Got That? The Complex Story of African Mammal Evolution
The article by Jean-Jacques Jaeger in the Dec. 4 issue of Nature1 is pretty upbeat about the evolutionary history of African mammals, but takes a bit of untangling to follow.
He begins confidently, “For some 40 million years, the Afro-Arabian landmass existed in splendid isolation. A newly described fossil fauna from the end of that time provides a window on the evolution of the continent’s large mammals.” (He refers to a fossil group named the Chilga biota, found in the Ethiopian highlands by Kappelman et al., described in the same issue.2) Let’s take a look out said window and see how evolution has unfolded:
During most of the Cenozoic era, from the Cretaceous�Tertiary boundary 65 million years ago until roughly 24 million years ago, Afro-Arabia was an island continent drifting steadily northwards towards Eurasia. Fossil mammals documenting this period are scarce and belong almost exclusively to endemic forms restricted to Afro-Arabia, such as proboscideans, hyraxes and elephant-shrews. But by around 24 million years ago, a permanent land bridge had formed between the two landmasses. A burst of faunal interchange followed: many Eurasian mammals, such as rhinos and ruminants, dispersed into Africa, and some Afro-Arabian mammals, such as elephants, migrated in the opposite direction. (Emphasis added in all quotations.)
That forms the plot line, but there are problems. The Chilga specimens he describes seem to fit the story, but there are puzzles among the bones:
Among the proboscideans recorded are primitive forms such as Palaeomastodon and Phiomia (also known from older deposits in Egypt). But there are also representatives of modern families, for example taxa such as Gomphotherium, the earliest proboscidean on the branch leading to extant elephants. Another surprise is the oldest occurrence of deinotheres, peculiar proboscideans with downward-curved lower tusks, which were previously recorded only from rocks younger than 24 million years old. The new species of deinothere displays molars that are more ‘bunodont’ in form (that is, made of several distinct cusplets arranged in transverse crests) than its descendant, whose molars display plain transverse crests. This discovery seems to rule out the possibility that deinotheres are derived from an ancestor bearing plain, transverse-crested molars, as was formerly supposed, and provides new evidence about proboscidean evolution.
Jaeger bemoans the scarcity of the fossil record for this period, but claims, “Nonetheless, considerable information has been inferred from the evidence we do have.” He talks about how systematists have grouped the African fauna into a superorder Afrotheria based on fossil and molecular evidence. Though “African mammalian faunas are dominated by these endemic forms,” a few other groups did get over to the big island somehow, including our alleged remote ancestors, the catarrhine primates, fathers of hominoids. These “newcomers” went through “rapid evolution” on the landmass, he claims.
Even though the Chilga fossils are supposed to pre-date the land bridge, Jaeger says, “The Chilga mammals also yield insights into the dynamics of the faunal interchange between Afro-Arabia and Eurasia.” How is that possible? By seeing what pre-existed before the interchange, he feels it is possible to document that “the ensuing ecological competition ended with winners and losers.” I.e., some animals were destined to fall in numbers, others to multiply and diversify.
The Chilga fossils do leave a few research items for paleontologists:
Finally, the discoveries of Kappelman et al. highlight two other palaeobiological issues. First, on northern continents glaciation caused a significant cooling around 33 million years ago, which resulted in numerous extinctions among mammalian communities. From these new data, however, it seems that large Afro-Arabian herbivores were not affected, either at that time or later, implying that the climatic changes were less severe on southern continents. Second, the fossil record of the Afro-Arabian continent is not only scanty but also largely concentrated on the northern edge. This has led to the proposal that other groups of mammals existed in Afro-Arabia during its period of isolation, but that they were restricted to more southern latitudes. However, the Chilga mammal community is rather like that found at Fayum in Egypt, which is some five million years older, providing hints that there was little provinciality among Afro-Arabian mammals at that time. As yet, though, we have unveiled only a few of the secrets of mammal evolution on the Afro-Arabian continent. Many more surprising discoveries are to be expected.
1Jean-Jacques Jaeger, “Mammalian evolution: Isolationist tendencies,” Nature 426, 509 – 511 (04 December 2003); doi:10.1038/426509a.
