1.15 Pseudoscience and misleading anecdotal evidence can obscure the truth.

0 ne of the major benefits of scientific thinking is that it can prevent you from being. taken in or fooled by

false claims. Two types of "scientific evidence" are cited iii the popular media frequently and are responsible for people erroneously believing that two tbings are linked, when in fact they are not.

1. Pseudoscience, in which individuals make scientific-sounding claims that are not supported by trustworthy, methodical scientific studies

2. Anecdotal observations, in which, based on just one or a few observations, people conclude that there is or is not a link between two things

Pseudoscience is all around us, particularly in the claims made on the packaging of consumer products and food (llmlmlDfJ). Pseudoscience capitalizes on a belief shared by most people: that scientific thinking is a powerful method for learning about the world. Beginning in the 1960s, for example, consumers encountered the asser­tion by the makers of a sugarless gum that "four out of five dentists surveyed recommend sugarless gum for their patients who chew gum." Maybe the statement is factu­ally true, but the general relationship it implies may not be. How many dentists were surveyed? If the gum mak­ers surveyed only five dentists, then the statement may not represent the proportion of all dentists who would make such a recommendation. And how were the dentists sampled? Were they at a shareholders' meeting for the sugarless gum company? What alternatives were given­perhaps gargling with a tooth-destroying acid? You just don't know. That's what makes it pseudoscience.

We are all familiar with anecdotal evidence. We may find compelling parallels between suggestions made in horo­

scopes and events in our lives, or we may think that we have a lucky shirt. That's how super­stitions develop. Anecdotal observations can seem harm­

less and can be emotionally powerful. But because they do not include a sufficiently large and representative set of observations of the world, they can lead people to draw erroneous conclusions.

22 CHAPTER 1 • SCIENTIFIC THINKING

lllll!1!IDIEI Pseudoscientific claims are often found on food products.

One such erroneous conclusion involves the develop­mental disorder autism and the vaccination for measles, mumps, and rubella (commonly called the MMR vaccine).

In 1998, the prestigious medical journai The Lancet pub­lished a report by a group of researchers that de­scribed a set of symptoms (diarrhea, abdominal pain, bloating) related to bowel inflammation in 12 children who exhibited the symptoms of autism. The parents or physi­cians of 8 of the children in the study said that the behav­ioral symptoms of autism appeared shortly after the children received MMR vaccination. For this reason, the authors of the report recommended further study of a possible link between the MMR vaccine, the bowel problems, and autism.

In a press conference, one of the paper's authors suggested a link between autism and the MMR vaccine, recommend­ing single vaccines rather than the MMR triple vaccine until it could be proved that the MMR vaccine did not trigger

autism. The press and many people took the claims made by the researcher at the press conference as evidence that the MMR vaccine causes autism. Over the course of the next few years, the number of children getting the MMR vaccine dropped significantly, as parents sought to reduce the risk of autism in their children~) .

Unfortunately, this is a notable case of poor implementa­tion of scientific thinking. The study was small (only 12 children), the sample was not randomized (that is, the re­

Q Does the vaccine for measles,

mumps, and rubella cause autism?

searchers selected the study participants based on the symptoms they showed), and no control group was included for comparison (for example, children who had

been vaccinated but did not exhibit autism symptoms). As flawed as the study was, it did not actually find or even report a link between autism and the MMR vaccine. That purported link came only from the unsupported, suggestive statements made by one of the study's authors at the press conference.

Those design flaws were not the only weaknesses in the re­search. It later was discovered that before the paper's pub­lication, the study's lead author (the one who spoke at the press conference) had received large sums of money from lawyers seeking evidence to use in lawsuits against the MMR vaccine manufacturers. That author had also applied for a patent for a vaccine to compete with the most commonly used MMR vaccine. In the light of these initially undisclosed biases, 10 of the paper's 12 authors published a retraction of their original interpretation of their results. The British Medi­cal Journal published an article in 2011 declaring that the "article linking MMR vaccine and autism was fraudulent."

In the years since the original paper was published, many well-controlled, large-scale critical experiments have been conducted. All have been definitive in- their conclusion that there is no link between the MMR vaccine and au­tism. Here are a few of these studies.

1. A study of all children born in Denmark between 1991 and 1998 found no difference in the incidence of autism among the 440,655 children who were vaccinated with the MMR vaccine and the 96,648 children who were not vaccinated.

