Ida smackdown

If you’ve been following the evolution blogs, you’ll know that the wonderful primate fossil Darwinius masillae was touted by its discoverers (and by the book The Link) as a key “transitional form” in human evolution: a link between the two major branches of primate evolution, the anthropoids on one hand and the lemurs and lorises on the other.  Many bloggers who read the initial paper were dubious, asserting that the phylogenetic analysis was too sketchy to put Ida in this position (see here, here, here, and here).  I’m not a paleontologist, but agreed with the criticism that Ida’s placement as a “missing link” was premature.

Well, it looks as if the bloggers were right and the scientists who wrote up Ida were wrong.  A paper in today’s Nature describes a new fossil (Afradapis) from Egypt that appears to be in the same clade (single-origin group of related species) as Darwinius.  The paper is full of technical detail, but the upshot is this:  the dental and jaw features of Darwinius (and Afradapis) that made her discoverers group her with anthropoid apes are probably not homologous to those of anthropoid apes, but convergent (i.e., the traits don’t show that Ida belongs with the anthropoids; instead, these features evolved at least twice in two unrelated groups).  As the authors say:

It has long been known that some adapiform lineages evolved derived morphological features that are also seen in living and extinct anthropoids (for example, fused mandibular symphyses, upper canines with mesial grooves, enlarged and spatulate upper and lower incisors, short and tall rostra)16. The phylogenetic significance of these features has been a source of ongoing debate for decades. Of all known fossil prosimians (including Darwinius), Afradapis provides perhaps the most detailed examples of derived anthropoidlike adaptations in its dental and mandibular morphology. As isthe case for many of the morphological features that some have argued link adapiforms to anthropoids, however, the anthropoid-like features of Afradapis (fused mandibular symphysis with transverse torus, deep mandibular corpus, deep masseteric fossa, large upper molar hypocones, absence of P2/2 and presence of an enlarged P3 with a honing facet for the upper canine) are not present in the most primitive undoubted fossil anthropoids, such as Biretia and Proteopithecus, indicating that the features are likely to have been acquired through convergent evolution.

In the end, both Afradapis and Darwinius appear to belong to the group of primates known as adapiforms, a group that went extinct without leaving descendants.  For all its beauty, then, the Darwinius fossil is not a link to any living species.

There is lots of publicity about this new finding: see the Times online commentary by Brian Switek,  another Times piece by Brian Henderson, and a piece in The Guardian.  It’s refreshing to see the refutation of hyped-up claims about science given as much space as the original hype. Let’s hope that American papers such as The New York Times follow suit.

Curiously, today two “formal corrections” appeared in the PLoS paper. The first says this, in part:

The following subsection should be added beneath the Methods subsection “Terminology”:

Nomenclatural Acts

The electronic version of this document does not represent a published work according to the International Code of Zoological Nomenclature (ICZN), and hence the nomenclatural acts contained herein are not available under that Code from the electronic edition. A separate edition of this document was produced by a method that assures numerous identical and durable copies, and those copies were simultaneously obtainable (from May 21st 2009) for the purpose of providing a public and permanent scientific record, in accordance with Article 8.1 of the Code. The separate print-only edition is available on request from PLoS by sending a request to PLoS ONE, 185 Berry Street, Suite 3100, San Francisco, CA 94107, USA along with a check for $10 (to cover printing and postage) payable to “Public Library of Science”.

Presumably PLoS One is not considered a valid venue for publishing descriptions of new species.  Does this have something to do with its less-then-complete peer review?

The second correction is this:

The authors have supplied an updated Competing Interests statement, which reads as follows:

The authors wish to declare, for the avoidance of any misunderstanding concerning competing interests, that a production company (Atlantic Productions), several television channels (History Channel, BBC1, ZDF, NRK) and a book publisher (Little Brown and co) were involved in discussions regarding this paper in advance of publication. However, to clarify, none of the authors received any financial benefit from any of these associations and these organizations had no influence over the publication of this paper or the science contained within it. The Natural History museum in Oslo will receive some royalty from sales of the book, but no revenue accrues to any of the scientists. In addition, the Natural History Museum of Oslo purchased the fossil that is examined in this paper, however, this purchase in no way influenced the publication of this paper or the science contained within it, and in no way benefited the individual authors.

