‘ANIMALS
DON’T
JUST GROW
FEATHERS
WHEN THEY
WANT TO...’
Terry Russell and Linda McGuigan share more of their
research into teaching evolution and inheritance
Key
words:
Research
Evolution
CPD
18
T
he short view of inheritance
is that it is about what
every organism gets from
its parents, one generation to the
next. Young children appreciate
that offspring have strong
similarities with their parents.
A longer perspective embraces
the similarities and diversity in
relatives’ features; it includes the
characteristics of predecessors
within and beyond the extended
family, to include members of
a species going back thousands
of generations. In this longer
view, the slow but significant
changes we call ‘evolution’ make
sense. Evolution connects ideas
of inheritance from the pool
of variation over ‘deep time’
that give rise to evolutionary
change as a response to shifting
environmental circumstances.
Thus emerges a beautifully
elegant, complex way of
understanding the world.
Within the English National
Curriculum for Science 2014,
the strand ‘Evolution and
inheritance’ is identified with
upper key stage 2 (ages 9–11). Our
orientation to science education
favours a focus on conceptual
progression by identifying
developmental trajectories in
learners’ understanding. This
approach avoids the introduction
of key ideas in a disconnected
manner and so is more supportive
of teachers wishing to adopt a
formative style of teaching and
learning. This wider concern
leads us to include children from
reception to key stage 2 (ages
4–11) in the Nuffield Foundation
funded research reported here.
Here is a view expressed by an
11-year-old child within a science
discourse session, also known as
‘working scientifically’:
when they want to. They inherit
them from their parents.
Their teacher had just read Charlie
and Kiwi (Reynolds, 2011) and
invited the class to explain what
they thought was meant by
evolution. The ‘time machine’ story
line encompasses the evolution
of birds from dinosaurs. There is
a lot in this child’s contribution,
the more pervasive view among
younger children of individual
change and personal needs driving
evolution being displaced by a
view of change over generations
and over deep time.
Thinking creatively about
resemblances between
parents and offspring
The early years and key stage 1
(ages 4–7) teachers in our research
group focused initially on the
imaginary world, using narrative
Evolution is slow changes over
fiction to draw out children’s
millions of years. Many generations. ideas about animals’ offspring. A
Animals don’t just grow feathers
reception group used a fictional
Primary Science 138 May/June 2015
Evolution and inheritance
eness
lik
Box 1 Family
‘mummy dog’
e model of the
th
at
th
d
ne
ai
of the pictured
ild expl
the white tail
d
A 4-year-old ch
an
gs
le
ge
.
ur oran
se and mouth
included the fo
e eyes, black no
th
as
l
el
w
as
offspring dog,
Resemblance between
imaginary pets and their
story (Donaldson and Scheffler,
offspring
2000) of a butterfly helping a
In a year 2 class (ages 6–7), the
young monkey to find its mother.
teacher used an imaginary context
The twist in the plot is, of course,
to explore children’s awareness
the fact of the butterfly’s and
of how offspring might be similar
the monkey’s (and possibly the
to their parents. Children were
children’s) differing assumptions
invited to create 3-D models of
about likeness passed between
two imaginary parent pets and
generations being confounded by then to make their offspring as
the fact of insect metamorphosis.
they imagined they might look.
Following the context set by
Children decided the features
the story, children were asked
of the parents and the offspring.
to choose one of a number of
The art materials engaged
pictures of dogs and to show
their interest and also
what the mother dog would look enabled them to show in
like using modelling clay and art
an imaginative way the
materials (Box 1). The invitation
size, shape, colour, specific
to reverse engineer a parent rather features, and so on, that
than anticipate the offspring was
would be present in the
novel within the project. The
progeny. Many children
teacher believed the narrative of
represented the parents as
the monkey story, with its focus
alike and the offspring as just
on finding a lost mummy and
like the adults, only smaller.
children’s attachment to their own
Occasionally, there was an
mothers, would help make the
appreciation of the possibility
task accessible.
of differences between the
The view that the ‘mummy’
parents, together with a
should look like the offspring
suggestion that the offspring
was strongly held. Only one child
would ‘get features’ from
reasoned that the mummy dog
mum or dad (Box 2).
would look different. She explained
that the pictured dog had a sad face
and her mummy dog would have
a happy face! While children in this
class had a developing awareness
that living things – in this instance,
dogs – produce offspring of the
same kind, they tended to think
they would be exactly the same:
identical.