2. A 2005 study in Japan showed that after use of the MMR vaccine was stopped in 1993, the incidence of autism continued to increase.

WHt.T 1c S1..IE~CE . SCIENTIFfC THINk"!NG

What did Hannah bring back from vacation?

a) t-shirt b) snow globe c) measles

Vacclne·preventable diseases are stiU out there.

Le•m how to P'ote<t you' family •t: www.VacclnateYourBaby.org

n A misguided fear of "catching" autism has caused some I V parents to decline immunizations for their children.

~ Bad science leads to dangerous behavior.

3. A study of 1.8 million children in Finland who were followed up for 14 years after getting the MMR vaccine found no link at all between the occurrence of autism and the vaccine.

At this point, the consensus of the international scientific community is that there is no scientific evidence for a link between the MMR vaccine and autism.

"Science is a way to call the bluff of those who only pretend to knowledge. It is a bulwark against mysticism, against superstition, against religion misapplied to where it has no business being. If we're true to its values, it can tell us when we're

being lied to."

- Carl Sagan, in The Demon-Haunted World:

Science as a Candle in the Dark, 1997

• EXPERIMENTM DESIGN DECISION MAKING 1HEMES IN

BIOLOGY

23

So what explains the observation that there are more au­tism cases now than in the past? It seems that this is a function of the better identification of autism by doctors and changes in the process by which autism is diagnosed. Another reason for the perceived link between autism and the MMR vaccine was simply the coincidence that most children receive the vaccine at around 18-19 months of age, which happens to be the age at which the first symp­toms of autism are usually noticed. In the end, what we learn from this is that we must be wary that we do not

generalize from anecdotal observations or let poorly de­signed studies obscure the truth.

TAKE HOME MESSAGE 1.15 » Pseudoscience and anecdotal observations often lead people to believe that links between two phenomena exist, when in fact there are no such links.

1.16 There are limits to what science can do.

Scientific thinking gives us a framework to make sense of what we see, hear, and read in our lives. There are limits,

however, to what science can do. The scientific method will never prove 6r disprove the existence of God. It won't help us understand the mathematical elegance of Fermat's last theorem or the beauty of Shakespeare's sonnets. Nor

Applying scientific findings to solve a problem can result in sophisticated technical innovati~ns, like this thought-controlled prosthetic arm. )

~ The application of science. A prosthetic arm is tested in the lab.

24 C HAPTER 1 • SCIENTIFIC THINKING

can it address the question of whether we should allow the cloning of humans.

Scientific thinking differs from nonscientific approaches such as mathematics and logic and the study of artistic expression in that it relies on measuring phenomena in some way. The generation of value judgments and other types of non-quantifiable, subjective information-such as religious assertions of faith-falls outside the realm of science. Scientific thinking does not, for example, generate moral statements, and it cannot give us insight into ethical problems. What "is" (i.e., what we observe in the natural world) is not necessarily what "ought" to be (i.e., what is morally right). It may or may not be.

Also, much of what is commonly considered to be science, such as the construction of new engineering marvels or the heroic surgical separation of conjoined twins, is not scientific at all. Rather, these are technical innovations and developments. While technology relies on sophisticated scientific research, it represents the application of research findings to varied fields such as manufacturing and medi­cine to solve problems ~).

TAKE HOME MESSAGE 1.16 » Although scientific thinking may be the most effective path toward understanding the observable world, it cannot give us insights into the generation of value judgments and other types of non-quantifiable,

subjective information.

On the road to biological literacy: what are the major themes in biology?

Feather identification expert Roxie Laybourne, with a portion of the bird collection at the National Museum of Natural History.

1.17 What is life? Important themes unify and connect diverse topics in biology.

Biology is, literally, the study of life. But what is life? And how is it distinguished from non-life? Spend a few mo­

ments trying to define exactly what life is and you'll realize that it is not easily described with a simple definition. A useful approach is to consider the characteristics shared by all living organisms and living systems:

A complex, ordered organization consisting of one or more cells. Cells carry out the functions necessary for life.

The use and transformation of energy to perform work. Organisms can perform many reactions and activities, by acquiring, using, and transforming energy.

Sensitivity and responsiveness to the external environment. Living organisms are able to respond to stimuli-such as light, moisture, or another organism.

Regulation and homeostasis. Organisms are able to maintain relatively constant internal conditions that may differ from the external environment.

