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Sometimes I wish I taught quantum physics. My
students would be convinced it is hard science,
many would have very little background knowledge
of the subject and no moral objections would be
raised. Instead, I teach ULS2202 "Evolution" under
the University Scholars Programme (USP) and
LSM3252 "Evolution and Comparative Genomics"
under the Life Sciences Programme, where a large
proportion of my students come to class armed with
religiously motivated objections to the subject. Thus,
unlike other modules, evolution lecturers do not have
the luxury of starting on a 'clean slate' when they
teach this subject. Past surveys revealed that while
most NUS students were never taught evolution in
school, many believed they understood the subject
from discussions with parents and friends and TV
shows they had seen.
What is the best approach for dealing with this
challenge? With evolution playing a central role in
the life sciences, this issue is actively discussed by
biologists and organisations such as the National
Academy of Sciences and Institute of Medicine
(2008). Among the more controversial issues being
raised is whether objections to evolution in the
form of 'intelligent design' (a secular version of
creationism) should be covered in a science class.
Scott and Branch (2003) argue that such alternatives
to established theories should not be mentioned
unless they meet the following criteria:
- Students are interested in the controversy.
- The scientific community accepts that these
issues are valid for discussion.
- The issues are well documented.
- All aspects of the arguments have been well
thought out and are intellectually stimulating.
- The issues are easily understood by students.
According to Scott and Branch (2003), the 'evolution
versus intelligent design' debate fails to meet
some of these requirements and thus should not
be covered. However, I would argue that Scott and
Branch overlook the fact that students come to
evolution classes armed with these objections, which
makes addressing them unavoidable. I was initially
unaware of the widespread skepticism among NUS
students towards evolution and only realised late in
my first semester in Singapore, during Academic
Year 2002/2003, that Scott and Branch's approach
does not work as students end up being detached
from the subject. For them, the burning question is
finding out why evolution should be preferred over
'intelligent design' and not whether a particular
model, for example, offers the best explanation for
sexual selection. As such, ignoring the controversy
is not an option.
To deal with these challenges , I adopt a
constructivist's approach to teach evolution (Scott
& Branch, 2003). This approach uses the debate to
illustrate how Science uses evidence to select from
among competing hypotheses. To implement this
approach effectively, students have to be actively
involved in characterising the alternatives to
accepted scientific theories and be directly exposed
to relevant evidence. For example, in ULS2202 I
introduce evolution, while I ask students to use
resources of their own choosing to define the main
elements of 'intelligent design'. They soon realise
that 'intelligent design' is mostly a collection
of objections against evolution, and offers no
alternatives to theories such as the Tree-of-Life
and only nebulous notions about the origins of
adaptations.
A similar approach can be adopted to address other
objections against evolution. Students are asked to collect these objections, which are generally about
the existence of supposedly 'irreducibly complex
systems' and the 'lack of transitional fossils'. The
first objection can be challenged using examples
such as the gradual evolution of the vertebrate
eye (Nilsson & Pelger, 1994). Similarly, exposing
students to 't ransitional' fossils effectively
counters the second objection. For example, one
practical session in ULS2202 and LSM3252 is
devoted to gathering morphological differences
between human and chimpanzee skulls. After
t hese differences have be en characterised ,
skulls from human fossil records are introduced
for compa rison. Students realise that these
skulls display a mosaic of ape- and human-like
features and that the older fossils are more apelike.
Exposing students to molecular evidence
is another powerful method of addressing such
objections. In another practical session, they
learn to reconstruct evolutionary trees based
on mitochond r ial gene s for mon keys, apes,
Neanderthals and humans. They discover that the
common ancestry of humans and chimps and the
intermediacy of Neanderthals is still supported
even when 95% of all evidence is deleted or only
synonymous mutations are considered (Wildman
et al., 2003).
Based on my experience, I believe that using
the constructivist's approach to 'teach the
controversy' is more productive than ignoring
it. As we address these controversies, students
also learn to gather and evaluate evidence from a
scientific perspective.

Publicity E-poster for ULS2202 Evolution. Reprinted with permission
from the University Scholars Programme
References
National Academy of Sciences and Institute of Medicine
(2008). Science, Evolution and Creationism. Washington
DC: National Academies Press.
Nilsson, D. E. & Pelger, S. (1994). 'A Pessimistic Estimate of
the Time Required for an Eye to Evolve'. Proceedings of the
Royal Society of London, Series B, Vol. 256, pp. 53-58.
Scott, E.C. & Branch, G. (2003). 'Evolution: What's Wrong
With '"Teaching the Controversy".' Trends in Ecology &
Evolution, Vol. 18, Issue 10, pp. 499-502.
Wildman, D. E., Uddin, M., Liu, G., Grossman, L. I. &
Goodman, M. (2003). 'Implications of Natural Selection
in Shaping 99.4% Nonsynonymous DNA Identity Between
Humans and Chimpanzees: Enlarging Genus Homo.'
Proceedings of the National Academy of Sciences USA,
Vol. 100, Issue 12, pp. 7181-7188.
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