Evolution, Genetics and Experience PDF

Evolution, Genetics and Experience  BIOLOGY OF BEHAVIOR 01 EVOLUTION 02 FUNDAMENTAL GENETICS 03  01 BIOLOGY OF BEHAVIOR Dichotomous Thinking The allure of this way of thinking is its simplicity. The tendency to think about behavior in terms of dichotomies is illustrated by two...

Evolution, Genetics and Experience  BIOLOGY OF BEHAVIOR 01 EVOLUTION 02 FUNDAMENTAL GENETICS 03  01 BIOLOGY OF BEHAVIOR Dichotomous Thinking The allure of this way of thinking is its simplicity. The tendency to think about behavior in terms of dichotomies is illustrated by two kinds of questions commonly asked about behavior: (1) Is it physiological, or is it psychological? (2) Is it inherited, or is it learned? Both questions have proved to be misguided, yet they are among the most common kinds of questions asked in biopsychology classrooms. That is why we are dwelling on them here. Physiological or Psychological ? Physiological or Psychological ? The idea that human processes fall into one of two categories, physiological or psychological, rose to prominence following the Dark Ages in response to a 17th-century conflict between science and the Roman Church. For much of the history of Western civilization, truth was whatever was decreed to be true by the Church. Some Renaissance scholars were not content to follow the dictates of the Church; instead, they started to study things directly by observing them—and so it was that modern science was born. Much of the scientific knowledge that accumulated during the Renaissance was at odds with Church dictates. Physiological or Psychological ? René Descartes- advocated a philosophy that, in a sense, gave one part of the universe to science and the other part to the Church. He argued that the universe is composed of two elements: ○ Physical matter, which behaves according to the laws of nature and is thus a suitable object of scientific investigation—the human body, including the brain, was assumed to be entirely physical, and so were non-human animals ○ Human mind (soul, self, or spirit), which lacks physical substance, controls human behavior, obeys no natural laws, and is thus the appropriate purview of the Church. Physiological or Psychological ? Cartesian Dualism, as Descartes’s philosophy became known, was sanctioned by the Roman Church, and so the idea that the human brain and the mind are separate entities became even more widely accepted. Most people now understand that human behavior has a physiological basis, but many still cling to the dualistic assumption that there is a category of human activity that somehow transcends the human brain. Inherited or Learned? Nature Nurture Inherited or Learned? This debate is commonly referred to as the nature–nurture issue. Most of the early North American experimental psychologists, including the father of behaviorism--John B. Watson, were totally committed to the nurture (learning) side of the nature–nurture issue. Ethology (the study of animal behavior in the wild) was becoming the dominant approach to the study of behavior in Europe. ○ European ethology, focused on the study of instinctive behaviors (behaviors that occur in all like members of a species, even when there seems to have been no opportunity for them to have been learned), and it emphasized the role of nature, or inherited factors, in behavioral development. Because instinctive behaviors are not learned, the early ethologists assumed they are entirely inherited. Problems with Thinking about the Biology of Behavior in Terms of Traditional Dichotomies Physiological or Psychological ? Two lines of evidence against physiological or psychological thinking (the assumption that some aspects of human psychological functioning are so complex that they could not possibly be the product of a physical brain). ○ The first line is that even the most complex psychological changes (e.g., changes in self-awareness, memory, or emotion) can be produced by damage to, or stimulation of, parts of the brain. ○ The second line s that some nonhuman species, particularly primate species, possess some abilities that were once assumed to be purely psychological and thus purely human. Physiological or Psychological ? First line: Most complex psychological changes can be produced by damage to, or stimulation of, parts of the brain ○ In Oliver Sacks’s (1985) account of “the man who fell out of bed” the patient was suffering from asomatognosia, a deficiency in the awareness of parts of one’s own body. ○ Asomatognosia typically involves the left side of the body and usually results from damage to the right parietal lobe. ○ The point here is that although the changes in self-awareness displayed by the patient were very complex, they were clearly the result of brain damage: Indeed, the full range of human experience can be produced by manipulations of the brain. Physiological or Psychological ? The second line: Some nonhuman species, particularly primate species, possess some abilities that were once assumed to be purely psychological and thus purely human ○ G. G. Gallup’s research on self-awareness in chimpanzees shows that even nonhumans, which are assumed to have no mind, are capable of considerable psychological complexity—in this case, self-awareness. ○ Although their brains are less complex than the brains of humans, some species are capable of high levels of psychological complexity. Inherited or Learned? First, factors other than genetics and learning were shown to influence behavioral development; factors such as the fetal environment, nutrition, stress, and sensory stimulation all proved to be influential. Next, it was argued convincingly that behavior always develops under the combined control of both nature and nurture not under the control of one or the other.  