Evidence
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  For most of us, science arrives in our lives packaged neatly as fact. But how did it get that way?

Science is an active process of observation and investigation. Evidence: How Do We Know What We Know? examines that process, revealing the ways in which ideas and information become knowledge and understanding.

A CASE STUDY IN HUMAN ORIGINS
In this case study in human origins, we explore how scientific evidence is being used to shape our current understanding of ourselves: What makes us human—and how did we get this way?

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Articles, photo essays, and video transcripts, with links to Flash videos
OBSERVING BEHAVIOR HOW SCIENCE WORKS
COLLECTING CLUES CAN YOU BELIEVE IT?
INVESTIGATING RELATIONSHIPS MAP YOUR KNOWLEDGE
FINDING PATTERNS PODCASTS & MORE
CONSIDERING POSSIBILITIES AT THE LAB
    ABOUT THE PROJECT
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OBSERVING BEHAVIOR
What behaviors separate us from our primate relatives? Tool use? Intelligence? "Human" kindness?
The answers may surprise you.
Chimpanzee Science begins with noticing.
INTRODUCTION > Only by carefully observing a system can we learn enough about it to ask meaningful questions. . . .
   
Svante Paabo What separates us from other primates?
VIDEO > Evolutionary geneticist Svante Pääbo explains that culture—long thought to be developed only by humans—is evident among other primates as well. [VIDEO TRANSCRIPT]
ARTICLE > Culture —learned patterns of behavior that vary from group to group — was long thought to be an exclusively human trait. . . .
   
Christophe Boesch How do chimps use tools?
Primatologist Christophe Boesch demonstrates and discusses several aspects of chimpanzee behavior.
VIDEO > Leaf Clipping [VIDEO TRANSCRIPT]
VIDEO > Ant Dipping [VIDEO TRANSCRIPT]
VIDEO > Hive Raiding [VIDEO TRANSCRIPT]
VIDEO > Nut Cracking [VIDEO TRANSCRIPT]
VIDEO > Culture Loss [VIDEO TRANSCRIPT]
   
Felix Warneken Who's more likely to help out, a child or a chimp?
Psychologist Felix Warneken explains how his research found answers to this question.
VIDEO > Altruism: The Instinct to Help [VIDEO TRANSCRIPT]
VIDEO >Observing Altruism: Field vs. Lab [VIDEO TRANSCRIPT]

   
Linda Vigilant Do brothers help brothers?
VIDEO > Do chimps cooperate even when they’re not related? The traditional answer is no, but primatologist Linda Vigilant explains how genetics is revising this belief. [VIDEO TRANSCRIPT]
ARTICLE > Historically, cooperation between unrelated individuals was assumed to be something rarely seen in non humans. . . .
   
Leipzig Zoo What do apes know about physics, planning, and payback?
Primatologist Josep Call discusses research designed to test primates’ ability to plan for the future and solve problems. He also explains why it would be interesting to know if primates can remember and repay favors.
VIDEO >
Planning for the Future [VIDEO TRANSCRIPT]
VIDEO > Solving Problems [VIDEO TRANSCRIPT]
VIDEO > Repaying Favors [VIDEO TRANSCRIPT]
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COLLECTING CLUES
Are you a Homo erectus or a Homo sapiens? Take the pencil test and find out.
Fossil skull Clues aren't just for detectives.
INTRODUCTION > Scientists look for clues, too, in much the same way as detectives do, by visiting a scene and gathering evidence. . . .
   
cast of fossil skull How do you find a fossil?
Anthropologist Katerina Harvati explains how scientists from various disciplines work together to find fossilized human remains, and explains the importance of cast collections to the study of human evolution.
VIDEO > Finding Fossils [VIDEO TRANSCRIPT]
VIDEO >
Collecting Casts [VIDEO TRANSCRIPT]
   
geological map Geology for Fossil Hunters
PHOTO ESSAY> Search a geological map of Ethiopia for fossils.
   
Cast collection How can a pencil help you tell one fossil skull from another?
VIDEO > Various features of a fossil skull help anthropologists determine what species it belongs to. Here, anthropologist Katerina Harvati explains how a pencil can be used to distinguish between ancient species. [VIDEO TRANSCRIPT]
   
Hominid timeline Tracing Fossil Finds: A Hominid Timeline
PHOTO ESSAY> Explore a timeline of homind fossils.
   
