Chapter 1, Human Biology PDF

BIO 103 Human Biology The most important class you’ll take at AUS! Dr. Aaron Bartholomew BSc. In Marine Science / Biology, minor in Chemistry from University of Miami. GPA: 3.99 / 4 PhD. in Marine Science (Marine Ecology) from The College of William and Mary. GPA: 3.94 / 4 I...

BIO 103 Human Biology The most important class you’ll take at AUS! Dr. Aaron Bartholomew BSc. In Marine Science / Biology, minor in Chemistry from University of Miami. GPA: 3.99 / 4 PhD. in Marine Science (Marine Ecology) from The College of William and Mary. GPA: 3.94 / 4 I have been at beautiful AUS since 2002 I have written 31 papers / chapters that have been cited more than 2,500 times. Read the syllabus (on ilearn) Read the slides and book before watching the lecture Take notes in class Optional homework questions (also on ilearn) can help your grade Feel free to contact me: office and via e-mail. Statistics lab data sheet due on Jan. 25th  CHAPTER 1 Learning about human biology Objectives Learn the scientific method Learn the characteristics of life Learn the characteristics of humans  You cannot prove anything Logic dictates that you cannot prove anything. You can disprove incorrect ideas, however. If a à (then) b If this is assumed true If b à (then) a Then this is also true, If b à (then) a but this is not true  So how does science work? We can disprove wrong ideas. We cannot “prove” ideas to be true, we can only accumulate evidence supporting ideas.  The scientific method 1 Make general observations 2 Form a general hypothesis or “idea” or “educated guess” 3 Form testable hypotheses and plan an experiment 4 Perform experiments or observations that randomly sample the population of interest, and with proper controls 5 Do your results support your general hypothesis? If not change your general hypothesis. 6 Make further predictions and perform further experiments to support (or not) your general hypothesis 7 Publish your results 8 If a hypothesis has broad support, has never been disproven, and explains many natural phenomena, it may become a theory 1 General Observation “Many people that are smokers are having serious health problems, including lung cancer (and also high blood pressure, heart attacks, strokes, emphysema and stinky breath)” 2 General hypothesis People who smoke are more likely to get lung cancer than people who do not smoke. 3 Observational study and testable hypotheses Question: Do UAE smokers have a higher lung cancer risk? Randomly sample from the UAE: 100,000 smokers and 100,000 non- smokers and count the number of people that get lung cancer in each group after many years. Why is random sampling important? Why is it important to avoid confounded experiments? What is the control group, and why is it important? What is the experimental group? Testable hypotheses: 1 There is no significant difference in the incidence of lung cancer between the two groups (null hypothesis) 2 There is a significant difference in the incidence of lung cancer between the two groups (alternate hypothesis) Observational Study Results Smokers: 60 cases of lung cancer out of 100,000 Non-smokers: 2 cases of lung cancer out of 100,000 What does this mean? At what point is the other person cheating? Other:You 31:31 32:30 40:22 56:6 60:2 62:0 Rejection of null hypothesis at p < 0.05 = 1/20 times or less it would happen. Reject null hypothesis Testable hypotheses: 1 There is no significant difference in the incidence of lung cancer between the two groups (null hypothesis) 2 There is a significant difference in the incidence of lung cancer between the two groups (alternate hypothesis) Evidence supports the idea that cigarettes may cause lung cancer, but does not prove this! 4 Experimental study to test hypothesis Experimental plan: Take 200,000 mice and randomly divide them into 2 groups of 100,000. Expose one group to cigarette smoke throughout their life, and do not expose the other group. Which is the control group? What is the experimental group? Testable hypotheses: 1 There is no significant difference in the incidence of lung cancer between the two groups 2 There is a significant difference in the incidence of lung cancer between the two groups Which is the null hypothesis, which is the alternate hypothesis?  Experimental study results Compare incidence of lung cancer in mice Results: Smoking Non-smoking 210 4 Once again, after doing statistics we reject the null hypothesis, and support the alternate hypothesis. Cigarette company (skeptical) response: “These two studies do not prove that cigarettes cause lung cancer, the first was merely bad luck, and besides it only looked at one country. The second involved MICE not people”. We did not prove cigarettes caused cancer, but we did accumulate evidence. Only through the accumulation of overwhelming scientific evidence from a variety of studies the world over did cigarette companies admit that smoking causes lung cancer. Smoking advertising: then vs. now  Ways to Disseminate Findings Peer-reviewed journals: (most reliable results come from these sources, these are available online and often as hard copies also) Presentations at scientific meetings: (material is often times not yet peer-reviewed) Popular press and reputable websites: online newspapers / magazines / websites (they may mis-represent the findings, and are usually not peer-reviewed). It’s very important to realize that a lot of the “scientific” information online is “junk” = not accurate. Try to get your information from reliable web sites, with high professional standards. Examples: Online newspapers that have real journalists (New York Times, The Guardian, Wall Street Journal, The Hindu, Khaleej Times, etc.) Government websites University websites Websites of well-known, reputable organizations (American Heart Association, Mayo Clinic, American Cancer Society, etc.) What are the characteristics of life?  