1. The Biological Roots of Behavior Part I: the complex interaction between our genes and the environment to the music of evolution

2. Genetics the basics Chromosomes – strands of hereditary material Humans have 46 – 23 from their mother, 23 from their father Found in the nucleus of each cell The master blueprint or recipe for each individual

3. Genetic basics ii Genes – sections along a chromosome which control the chemical reactions that direct development Humans have around 25,000 Composed of DNA Play an essential role in not only in how we develop, but when we develop, as switches, turning other genes off & on 2001- the Human Genome Project

4. Does one gene control anything? Media reports seem to indicate that certain genes are responsible for certain traits or abilities. True or false? Very few traits or abilities are controlled by a single gene, most rely on an interaction between several genes and the environment.

5. Nature vs. nurture ? Is the person we are today a result of the genes we inherited from our parents? Or, instead, are our traits, abilities, strengths and weaknesses caused by our environment? This question, which caused furious debate for centuries, has been answered.

6. A mysterious dance Now we know that neither nature (genes) nor nurture (the environment) are primarily responsible for the person we are. A complex, ever-changing, interaction between these two forces creates the complex, unique people we are today, ready to change as our lives and circumstances do.

7. Why are we so similar? 6 billion and counting, yet we are remarkably alike How can this be? Evolutionary psychologists claim that this is due to genetic qualities, carried in our DNA that developed while we evolved from our ancestors

8. Mental Modules Evolutionary psychologists - mind not as a general-purpose computer waiting to be programmed by our experiences Instead, a collection of specialized and independent modules developed to solve specific survival problems One module often involves different parts of the brain working together

9. Born to conquer These mental modules are put into place by messages from our DNA as we mature They allow us to be proficient at various tasks and abilities without much, or any, experience or teaching

10. We all share … Without any work or effort, and at an early age, humans show certain characteristics: a) Infant reflexes – no one needs to teach us to nurse b) curiosity – we are eager to try new things and manipulate objects c) play – develops physical/social skills

11. Our innate cognitive tool set At birth we can: a) interpret gestures & expressions, b) identify faces, c) understand what others are thinking or feeling, d) understand, to some extent, numbers; e) acquire language

12. The wonder and mystery of Language How do we readily turn random sounds into words and sentences that convey thoughts, feelings and complex information? Darwin said that there is something unique and special about the human brain that allows a baby, with limited aide from the environment, quickly master language.

13. Don’t animals have language? Yes, but only in a limited sense. Chimpanzees, gorillas and even parrots can, with exhaustive coaching, pick up many aspects of language But it’s not easy or natural Humans, on the other hand, develop extraordinary language abilities naturally given the most basic of opportunities

14. Language’s key ability But still, many animals communicate in their environment, isn’t that language? Not in the fullest sense. A true language must have productivity – the capacity to express an infinite number of novel utterances, right there on the spot, as circumstances demand

15. The puzzle of language development How do we learn to talk (sign)? Is it through imitation and positive reinforcement? Partially, but not completely. Poverty of stimulus – adults do not give children sufficient instruction to explain their rapid acquisition of proper language

16. How do we do it? Noam Chomsky, way back in 1957, claimed that we are all born a mental module, the language acquisition device, that is just waiting, as the child matures, to understand and use universal grammar We are born with a “software” package that employs primitive grammar and understands nouns, verbs, negatives, etc.

17. Evidence supporting Chomsky 1) World-wide consistency 2) Novel word combinations 3) Poor or non-existent adult modeling 4) Spontaneous language development

18. On the other hand.. Intense observation of mothers interacting with infants showed much more interaction than researchers had anticipated The power of positive reinforcement Expansions

19. Evolutionary perspective? This amazing facility for language evolved, through natural selection, because it helped humans survive and have children who also survived to have children We could, easily and precisely, tell each other about dangers and opportunities, as well as cooperate and band together

20. Physical evidence? Genes have been located which conclusively influence language development Brain structures (left hemisphere) also have a direct link to language capabilities: a) Wernicke’s area - comprehension b) Broca’s area - production c) Heschl’s gyrus – learning a new language

21. But what about behavior? Sure, some capacities have developed through evolutionary processes – we see it in the brain and genes Complex social behaviors though? The realm of sociobiology – evolutionary explanations for social behaviors, including humans

22. Sociobiology examples Jackal “helpers” – why do they sacrifice their own reproductive opportunities? Mongoose rescues Lion infanticide

23. Humans? Can we explain the origins of human behaviors? Junk food obsessions Social behaviors? Niece/nephew adulation

24. Better yet, …. Do male and female sexual strategies arise from evolutionary influences? Huge controversy

25. David Buss’ big question What do male’s and females look for in a mate? In 37 wildly different countries he found the same answers From Scandinavia to the South Pacific they were looking for the same thing

26. Males like … Why do women try so hard to look young and healthy? Because those are the qualities that men, all over the world, select in picking a wife. They offer the best chance of producing the most children.

27. What women really want Why do men, everywhere, strive so hard for status, dominance and $$? Because that is what women look for in a mate. Someone who could provide a stable home and adequate resources to raise children.

28. Other Points Evolution is a battle fought by individuals not species. It’s not really, “the survival of the fittest.” More accurately, it is. “You must breed to succeed.”

29. It takes all kinds Evolution explains why we share basic features and capabilities But why are we so different? We have inherited differing traits

30. Heritability an estimate of the variance within a population that is due to genetics A measure of nature, excluding nurture Ranges from 0 (no genetic influence) to 1

31. Measuring heritability The heritability of a behavior is estimated in three ways 1) comparing monozygotic (identical) and diozygotic (fraternal) twins 2) looking at identical twins raised in different households 3) seeing whether children more closely resemble their adoptive or biological parents

32. Limits on heritability Applies only to a group living in a particular environment Children who face severe malnutrition might not grow very tall, even if their parents were giants

33. IQ and Heritability Strong relationship – up to 87% for identical twins raised together Amazingly, the genetic influence grows even stronger as we age Correlations between those adopted and their adopted family disappear altogether

34. What about group differences? We find consistent differences between races. Are some races genetically inferior? Huge controversy Long history The Bell Jar

35. Group differences in IQ

36. Why it’s not the genes The Tomato Plant Experiment Differing environments lead to different outcomes Expectations Overlap Raised elsewhere? African purity means nothing

37. The guy you are talking to Heritability estimates don’t tell us anything about an individual, just a large group Huge numbers Big overlap Tremendous variations in environment Your genetic blueprint and your environment are unique

38. Nature or Nurture It is the interaction of our genes and the environment in which they are expressed that determine our behavior, experiences and personality

39. Genes & behavior Researchers have found moderate levels of heritability for almost all behaviors Some genes influence behavior directly But often genes influence our behavior indirectly by giving us advantages or deficits that have great effect on both what we do within our environment and how it responds to us