Growth, development, and reproduction. Organisms can grow and develop, and they carry information relating to these and other processes that they can pass on to offspring.

Evolutionary adaptation leading to descent with modifiCation over time. Populations have the capacity to change over time. As a consequence of organisms' ability to reproduce and of evolutionary change, populations may become better adapted to their environments .

In this guide to biology, as we explore the many facets of bi­ology and its relevance to life in the modem world, you will find two central and unifying themes recurring throughout.

Hierarchical organization. Life is organized on many levels within individual organisms, including atoms, cells, tissues, and organs. And in the larger world, organisms themselves are organized into many levels: populations, communities, and ecosystems within the biosphere.

The power of evolution. Evolution, the change in genetic characteristics of a population over time, accounts for the diversity of organisms and the unity among them.

These central unifying themes connect the diverse top­ics in biology, which include the chemical, cellular, and energetic foundations of life; the genetics, evolution, and behavior of individuals; the staggering diversity of life and the unity underlying it; and ecology, the environ­ment, and the links between organisms and the world they inhabit. Let's continue our exploration of life!

TAKE HOME MESSAGE 1.17 » "Life" is not easily described with a simple definition. The characteristics shared by all living organisms include complex and ordered organization; the use and transformation of energy; responsiveness to the external environment; regulation and homeostasis; growth, development, and reproduction; and evolutionary adaptation leading to descent with modification.

~XPER 1'4ENTAL DESIG DI:C.ISION t-'Ah:lr~G •

THEMES IN BIOLOGY

25

Usin~ evidence to guide decision making in our own lives

Rainy days and Mondays Q: What's the most important outcome of scientific thinking? Scientific thinking tells us when to change 0ur minds about the natural world. Let's consider a questi<iln that might seem silly-even trivial-and watch our minds opem.

Q: It often seems ta rain more on weekends. Could it be true? Before you read on, write down your one-word ams:wer (amd a justification for it, if you'd like).

Q: Well, does It rain more on weekends? At first, it seems that tl\le answer must be no. How could the weather even "know" what day it is? Weather, after all, existed long before humans, calendars, and Monday m<ilrnings.

Rather than relying on common sense, let's think sc::lentlflc::ally.

My hypothesi5: It rains more on weekends.

Restated as a null hypothesis: The amount of rainfall does m0t differ across the days of the week.

A testable pr.edicllion: The amount of rainfall should not differ depemding 0n what day of the week it is.

And new the data . . . In a 1998 study published in the j0urnal Nature, researchers used 17 years of data to analyze rainfall a.©ng the eastern coast of North America. Here's

26 CHAPTER 1 • SCIENTIFIC THINKING

what they found: there was 22% more rain on Saturdays than 0n Mondays!

Q: Haw can this be? The researchers also tracked the p0llutamts carb0n monoxide and ozone, and f.oumd that li>0th giadually increased from Monday througlil Friday. This pattern, they suggested, is probably related t0 accumulations from driving, which is gr.eater during the week than on weekends. 'Ihey suggested that the weekly pollution cycle causes increased cloud formatioH and rain on weekends (whi.le t1le redl!lced pollution on Mondays leads to reduced rain(all). In other words, human activities are influencing t1le weather!

One gaod hypothesis deserves another. If their suggesti0m is true, we should expect the "Rainy Saturday/Dry Monday" phenomenon to occur only in the vicinity of human activities. As a test of this hypothesis, researchers measured daily rainfall patterms over the oceans in the northern hemisphere, away from laLge human populations. Here they found that 0me-sev:emt1l of the rain fell on each day of the week, with n0 days rainier than others.

Q: The take-heme message here? Scientific thinking rewaFds 0pem minds with satisfying answers.

GRAPHIC CONTENT Thinking critically about visual displays of data

1 What does the green portion of the pie chart represent? What does the gray

portion represent? What does the " whole pie" represent?

PERCENTAGE OF PAPERS PUBLISHED WITH FEMALE FIRST AUTHOR

When the reviewers knew the sex of the author:

When the reviewers did NOT know the sex of the author:

2 Why are there two pie charts?

3 What can you conclude from this figure?

4 What might be an alternative explanation (other than bias ·against female scientists)

for the phenomenon shown here?

5 How big was the increase in number of papers published with a female first

author following the institution of a double­blind review policy?

