The Nose Knows

Photo credit: Eric Zamora
Jonathan I. Bloch and Skull (Photo credit: Eric Zamora)

It’s a long, old story. To be somewhat exact, 54-million years old.

To make it short, the nose knows.

And the nose led to the brain that could, well, create music and design spaceships to the moon and cook food à la Ferran Adrià i Acosta (molecular gastronomy):**

“You can think of it as a cousin of the main line lineage that would have given rise ultimately to us.” ~~~ Jonathan I. Bloch

Virtual endocast of Ignacius graybullianus (Paromomyidae, Primates) and brain evolution in early primates, Proceedings of the National Academy of Sciences (June 22, 2009)

Mary T. Silcoxa,1, Claire K. Dalmynb and Jonathan I. Blochc

Abstract

Extant primates are distinctive among mammals in having relatively large brains. As stem primates, Paleogene plesiadapiforms provide direct information relevant to the earliest stages in the evolution of this characteristic. Here we describe a virtual endocast reconstructed from ultra high resolution X-ray computed tomography data for the paromomyid plesiadapiform Ignacius graybullianus (USNM 421608) from the early Eocene of Wyoming. This represents the most complete endocast known for a stem primate, allowing for an unprecedented study of both size and fine details of anatomy. Relative to fossil and extant euprimates, I. graybullianus had large olfactory lobes, but less caudal development of the cerebrum and a poorly demarcated temporal lobe, suggesting more emphasis on olfaction and a less well-developed visual system. Although its brain was small compared to those of extant primates, the encephalization quotient of I. graybullianus is higher than that calculated for Paleocene Plesiadapis cookei and overlaps the lower portion of the range documented for fossil euprimates. Comparison to the basal gliroid Rhombomylus suggests that early primates exhibited some expansion of the cerebrum compared to their ancestors. The relatively small brain size of I. graybullianus, an arboreal frugivore, implies that neither arboreality nor frugivory was primarily responsible for the expanded brains of modern primates. However, the contrasts in features related to the visual system between I. graybullianus and fossil and extant euprimates suggest that improvements to these portions of the brain contributed to increases in brain size within Euprimates.

Now that takes care of the serious part of the day.

For fun, go to Jamie Schler’s delightful blog, Life’s a Feast: Confessions of a Gourmande, and enjoy her unique take on food, memories, 1950s U.S. history, and cooking (with great pictures, too).

aDepartment of Anthropology, University of Winnipeg, 515 Portage Avenue, Winnipeg, MB R3B 2E9, Canada;

bDepartment of Social Anthropology, York University, 4700 Keele Street, Toronto ON, M3J 1P3, Canada;

cFlorida Museum of Natural History, University of Florida, P. O. Box 117800, Gainesville, FL 32611

**For the next few weeks, I am going to be on a “working vacation,” so my posts will be somewhat more abbreviated. I will still provide you with something substantial to chew on, though!

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