Page 18 - Introduction to Paleobiology and The Fossil Record
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PALEONTOLOGY AS A SCIENCE 5
to disprove the hypothesis that this animal fed “speculation” is the problem, because it sounds
exclusively on meat. as if the paleontologist simply sits back with a
Science is of course much more complex glass of brandy and a cigar and lets his mind
than this. Scientists are human, and they are wander idly. But speculation is constrained
subject to all kinds of infl uences and preju- within the hypothetico-deductive framework.
dices, just like anyone else. Scientists follow This brings us to the issue of hypotheses
trends, they are slow to accept new ideas; they and where they come from. Surely there are
may prefer one interpretation over another unknown millions of hypotheses that could
because of some political or sociological be presented about, say, the trilobites? Here are
belief. Thomas Kuhn (1922–1996) argued a few: “trilobites were made of cheese”, “trilo-
that science shuttles between so-called times bites ate early humans”, “trilobites still survive
of normal science and times of scientifi c revo- in Alabama”, “trilobites came from the moon”.
lution. Scientifi c revolutions, or paradigm These are not useful hypotheses, however, and
shifts, are when a whole new idea invades an would never be set down on paper. Some can be
area of science. At first people may be reluc- refuted without further consideration – humans
tant to accept the idea, and they fi ght against and trilobites did not live at the same time, and
it. Then some supporters speak up and support no one in Alabama has ever seen a living trilo-
it, and then everyone does. This is summa- bite. Admittedly, one discovery could refute
rized in the old truism – when faced with a both these hypotheses. Trilobites were almost
new idea most people at first reject it, then certainly not made from cheese as their fossils
they begin to accept it, and then they say they show cuticles and other tissues and structures
knew it all along. seen in living crabs and insects. “Trilobites
A good example of a paradigm shift in came from the moon” is probably an untest-
paleontology was triggered by the paper by able (as well as wild) hypothesis.
Luis Alvarez and colleagues (1980) in which So, hypotheses are narrowed down quickly
they presented the hypothesis that the Earth to those that fit the framework of current
had been hit by a meteorite 65 million years observations and that may be tested. A useful
ago, and this impact caused the extinction of hypothesis about trilobites might be: “trilo-
the dinosaurs and other groups. It took 10 bites walked by making leg movements like
years or more for the idea to become widely modern millipedes”. This can be tested by
accepted as the evidence built up (see pp. studying ancient tracks made by trilobites, by
174–7). As another example, current attempts examining the arrangement of their legs in
by religious fundamentalists to force their fossils, and by studies of how their modern rel-
view of “intelligent design” into science will atives walk. So, hypotheses should be sensible
likely fail because they do not test evidence and testable. This still sounds like speculation,
rigorously, and paradigm shifts only happen however. Are other natural sciences the same?
when the weight of evidence for the new Of course they are. The natural sciences
theory overwhelms the evidence for the previ- operate by means of hypothesis testing. Which
ous view (see p. 120). geologist can put his finger on the atomic
So science is curiosity about how the world structure of a diamond, the core–mantle
works. It would be foolish to exclude any area boundary or a magma chamber? Can we
of knowledge from science, or to say that one prove with 100% certainty that mammoths
area of science is “more scientific” than another. walked through Manhattan and London, that
There is mathematics and there is natural ice sheets once covered most of Canada and
science. The key point is that there can be no northern Europe, or that there was a meteor-
proof in natural science, only hypothesis ite impact on the Earth 65 million years ago?
testing. But where do the hypotheses come Likewise, can a chemist show us an electron,
from? Surely they are entirely speculative? can an astronomer confi rm the composition
of stars that have been studied by spectros-
copy, can a physicist show us a quantum of
Speculation, hypotheses and testing
energy, and can a biochemist show us the
There are facts and speculations. “The fossil is double helix structure of DNA?
6 inches long” is a fact; “it is a leaf of an ancient So, the word “speculation” can mislead;
fern” is a speculation. But perhaps the word perhaps “informed deduction” would be a
