EDST 391-082 Intelligence in Everyday Life


P/F Writing Assignment for Day 14

Homo sapiens’ big brains


·         Buss (Pp. 384-398 of Chap. 13, “Toward a unified evolutionary psychology”)

·         Adams ("The evolution of idiots" --very short, very funny piece from a Dilbert book on the trouble that smart people create for everyone else)


·         NOTE: I just got this notice from the federal agency that keeps track of morbidity and mortality patterns in the US. Take a look if you get a chance. It’s not only fascinating in its own right (Who in his right mind would “car surf”?!!), but also illustrates one hazard of “deadly innovations.”





The Buss excerpt briefly describes 3 different explanations for why humans have evolved such big brains—that is, such extraordinary intelligence compared to other species. Any evolutionary scenario must provide a selection mechanism or “selection walk,” that is, explain how and why—over evolutionary history—the brighter individuals in human groups tended to leave more genetic descendents (offspring).


1.      Peacock’s Tail (or Sheherazade) Hypothesis (p. 395)

o   Cleverness is sexy (“mate with me because my big brain says I have good genes. Only someone with really good genes could afford to put on such a lavish display of useless finery!”)

2.      Social Brain (Or Ecological Dominance) Hypothesis (pp. 396-397)

o   Cleverness helps you control other people and their resources

3.      Deadly Innovations Hypothesis (pp. 397-398); ALSO THE DILBERT PIECE!

o   Cleverness helps you avoid accidental injury and death


The first is called a sexual selection theory, because it argues that (1) brighter individuals are more successful in finding mating partners. The other two are ecological selection theories because they rest on brighter individuals relatively more often surviving the adversities in their external environment or better exploiting its resources. In these explanations, brighter individuals contribute relatively more children to future generations either because (2) they “live higher on the hog” (my best guess, because this camp never explains the “why”), or (3) they live longer to conceive and raise more children.


Writing assignment:


1.      Please describe a real-life example that would seem to illustrate each of the proposed selection mechanisms in action (one example each). Please explain how your examples illustrate the theory in question.

2.      Now play the skeptic: For each theory, raise one trenchant question or doubt about its validity. Explain.