He applied the “Page 99 Test” to his new book, Human: The Science Behind What Makes Us Unique, and reported the following:
Whether the page 99 test hypothesis would stand up to the scientific method would be a fun problem to tackle, and in the case of my book Human, The Science Behind What Makes Us Unique, it would garner support. By definition, a species is unique, and has adapted to different conditions to survive. Adaptive changes that occurred to both the physical body, and how the human brain is hooked up, have allowed Homo sapiens to be both highly sociable and have a unique type of intelligence. Page 99 is from the chapter about social relationships and how our brain, a product of natural selection, is connected to promote social exchange. First there is a quote from the evolutionary psychologist Leda Cosmides making the point that when we understand that the human mind is a product of natural selection that occurred in a hunter-gatherer environment, selected to deal with problems that hunter-gathers faced, we are better able to present modern information to it in formats that are easier to understand:Read an excerpt from Human: The Science Behind What Makes Us Unique, and learn more about the book and author at the publisher's website and Michael Gazzaniga's faculty webpage.
Let's say you have a positive mammogram. How likely is it that you actually have breast cancer? The typical way of presenting the relevant data - in percents - makes this difficult. If you said that 1% of women randomly screened have breast cancer, and all of these test positive, but there is a 3% false alarm rate, most people mistakenly think a positive mammogram means they have a 97% chance of having breast cancer. But let me give you the same information in absolute frequencies - an ecologically valid information format for a hunter-gatherer mind: Out of every 1000 women, 10 have breast cancer and test positive; 30 test positive but do not have breast cancer. So: out of every 1000 women, 40 will test positive, but only 10 of these will have breast cancer. This format makes it clear that, if you had a positive mammogram, your chance of having breast cancer is only 1 in 4 - that is, 25%, not 97%.
The rest of the page begins Cosmides research on cheater detection in social exchanges. She has found evidence for a specific brain module, or circuit, that allows humans to detect cheaters in social situations, but the same type of problem, if not in a social context format, is much more difficult for people to solve. Here is the example from page 99, and I am going to cheat myself and include part of page 100 to let you see the whole deal.
There are four cards on a table. Each card has a letter on one side and a number on the other. Currently you can see R Q 4 9. Turn over only those cards that you need to, to prove whether the following rule is true or false: If a card has an R on one side, then it has a 4 on the other. Got it? What's your answer? The answer is R and 4. OK, now try this one: There are four people sitting at a table. One is sixteen, the second is 21, the third is drinking coke and the fourth is drinking beer. Only those over 21 can drink beer legally. Who should the bouncer check to make sure the law isn't being broken? That one is easier isn't it? The answer is the 16 year old and the beer drinker.
Reciprocity is the basis of our social structure, but it can't exist if cheaters go undetected. To find out why and learn what other modules we have.... Read on!!!