02 EVOLUTION Darwin’s Theory of Evolution Modern biology began in 1859 with the publication of Charles Darwin’s On the Origin of Species. Darwin was not the first to suggest that species evolve (undergo gradual orderly change) from preexisting species, but he was the first to amass a large body of supporting evidence and the first to suggest how evolution occurs Darwin presented evidences to support his assertion that species evolve. Darwin’s evidences He documented the evolution of fossil records through progressively more recent geological layers. He described striking structural similarities among living species (e.g., a human’s hand, a bird’s wing, and a cat’s paw), which suggested that they had evolved from common ancestors. Darwin’s evidences He pointed to the major changes that had been brought about in domestic plants and animals by programs of selective breeding. He pointed out that the members of each species vary greatly in their structure, physiology, and behavior and that the heritable traits associated with high rates of survival and reproduction are the most likely ones to be passed on to future generations. Darwin’s Theory of Evolution He argued that evolution occurs through natural selection. ○ When repeated for generation after generation, leads to the evolution of species that are better adapted to surviving and reproducing in their particular environmental niche. Nature creates fitter animals by selectively breeding the fittest. ○ Fitness, in the Darwinian sense, is the ability of an organism to survive and contribute its genes to the next generation. Evolution and Behavior Social Dominance The males of many species establish a stable hierarchy of social dominance through combative encounters with other males. Once a hierarchy is established, hostilities diminish because the low-ranking males learn to avoid or quickly submit to the dominant males. Social Dominance Why is social dominance an important factor in evolution? One reason is that in some species, dominant males copulate more than non dominant males and thus are more effective in passing on their characteristics to future generations. Another reason is that dominant females are more likely to produce more and healthier offspring. Courtship displays Courtship displays are thought to promote the evolution of new species. A species is a group of organisms reproductively isolated from other organisms; that is, the members of a species can produce fertile offspring only by mating with members of the same species. Courtship displays A few members of a species may develop different courtship displays these may form a reproductive barrier (which discourages breeding; it could be geographical or behavioral) between themselves and the rest of their conspecifics (members of the same species): ○ Only the suitable exchange of displays between a courting couple will lead to reproduction. SINGLE-CELL ORGANISMS TO HUMANS Evolution of Vertebrates Complex multicellular water-dwelling organisms first appeared on earth about 600 million years ago. About 150 million years later, the first chordates evolved (animals with dorsal nerve cords). The first chordates with spinal bones to protect their dorsal nerve cords evolved about 25 million years later. Evolution of Vertebrates The spinal bones are called vertebrae, and the chordates that possess them are called vertebrates. The first vertebrates were primitive bony fishes. Today, there are seven classes of vertebrates: three classes of fishes, plus amphibians, reptiles, birds, and mammals. Evolution of Amphibians About 410 million years ago, the first bony fishes started to venture out of the water. Fishes that could survive on land for brief periods of time had two great advantages: ○ They could escape from stagnant pools to nearby fresh water ○ They could take advantage of terrestrial food sources. Evolution of Amphibians The advantages of life on land were so great that natural selection transformed the fins and gills of bony fishes to legs and lungs, respectively. The first amphibians evolved about 400 million years ago. Amphibians (e.g., frogs, toads, and salamanders) in their larval form must live in the water; only adult amphibians can survive on land. Evolution of Reptiles About 300 million years ago, reptiles (e.g., lizards, snakes, and turtles) evolved from a branch of amphibians. Reptiles were the first vertebrates to lay shell-covered eggs and to be covered by dry scales. ○ Both of these adaptations reduced the reliance of reptiles on watery habitats. Evolution of Mammals About 180 million years ago, a new class of vertebrates evolved from one line of small reptiles. The females of this new class fed their young with secretions from special glands called mammary glands. The members of the class are called mammals. Evolution of Mammals Eventually, mammals stopped laying eggs; instead, the females nurtured their young in the watery environment of their bodies until the young were mature enough to be born. It provided the long-term security and environmental stability necessary for complex programs of development to unfold. Evolution of Mammals Today, most classification systems recognize