overhaul of the horse series. For one thing, they concluded that many specimens relegated to separate species are actually variations on the same species. For another, they found that for evolution to be true there had to be sudden bursts of diversification – Cambrian-like explosions within the horse family – contrary to Darwin’s prohibition of great and sudden leaps. Here’s how they began:
The rich fossil record of the family Equidae (Mammalia: Perissodactyla) over the past 55 MY has made it an icon for the patterns and processes of macroevolution. Despite this, many aspects of equid phylogenetic relationships and taxonomy remain unresolved. Recent genetic analyses of extinct equids have revealed unexpected evolutionary patterns and a need for major revisions at the generic, subgeneric, and species levels. To investigate this issue we examine 35 ancient equid specimens from four geographic regions (South America, Europe, Southwest Asia, and South Africa), of which 22 delivered 87?688 bp of reproducible aDNA mitochondrial sequence. Phylogenetic analyses support a major revision of the recent evolutionary history of equids and reveal two new species, a South American hippidion and a descendant of a basal lineage potentially related to Middle Pleistocene equids. Sequences from specimens assigned to the giant extinct Cape zebra, Equus capensis, formed a separate clade within the modern plain zebra species, a phenotypicically [sic] plastic group that also included the extinct quagga. In addition, we revise the currently recognized extinction times for two hemione-related equid groups. However, it is apparent that the current dataset cannot solve all of the taxonomic and phylogenetic questions relevant to the evolution of Equus. In light of these findings, we propose a rapid DNA barcoding approach to evaluate the taxonomic status of the many Late Pleistocene fossil Equidae species that have been described from purely morphological analyses.
What they are saying is that the horse series had been built on morphological analyses – comparing the outward features of skeletons. The molecular data they studied (ancient DNA) doesn’t match up. They spoke of “explosive diversification” twice in the introduction, and then “rapid radiation” once for horses and another time for elephants and bears. The only time they mentioned “gradual” was to debunk it: “The original linear model of gradual modification of fox-sized animals (Hyracothere horses) to the modern forms has been replaced by a more complex tree, showing periods of explosive diversification and branch extinctions over 55 MY” [million years]. Similarly, the only instance of the word “transition” connotes another bang: “The end of the Early Miocene (15?20 MYA) marks a particularly important transition, separating an initial phase of small leafy browsers from a second phase of more diverse animals, exhibiting tremendous body-size plasticity and modifications in tooth morphology. This explosive diversification has been accompanied by several stages of geographic extension from North America to the rest of the New and Old Worlds.” What this means is that these animals appeared in the fossil record suddenly without the gradual transitions Darwin expected, then appeared quickly all over the world.
They tried nonetheless to put the data into an evolutionary tree. What resulted was confusion, disjunction, and irresolution. Sample quote: “The lack of resolution is complicated by the short divergence time among caballines and New World horses (circa 0.5 MY; nodes A and B/B1/B2; Table S4) and the lack of a close outgroup, as has been noted with mammoths (30, 31). When the rhino was used as an outgroup, the data were RY coded to reduce possible mutation saturation artifacts resulting from this the deep divergence (55 MYA), but this removed support for most nodes.” Not only that, their best fit was at odds with previous theories. This quote gives the feel of their frustration:
According to our molecular dating estimates, the different equid lineages (hippidiforms, NWSL, caballines, and noncaballines) originated 3.7?4.3 MYA (95% confidence range: 2.8?6.2 MYA; Table S4). This directly contrasts with classical palaeontological models of hippidiform origins as descendants of the Pliohippines (divergence time with the Equus lineage ~10 MYA) (19) or as a lineage diverging from a (Dinohippus, Astrohippus, and Equus) clade ~7?8 MYA (32), and considerably reduces the time gap between the supposed divergence of the hippidiform lineages and their first appearance in the fossil record 2.5 MYA (20).