Katerina Harvati Why did the Neanderthals dissappear?
Some 3035,000 years ago, Neanderthals became extinct. Climate change and a taste for steaks may be to blame. (Sound familiar?) Anthropologist Katerina Harvati explains, and dispels popular myths about Neanderthals.
VIDEO > Adapting to Change [VIDEO TRANSCRIPT]
VIDEO >
Neanderthals: Fact vs. Fiction [VIDEO TRANSCRIPT]
   
Neanderthal sculpture Did modern humans mix and mingle with Neanderthals?
VIDEO > Anthropologist Jean-Jacques Hublin gives evidence suggesting that humans and Neanderthals exchanged culture and technologies. [VIDEO TRANSCRIPT]
ARTICLE > Now extinct, Neanderthals were our closest relative so close, in fact, that some have argued that they should actually be considered members of our own species. . . .
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INVESTIGATING RELATIONSHIPS
Are Neanderthals our ancestors? Why can only humans speak?
Genetics tells us how and when we became human.
DNA assay on screen In some ways, collecting evidence is the easy part of science.
INTRODUCTION > Much trickier are evaluating the data, figuring out how one piece of information relates to another, and deciding what it all means. . . .
   
DNA gel Extracting DNA from Neanderthal Bones
PHOTO ESSAY> Explore the process of ancient DNA extraction.
   
Svante Paabo Why is it so hard to reconstruct Neanderthal genes?
VIDEO > Evolutionary geneticist Svante Pääbo explains that analysis of ancient Neanderthal DNA is very tricky work, thanks to fragmentation and contamination of genetic material. [VIDEO TRANSCRIPT]
ARTICLE > Genetic information DNA is composed of strands of amino acid pairs called base pairs, strung together like beads on a necklace. . . .
   
Wolfganag Enard Is speech in our genes?
VIDEO > Evolutionary geneticists Wolfgang Enard and Svante Pääbo discuss the genetic underpinnings of speech and language.[VIDEO TRANSCRIPT]
ARTICLE > Is a single gene, FOXP2, the secret to human speech?. . .
   
Mark Stoneking What is mitochondrial DNA. . .and who is Mitochondrial Eve?
VIDEO > Geneticist Mark Stoneking describes a special type of genetic material called mitochondrial DNA which is passed directly from mother to child. Largely unchanged from generation to generation, this genetic material gives researchers a way to track populations back in time.[VIDEO TRANSCRIPT]
ARTICLE > Inside each cell in your body is a nucleus that contains your DNA, your unique genetic material. . . .
   
DNA chip How can Neanbderthal DNA tell us about ourselves?
VIDEO > Evolutionary geneticist Ed Green discusses the key questions researchers hope to answer by analyzing the Neanderthal genome.[VIDEO TRANSCRIPT]
ARTICLE > Scientists study the Neanderthal genome not just to learn about Neanderthals. . . .
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FINDING PATTERNS
Our life stories are written in our teeth. How can we read them?
tooth cross-section Careful measurement is the cornerstone of science, and here's why:
INTRODUCTION > The measurements that scientists make allow them to identify patterns and variations in those patterns, both of which can tell useful stories. . . .
   
Tanya Smith What can we learn from a tooth?
VIDEO > Anthropologist Tanya Smith explains that invisible microstructure inside teeth creates a durable record of life history, including events such as birth, illness, famine, stress, and death.[VIDEO TRANSCRIPT]
ARTICLE >
Have you ever seen someone with dark horizontal lines in their teeth?. . .
   
Microscope image of tooth Look Inside a Tooth
PHOTO ESSAY> Explore the insides of fossil teeth at a microscopic level.
MAGNIFY IMAGE > Zoom into a fossil chimp tooth.
   
Jean-Jaque Hublin How do bones and teeth grow?
VIDEO > Anthropologist Jean-Jacques Hublin explains what scientists can learn from bones and teeth.[VIDEO TRANSCRIPT]
ARTICLE >
Bones seem solid and unchanging, but in fact your bones are constantly being destroyed and recreated. . . .
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CONSIDERING POSSIBILITIES
Most fossils are found broken and incomplete, but hi-tech reconstruction can undo the ravages of time. What can we learn from them?
Virtual model of skull Speculation and theory play useful roles in the scientific process.
INTRODUCTION > When evidence is unavailable or incomplete, theories and models let us test out ideas that we can't yet prove. . . .
   
