New BioLogos Post is Up

My latest installment at BioLogos on human origins is up and can be found here. As always, comments are welcome both here and there.

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New BioLogos Post Is Up

The next BioLogos post on the Dispersal of the Australopithecines is up. As always, comments are welcome both there and here.

Human Fossil Record, Part 3

My next BioLogos installment is up, here. It deals with the initial discovery of Australopithecus and the nature of palaeospecies. Comments are, of course, welcome.


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Post at BioLogos

My first post over at BioLogos is up. It is an edited version of my take on Casey Luskin's attack on the Smithsonian human origins exhibit. Wander over and comment, if you like.

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Casey Luskin on The Smithsonian Human Origins Exhibit

Casey Luskin has an article on Evolution, News & Views on the Smithsonian exhibit called "What Does It Mean To Be Human?" Luskin addresses the standard creationist argument that gaps in the fossil record disprove evolution. He quotes from the educator's guide, which reads:

Misconception: Gaps in the fossil record disprove evolution.

Response: Science actually predicts gaps in the fossil record. Many species leave no fossils at all, and the environmental conditions for forming good fossils are not common. The chance of any individual organism becoming fossilized is incredibly small. Nevertheless, new fossils are constantly being discovered. These include many transitional fossils—e.g., intermediary fossils between birds and dinosaurs, and between humans and our primate ancestors. Our lack of knowledge about certain parts of the fossil record does not disprove evolution.

Luskin responds:

Did you get that? Ignoring the fact that transitional fossils are often missing even among taxa whose records are very complete, now Darwin’s defenders argue that their theory “predicts gaps in the fossil record.” How convenient!

This is a semantic trick. It is the same as saying Black Holes don't exist because we cannot see them. Such a statement completely overlooks the fact that there is a very large amount of evidence, based on how astronomical bodies behave under the influence of strong gravimetric forces, that, yes indeed, Black Holes do exist. I would venture to guess that very few professional astronomers doubt the existence of Black Holes.

Because we are missing sections of the fossil record, even large sections of the fossil record overtrivializes the fact that we do have very good fossils to work with and almost unbroken sequences of fossils of many different orders. Luskin, in fact, ignores the second part of the paragraph that he quotes.

That we have gaps is unavoidable. Evolutionary theory doesn't predict gaps. Geology predicts gaps. There is simply no way short of a miracle that we would have completely fossil rich preservation sites for every conceivable depositional environment. Such an expectation misunderstands how geological processes work. Expecting such a fossilized environment misunderstands how taphonomy works. Luskin continues:

What's ironic, however, is that if you ask the question How Do We Know Humans Evolved? the answer you’re given is, “Fossils like the ones shown in our Human Fossils Gallery provide evidence that modern humans evolved from earlier humans.” So whether you find fossils or you don’t, that’s evidence for evolution.

Here's irony for you. The human fossil record, in fact, is replete with transitional forms. Here are a few:

• The recently discovered and described Ardipithecus shows the transition to from a quadupedal gait to bipedalism.
  
• The material from Hadar and Laetoli show more advanced bipedalism relative to Ardipithecus in A. afarensis, which still possesses slightly curved fingers to grasp limbs, indicating that some time was still spent in the trees.
  
• A. afarensis also shows remarkable features in the face that are exactly intermediate between apes and later humans.
• There is a flurry of different australopithecine forms between 3.5 and 2.0 million years ago, some robust, some gracile. All are related and yet are different, showing regional variation and change through time.
  
• The remains attributable Homo habilis, whether they be one species or many, show brain expansion on a basically australopithecine face (this is especially true with KNM-ER1470).
  
• There is a remarkable series of gradations from what is considered Homo habilis to what is considered Homo erectus or Homo ergaster. There is disagreement about how many species are represented because the material is quite variable—and shows considerable change over time. This is also why we are having trouble figuring out which group early Homo came from.
  
• There is considerable disagreement about when Homo erectus ends and archaic Homo sapiens begins due to the transitional nature of much of this material. This has led some, such as Milford Wolpoff, to suggest sinking H. erectus into the Homo sapiens line, arguing that it represents one long lineage.
  
