Or is Homo naledi Actually Homo erectus?

California Magazine, from the University of California at Berzerkeley, has an article written by Glen Martin, in which he details the skepticism about the taxonomic status of Homo naledi, specifically, that it does not represent a new species.  Martin writes:

The popular science press went bonkers last month with news that fossilized bones of a previously unknown hominid had been discovered in a cave system in South Africa. Dubbed Homo naledi by lead researcher and University of the Witwatersrand paleoanthropologist Lee Berger, these proto-humans appeared to have lived somewhere between 1 to 3 million years ago, used tools, walked upright, and may have buried their dead, a practice that has only been attributed to our own species, Homo sapiens, and Neanderthals.

So there was a lot of talk of a “missing link”—the biggest find in paleoanthropology since Lucy, the skeleton of a female Australopithecus, was excavated from a gully near Ethiopia’s Awash River in 1974. (Donald Johanson, the lead researcher in Lucy’s discovery team, founded the Institute of Human Origins, which later moved from Berkeley to Arizona State.)

As I mentioned in my post on the find, echoed by PZ Myers, at Pharyngula, this notion of a “missing link” is a straw man that has been created by the popular press and jumped on by organizations like the Discovery Institute and Answers in Genesis.  Martin continues:

Amid all the hoopla and confetti, however, a growing number of scientists are advising caution. They’re not denying the importance of the find; the fossils, they say, are invaluable. But they contend that the bones may not represent a new species. The evidence these skeptics point to suggests that the finds may actually be bones from
Homo erectus, the earliest known hominid to manifest the general proportions, stance and gait of modern humans. H. erectus had a long tenure on the planet, living from about 2 million to 70,000 years ago. The species was widely distributed (from Africa to East Asia and possibly southern Europe), used tools and fire, and may have constructed rafts to cross wide bodies of water.

Berger maintains that the skulls are too small, with too many primitive characteristics to be Homo erectus.  Once again, though, we come to the problem of how old the bones are.  Here, White is particularly critical:

One tibia, for example, was white on one end, a clear indication it had been snapped off in the recent past,” said White. “This (region’s) complex is extensive and like Swiss cheese, and it’s a favorite with spelunkers. You find beer cans next to fossils that are 3.5 million years old. So it’s important not to jump to conclusions.”

If the bones are late, as is possible, then the finds (or at least parts of them) might represent a Homo erectus population that has late primitive retentions. Even if there is more than one species present, there is no getting around the fact that the small, primitive cranium is where the Homo erectus traits are found, as well.

Berger is quoted as saying that this debate should play out in the published literature.  I suspect it will and that, eventually, we will figure out what sorts of primitive and derived traits the cache in the cave actually represents, even if we might never know exactly how old they are.

PZ Myers on Casey Luskin

PZ Myers, over at Pharyngula, has some harsh words for Casey Luskin's examination of Homo naledi.  In the post, he points out something that I have pointed out in several posts for BioLogos and in my rebuttal to Luskin's post on Homo naledi: a complete lack of understanding of systematics:

I’m not going to dissect every point in Luskin’s tediously long article in detail — really, he’s just echoing every question anyone has asked about H. naledi in the last few weeks, in an attempt to construct a litany of doubt — but I have to point out the numerous ways he misrepresents evolutionary biology to pretend that H. naledi is somehow a refutation of Darwin. As I’ve pointed out many times before, Luskin is a scientific illiterate who doesn’t actually understand anything remotely biological, from genetics to embryology to molecular biology to, now, paleontology. Actually, this isn’t the first time Luskin has tripped over himself in a rush to deny — he also didn’t like Tiktaalik. So this is just more of the same.

Luskin has a bad case of missinglinkitis. This is the idea that there is a linear series of steps in a progression leading from ape to human, and all we have to do is find each frame in the movie and we can replay everything in science class. He wants a “link”, a word he uses multiple times, and he wants “transitional fossils”, unaware that every individual is a transition between parent and progeny.

The key is to focus on the traits, something that Luskin and other Intelligent Design supporters fail to do. Myers further points out, as I did, that just about every fossil that we find is a mosaic of traits and when we follow the trait patterns, we can develop phylogenies.  This line of thinking has led to remarkable understanding of the evolution of Devonian tetrapods and the transition from theropod maniraptoran dinosaurs into birds. 

He also makes light of a point that Luskin makes about the venue that Berger and colleagues took when they wanted to publish the paper:

I have to mention two other lesser points from the paper. Luskin really knows nothing.

The technical paper, “Homo naledi, a new species of the genus Homo from the Dinaledi Chamber, South Africa,” appeared in a lesser-known journal, eLife. It’s a great find due to the sheer number of bones that were found, but to my mind its publication in eLife is an immediate hint that this fossil isn’t an earthshattering “transitional form,” because if it were, we almost unquestionably would have seen the fossil published in Science or Nature.