about 20 different orders of mammals. ○ The order to which we belong is the order primates (from the Latin term primus, which means “first” or “foremost.”). Examples of four different families of primates A comparison of the feet and hands of a A taxonomy of the human species. human and a chimpanzee. Emergence of Humankind Primates of the tribe that includes humans are the hominini which is composed of 6 genera: ○ Australopithecus ○ Paranthropus ○ Sahelanthropus ○ Orrorin ○ Pan ○ Homo Homo is thought to be composed of at least eight species with 7 now extinct, whereas Homo sapiens (humans) are not. Emergence of Humankind Primates of the tribe that includes humans are the hominini. Three important hominini fossil discovered recently: ○ An uncommonly complete fossil of a 3-year-old early Australopithecus girl in Ethiopia. ○ Fossils indicating that a population of tiny hominins inhabited the Indonesian island of Flores as recently as 18,000 years ago. ○ Several early Australopithecine fossils with combinations of human and nonhuman characteristics in a pit in South Africa. Emergence of Humankind The first Homo species are thought to have evolved from one species of Australopithecus about 2 to 2.8 million years ago. ○ Early Homo species also existed outside of Africa for about 1.85 million years. About 275,000 years ago, early Homo species were gradually replaced in the African fossil record by modern humans (Homo sapiens). ○ Then, about 130,000 years ago, modern humans began to migrate out of Africa. Evolutionary psychology and the study of mate bonding The study of mate bonding In most vertebrate species, mating is totally promiscuous—promiscuity is a mating arrangement in which the members of both sexes indiscriminately copulate with many different partners during each mating period. However, the males and females of some species form mating bonds (enduring mating relationships) with particular members of the other sex. The study of mate bonding The pattern of mate bonding that is most prevalent in mammals is polygyny, an arrangement in which one male forms mating bonds with more than one female. Polyandry is a mating arrangement in which one female forms mating bonds with more than one male. ○ Polyandry does not occur in mammals; it occurs only in species in which the contributions of the males to reproduction are greater than those of the females. The study of mate bonding Although most mammals are polygynous, about 9% of mammalian species are primarily monogamous. Monogamy is a mate-bonding pattern in which enduring bonds are formed between one male and one female. ○ Monogamy is thought to have evolved in those mammalian species in which each female could raise more young, or more fit young, if she had undivided help. The study of mate bonding Evolutionary theory of mate bonding has led to several predictions about current aspects of human mate selection. ○ Men in most cultures value youth and attractiveness (both indicators of fertility) in their mates more than women do; in contrast, women value power and earning capacity more than men do. 03 FUNDAMENTAL GENETICS  Darwin did not understand two of the key facts on which his theory of evolution was based. ○ He did not understand why conspecifics (members of the same species) differ from one another, and ○ He did not understand how anatomical, physiological, and behavioral characteristics are passed from parent to offspring. While Darwin puzzled over these questions, an unread manuscript in his files contained the answers. It had been sent to him by an unknown Augustinian monk, Gregor Mendel. Mendelian Genetics Mendel studied inheritance in pea plants. In designing his experiments, he made two wise decisions: ○ He decided to study dichotomous traits, and ○ He decided to begin his experiments by crossing the offspring of true-breeding lines. Dichotomous traits occur in one form or the other, never in combination. For example, seed color is a dichotomous pea plant trait. Every pea plant has either brown seeds or white seeds. True-breeding lines are breeding lines in which interbred members always produce offspring with the same trait (e.g., brown seeds), generation after generation. Mendelian Genetics One trait, which he called the dominant trait, appeared in all of the first-generation offspring. The other trait, which he called the recessive trait, appeared in about one-quarter of the second-generation offspring. An organism’s observable traits are referred to as its phenotype; The traits that it can pass on to its offspring through its genetic material are referred to as its genotype. Mendelian Genetics Mendel devised a theory to explain his results. It comprised four ideas: ○ First, Mendel proposed that there are two kinds of inherited factors for each dichotomous trait. Today, we call each inherited factor a gene. ○ Second, Mendel proposed that each organism possesses two genes for each of its dichotomous traits; The two genes that control the same trait are called alleles. Organisms that possess 2 identical genes for a trait are said to be homozygous for that trait; those that possess 2 different genes for a trait are said to be heterozygous. Mendelian Genetics Third, Mendel proposed that one of the two kinds of genes for each dichotomous trait dominates the other in heterozygous organisms. Fourth, Mendel proposed that for each dichotomous trait, each organism randomly inherits one of its “father’s” two factors and one of its “mother’s” two factors. THANKS