Mean Genes: From Sex to Money to Food Taming Our Primal Instincts
by Terry Burnham and Jay Phelan
This book is about the reward circuitry of the brain and how it evolved under very different circumstances, leaving us vulnerable in today's environment. The book is easy to understand, informative and extremely entertaining. Phelan is a UCLA biology professor. Link to second edition
Here are two excerpts:
- We need to recognize that our only true errogenous zones are in our brains. In some completely paralyzed men, for instance, it is possible to stimulate the genitals to produce erections and even ejaculations. These patients, however, find no satisfaction because their brains never get the message. The same patients can, however, experience sensations like orgasms if the pleasure centers of their brains are stimulated. The trouble is, the brain has to be signaled about our behavior through the nervous system, and any signaling system can be manipulated.Consider, for example, how predators lethally exploit the signaling system of the firefly. If you sit in a field on a summer night, you may be treated to a whirl of fireflies flashing in the dark. This dance is not for our pleasure; they are performing a mating ritual. It's pitch black in the field, and many differnt species are flying around. The flies need to find members of their own species in order to mate successfully, so they use a speical Morse code signaling system that says, "Hey, I'm your type and I'm ready for action."
The fireflies don't actually see their potential lovers but instead communicate with belly lights. One species may beckon with two long flashes and a short while another may use four shorts followed by a long. When a sexually charged fly detects the right series of flashes, he or she swoops in, ready to begin a family.
Some of these flying Romeos and Juliets receive a rude shock. Arriving at the signaler, tiny loins aflame, they find jaws of death, not arms of love. Devious predators take advantage of the signaling system by producing the exact sequence of flashes sent by a willing mates. When a fly comes a-courtin' at the wrong home, it's dinnertime for the talented predator.
Our brain's signaling system can be similarly tricked— with disastrous consequences. When we do something good, our pleasure is caused by chemicals called neurotransmitters that stimulate our brains' do-it-again centers. ...
When we take a pleasure-causing drug, our brain acts as if appropriately released neurotransmitters were flooding the system. The brain thinks we have done something great, such as finding food or warmth, when in fact we may be crouched over a filthy toilet with a hypodermic of heroin in our arm. Our pleasure centers know only that they are bathed in a precise set of chemical signals that induce bliss.
- Chantek is a smart, lovable orangutan who lives at the Atlanta zoo. Trained in sign language, he has a vocabulary of more than 150 words, and he is considered a decent artist. …Growing up in this human setting, Chantek became REALLY FAT, weighing in at five hundred pounds, roughly three times his ideal size. Afraid that the massive bulk would collapse his lungs, scientists placed him on a strict diet. Formerly five hundred pounds of fun, he became four hundred pounds of anger. During the diet, his favorite sign language symbol became "candy." He refused to draw and instead ate the crayons given for his artistic use.
While on his diet, Chantek even pulled off an escape. … He was eventually found sitting next to the up-ended food barrel, using all four limbs to stuff monkey chow into his mouth.
Chantek is unique, not only for his human contact and his linguistic and artistic abilities but also for his weight. You see, there are no fat orangutans outside zoos and research centers. Wild orangutans, despite sharing Chantek’s genetic zest for a fine meal, maintain a svelte 160 pounds or so because food is relatively scarce and difficult to obtain in the jungles of Borneo.