Science Never Proves Anything: How Biology Finds Things Out

Science does not claim to prove anything. Whatever scientists understand can change when new information arrives, and that openness to being shown wrong is what separates a science from what is not one. A good hypothesis has to be testable, and it has to be falsifiable — an experiment must be able to disprove it. The presence of the supernatural, for instance, is neither, which is why it lies outside science.

Biology — the study of living things and how they interact with one another and with their surroundings — works on that principle at every scale, from a single cell to ecosystems and the whole living planet.

Cyanobacteria, once called blue-green algae, at 300x magnification: some of Earth's oldest life forms. Credit: modification of work by NASA; scale-bar data from Matt Russell.

Stromatolites on the shore of Lake Thetis in Western Australia, ancient structures built up by layers of cyanobacteria in shallow water. Credit: modification of work by Ruth Ellison.

What counts as a science

Science comes from the Latin scientia, "knowledge": knowledge of general truths or general laws, especially when gained and tested by the scientific method. Testing hypotheses with repeatable experiments is central to that method — but it cannot be the whole definition. Physics and chemistry repeat experiments easily; archaeology, psychology and geology often cannot.

They are sciences all the same. An archaeologist who finds a piece of pottery can propose that an ancient culture existed, and further finds will support or contradict that idea and what follows from it. A hypothesis supported that way can become a theory: a tested and confirmed explanation for what is observed. Science is better described as the fields that try to understand the nature of the universe.

The natural sciences are the ones about the physical world, and even they have no agreed list:

Biophysics and biochemistry draw on both. The natural sciences are sometimes called "hard science" because they rely on quantitative data; the social sciences, which study society and human behavior, lean more on qualitative assessment. Within biology, cell biologists study cells, anatomists the structure of whole organisms, physiologists how organisms work inside; botanists study plants and zoologists animals.

E. coli normally lives in our digestive tract and helps absorb vitamin K and other nutrients, though virulent strains cause outbreaks. Credit: Eric Erbe, digital colorization by Christopher Pooley, both of USDA, ARS, EMU.

Two directions of reasoning

The two meet constantly. In the 1940s a man noticed that the burrs stuck to his clothes and his dog's fur had tiny hooks, found on closer inspection that they gripped more reliably than a zipper, and went on to produce the hook-and-loop fastener known as Velcro — an observation that became a question, and a question that became a product.

The conclusion of inductive reasoning often becomes the premise of deductive reasoning. From OpenStax.

The method, on a toaster

The scientific method was used in ancient times, but Sir Francis Bacon (1561–1626) of England was the first to document it, setting out inductive methods of inquiry.

Sir Francis Bacon. Credit: Paul van Somer.

Observation, question, hypothesis, prediction, experiment, results — and a new hypothesis when the data do not support the old one. From OpenStax.

The textbook offers an everyday case and leaves it for the reader to sort. Put in order, it runs:

The prediction failed, so the hypothesis is rejected — and that is all the result shows. Rejecting one hypothesis does not confirm another; the next candidates (the toaster is broken, or was never switched on) need tests of their own. Every experiment has variables and controls: the control group is identical to the experimental group except for the one change being tested, so a difference in results can be put down to that change rather than something outside it.

The method is less rigid than a flow chart makes it look: an experiment can change the approach or raise new questions, and research often finds patterns as it goes rather than in a line. A newer route is "in silico" research: computer algorithms and statistics run over the fast-growing data held in databases, which raises demand for people trained in both biology and computer science.

Knowledge for its own sake, or for a use

The two depend on each other. Understanding how DNA copies itself before a cell divides, which followed the discovery of DNA's structure, gave laboratories the techniques now used to identify genetic diseases, place individuals at a crime scene and determine paternity. The Human Genome Project, a 13-year effort across several fields, mapped each human chromosome, relying on basic research with simpler organisms first, and was completed in 2003; using its data for cures and early diagnosis became a goal along the way.

A brown pelican rescued by the U.S. Fish and Wildlife Service after Hurricane Ike struck the Gulf Coast in 2008; applied science told its rescuers how to rehabilitate it. Credit: FEMA.

Credit: the U.S. Department of Energy Genome Programs.

Some discoveries come by luck. Alexander Fleming accidentally left a petri dish of Staphylococcus bacteria open; a mold grew on it and killed them. The mold was Penicillium, and a new antibiotic had been found — luck, combined with an observant mind.

How findings are shared

Results that nobody can check are not much use to science, so most scientists publish in peer-reviewed journals: colleagues qualified in the same field judge whether the work is original, significant, logical and thorough before it appears. Requests for research money, grant proposals, are reviewed the same way. Publishing lets others repeat the experiments under similar or different conditions, and the results must agree with other scientists' findings.

A research paper usually follows the IMRaD format, with an abstract first and acknowledgments and references at the end:

Review articles do not use this format: they report no original findings, but summarize and comment on published ones, with long reference lists.

Sources

• Connie Rye, Robert Wise, Vladimir Jurukovski, Jean DeSaix, Jung Choi and Yael Avissar, Biology, section 1.1, "The Science of Biology", OpenStax (Rice University), licensed under CC BY 4.0. Changed: rewritten in hubnx's own words and shortened, the exercises answered or left out; the figures and their credits are the book's. This page is shared under the same licence.