This is a tad disingenuous, since “benefit” to scientists includes far more than money: it includes (or included) all the hype and buzz around the initial description of Ida as a “missing link” — publicity that of course redounds to a scientist’s career.  And, of course, money that goes to the Museum of Oslo also benefits any author associated with that Museum, even if he/she doesn’t get the dosh directly.

h/t:  Greg Mayer and Daniel Matute

__________________

Erik R. Seiffert, Jonathan M. G. Perry, Elwyn L. Simons & Doug M. Boyer. 2009.  Convergent evolution of anthropoid in Eocene adapiform primates.  Nature 461:118-1122.

6 Comments

  1. Posted October 22, 2009 at 8:59 am | Permalink

    It’s refreshing to see the refutation of hyped-up claims about science given as much space as the original claim.

    Eh, normally I’d agree with this statement in just about any context, but I can’t help but read the subtext of the media coverage of this (highly technical!) paper refuting the Ida thing as: “Ah hah! They didn’t find the ‘missing link’ proving our ape ancestry after all! You can all recommence mumbling ‘my uncle ain’t no monkey!’ now.”

    I’m not saying the UK media is promoting Creationism, and I’m not even saying they are consciously pandering to Creationists. It just seems like, collectively, society wants to keep the “missing link” meme alive, and I suspect it has to do with a subconscious revulsion towards ape-men. Seriously!

  2. Posted October 22, 2009 at 9:11 am | Permalink

    Presumably PLoS One is not considered a valid venue for publishing descriptions of new species.

    You can read an extensive coverage about this issue at this The Loom’s post.

  3. newenglandbob
    Posted October 22, 2009 at 9:24 am | Permalink

    The title of this article should not be “Ida smackdown” but should be “Ida paper authors smackdown”.

    Ida the fossil Darwinius masillae still stands.

  4. Brian English
    Posted October 22, 2009 at 10:05 am | Permalink

    Convergent evolution in primates? Simon Conway-Morris with be having an orgasm about now declaring that it proves God’s metaphysical fingerprint is all over this. It’s the logic of evolution that points to the metaphysical bla-bla that shows that God did it.

  5. Posted October 22, 2009 at 11:26 am | Permalink

    Presumably PLoS One is not considered a valid venue for publishing descriptions of new species. Does this have something to do with its less-then-complete peer review?

    It has to do with the ICZN rules which require paper copies to be deposited at a minimum number of institutions. There has been substantial confusion about the status of online journals in this system, and the stopgap solution is to print out physical copies to satisfy the rules.

    The PLoS ONE research paper was reviewed under disciplinary standards, and is very much a data-rich morphological and site description that refers to phylogenetic hypotheses only in the discussion. That’s one reason why some the claims made in the press and documentary were not repeated in that research paper.

  6. Posted October 22, 2009 at 11:47 am | Permalink

    It’s a shame that such a great fossil in its own right will end up being discounted because of the unbelievable hype with which it was presented to the world.

    I hope this costs the hypesters, including the History Channel. They do a few things right, and then they embarrass science with both this unbalanced coverage of genuine science, plus a whole host of junk science and pseudo-science.

    Glen Davidson

    http://tinyurl.com/mxaa3p


2 Trackbacks/Pingbacks

  1. [...] Jerry Coyne talks about a recent discovery which was presented as a missing link between primates and humans but was really a transitional [...]

  2. [...] PLoS ONE, a journal that doesn’t exercise stringent scientific review of submitted papers.  The reaction of both bloggers and scientists was very critical, with many pointing out that Ida didn’t look like a missing link at all, but may have merely [...]

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