No. Wrong. A lot of scientists resent the tyranny of the magical CV-enhancing powers of those two journals, and think they have an inflated and dangerously dominant reputation. eLife is an entirely credible new journal which, to all appearances, has a robust reputation for good, solid peer-review…and is also open source. There are a lot of scientists who are eager to see scientific information disseminated more widely without the limiting restrictions of traditional journal publishing, and Lee Berger, the lead investigator in this work, doesn’t need the résumé reinforcement that publishing in Nature or Science provides.

This is only half-correct. While it is quite true that many scientists like to publish in open-source publications like eLife and PLoS, this is not always the perspective of the managers and department heads, many of whom would much prefer that their researchers publish in high-profile journals, like Science and Nature.  I know this to be true through my work not just in publishing but in dealing with funders.  They like flashy papers.  This often (but not always) conflicts with the desires of the researchers, themselves.  Even though there are plenty of researchers who would like just to publish and get the information out there as fast as possible, I know of quite a few researchers who don't mind padding their resumes a bit with high-profile papers because they are angling for a position higher up on the academic food chain.  We would love to think otherwise, but it just isn't always true. 

The Friendly Atheist on “The Whole Truth”

Since this seems to be the theme of the week, I noticed that the Friendly Atheist has a piece on how pushy atheists should be when confronting Christians or others who believe in a higher power. Referring to the atheism of PZ Myers and Chris Mooney, he writes:

Here’s the difference between the two sides: You know that courtroom phrase, “tell the truth, the whole truth, and nothing but the truth”?

Both Mooney and PZ want to tell the truth about science and evolution.

Only PZ is willing to tell the whole truth — that the logical conclusion of accepting science fully is that you must dismiss any notion of gods, miracles, and the supernatural.

Mooney thinks it’s bad PR for us to admit that — and he may be right — but it’s wrong to let Christians keep thinking science and religion are perfectly compatible when they really aren’t.

There are two striking assumptions here that Mehta expects us to take at face value: that PZ Myers’ perspective is “the whole truth” and that the logical conclusion of accepting science is that you must reject any notion of the existence of the supernatural.

This odd conflation of methodology with worldview, is known as philosophical naturalism. It means that in my scientific endeavors, I must believe that a supernatural entity does not and cannot exist. In this case, my worldview may or may not be divorced from reality. Performing science with the assumption that there is no interference from a higher power does not mean that there is not one. Absence of evidence is not evidence of absence.

I would also make the case that it is intellectually dishonest. I contend that science cannot address the existence of God one way or the other. It simply is not equipped to do so. Astrophysicist Hugh Ross, who wrote The Fingerprint of God, which deals with the level of “tweaking” that the universe exhibits in order to sustain life on this third rock from the sun, believes that this points to the existence of God. As far as he and other progressive creationists and intelligent design supporters are concerned, while not a smoking gun, this level of inferential evidence is enough. Maybe, but it is a post hoc argument. It only looks tweaked because we are here to observe it. One of the main complaints about ID is that it has no theoretical construct to test for the existence of God. Michael Behe suggests that evolution cannot explain the flagellar motor or the blood-clotting cascade in humans. Even if, by some chance that is true, it still presents no support that God produced either in ex nihilo fashion.

By the same token, the statement that there is no god is a statement of faith. It is only the whole truth if you subscribe to the reductionistic view that all we can see is all that exists. Once again, science cannot address that question. To be completely honest, we must be scientifically agnostic. What we believe to be true is a matter of faith. PZ Myers and Herment Mehta believe in their hearts that there is no god. I believe that there is.

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Raining on Other Writers' Parades

Josh Rosenau wonders why people who write books about evolution are both critical of a book lamenting the state of U.S. science education. PZ Myers and Jerry Coyne are both critical of Unscientific America: How Scientific Illiteracy Threatens our Future, by Chris Mooney and Sheril Kirshenbaum, despite agreeing with the premise. He writes:

I find it odd that the author of a book intended to bring already published information to a new audience would criticize another author for publishing material already available in the technical literature in a way more accessible to the general public.

I find it doubly odd that PZ would echo this criticism. Not only did PZ rise to fame by rendering the technical literature in developmental biology accessible to those outside his field (adding not argument, but clarity), he is now famous for plowing the fields of atheism with arguments not dissimilar to those already made famous by recent writers Sam Harris, Richard Dawkins, Chris Hitchens, Vic Stenger, etc. He is (I believe) writing yet another book in that vein. It is a well-worked vein, with works touting evolution as an attack on theism dating back to Darwin's day, and no discernibly novel arguments in these popular atheist writings since that time. As one student of the field writes: "There's really only a handful of arguments for atheism in the first place."

This kind of squabbling is not helpful at a time when it is becoming clear that the average person knows little about science, even less about biology and next to nothing about evolution. That is exactly the way that groups like the Discovery Institute, the Institute for Creation Research, and Answers in Genesis want it. Why are we trying to help them? A book that is well-written and sourced that is supportive of evolution should be trumpeted.

Furthermore, I have no sympathy for arguments for atheism by evolutionary biologists in the first place. All they do is cement in the eyes of the general public the already perceived link between evolution and atheism. This just makes it harder for everyone concerned who think that evolution and faith can coexist.


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