3D print of skull What can you do with a squashed skull?
VIDEO > Anthropologist Philipp Gunz explains the process of virtual fossil reconstruction, a technique that can reverse the damage done to fossils by time and the elements.[VIDEO TRANSCRIPT]
ARTICLE >
Traditonally, paleontologists used clay to reconstruct the missing parts of fossils. . . .
   
virtual model of skull

Building a Virtual Skull
PHOTO ESSAY> Explore the process of reconstructing a skull
as a 3-D model.

   
fossil cast of skull Why are fossils so rare?
VIDEO > Anthropologist Katerina Harvati explains the rare convergence of circumstances that are necessary for the discovery of a fossil specimen. [VIDEO TRANSCRIPT]
ARTICLE >
Pick up a fossil skull and you'll notice it's surprisingly heavyas heavy as a rock. That's because it is a rock, more or less. . . .
   
3D prints of skull variations What happens when scientists diagree?
VIDEO >
Anthropologist Jean-Jacques Hublin discusses the role of conflict in the scientific process.[VIDEO TRANSCRIPT]
ARTICLE >
Science is a collective effort. Individuals around the world contribute their findings and debate their significance. . . .
   
scientific journal Sharing Findings: The Anatomy of a Peer-Reviewed Paper
PHOTO ESSAY> Explore the elements of a scientific paper.
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HOW SCIENCE WORKS
A STEP-BY-STEP GUIDE TO THE PROCESS OF SCIENCE
scientist writing in notebook What's the question?
ARTICLE >
Scientific research builds on itself, and it's often the case that one research question will lead naturally to another. . . .
   
How do I answer the question? How do I answer the question?
ARTICLE >
Designing an experiment is a crucial part of the scientific process, and trickier than it might seem. . . .
   
How do I make this happen? How do I make this happen?
ARTICLE >
Most scientific research requires a convergence of collaborators, facilities, equipment, and funding. . . .
   
What's the data? What's the data?
ARTICLE >
Data is at the heart of the scientific process, and the methods used to collect it are subject to the tools and trends of the times. . . .
   
What does the data mean? What does the data mean?
ARTICLE >
Collecting data is one thing; deciding what it means is another. . . .
   
Am I sure? Am I sure?
ARTICLE >
The ultimate test of any experiment is reproducibility. . . .
   
Do they buy it? Do they buy it?
ARTICLE >
Justly or not, the health of a scientist's career is often assessed by the frequency of his or her publications. . . .
   
Now what? Now what?
ARTICLE >
It's not unusual for scientists to be thinking about their next question even before the current one is answered. . . .
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CAN YOU BELIEVE IT?
7 QUESTIONS TO ASK ABOUT ANY SCIENTIFIC CLAIM
Seven questions to ask about any scientific claim 7 questions to ask about any scientific claim
INTRODUCTION > Screaming headlines abound in our media-saturated world. . . .
   
What's the claim? What's the claim?
ARTICLE >
Simple as it may sound, the first step toward weighing a scientific claim is to establish what it is, as well as what it isn't. . . .
   
Who says? Who says?
ARTICLE >
They say you're only as good as your reputation . . . but who is "they"?. . .
   
What's the evidence? What's the evidence?
ARTICLE >
Evidence is the bread and butter of science. . . .
   
How did they get the evidence ? How did they get the evidence?
ARTICLE >
Where data collection is concerned, the devil is in the details. . . .
   
Is there anything (or anyone) to back up this claim? Is there anything (or anyone) to back up this claim?
ARTICLE >
No one not even an astrophysicist works in a void. . . .
   
Could there be another explanation ? Could there be another explanation?
ARTICLE >
Sometimes, it's not the research methods or the data that are flawed, but the interpretation of the data. . . .
   
Who cares? Who cares?
ARTICLE >
There are always people interested in the outcome of scientific research. . . .
   
