PZ Myers. 2005 Mar 07. Homo floresiensis's brain—Igor didn't screw up!. <http://pharyngula.org/index/weblog/homo_floresiensiss_brainigor_didnt_screw_up/>. Accessed 2008 Dec 01.
Posted on M00o93H7pQ09L8X1t49cHY01Z5j4TT91fGfr on Monday, March 07, 2005
Homo floresiensis's brain—Igor didn't screw up!
I'm looking at the endocast scans that Dean Falk did of the Homo floresiensis specimen (as reported by Carl Zimmer), and I'm reasonably well convinced that this is not a microcephalic. Here are some very nice comparative images. The H. floresiensis specimen is in the center, with H. sapiens above it, a chimpanzee below it, a microcephalic to the left, and H. erectus to the right. Here's a view from the left of a computer reconstruction:
And this is the frontal view:
There's also a whole series of quantitative plots of various parameters of relative brain dimensions, and in every case, the microcephalic is the odd man out, as you might expect of a pathology. H. floresiensis looks to have had a brain that was normal in its gross organization, just small.
Science • EvoDevo • Organisms • 2 Trackbacks • Other weblogs • Permalink
-
Fascinating. I have to say this whole story has been the highlight of the last year for me, science-news-consumer-wise.
So a small but normal brain, eh. Have they ruled out its being Republican yet?#: Posted by Chris Clarke on 03/07 at 03:14 PM -
Maciej Henneberg is now saying, however, that Falk et al. compared the hobbit to a different type of microcephalic than the one he did. It's true that there are different types of microcephalics, so this is possible. Whether it matters is another question; it hasn't yet been demonstrated that this other type of microcephalic has any especial resemblance to the hobbit, so there is still that loose end to chase down. A number of scientists who have looked at the paper on the Cretan microcephalic Henneberg has in mind don't consider that it has a close resemblance to hobbit; my guess is that a brain scan of that microcephalic won't show a compelling resemblance to the hobbit either. See links in the Mar 7 blog entry at http://www.talkorigins.org/faqs/homs/.
In response to the previous comment: it's not a "normal" brain, in the sense of being a miniature sapiens brain; it is normal in the sense that it's not obviously pathological and is therefore a "normal" floresiensis brain as best we can tell. -
I'm having trouble making sense of the microcephalic's cast; it looks so odd compared to the others. Is the smoothness relevant, or is that just an artifact of the casting/scanning process?
#: Posted by on 03/07 at 06:24 PM
-
Apparently, yes.
From the report at the Loom, linked to in the parent post:
The most straightforward results are the ones that address the skeptical suggestions about a small-brained human. The Hobbit brain doesn't look anything like the brain of a microcephalic. Microcephalics have smooth brains, for example; the Hobbit has a normal convoluted surface. Microcephalic brains have a pointed top and a sloping forehead; the Hobbit brain is rounded on top and unsloped in front.
#: Posted by on 03/07 at 07:02 PM -
Right. There's that difference, and the paper has a great deal of data on the ratios of various dimensions that show just how grossly pathological the microcephalic brain is, and how relatively normal the H. floresiensis brain is.
At this point, the microcephalic hypothesis just doesn't look supportable. -
I'm not suprised. Falk does some pretty good work. It seems to me that the people who are going to continue to argue microcephaly are going to have a tough time making that argument. Microcephaly is pretty rare in the archaeological record. Claiming it is some rarer form that falk didn't consider is unconvincing at best. Really, the burden of proof is on them.
I agree with Chris, this has been the highlight of the year for me as well.#: Posted by on 03/07 at 07:29 PM