Evolution

Psy391h - Class 24

(This page last updated 1 May 2006.)

Wason Card Selection Task 

The Nature of Evolution

Appearance of design

The Comparative Approach

• Homology
  • Prosimians, new world monkeys, and old world monkeys all have a visual area similar to MT.
  • This area must have evolved before the appearance of prosimians.
• Homoplasy
  • Cats also have a visual area devoted to motion.
  • However, other mammal species similar to both cats and monkeys do not.
  • The cat motion area probably developed independently of the monkey visual area.

Abilities evolve if they improve the species' chances of survival within its environment.

• Different reproductive strategies may require different abilities.
  • If males and females within a species have different strategies, they may have different abilities.
• Differences across vole species
  • prairie vole: monogamous
  • meadow vole: polygamous
• Male meadow voles will travel over a larger area than male prairie voles.
• Comparing Spatial Abilities
  • Little difference between male and female in (monogamous) prairie voles.
  • Male meadow (polygamous) voles better at maze than females.
  • Spatial abilities tied to need to travel longer distances.

Human Evolution

Diverged from apes 6 million years ago.

Most evolutionary changes probably occured during period of foraging in African grasslands.

How have our cognitive abilities been shaped by evolution?

General purpose mechanisms or specially suited for environment?

Why did humans develop cognitive abilities not seen in other species?

1. three dimensional vision
   
   
2. hands
   
   
3. hunting (and maybe gathering)
   
   
4. living in groups
   • Social contracts - cost and benefit
   • Detecting cheaters - those who take the benefit without paying the cost

Enforcing the Drinking Law

Errors in Logic

Why do we Make these Errors in Reasoning?

One explanation: Availability

We do better when we can recall situations similar to the problem.

Alternative explanation: Detecting cheaters

We do better whenever we can understand the problem in terms of a social contract.

Testing the two alternatives - Leda Cosmides

From this test, Cosmides concludes that the Social Contract explanation wins over the Availability explanation. She goes on to conclude that our ability to detect cheaters on social contracts have developed through evolution.

Evolutionary Psychologists argue against broad general-purpose cognitive mechanisms. Instead, they believe we have specific mechanisms that worked well in the environment of our ancestors.

Additional Reading

If you would like to read more about Evolutionary Psychology, here are some suggestions.

Pinker, S. (1997). How the Mind Works.

Chapter 3: "Revenge of the Nerds", pp. 149-210.
If you prefer, you can skip the first part of the chapter, and start with the section entitled "The Blind Programmer" on p. 175.

Chapter 8: "The Meaning of Life", pp. 521-565.
There is a very interesting section on the fundamentals of music from p. 528 to p. 534. However, if you find that section difficult to follow, you can skip it.

Dawkins, R. (1981). Selfish genes and selfish memes. In D.R. Hofstadter and D.C. Dennett (eds.) The Mind's I.
This chapter provides a helpful introduction to some important concepts in evolution. You might find it useful to read this before reading the chapters from Pinker's book. For a more detailed discussion, see Dawkin's book The Selfish Gene, from which this excerpt was taken.

Tooby, J., & Cosmides, L. (1996). The psychological foundations of culture. In J.H. Barkow, L. Cosmides, and J. Tooby (eds.), The Adapted Mind. Oxford, pp. 19-136.
Here are a few excerpts from this chapter.

Cosmides, L. and Tooby, J. (1997). Evolutionary Psychology: A Primer. [On-line]. Available: http://www.psych.ucsb.edu/research/cep/primer.html.

Pinker, S. (1997). How the Mind Works. chapter 5, "Good Ideas", pp. 299-362.
This chapter covers evolutionary explanations for our reasoning and decision-making abilities.

For arguments against evolutionary psychology, see Gould, S.J. (2000). More things in heaven and earth. In H. Rose and S. Rose (eds.), Alas, Poor Darwin. London: Jonathan Cape. The part that is most relevant for us is at the end, pp. 98-105.

Related Website:

Center for Evolutionary Psychology, University of California, Santa Barbara

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Psych 391h: Cognitive Neuroscience Kyle Cave Psychology Dept. U. Mass.