BIOLOGY AND EVOLUTION: An Introduction to Heredity
Do Now: • Based on your homework, turn to a partner and discuss whether or not you feel that evolution is valuable or detrimental and why. Make a T-Chart discussing both arguments. Valuable Unjust
Religion and Science • Religion is not always in competition with science…sometimes they work hand-in-hand. • Evolution is one way of looking at the beginning of “life,” while many religions suggest alternative views to these understandings. • The most current philosophy is that creationism and the theory of evolution can co-exist—both of them may suggest the existence of God.
EVOLUTION IS A THEORY. What does this really mean? Does this discredit evolution?
What is a Theory? • In science, a theory is a rigorously tested statement of general principles that explains observable and recorded aspects of the world. • A scientific theory describes a higher level of understanding that ties "facts" together. • A scientific theory stands until proven wrong -- it is never proven correct. • The Darwinian theory of evolution has withstood the test of time and thousands of scientific experiments; nothing has disproved it since Darwin first proposed it more than 150 years ago. • Many scientific advances, in a range of scientific disciplines including physics, geology, chemistry, and molecular biology, have supported, refined, and expanded evolutionary theory far beyond anything Darwin could have imagined.
What is Evolution…Basically? • Biological evolution refers to the cumulative changes that occur in a population over time. • These changes are produced at the genetic level as organisms' genes mutate and/or recombine in different ways during reproduction and are passed on to future generations. • Sometimes, individuals inherit new characteristics that give them a survival and reproductive advantage in their local environments; these characteristics tend to increase in frequency in the population, while those that are disadvantageous decrease in frequency. • Non-genetic changes that occur during an organism's life span, such as increases in muscle mass due to exercise and diet, cannot be passed on to the next generation and are not examples of evolution.
Evidence of Evolution • The Fossil Record – • Example: The fossils we find in rocks formed when the earth was more covered in ice show organisms better adapted for living in icy conditions. • DNA— • Example: Humans have 23 pairs of chromosomes, but our closest relatives, the great apes - chimpanzees, gorillas and orangutans - all have 24 pairs of chromosomes. One of the pairs of chromosomes in humans is exactly the same as 2 of the chimp chromosomes but fused together. • Observation— • Evolution is an ongoing process - everything is still evolving and we can see it evolving. • Example: The bacteria and viruses that make us ill. These organisms live, die and reproduce so quickly that they evolve extremely quickly, too. Why do we need to have a new flu vaccination every year? Because the influenza virus evolves. Why do we need to finish a course of antibiotics if they are prescribed? Because if we only use half of the antibiotics, we only kill the weakest half of the bacteria making us ill. The strongest half lives on and reproduces even more (because they won't have competition from their weaker brethren). We'd be helping the bacteria to evolve.
The Classification System • Carolous Linnaeus develops the system of taxonomy. • Within this system, he creates various taxonomic categories to classify beings and look at connections across living things. • He would classify things based on: • Body structure • Body function • Sequence of bodily growth Humans are Homo (Genus) sapiens (Species).
How Does Evolution Work? 1) How has Mickey Mouse changed? 2) Mickey clearly has evolved. But why? Why did Walt Disney make this “selection”?
The Father of Evolutionary Theory Charles Darwin • First Discoveries: • The observations made on a journey he took around the world with companion Captain Fitzroy • Observed diversity of living creatures and fossils • Natural Selection- • The process by which forms of life having traits that better enable them to adapt to specific environmental pressures, as predators, changesin climate, or competition for food or mates, will tend to survive andreproduce in greater numbers than others of their kind, thus ensuring the perpetuation of those favorable traits in succeeding generations. • As generation succeeds generation, nature selects the most advantageous variations, and species evolve. • “Survival of the fittest”- those who are eliminated in the struggle for existence are the unfit.
Natural Selection • Green beetles have been selected against, and brown beetles have flourished. • What important traits do brown beetles have to protect them from their environment?
Heredity • Dominant vs. Recessive Genes
Heredity • Co-Dominance • Later studies suggest that some patterns of inheritance are not so simple. In some cases, neither allele is dominant, but rather both are co-dominant. • Example: Blood Types • Type A is produced by one allele, Type B is another. • A Co-Dominant individual will have AB, causing neither allele to dominate the other.
DEBATE: Should we naturally select our own genetic traits? • Read and take notes on each form of genetic engineering. • You may include your own opinion in the development each side.