@ See answers at the back of the book.

6 Why wasn 't the percentage of papers published with a female first author

50%, even after the new review policy? Is that cause for concern? What data would help you to answer that question?

KEY TERMS IN SCIENTIFIC THINKING anecdotal observation, p . 22 biological literacy, p . 3 biology, p. 2 blind experimental design,

p . 14 control group, p. 12 critical experiment, p . 8 dependent variable, p. 12

double-blind experimental design, p . 14

empir ical , p. 4 experimental group, p . 12 hypothesis (pl. hypotheses),

p. 6 independent variable, p . 12 null hypothesis, p. 7

placebo, p . 9 placebo effect, p . 14 positive correlation, p . 21 pseudoscience, p. 22 randomized, p. 14 replication, p. 17 science, p. 2 scientific l iteracy, p. 3

7 Dothese graphs prove a

general bias against female scientists?

scientific method, p. 4 scientific thinking, p. 4 scientific theory, p. 11 statistics, p. 20 superstition, p. 22 technology, p . 24 treatment, p . 12 variable, p. 12

27

BRIEF SUMMARY

More than just a collection of facts, science is a process for understanding the world.

• Through its emphasis on objective observation, description, and experimentation, science is a pathway by which we can discover and better understand the world around us.

• To make wise decisions, it is essential for individuals and societies to achieve biological literacy.

A beginner's guide to scientific thinking.

• Scientific thinking is an empirical process that incorporates making observations, · articulating hypotheses, generating predictions, designing experimental tests, and drawing conclusions. It is a flexible, adaptable, and efficient process, and it can tell us when we must change our beliefs.

•· Scientific thinking begins by making observations about the world, noting apparent patterns or cause-and-effect relationships.

• A hypothesis is a proposed explanation for an observed phenomenon.

• For a hypothesis to be useful, it must generate a testable prediction.

• A critical experiment is one that enables us to decisively determine whether a particular hypothesis is correct.

• Based on the results of experimental tests, we can revise a hypothesis and explain the observable world with increasing accuracy.

• Scientific theories are hypotheses that have been so persuasively supported by empirical observations that they are unlikely to be altered by new evidence.

Well-designed experiments are essential to testing hypotheses.

• To draw clear conclusions from experiments, it is essential to hold constant the variables we are not interested in. Control and experimental groups should differ only with respect to the treatment.

• Biases can influence our behavior, including our collection and interpretation of data. With careful controls, we can reduce the impact of biases.

Scientific thinking can help us make wise decisions.

CHECK YOUR KNOWLEDGE

Short Answer 1. In nationwide advertisements, the Dannon Company claimed that its Activia yogurt relieved irregularity and helped with "slow intestinal transit time." Dannon also claimed that its DanActive dairy drink helped prevent colds and flu. These claims were based on no evidence. How would you design an experiment to try to test these statements?

2. Describe two examples of biological literacy.

3. Scientific thinking can be distinguished from alternative ways of acquiring knowledge in that it is empirical. What does empirical mean,

and how does it relate to the study of biology? 4. An especially important feature of scientific thinking is that its steps are self-correcting. What does self-correcting mean in this context? S. Describe something that you have observed in the world around you that you could study using scientific thinking. Describe something that you could not study scientifically. 6. A researcher hypothesizes that the more a person exercises, the less acne he or she will have. What would the null hypothesis be in this situation? 7. What would be a reasonable prediction for the hypothesis "Eating fresh fruit

28 CHAPTER 1 • SCIENTIFIC THINKING

• Visual displays of data can aid in the presentation and exploration of the data. Their effectiveness is influenced by the precision and clarity of the presentation.

• Statistics can help us evaluate whether differences between a treatment and a control group can be attributed to the treatment rather than chance.

• Pseudoscience and anecdotal observations often lead people to believe that links between two phenomena exist, when in fact there are no such links.

• Scientific thinking can't give us insights into value judgments and other non­quantifiable, subjective information.

On the road to biological literacy: what are the major themes in biology?

• The characteristics shared by all living organisms include complex and ordered organization; the use and transformation of energy; responsiveness to the external environment; regulation and homeostasis; growth, development, and reproduction; and evolutionary adaptation leading to descent with modification.

reduces the likelihood that you will get sick"? 8. Describe the key features of a critical experiment. 9. Many claims have been made concerning the health benefits of green tea. Suppose you read a claim that alleges drinking green tea causes weight loss. You are provided with the following information about the studies that led to this claim: • People were weighed at the beginning of the study. • People were asked to drink two cups of green tea every day for 6 weeks. • People were weighed at the end of the study.