2Kappelman et al., “Oligocene mammals from Ethiopia and faunal exchange between Afro-Arabia and Eurasia,” Nature 426, 549 – 552 (04 December 2003); doi:10.1038/nature02102.
Our policy before commenting on a paper is to approach it with an open mind as much as possible, and give the author the benefit of the doubt. We give the author or authors their day in court, and begin with the premise innocent till proven guilty. But we also want to see hard data that support any conclusions, and the conclusions must survive the Baloney Detector to be granted any credibility or respect. Bluffing is a big turn-off.
With that in mind, not much survived in this paper. Jaeger sounds very confident that evolutionists are very well on the way to understanding mammal evolution; it’s just a matter of time, cleaning up a few remaining puzzles. His position is typical of evolutionists. The story only makes sense to someone already convinced evolution is true. The puzzles outnumber the confirmations, but since non-evolutionary alternatives are disallowed from the outset, no amount of negative data can ever falsify their claim that all animals have bacteria ancestors.
How Jaeger can keep from biting his fingernails at the sheer number of puzzles is the real puzzle. With your critical, open-minded eye, consider his confessions of these non-evolutionary observations:
- The fossil record is scanty.
- Known fossils are restricted to isolated locales on the northern periphery of Africa.
- “Modern” representatives are mixed in with alleged “primitive” specimens, even though the Afrotheria were supposedly isolated from Europe and Asia for millions of years and had plenty of time and space to evolve all they wanted.
- The teeth of the deinotheres evolved from complex to simple, not the other way around.
- Some critters managed to get to Africa, while others remained isolated. Was there some kind of discriminatory ferry system operating?
- After the land bridge formed, there were winners and losers, but no way to predict according to evolutionary theory who would win or lose.
- A long global ice age seemed to have no effect on the Afrotheria.
- There was little provinciality among African mammals (i.e., geographic isolation; the animals were free to roam widely), yet fossils are rare in the interior.
Anyone see evolution here? From just a few bones, at a few locations on the northern edge of the huge continent of Africa, Jaeger proceeds to weave a magical mystery tale out of thin air (and hot, spinning air at that). He daydreams about floating continents, selective weather, selective migrations, selective fossilizations, selective winners and losers, and land bridges that both increase and decrease the evolutionary adaptations of immigrants. Almost every observation is counter to what was previously believed. Nowhere does the reader see any hard evidence of transitional forms. The only solid evidence points to are dead things; remnants of advanced, complex, large, healthy, well-adapted mammals. The dates are part of the myth; they are made up, based on methods that depend for their validity on evolutionary assumptions and wild extrapolations into the unobservable past.
In a courtroom, the attorneys have the opportunity to give an opening statement. These are usually overconfident claims that the facts of the case are going to prove their side. But then, witnesses have to submit to cross-examination on matters of fact, and the attorneys are prevented from spin doctoring, asking leading questions, or going beyond the evidence. Unfortunately, the news media often take the opening statement of the Darwinist lawyer at face value and parrot it uncritically to their readers. Here at Creation-Evolution Headlines, we feel our readers deserve to watch a fair trial. Jaeger is charged with five counts: doctoring evidence, manufacturing just-so stories, refusing to consider nonevolutionary alternatives, making inferences beyond what scientific caution would allow, and assuming what needs to be proved. We have swept away the storytelling elements and stared at the evidence, and have reached our conclusion. Guilty, your honor.
For more examples of evolutionary storytelling contrary to hard evidence, see these other recent headlines on supposed mammal evolution: 12/12/03 on marsupials, 11/17/03 on Smithsonian’s Mammal Hall, 10/30/03 on cave packrats, 10/13/03 on monkey color vision, 07/16/03 on development, 11/22/02 on dogs, 11/01/03 on placentas, 06/04/02 on tooth evolution, and especially 03/18/03, National Geographic’s embarrassing April 2003 cover story on “the rise of mammals,” and the PNAS hall of shame from 05/28/02. For that matter, how about the next headline below?