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Monday, April 20, 2009

Fun with Einstein's Brain

I stumbled across a little blurb today in ScienceNow about a new study by Dean Falk (University of Michigan PhD, 1976!) about Einstein's brain. Luckily, back in good olde 1955, when urban money was moving to suburbs and Marty McFly was trying not to screw up the future, people realized that the recently-late Einstein was a genius whose brain needed to be preserved. Fun facts that I found out:

Einstein's brain was only 1230 cc. The average for modern people is around 1400 (Holloway 2000). Here's a list of ancient Homo fossils, from Holloway (2000) and some others, whose cranial capacities are about the same as or greater than Einstein's:
Zhoukoudian X (Chinese H. erectus, ~1225 cc), Ngandong 10 (Javanese H. erectus, ~1231 cc); Kabwe, LH 18, Eyasi, Saldanha, BOU-VP 16/1 (African "archaic" Homo sapiens); Narmada, Jinniushan, Yinkou (Asian "archaic" Homo sapiens); Vertesszolos 2, Reilingen, Steinheim, Swanscombge, Fontachevade, Ehringsdorf, Biache, Petralona, Atapuerca 4 (European "archaic" Homo sapiens); and most Neandertals.
This shows that, while brain size was important in the evolution of human cognition, it is not everything. I mean, how many of these hominins could begin to fathom something like special relativity? Of course, back in the Paleolithic, when life was hard and one has to worry about how to obtain food, ward off predators and persist in some sort of society, who had time for such things? On the other hand, I'm a modern human--I have no idea how large my brain is--but I can barely wrap my mind around most things in physics. So it seems that human cognition--even genius-level, such as Einstein's--is founded in biology, but also culture and environment.

The article also suggests to me that no one really knows how the brain works. Yes, the parietal regions are associated with maths and such, and Einstein had relatively large parietal lobes. But how and why do one person's parietal lobes confer greater math capabilities than another? (If the parietal lobes relate to mathematical ability, I might lack these)

The article also tells that Falk found a "knob-like structure" in the motor cortex, and that such "knobs" have also been associated with musical abilities. I'm not a neuroscientist, and I don't know what these 'knobs' are. But it sounds like scientists kind of know what these do, since they see these structures more in people who are notable for a given talent (math, music, etc) But are these inherent in the brain and allow people these special abilities, or are they more environmental in origin, arising from certain experiences and exposures? More importantly, what do these do?! Falk also found other brain abnormalities, "that she speculates might somehow be related to Einstein's superior ability to conceptualize physics problems." This may well be the case, but it is still unclear why this should be so.

So I think this study is great, because it can provide neuroscientists with bases for future research on brain function and anatomy. At the same time, it underscores the fact that as smart as we humans are, we don't yet understand how or why we are so special.

Reference

Holloway, R.L. 2000. Brain. In: Delson et al, eds. Encyclopedia of Human Evolution and Prehistory. New York: Garland Publishing, Inc. p 141-149.

Tabūn Pelvis Reconstruction

News: Weaver and Hublin (2009) virtually reconstructed the Tabūn C1 female Neandertal pelvis using CT scans.

Background: This is the closest we have to a complete female Neandertal pelvis, so a lot of the discussion centers around obstetrics. When a modern human woman gives birth, the infant enters the birth canal facing sideways so that the head will fit through the transversely oval inlet, then turns 90 degrees so it is facing the back so that the head will fit through the AP oval midplane and outlet, and finally turns another 90 degrees after the head passes through the outlet so that the shoulders can also fit through the outlet.

Tabūn conclusions: Neandertal infants (based on Tabūn’s inlet, midplane, and outlet diameters) only required two rotations: the initial turn so the head faces laterally, and the last turn so the shoulders fit through the transversely oval outlet. This means the infant comes out with the head facing sideways and the shoulders facing front (this is also how australopithecines are thought to give birth). This, the authors suggest, means that Neandertals were more primitive than modern humans. Furthermore, the transversely oval birth canal reflects the cold-adapted wide pelvis associated with Neandertals.

Problems:
  1. Methods: There is no sacrum for Tabun. None. It is possible to predict sacral width and thus reconstruct the inlet, but it is improbable for the outlet to be reconstructed accurately without knowing the sacrum’s length, curvature, and orientation.
  2. Sexual dimorphism: They confuse this throughout the paper. First, they female-ize Kebara (a complete male Neandertal pelvis) by assuming that Neandertals were as sexually dimorphic as modern humans. This has been shown to be wrong previously, so it was a dumb assumption. They also find that this is not the case, making me wonder why they bothered with it in the first place. Then, they claim that the difference between Neandertals and modern humans is that Neandertals are like modern males (who have short pubic rami) when really they’re like modern females (who have long pubic rami). See Rosenberg (2007) for more discussion of this.
  3. Cold- and warm-adaptations: They say that Neandertals were cold-adapted because of the wide birth canal, in contrast to warm-adapted modern humans from Africa. First, wide birth canals do not go hand-in-hand with wide pelves. Second, Tabūn lived in the Levant and thus did not need to be cold-adapted. Third, the Busidima female Homo erectus pelvis from Gona is also wide and also not cold-adapted. Fourth, modern humans in Africa evolved a narrow pelvis to be better adapted to the warm environment is based on... uh... KNM-WT 15000? No, wait, that's also a H erectus, and Gona has already shown that they have wide pelves despite their climate. But what else is there to support this long-held idea? Answer: Not much.
Citations:
  • Weaver, TD and JJ Hublin (2009) Neandertal birth canal shape and the evolution of human childbirth. PNAS Early Edition: 1-6.
  • Rosenberg, KR (2007) Neandertal Pelvic Remains From Krapina: Peculiar or Primitive? Periodicum Biologorum 109(4).

Friday, April 17, 2009