Thursday, December 6, 2007

A Zombie’s Inquiry Into the Evolution of His Most Favorite Meal IV: Genes that Code for Tasty brains

There are two main approaches to look at the differences between humans and other non-human primates such as chimpanzees: ethological studies of animal behavior and their cognitive abilities (it looks like there is a difference between Cognitive Ethology, Comparative Ethology & Comparative Psychology, but as it seems this is more a matter of whether you emphasize the biological, cognitive science, or psychological aspect of behavior) and genomic comparisons.

On the side of genetic comparisons, we already have the sequenced genome of humans, chimpanzees, and macaques, which, somewhere in the relatively near future, the future, are to be joined by the genomes of Neanderthals, bonobos, (both sequenced by our friends at the Max Planck Institute for Evolutionary Anthropology - gosh! it would really have been a tremendous loss for science if its members had been eaten by zombies… So thanks for that George) gorillas, and gibbons. As Kambiz Kamrani pointed out over at, the more primate genomes we get together, the better we are able to make out human specialness (as well as Chimpanzees-Specialness, Bonobo-Specialness, Gorilla-Specialness etc.), as well as the things we share with other primates, in terms of specific genes.
This may indeed help us ““to find out what being human is.” James Watson originally hoped this would be the result of the sequencing of the human genome. (Pennisi 2007: 218) but now, with an ever-growing genetic database, we somewhere in the future we may indeed be able “to trace back the evolutionary changes that occurred at various time points, leading from the common ancestors of the primate clade to Homo sapiens,” as Bruce Lahn puts it. (Pennisi 2007: 218). Researchers all over the world further plan on sequencing the genomes of the orangutan, the marmoset, the tarsier, the mouse lemur, the galago, the tree shrew as well as the lemur in order get an ever broadening picture of our evolutionary history, ultimately tracing back 83 million years of evolutionary time.
Within this comparative context, we of course may really see the “dawn of cognitive genetics” (Pinker 2001: 465). In the field of language evolution, for example, we may finally establish the genetic foundations and extensions that made human language possible. But at the moment, it seems as if there are still so much things that are maddeningly unclear, (and I as layman, naturally don’ understand anything about “regulatory sequences”, “junk DNA” and messy genetic differences at the molecular level…) so it’s definitely still a very long way until we can go beyond FOXP2, MPH1, and ASPM (not to speak of understanding even the exact roles of these genes.)

On the side of ethological studies, the methods employed and results obtained (which I describe in my last post) by Herman et al. (2007) clearly show interesting avenues of future research, and hint at a possible meeting point between the two approaches:
“A major avenue of future research is thus to use [the research methodologies employed by Herman et al.] to characterize the behavioral-cognitive phenotype of a wide variety of primate species. This could be done through systematic testing of carefully chosen representatives of the more than 50 genera of primates, which should then enable us to map out cladistically the evolution of primates’ most important cognitive skills at the level of both the phenotype and, ultimately, the genotype.” (Herman et al. 2007: 1365)
For our Zombie-Scientist George the main question remains: “Why are human brains so tasty ?” (let’s presume that in our Parallel zombieverse, the zombie-gourmet is only fond of human brains and not that of other non-human brains.) The Theory by which George now arrives looks like this: “The unique tastiness of human brains basically must boil down to some uniquely human genes (or genetic combinations or gene expressions)” That’s why I will lok a bit at the differences between human and chimp-genes in my next post.


Hermann, Esther Josep Call, María Victoria Hernández-Lloreda, Brian Hare, and Michael Tomasello. 2007. “Humans Have Evolved Specialized Skills of Social Cognition: The Cultural Intelligence Hypothesis” Science 317: 1360-1366.

Pennisi, Elisabeth. 2007 “Genomicists Tackle The Primate Tree.” Science 316: 218-221.

Pinker, Steven. 2001. “Talk of genetics and vice versa“ Nature 413: 465-466

No comments: