Heredity: implying something is fixed, and is unalterable. This is contrasted with behaviour which is environmentally caused  independent of genes and can be readily changed.

  • Nature vs. Nurture
  • Heredity vs environment
  • Cultural vs. biological

Evolutionary model: all behaviour emanates from BOTH genes and environment  cannot be attributed to solely one or the other.

‘all behaviour is based on genes’: behaviour (thoughts, feelings, actions) comes from the same protoplasm as everything else. Same function as everything else. Cannot have function without structure  something material underlying this.

  • All biological structures begins with genes.
  • Genes are basic in all biological structures.

Genes carry DNA, DNA controls various proteins in the body, the nature of the proteins dictate the nature of the cells like neurons, nerves etc, all thought feelings and actions are affected by nerve cells.

  • If the nerve cells are impaired, then function is impaired.
  • Nerve cells stop when you die, and all feeling is gone as well.

Does not rule out environment  complex behaviour (not reflexes) occur in response to environmental events. In the evolutionary model, must view the environment with its interaction with genetic material.

Evolutionary model:

Genes program the organism to react in certain ways to certain environmental events.

These interactions underlie all behavioural development

  • Originate in evolution, the history of the animal, by means of natural selection, and the individuals survival/adaptation.

Ex. Bird songs

Every species has a unique song, which has a role in courtship. Male sings a song, female responds to this.

  • Reproductive value  Keeps birds from mating outside their species. Genetically determined behaviour.
  • Must learn this song, so they listen to adult birds sing this song. “Critical Period”  where the bird learns this.
  • Can only learn their own song  genetically wired to learn the song of their own species. Species switched eggs, and most of the time they did not learn the song. Combination of their own song and the song of their adoptive species.

Called hardwired behaviour: the genes play a strong role. Highly specific event grounded in genes Facultative: complex interactions. The genes program loosely, and leave options for the environment to have a larger role.

Ex. Differential mating strategies of the scorpion fly. Male scorpion fly courts the female by finding her food, and wrapping it in his saliva. While she eats it, he copulates with her. Does not find prey  he will coerce her.

Ex.2: family planning: optimal size. Adjusts birth rate to available resource. Lots of resouruces  lays a lot of eggs. Less – she will lay fewer eggs.

Ex.3: Antlors (?) use environment to find out when to retreat, outflank, escape etc. They look slaves, and feed them less than their own.

Ex. 4: incest taboos – universal in human cultures. Several adaptive functions: increase diversity in the gene pool to protect from environmental factors, and to avoid inbreeding depression.

Def’n inbreeding depression: your maladaptive traits collect in your recessive genes. Since close relatives are more similar than non, there is a high probability of relatives to develop a high rate of maladaptive rates.

–       Physical disabilities, retardation etc.

2 ways in which genes program species not to inbreed

  1. Dispersal: emigration of 1 or more sexes before sexual maturity.  LEAVE home/place where family lives. Can be voluntary or forced. Ex. Whales force their young to leave when the time is come.
  2. Behavioural avoidance: a lack of post pubital sexual interest for those who are likely to be close family members. Sexual avoidance response to close relatives.
  • Close exposure to relatives during critical periods. Without this, you are more likely to develop the incest taboo.

Chimps: major method of incest avoidance is dispersal. Most chimps (females) will voluntary leave their troops during their first ovulatory period.

  • The chimps who do not leave show avoidant behaviour towards their close relatives.

Timerlan: experiments with monkeys. Raised a female chimp in his house, and the chimp was affectionate to the family equally. At puberty, he showed hostility toward his son and himself. –   Look him up.

Male chimps do not transfer outside their male troops, but show avoidance behaviour unless they were separated.

  • Will not approach sisters or mothers with mating.
  • Males will wait for immigrating females to arrive from other groups.

Baboons: males transfer voluntarily, females stay home.

Variations on this incest taboos

Squirrels: have 2 mating seasons, short one in Jan and a long one in July. When they are not in mating seasons, they are territorial. Family groups occupy a specific territory to bury nuts.

  • During mating season, the barriers are off, and then they go back to their families once it is over. – Gene/environment interaction.

In humans, it is avoidance rather than dispersal. Not born with avoidance, we need to have exposure during the critical period.