The Characteristics of Life How are living things different from nonliving things? Living things: Take in energy and raw materials from surroundings Have different chemical compositions Are composed of at least one cell Maintain homeostasis Sense and respond to their environment (often by moving) Grow and reproduce Have DNA (although some non-living viruses do too) Populations of living things are capable of evolving The Characteristics of Life Living things take in energy and raw materials from their surroundings Plants, some bacteria and some protists (Autotrophs): Energy: from sunlight (usually) Materials: water, carbon dioxide, nitrogen, phosphorus, etc. Plants create their own food through photosynthesis. Animals, fungi, some bacteria, some protists (Heterotrophs) Energy: chemical bonds from eating (or decomposing) other animals / plants. Materials: from other organisms.  The Characteristics of Life Living things have different chemical compositions The molecules of life are: Proteins (examples: enzymes, muscle proteins, structural proteins like: keratin (hair / nails), collagen (tendons, ligaments, cartilage, etc.) Carbohydrates (energy stored: starches in plants, glycogen in animals, converted to glucose as fuel) Lipids (energy stored in body fat, every cell membrane) Nucleic acids (DNA, RNA). Carbon: in life vs. in environment: 18% vs. 0.03%. The Characteristics of Life Cell theory of biology: A cell is the smallest unit of life, so all living things have at least one cell. All cells come from pre-existing cells. Unicellular vs. multicellular. A unicellular amoeba A rabbit neuron  The Characteristics of Life Living things: maintain homeostasis Internal environment maintained within a narrow chemical and physical range for cells to survive Maintenance of this environment is called: homeostasis. Examples: Human body temperature around 37 C. (Slightly warmer after exercise, slightly cooler when sleeping) Maintained by: sweating, shivering, changing blood circulation to skin: less blood if it is cold out, more blood if it is warm out  The Characteristics of Life Living things: sense and respond to the environment Living things are irritable: they perceive and respond to external stimuli. Examples: Humans withdraw their hands from hot objects, Some plants grow towards the light and move their leaves to catch the maximum amount of sun, Bacteria move away from noxious chemicals. The Characteristics of Life Living things: grow and reproduce Asexual reproduction: organism produces an offspring that is an exact genetic copy of itself. Sexual reproduction: sperm and egg (gamete) cells join. Offspring have ½ of their genetic material from each parent. ! Warning ! The next slide shows sexual reproduction, look away if this will be offensive to you. Sexual reproduction: toads mating Asexual reproduction: a unicellular amoeba dividing into two identical individuals Asexual reproduction: a multicellular hydra budding off an offspring The Characteristics of Life Populations of living things: are capable of evolving Evolution: a change in frequency of genetic traits in a population of organisms. Sometimes the population may change, over time, into a new species. Natural selection: (“survival of the fittest”) animals with “good genes” are more likely to survive and reproduce, thus passing these good genes on to their offspring. Nature “selects” animals with the best traits for survival and reproduction because unfit animals, with less fit genes, may die without reproducing and do not pass on their less fit genes. An example of evolution The peppered moth: flies around at night, rests on tree trunks during the day. Birds eat them when they rest on trees, if they see them. In 1800’s in England, lots of air pollution (coal) and tree trunks became black in some places. The moth had 2 different color types: 1) Black 2) White / speckled. Black moths at first: very rare (not seen in surveys) In industrialized areas: black moths increase in number (90%). Less industrialized areas: black form rarer. Now: black form is declining again (less pollution). The gene frequencies within the population changed over time: the moth population evolved. What are the Defining Features of Humans?  Defining Features of Humans Bipedalism in mammals (although bonobo chimpanzees often walk upright) This frees the hands for carrying / making things Opposable thumbs (that can touch fingertips) With fine motor skills, we can use tools Large brain, relative to body size Our key evolutionary “innovation” Capacity for complex language Enables complex communication and transmission of information and customs between generations (complex culture). High intelligence! Humans have the largest brains relative to body size of any animal. Example: Porpoises are 2.5 times heavier than us, but their brains are only 1.2 times bigger than ours. http://www.planet-pets.com/plntamba.htm http://www.ultranet.com/~jkimball/BiologyPages/E/ExcitableCells.html http://www.reefquest.com/topics/nose.htm http://www.ai-design.com/stargig/raptor/global/content/report/Broad-wingedHawkLarge.html Chiras, D.D. 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