• It is also clear that some traits persist in some populations longer than others. Homo antecessor, from Spain, shows incipient archaic Homo sapiens characteristics at 800 000 years ago, while over in Germany, the Mauer mandible from Heidelberg, still shows H. erectus traits.
• Over in China, Homo erectus (Zhoukoudian, Hexian) persists until around 250 000 years ago, while at 200 000, obvious changes have occurred in the face (Dali, Maba) in the Homo sapiens direction.
• Modern human traits do not appear all at once, but rather over a period of 60 to 80 000 years in Africa (Herto, Klasies River Mouth, Border Cave) and the Near East (Mugharet-es Skhul, Jebel Qafzeh). Early "modern" specimens still show a mix of archaic and modern features
  

I could go on for pages and pages. The point is that, despite the fact that we have gaps in the fossil record, what we do have is good enough to make some pretty dang good assessments of what happened in the past. The human fossil record is a wealth of information about our history as a species. To dismiss it out of hand because there are gaps is simplistic at best and ignorant at worst. He ends by quoting the great evolutionary biologist Ernst Mayr, who passed away a few years ago:

But the exhibit gives no evidence of dissent from the official party line, such as an admission from Ernst Mayr in 2004 that "[t]he earliest fossils of Homo, Homo rudolfensis and Homo erectus, are separated from Australopithecus by a large, unbridged gap,” and therefore we’re in a position of “[n]ot having any fossils that can serve as missing links."

Mayr was a brilliant evolutionary biologist but he did not work in the human fossil record. He is incorrect about his assessment. There are fossils of all shapes and sizes between the late australopithecines and Homo erectus. The problem is that there is no agreement about what they represent. It is, nonetheless, not an unbridged gap. Finds like Australopithecus sediba help to bridge that gap. Maybe it is not a direct ancestor to early Homo. It still show the progression toward the Homo line in one of these late australopithecines.

The fact that there are gaps in the fossil record has nothing to do with the fact that evolution has or has not taken place. How does Mr. Luskin explain the areas where there aren't gaps?

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New Smithsonian Human Origins Exhibit

The Smithsonian Institution has unveiled their new human origins exhibit and if ever there was a reason for a trip to D.C., this is it. Dan Vergano of USA Today has the story:

Fantastic it is. A glittering time tunnel greets entrants with its portraits of early human species from the last 6 million years. Throngs of visitors take turns pawing the real-scale model skulls of humanity's ancestors, set on swivels at the entrances.The exhibit is the Smithsonian's effort to tell the story of human evolution, from the ape-like Sahelanthropus tchadensis to Homo sapiens.

Light and airy, with the wired-in feel of an Apple store (terminals and gadgets abound) instead of a stuffy cabinet of wonders, the exhibit features original artifacts such as the first Cro-Magnon man skull discovered, cast skeletons including Homo floresiensis (a.k.a. "hobbits") and Homo erectus, interactive theaters and even a vividly-recreated "cave art" wall. "They are using everything," said curator and paleoanthropologist Rick Potts, buffeted by visitors on the exhibit's second day.

The article is descriptive but lacking in images so one is invited to imagine what the exhibits look like. As if to provoke a response where none was needed, USA Today asked Ken Ham what he thought:

As for creationists' take on the exhibit? "I haven't really paid too much attention to it," says Ken Ham of Answers in Genesis, which runs the Creation Museum in Petersburg, Ky. Famed for its juxtaposition of people and dinosaurs, the museum promotes a literal reading of the Old Testament in its view of human and the Earth's origins. "I'm amused how much the (Smithsonian) exhibit cost. We built a whole museum for that much," Ham says.

For anyone keeping score, the Smithsonian's Hall of Human Origins measures 15,000 square feet and the Creation Museum encompasses 70,000 square feet of exhibits.

Warming to his topic, Ham called it "child abuse" for the Smithsonian to "promote the secularist view that people are just animals. So, if you are an animal, you might as well do anything you want."

Aside from the fact that his response is simplistic in the extreme, it just wasn't necessary to include this bit of controversy in the story. Yes, controvery exists in this kind of exhibit but at least it seems that Rick Potts, the curator, is letting the exhibit speak for itself. A small video for class would be nice.

Ida May Not Be Related to Humans After All

The Guardian is reporting work being published in Nature suggesting that Ida is not on the line that gave rise to the higher primates. The story, by Ian Sample states:

"Our analysis and results have convinced us that Ida was not an ancestor of monkeys, apes, or humans, and if anything has more relevance for our understanding of lemur and loris origins," said Erik Seiffert, a fossil hunter at Stony Brook University in New York who led the Nature study.

Researchers behind the Ida fossil, known formally as Darwinius masillae, immediately defended their own interpretation, which is based on two years of meticulous measurements of the remains.

"We expected a challenge like this and it's interesting it has taken five months for the first attack to come," said Jørn Hurum, a palaeontologist at Oslo University's Natural History Museum where the fossil is now lodged. "What we claim about Ida is really quite controversial."

So controversial, in fact, that it might be wrong. Which ever way this one goes, it will be a classic example of science in action. Palaeoanthropologists have no vested interest in whether or not Ida is an ancestor to humans. This research will, however, provide us with a good example of a primate that was running around c. 50 million years ago. Hopefully, more discoveries will allow us to see how she fit into the grand scheme of things.

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