Monday, March 8, 2010

Reconsidering Ida

You might recall my lament over Ida and hype-driven science. Described in a PLoS ONE paper by Franzen et al., Ida is an Eocene primate fossil, stunningly preserved, and the subject of a media blitz last summer. Ironically, it's a blitz that few people really bought into.

From my original post:
I could sort of understand this level of excitement if we just put a man on Mars or cured cancer. But it's a monkey. Yes, it's a neat monkey, and it's unusual, and it's really, really beautifully preserved. But it's a monkey. It's supposed to help us understand which group of primates the great apes evolved from, but even that is already contentious.
The irony is that even at that time, few people even in the gullible media bought the hype. Instead, they went to scientists who were skeptical of the find for commentary. The publicity sort of backfired, but I guess since everybody knows about Ida, it worked after all.

The core debate is the classification of Ida. Franzen et al. wanted to claim that Ida was similar to modern catarrhine and platyrrhine primates, which would make it an early ancestor of humans in an evolutionary perspective. Traditionally, Ida-like primates called adapiforms have been viewed as not similar to catarrhines and platyrrhines and thus just a side-branch of the human evolutionary tree.

Naturally, it's easy to poke holes in others' work, but it's harder to come up with your own explanation. So it's taken time for scientists to respond in a technical manner. The first treatment of Ida was by Seiffert et al. in a Nature paper from last October. In the context of describing an Eocene primate from Egypt, Afradapis, they did a cladistic analysis on 360 characters and 117 taxa that included Ida (Darwinius). They found one most parsimonious tree that supported the traditional classification of Ida and the adapiforms as a side-branch of the human evolutionary tree.

A new study by Williams et al. published online last week in the Journal of Human Evolution also confirmed the traditional classification. Williams et al. do a more traditional point-by-point critique of Franzen et al. and conclude:
Had Franzen et al. (2009) added the anatomical information on Darwinius to published data matrices of extinct and fossil primates they would have found, as Seiffert et al. (2009) have done, that Darwinius and other adapiforms fall within the strepsirrhine radiation.
That is, Ida is on a side-branch of the human evolutionary tree.

What does this mean to a creationist? I'm glad you asked. I've been working on a baraminological analysis of fossil hominids, which I hope to submit for publication very soon (like by the end of April). That will be the first look at fossil hominids using statistical baraminology. I could see following that up with more statistical baraminology studies of primates, which should help us to identify the significance of adapiforms like Ida (which are unlikely to have anything to do with the origin of humans).

In the meantime, I think evolutionist and creationist alike can learn from this incident to avoid making extravagant claims before the research has been thoroughly evaluated.

Franzen et al. 2009. Complete Primate Skeleton from the Middle Eocene of Messel in Germany: Morphology and Paleobiology. PLoS ONE 4(5): e5723. doi:10.1371/journal.pone.0005723

Seiffert et al. 2009. Convergent evolution of anthropoid-like adaptations in Eocene adapiform primates. Nature 461:1118-1121.

Williams et al. 2010. Darwinius masillae is a strepsirrhine - a reply to Franzen et al. (2009). J Hum Evol, doi:10.1016/j.jhevol.2010.01.003