Hymenoptera: have a caste systems

  • Females who rule, and males who serve them reproductively. – There are soldiers.

What determines if a female is a queen or soldier?

  • Depends in larval stage (early on) or pheromone (adult insects will squirt a pheromone into the larva and this will determine the # of soldiers, workers queen etc.
  • This is dependent on their status as well  war, lost their queen, etc. – Early environmental events will determine their roles in the colony.

Humans are a very status-oriented species in every culture – not born with an inclination toward a particular statue, but your gene provides a disposition to find your status.

  • Searching, and solidifying status.

Wilson: 2 streams of evolution – mammals and insects. Humans and ants have risen to the top of these sectors.

Interactionist models: you can see the shortcomings of behaviourism.

  • Still a theory that explains some things, but not everything.
  • Evolutionary psychological approach deomstrates this shortcoming.

Behaviourism: all behaviour is a product of learning and conditioning. Organism is a ‘tabula rosa’ (blank slate) at conception and its experience (how the world rewards or punishes them as + or – reinforcement) determines how they will develop.

Evolutionary psychologists maintain that organisms have considerable baggage at conception  NOT born blank slates. And these determine how the rewards and punishments will affect a person.

  • The individual’s genetic program will determine if their behaviour is more or less conditionable. The more a beh. relates to an animal’s survival, the LESS conditional it will be.

Ex. Training a dog: sitting is easier because it is natural to them. Making them roll over is harder  lying down is a sign of giving up/surrendering.

Ex. Train a bird to peck at different coloured circles, but trying to condition them to change their migratory patterns is impossible  the bird won’t let you b.c it is hardwired.

  • If you condition an animal to do something, generalizability to natural habitat is 0.
  • Rats will revert to its genetically determined instincts once it is back into its habitat.
  • Reward/punishment does not generalize into the natural habitat (like the classroom)

Genetic programming also determines how behaviour is conditioned

  • Which rewards work for which behaviours, and which punishments as well.

Behaviourists believed in ecopotentiality: any behaviour can be conditioned in any animal with any reward.

Disproved: Garcia – trying to condition specific flavor avoidance in rats. Gave them sweetened water and then avoidance (shocks, noises, etc) BUT could not do this with taste.

  • If you want to condition an animal not to eat something, the only punishment that works is to make them noxious.
  • The animal is only sensitive to one kind of neg. reinforcement  Taste conditioning. – This is adaptive to them as scavengers to avoid food that is toxic.

Training dogs: giving him a command to sit, then giving him a reward. And from then on, he will sit whenever he wants to please you.

  • IN the dog’s head, you are pleased with him when he sits
  • Domestic dogs evolved from wolves, and the wolf is a pack animal.
  • Alpha animal: pack leader. If the dog feels he is looking for the alpha, he will sit with you in order to please the alpha.
  • Different breeds of dogs show different capabilities for learning: artificial selection: natural selection but the humans train the animal. Breed for different attributes  Retrieving, tracking, herding, etc.

Breed dogs because of the polymorphous nature of wolves: wolves have a great deal of individual differences. This is why they are good pack animals, and have different roles in the hunt. Some are trackers, other are good killers.

  • Must know what your dog is bred for when you try to train him.
  • Collie dogs when herding do the same things when herding as wolves do when hunting  just select out the kill response when breeding them.

Pitbulls: bred in England, descendent of the Bull Dolgge which is now extinct. Bred to watch dogs tear bulls apart. The sport (bull bating) was banned. And these dogs were bred for dog fighting. Bred with terriers, to make them smaller, and made pit bull terriers.

  • Americans bred the English Pitbull, to a terrier, and wanted a toned down version of the English one. A fighting dog, but kept as a pet.
  • Breed today: massive chest, huge neck, quicker to anger, a higher level of L-tyrosene (it mediates aggression in the brain). 15 min or longer attacks.
  • Will stay in a fight when they are almost dead.

Why: Pitbulls generate a higher level of endorphin (natural painkiller). Pitbulls are almost seeking pain to get an endorphin buzz.

  • The threat display has been bred out of pitbills. When dogs encounter each other, they will bark and growl, bare teeth etc. It is their way of avoiding fighting. – Pitbulls don’t have this  either peace or kill.

Pitbulls are bred to fight, nothing to do with environment.