They had to leave resolution of these and other problems to future research. Here’s one of their main take-home lessons: paleontologists have been too quick to split specimens into different groups. The DNA data are showing that equids that appear morphologically different are really just variations of the same kinds. Their final paragraph showed that their bombshell discovery could have impacts on many other evolutionary trees – including those of human ancestors:
This pattern of taxonomic oversplitting does not appear to be restricted to equids but is widespread amongst other Quaternary megafauna [e.g., Late Pleistocene bison (49); Holarctic cave lions (50); New World brown bears (51), and ratite moas (52, 53)]. Together, these findings suggest that the morphological plasticity of large terrestrial vertebrates across space and time has generally been underestimated, opening the way to detailed studies of the environmental, ecological, and epigenetic factors involved. Interestingly, in this regard the human lineage shows a rich fossil record over the last 6 MY, spreading over seven possible genera and 22 species (54). The exact number of taxonomic groups that should be recognized is still debated, even within our own genus (55), and in this context it is pertinent to consider the degree of taxonomic oversplitting, from species to generic levels, that aDNA has revealed amongst Late Pleistocene equids and other megafauna. A further important implication of this finding is that the number of megafaunal extinctions and loss of taxonomic diversity from the Pleistocene to modern day may not have been nearly as large as previously thought, at least at the species or subspecies level. Conversely, at the molecular level, aDNA studies on a wide range of large mammal taxa (49, 50, 56, 57) have revealed that the loss of genetic diversity over this time period has been much larger than previously recognized with major implications for the conservation biology of surviving populations (58).
non-sequitur to link this story to current climate debates. At best, it is a distraction from the point of the article.
- Dinosaurs: Maybe Darwin’s gradualism can be rescued with dinosaur fossils. Not so; PhysOrg reported, “Fossils shake dinosaur family tree.” A well-preserved fossil found in New Mexico, named Tawa after a Hopi sun god, is generating a similar song and dance we just saw for the horse series: “…an interesting fact about dinosaur evolution: once they appeared, they very rapidly diversified into the three main dinosaur lineages that persisted for more than 170 million years.”
The operative word is appeared. This leaves important questions begging: appeared how and from what? Darwin’s theory of common descent wants answers. The new fossil is roughly similar to Herrerasaurus, considered by some to be the putative ancestor of the dinosaurs. But Herrerasaurus is shown by its resemblance to Tawa to be a theropod. In short, a fully-formed theropod “appeared” followed by an explosive appearance of all three main dinosaur types, which changed little for 170 million years in the evolutionary timeline. Here’s how Sterling Nesbitt (U of Texas at Austin) explained it: “Tawa pulls Herrerasaurus into the theropod lineage, so that means all three lineages are present in South America pretty much as soon as dinosaurs evolved.” This has to include the lumbering sauropods with their bird-hips and the carnivorous monster theropods with their lizard-hips; and what about the marine reptiles and pterosaurs? They, too, “appeared” as from nowhere.
Another complication about Tawa is what it suggests about the source location of the missing ancestor, and how the descendents migrated. At the New Mexico site, “Tawa skeletons were found beside two other theropod dinosaurs from around the same period,” the article continued. “Nesbitt noted that each of the three is more closely related to a known dinosaur from South America than they are to each other. This suggests these three species each descended from a separate lineage in South America, rather than all evolving from a local ancestor, and then later dispersed to North America and other parts of the supercontinent Pangaea. It also suggests there were multiple dispersals out of South America.” Positing three ancestral lines solves little; it multiplies the missing-ancestor problem threefold.
More on Tawa was reported by Nature News. Jeanna Bryner at Live Science put a positive spin on the story, claiming, “Geographic Origin of Dinosaurs Pinned Down.” She even put imaginary feathers (06/13/2007) on the critter: “Like Velociraptor, the dinosaur was likely covered with feather-like structures and sported claws and serrated teeth for snagging prey.” If the ancestor if this creature crawled like a crocodile or amphibian, that’s a pretty dramatic overhaul in the body shop. And what happened to the lumbering sauropods, if this is close to the ancestor of all dinosaurs? It already looks like an advanced theropod. Bryner did not explain how these dramatic changes in morphology occurred by an evolutionary process. She only suggested that climate was a factor: “They think the answer is climate. For some reason, only the carnivorous dinosaurs found temperatures in North America to be hospitable, the researchers suggest.” (Note that her venue is Live Science, not Live Speculation.)
This month in the Creation Research Society Quarterly, the multiple-PhD creationist Dr. Jerry Bergman examined the issue of dinosaur evolution.2 He showed that the ancestry of dinosaurs is a hodgepodge of speculation without evidence. He demonstrated this for the whole dinosaur clade, then specifically for the ceratopsids (like Triceratops) and the tyrannosaurids (like T. rex). The picture, he said, is one of abrupt appearance, stasis, and extinction. “Over 30 million dinosaur bones and parts, some in excellent states of preservation, have been identified, and although much speculation exists, not a single documented plausible direct ancestor has yet been located,” he said. “All known dinosaurs appear fully formed in the fossil record.” The news appears to confirm that picture.