Science News Widget & 7 Questions Booklet Science News Widget & 7 Questions Booklet
DOWNLOAD WIDGET [MAC OSX ONLY]> Use this widget to view current science news feeds on your computer or handheld.
DOWNLOAD BOOKLET> This folded booklet contains all 7 questions in a handy to-go format.
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MAP YOUR KNOWLEDGE
MyEvidence MyEvidence
What makes you believe in ghosts? Why do you think the earth is round? MyEvidence is a Web engine that let you "map" and examine the evidence you've used to construct your view of the world. This complex online tool has sophisticated community applications that lets users categorize information, share and compare beliefs, and save and retrieve information about the life experiences that have helped shape their scientific knowledge and understanding.

MyEvidence requires a monitor resolution of 1024 x 768, the Flash 9 player, and a high-speed Internet connection.
LAUNCH MY EVIDENCE >
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PODCASTS & MORE
Interviews and Science News: Thoughts on the pursuit of scientific knowledge
Mel Zucker Alfred Wegner's crazy idea
In the early 1900s, German meteorologist Alfred Wegener suggested that the earth's continents were once a single landmass that had somehow split into pieces, drifting their separate ways. Geologists the world over called his idea preposterous. Decades later, their ridicule shifted to admiration as new tools developed by the military to map the ocean floors revealed the engine that drives the continents' movement. Geology professor Mel Zucker tells the story of this brilliant earth scientist and how, long after his death, science finally caught up with Wegener's crazy idea.

DOWNLOAD OR LISTEN TO PODCAST > An interview with Mel Zucker, Professor of Geology, Skyline College, San Bruno, California, Run time: 24:49 minutes
   
Richard Carrier "Why do nutcrackers work?" and other historical questions of science
It's not enough to know that a nutcracker works; a scientist needs to know why. Historian Richard Carrier recounts how, in ancient Greece, pondering the nutcracker led to the physics of levers. He describes how Aristotle and others shaped the beginnings of Western scientific thought: the notion that knowledge of the natural world relies on being able to question, test, reproduce, and improve the accuracy of what's believed to be true. He explains why he sees science as a practice rooted in values, how it protects us from our own erroneous tendencies, and why questioning authority helps foster scientific thinking.

DOWNLOAD OR LISTEN TO PODCAST > An interview with science historian Richard Carrier, Run time: 11:17 minutes
   
Isabel Hawkins Ancient astronomy, modern knowledge
When astronomer Isabel Hawkins began exploring the astronomical work of Native Americans, their knowledge broadened her view of the night sky. She has since discovered several scientists incorporating the work of native people, both modern and ancient, into their current-day research. Isabel describes how she sees science as a cultural construct, the value of learning from personal experience, and that evidence comes in many forms.

DOWNLOAD OR LISTEN TO PODCAST > An interview with Isabel Hawkins, Co-director/Research Astronomer, UC Berkeley Space Sciences Laboratory; Co-director, NASA Sun-Earth Connection Education Forum, Run time: 15:28 minutes
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AT THE LAB
Asking questions and sharing ideas
At the Lab: Max Planck Institute for Evolutionary Anthropology At the Lab: Max Planck Institute for Evolutionary Anthropology
ARTICLE >
The scientists and research profiled in the human evolution case study featured in this Web site are all associated with the Max Planck Institute for Evolutionary Anthropology. . . .
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ABOUT THE PROJECT
About the Project

About the Project : How Do We Know What We Know?
ARTICLE > This project uses case studies to examine how scientists construct a functional understanding of the world by gathering, assessing, and making use of scientific evidence. . . .

   
Acknowledgements Acknowledgements
ARTICLE >
At the Exploratorium, no one works alone. Without the help of the Exploratorium staff, as well as those in the scientific community who shared their work with us, this site would not have been possible. . . .
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national science foundationmax planck institutemoore foundation

How Do We Know What We Know? Resources for the Public Understanding of Scientific Evidence is made possible by a grant from the National Science Foundation, with the additional generosity of the Gordon and Betty Moore Foundation, The Jim Clark Endowment for Internet Education, and the McBean Family Foundation.

© 2009 Exploratorium | The museum of science, art and human perception
at the Palace of Fine Arts, 3601 Lyon Street, San Francisco, CA 94123

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