• People who drank green tea for 6 weeks lost some weight by the end of the study. • It was concluded that green tea is helpful for weight Joss.

This study obviously had some holes in its design. Assuming no information other than that provided above, indicate at least four things that could be done to improve the experimental design.

10. Following an experimental conclusion, what is a likely next step? Why?

11. Compare and contrast "theory" and "hypothesis."

12. A pharmaceutical company plans to test a potential anti-cancer drug on human subjects. The drug will be administered in pill form. How should this study be designed so that appropriate controls are in place?

13. Describe what is meant by a randomized, controlled, double-blind study.

14. Biases can influence our behavior, including our collection and interpretation of data. Which type of experimental design can help us eliminate biases?

15. When analyzing results of a study, what role do statistical analyses play?

16. You notice that all of the male students who signed up for French tutoring have blue eyes. What conclusions can you draw from this observation?

17. You have heard that people from Scandinavia usually have blond hair and fair skin. Your roommate is from Sweden and he has darker hair and more olive skin. Does this disprove the idea that Scandinavians are fair and blond? Why or why not?

18. What are the two major unifying themes in this guide to biology?

Multiple Choice 1. Science is: a) a field of study that requires certain "laws of nature" to be taken on faith.

b) both a body of knowledge and an intellectual activity encompassing observation, description, experimentation, and explanation of natural phenomena.

c) a process that can be applied only within the scientific disciplines, such as biology, chemistry, and physics.

d) the only way to understand the natural world.

e) None of the above are correct.

2. Superstitions are:

a) evidence that not all phenomena can be understood purely through scientific thinking.

b) just one of many possible forms of scientific thinking.

c) true beliefs that have yet to be fully understood.

d) irrational beliefs that actions not logically related to a course of events influence its outcome.

e) proof that the scientific method is not perfect.

3. Empirical results: a) rely on intuition. b) are generated by theories. c) are based on observation. d) cannot be replicated.

e) must support a test~d hypothesis. OEASY ~

4. Which of the following statements is correct?

a) A hypothesis that does not generate a testable prediction is not useful. b) Common sense is usually a good substitute for scientific thinking when trying to understand the world. c) Scientific thinking can be used only to understand scientific phenomena.

d) It is not necessary to make observations as part of scientific thinking. e) All of the above are correct.

S. The placebo effect: a) is the frequently observed phenomenon that people tend to respond favorably to any treatment.

b) reveals that sugar pills are more effective than actual medications.

c) reveals that experimental treatments cannot be proven effective. d) demonstrates that most scientific studies cannot be replicated. e) is an urban legend.

6. In controlled experiments: a) one variable is manipulated while others are held constant. J

b) all variables are dependent on each another. c) all variables are held constant. d) all variables are independent of each another. e) all critical variables are manipulated.

~

7. If a researcher uses the same experimental setup as in another study, but with different research subjects, the process is considered: a) an uncontrolled experiment. b) intuitive reasoning. c) extrapolation. d) replication. e) exploration.

------~ -=:J--oiiiiiiioi-8. An independent variable: a) can cause a change in a dependent variable. b) is generally less variable than a dependent variable.

c) is plotted on they-axis in a line graph. d) can be controlled less well than a dependent variable.

e) is typically more important than a dependent variable.

9. Statistical methods make it possible to: a) prove that any hypothesis is true. b) determine how likely it is that certain results have occurred by chance. c) unambiguously learn the truth. d) reject any hypothesis. e) test non-falsifiable hypotheses.

10. Anecdotal evidence: a) is the basis of scientific thinking. b) tends to be more reliable than data based on observations of large numbers of diverse individuals. c) is a necessary part of the scientific method. d) is often the only way to prove important causal links between two phenomena. e) can seem to reveal links between two phenomena, but the links do not actually exist.

------~&-------11. Which of the following issues would be least helped by application of scientific thinking? a) developing more effective high school curricula b) evaluating the relationship between violence in video games and criminal behavior in teens c) determining the most effective safety products for automobiles d) formulating public policy on euthanasia e) comparing the effectiveness of two potential antibiotics

29