Science Daily’s write-up contained this illustration of how evolutionary speculation operates: “Based on an analysis of the relationships among Tawa and other early dinosaurs, the researchers hypothesize that dinosaurs originated in a part of Pangea that is now South America, diverging into theropods (like Tyrannosaurus rex), sauropodomorphs (like Apatosaurus) and ornithischians (like Triceratops); and then dispersed more than 220 million years ago across parts of Pangea that later became separate continents.” No basis for the analysis was given – other than a prior belief in evolution. The artist reconstruction of Tawa looks nothing like an Apatosaurus or Triceratops. The article did not mention any physical evidence of an ancestor or a location for it. It did not mention any plausible way for a putative ancestor to “originate” or “diverge” into three very different body types. Yet, somehow, this fossil “provides fantastic insight into the evolution of the skeleton of the first carnivorous dinosaurs” the article claimed. As for causes for these changes, the study attributed all the evolution to climate and the missing ancestor’s ability to move around. No evolutionary or genetic theory was defended, and no fossils were presented to support the “hypothesizing” Dittos for the short write-up in National Geographic, which partly funded the research. It claims the new fossil “boosts the theory” that dinosaurs “arose” then “diversified into three lineages and migrated out to the rest of the world, scientists say.” If anyone in any other field, or a dad telling his children a bedtime story, invoked such evidence-free speculation, would it be called science? The BBC News even allowed a scientist to state, without confrontation, that this fossil “filled a gap in the fossil record”.
As icons for Darwinian evolution, it appears that horses and dinosaurs are not pulling their weight. To show this is not an isolated problem, two other articles this week proclaim the same anti-gradualistic theme of abrupt appearance. A press release from Howard Hughes Medical Institute Dec. 10 talked about experiments on stickleback fish. “Biologists have been debating since Darwin’s time about whether evolution can proceed in a single large step or if numerous, individually minor changes are necessary.” the press release said. “The new study, reported in the December 10, 2009, issue of Science Express and led by HHMI investigator David Kingsley of Stanford University, provides evidence that evolution can leap rather than shuffle.” Even so, the article is primarily about gene loss and alterations in the regulation of existing genes – not the increases in genetic information that molecules-to-man evolution would require. The best they could characterize the study was, “we are getting the first tantalizing glimpses of how new variants arise.” Call back when you can see clearly.
Finally, Ken Smith reported for Nature News that “New species evolve in bursts.” PhysOrg waxed even more dramatic, saying “Evolution may take giant leaps.” What’s this about? Mark Pagel compared four models of speciation, using “more than 100 species groups from the animal and plant kingdoms, including bumblebees, turtles, foxes and roses.” His analysis refutes the “Red Queen” hypothesis of gradual, steady evolution, instead suggesting that “New species might arise as a result of single rare events, rather than through the gradual accumulation of many small changes over time, according to a study of thousands of species and their evolutionary family trees.” Though a staunch evolutionist himself, Pagel realized how anti-Darwinian his feather-ruffling conclusion is: “It really goes against the grain because most of us have this Darwinian view of speciation,” he said. “What we’re saying is that to think about natural selection as the cause of speciation is perhaps wrong.”
Maybe the new motto of the evolutionists should be, “One small step for a model; one giant leap for evolution.” Or is that a leap of faith?
1. Orlando et al, “Revising the recent evolutionary history of equids using ancient DNA,” Proceedings of the National Academy of Sciences published December 9, 2009, doi: 10.1073/pnas.0903672106.
2. Available to the public in PDF at CRS. Bergman, Jerry, “The Evolution of Dinosaurs: Much Conjecture, Little Evidence,” Creation Research Society Quarterly (Vol. 46, No. 2), Fall 2009.
Single rare events – could that include something like six days of creation? After all, the Darwinians are asking us to believe in miracles, anyway (sudden “giant leaps”, and animals that “arise” out of nowhere). While Darwin is mumbling pathetically, with tears in his beard, let’s think about what the fossil evidence is telling us.