Pleistocene Brains

We hear it often in our field that modern humans have Pleistocene brains, brains suitably adapted to life in the savannas of Africa where our ancestors lived for thousands of years. It was this period of stability that solidified our Pleistocene mind and all those fun modules. But is there any real evidence for this supposed Pleistocene mind/brain? I mean, any biological evidence other than just-so stories constructed based on clinical experiments with modern humans. I really would appreciate a point in the right direction. It seems patently false that we have Pleistocene brains, and also to fly in the face of evolutionary theory, which indicates our biology is constantly adapting.

Girls prefer pink? evolutionary or cultural causes

Lately a story stemming from an article in Current Biology has been circulating. This study allegedly demonstrates 1) that women prefer pink and 2) that there is an evolutionary explanation about this. Does that make you suspicous? Well it should.
This blog eloquently dissects it and seriously questions both conclusions. It is a good example of the abuse of evolutionary psychology and shows how easy it is to supply an evolutionary story to any experimental result. On closer scrutiny the experimental results do not support the evolutionary theory. Oh, and by the way the experimental results are, as shown in the blog, entirely explicable as having a cultural cause.
Instead of a study in evolutionary psychology it is a good study of a cultural effect in color preference.

This short article from Science shows that mind is conceptualized along two dimensions: experience (feelings) and agency, and experience is the most important.

Also see the supporting on-line material for more details.

Survival of the Sickest

I saw the author of the new book Survival of the Sickest interviewed on the Daily Show. It looks pretty interesting.

Writing as Ratchet

Deacon (1997) talks about Icon to Index to Symbol as hierarchically arranged. These systems, he argues, can be independent of the hardware. Recent work at UCSB and elsewhere has confirmed some of his argument with regard to the evolution of phonology out of primate visual systems. In this case, the hardware may evolve to make use of software in a kind of mutual ratcheting. That is, speech systems may be parasitic on visual systems (See Givon et al., The Evolution of Language out of Pre-Language). Studies in literacy often state that literacy isn't biologically instantiated, that it relies on more ancient mechanisms to do its work that evolved for different purposes. However, if we follow Deacon we can see this in a different light. In the same way that scholars before Deacon argued that biological changes had to precede "language", and he gave us a plausible argument for the reverse, we may say the same about written language. We see a similar process with literacy. This would lead us to substantially rethink what it means for something to be cognitive.

We find evidence for the ratcheting effect in the early story of writing from about 8000 to 3000 BCE as told by Denise Schmandt-Basseret. In the proto-stage human beings sculpted figurines representing various gods and animals for ritual purpose. In the next stage tokens of basic geometric shapes representing simple food staples were made out of baked clay. Next more complex tokens emerge that represent complex staples. These tokens come to be sealed in clay envelopes for accounting purposes, and so are connected to the rise of agricultural surpluses and cities. Since there is no way to tell what is in the envelope, in the next stage someone came up with the idea to embed tokens on the outside of the clay to tell what was inside and further a system of marks was developed for the same purpose. This facilitates a transition from three dimensional objects to two dimensional. Up to this point there is a one to one correspondence between an object and token, so for example, three jars of grain are represented by three tokens in or on the envelope. A sign represents the token inside the envelope, which in turn represents a commodity/staple. In the next stage clay tablets replace clay envelopes and a sign mark on the tablet is used to represent a token, marked either with a stylus or the corresponding token. The first recordings of numerals occur with these tablets. In other words, there is no longer a one to one correspondence. Here the sign represents a concept, not the particular object in question, and we move to greater degrees of abstraction. In the next stage, which she does not discuss, signs go from representing objects or concepts (pictures) to representing the sound of first syllable of the word for the concept (acrophonic principle) and eventually signs represent sounds.

Understanding Early Civilizations

I just stumbled on this book by Bruce Trigger: Understanding Early Civilizations. It is a survey of 7 early civilizations (Mesopotamia, Egypt, China, Maya, Aztec, Inka and Yoruba). He is an antrhopologist/archaeologist. Apparently he spent fifteen years writing the book. I have briefly browsed through it and it seems incredibly nuanced and well founded. He mentions cognitive theory frequently and in this article he makes it clear that cognitive and neuroscientific science needs to be integrated with social sciences.
I think there is a lot here that could be integrated with Boyers ideas of religious guilds and also with Whitehouses ideas of modes of religiosity. The good thing about this book is that it also integrates ecological, political and economical aspects.

You can see the table of contents and read the introduction here

You can even get it now in a paperback edition for just 16 squid!!

Gossping groups are more altruistic

A recent issue of Science has a couple of interesting articles on Cooperation and altruism. There are two types of agents Cooperators (C) and Defectors (D). Groups of only cooperators have a higher average fitness than groups of defectors, but defectors have a higher individual fitness than cooperators (Nowak 2006). Defectors will inevitably take over any group of cooperators if there are not any mechanisms to work against it. So, for cooperation to have evolve, mechanisms to prevent invasion by defectors must be in place. Such a battery of defense mechanisms against defectors may be seen ostrachism and punishment of rule violators and costly displays of allegience (Costly Signaling). But the article by Nowak indicates another possible mechanism.

One thing I found particularly interesting was a simple rule that describes under what conditions altruistic cooperation can take place in a situation of indirect reciprocity. Indirect reciprocity takes place in situations where there is no possibility for direct reciprocity, either because the persons will never meet again or becaue one is in a subordinate position and cannot reciprocate. In these cases altruistic helping behavior is explained by the fact that ”helping someone establishes a good reputation, which will be rewarded by others” (1561). A good reputation, therefore, increases the possibility that others will help you. Nowak concludes: ”Indirect reciprocity can only promote cooperation if the probablity, q, of knowing someone’s reputation exceeds the cost-to-benefit ratio of the altruistic act: q>c/b”(1561)
This is an interesting observation because the probaility of knowing someone’s reputation is dependent on factors such as population size, proximity of the action to home and dissemination of information about reputation. It is interesting to notice that gossip seems to be exactly this, information about reputation. Gossip therefore increases q which increases the sustainable cost-to-benefit ratio in the group. If the probability of knowing someones reputation is higher it is possible to establish cooperation with higher costs to lower benefits. Thus – gossiping populations favor altruistic acts. Gossip is therefore also a mechanism in fighting invasion by defectors.


Supporting online material containing the relevant equations: http://www.sciencemag.org/cgi/data/314/5805/1560/DC1/1


Nowak, M. A. (2006). "Five Rules for th eEvolution of Cooperation." Science 314(8 December): 1560-1563.