Evolutionary psychology tends to receive harsh criticism, and often rightly so. One of the main reasons for this is the severe lack of evidence for many of it's proposals given that the paucity of fossilised brains fails to bolster many a case. And it isn't even anyone's fault. That's just the way it goes sometimes, that the brain is a jelly-like substance that is subject to decay after death, and there's no way we can objectively analyse or verify any differences in brains of long ago with brains of today.This isn't set to change anytime soon, but the remarkable discovery of a medieval child's brain was the subject of a Neuroimage paper published recently. This is extremely exciting on many counts: the brain has been so fantastically preserved that it is possible to identify the frontal, temporal and occipital lobes, and even the sulci and gyri, the grooves and furrows channeled into brains.
However it is only the left-hemisphere that survived and not the entire brain, which had also shrunk to about 80% of it's original weight due to the (natural) mummification process. Although it was first discovered in 1998 and preserved all this time in a formalin solution, it was found in the skull of a 13th Century infant that was exhumed at an archaeological dig in north-west France. The body of the 18-month-old child was wrapped in leather and kept in a wooden coffin with a pillow underneath the head.
The presence of acidic clay soil and fresh briny water around the burial site is believed to have contributed towards the excellent preservation of the brain. To a certain degree, even the innate cellular structure had been preserved, so much so that intact neurons and dendrites - branched fibres that extend from the cell body of a neuron - had survived for observation in the 21st Century. It was also possible to identify grey and white matter. Apart from the external burial conditions, the toughness of the neuronal myelin sheath and collagen fibres are said to be the reasons for why the brain tissue had been nicely preserved.
It cannot be said for sure how the infant died, but the presence of an unhealed circular head fracture may have been the likeliest cause. High levels of hemosiderin suggested that the infant had heavy bleeding for several days prior to death. Poor little mite.
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Papageorgopoulou, C., Rentsch, K., Raghavan, M., Hofmann, M., Colacicco, G., Gallien, V., Bianucci, R., & Rühli, F. (2010). Preservation of cell structures in a medieval infant brain: A paleohistological, paleogenetic, radiological and physico-chemical study NeuroImage, 50 (3), 893-901 DOI: 10.1016/j.neuroimage.2010.01.029
Interesting. I wonder if any of the neurochemistry has survived intact, to allow people to do analyses like these...
ReplyDeleteWhat does this have to do with evolutionary psychology?
ReplyDeleteI realize that you're not denigrating evolutionary psychology, but I'd like to tackle the widely-held notion that there's no evidence in support of evolutionary psychology. May I remind you that there's also no evidence in support of the Big Bang theory? We have only the present state of the universe to go on -- we have to extrapolate backwards from present evidence to figure out what happened in the first microseconds of the Big Bang. True, we're able to rely on physical laws to make that extrapolation, but we're applying those physical laws in contexts in which they have never been tested. So what's the fundamental difference between Big Bang theory and evolutionary psychology? Why is the former theory trustworthy and the latter not trustworthy?
ReplyDeleteFor that matter, why not toss all the history books in the trash? After all, history isn't a science, so why shouldn't we dismiss the entire field? Historians engage in wild speculations based on flimsy evidence; they don't make any testable predictions, so their results are unworthy of serious consideration. Right?
Again, I'm not attacking you, because I suspect that you are sympathetic to my arguments, but I would like to stomp on what I perceive to be misconceptions regarding the nature of knowledge.
Gary, I just thought it'd grab some attention. :-)
ReplyDeleteChris, I am in fact sympathetic to evolutionary psychology but I take care not to get too carried away with some of the far-out theories floating out there.
Neuroskeptic, the paper mentions that the neurons were intact enough for fatty acids to be detected, such as ginkgolic acid (C13:0), myristic acid (C14:0), pentadecanoic acid (C15:0), palmitic acid (C16:0), heptadecanoic acid (C17:0), oleic acid (C18:1), stearic acid (C18:0) and 10-hydroxystearic acid (C18:0 10OH). Also, Nissl bodies were present, but staining for microsporidia was not possible but some fungi-like structures were detected.
ReplyDeleteBearing in mind that the mummified brain is 80% reduced from it's original size, it's a wonder they were able to glean what they could using CT and MRI!
Are the readers here aware of the paper reporting brain scans from DEAD fish!
ReplyDeleteGary
Gary, are you referring to this?
ReplyDeleteI believe Gary was referring to this study: http://neuroskeptic.blogspot.com/2009/09/fmri-gets-slap-in-face-with-dead-fish.html
ReplyDeleteNevertheless, it doesn't matter because they used fMRI and the study you mentioned only performed structural analyses with MRI and CT.
Btw, the evol psych red herring hurts your credibility more than it helps.
Yes, there are plenty of far-out ideas in evolutionary psychology, but most of those come from dilettantes, not serious scientists.
ReplyDeleteMy core point is that the experimental method is not the only path to knowledge. It is entirely reasonable to rely on pattern-based thinking when no other means is available. The pattern-based approach will never yield results as objectively reliable as those produced by the experimental method, but its results should not be dismissed as inherently unreliable. When practiced by a fully-informed expert, the pattern-based method often yields impressive results.