Creating an assistance
dog
Many children explored
inheritance through dog
breeding, possibly due to
the popularity of dogs as
pets: 25% of UK homes keep
dogs (see Websites). In most
classes, there was a link with
dog breeding through children’s
own experiences or that of the
teacher or teaching assistant. In
a year 4 (ages 8–9) project class,
one of the children’s siblings
had an assistance dog and this
knowledge stimulated children
to research and discuss useful
and preferred traits. Their list
included ‘good ears’, ‘good sense
of smell’, ‘trainable so that it would
do as it was told’ and ‘good with
children so it would fit in with a
family’.
Children were asked to
choose two varieties of dog to
breed together so as to create
their own assistance dog. To
inform their selection, they
researched different dogs.
Data collected included health,
average height, life span, hair
shedding, and so on. Children
often decided which breed
was the ‘mum’ and which the
‘dad’. Their discussions as to
how the resulting offspring
would acquire its characteristics
confirmed only the widely
held idea that the traits were
transmitted from either or both
parents. Children’s reasoning
as to which parent influences
what features is a line of
enquiry readers might wish to
pursue (Box 3).
Box 2 3-D families
These models of ‘mum’,
‘dad’ and ‘baby’ made
by a 6-year-old are very
similar apart from
the offspring being sm
aller. The mouths of
mum and dad differ in
colour and the ‘baby’
has ‘got the mum’s mo
uth’.
Primary Science 138 May/June 2015
19
Evolution and inheritance
theme of inheritance. Selective
breeding for desirable traits
seemed to be more intuitively
acceptable to children than
ld
o
rthe idea of preventing the
a
e
an 8-y
This work by
3
propagation of undesirable traits.
1
f
o
nition
shows recog
t
h
g
The general sense was that, faced
u
o
th
d
e chil
traits that th
e
with a disadvantageous trait,
n
o
m
o
ed fr
could be pass e next,
children’s inclination was not to
to th
generation
prevent breeding, and culling
d
n
a
t
n
e
peram
both of tem
was never countenanced. When
s.
ic
st
ri
racte
the question was posed as to
physical cha
ch
tion from ea
what to do with, for example,
The contribu
,
ars arbitrary
slow-running whippets, attention
y
parent appe
ir
further enqu
turned to nurture. Children
but warrants
re
rtain traits a
tended to emphasise the effects
as to why ce
be linked to
of environment, upbringing and
assumed to
der.
experience on offspring and
parental gen
bringing the slow mover up to
standard by a training regime
that would improve performance.
Ideas that skills could be learned
passed from adult to offspring
and then inherited by offspring
were revealed. Some believed
were commonly held and seem to
characteristics were from either
resonate with the historical (now
‘mum’ or ‘dad’. Many believed
discredited) Lamarckian view
that offspring would be a ‘mixture
of the heritability of acquired
of mum and dad’, ‘half mum, half dad’
characteristics.
or ‘50:50’.
An alternative suggestion was
Some children placed the two
to release animals that lacked
images together to show how the
desirable features into ‘the
designer dog might share physical
wild’. (Some disagreed with this
features of both parents. Further
strategy, citing pets’ dependence
probing revealed an appreciation
on humans.) Children tended
that the tactic was of limited value
to be democratic in their views
and that the designed dog might
about fitness to survive and
have a mixture of features (Box 4). caring for the underdog. Teachers
recognised inculcated values
The value of the ‘selective
about caring for one another in
breeding’ approach
the school and a strong belief in
The breeding of assistance dogs
social justice and equity being
(see Websites) and so-called
generalised to the animal world
‘designer pets’ were found to
and to training or redeeming the
be productive areas within the
weaker individuals. Disentangling
genetic and environmental
causes of differences (let alone
interactions between the two) was
found to be difficult.
A few children had some
awareness of DNA from
broadcast media, but it was not in
widespread use as an explanatory
concept at the upper end of the
primary phase.
tance
Box 3 Assis
dog
Creating a designer dog
The teaching assistant in a year
6 (age 10–11) class brought in
photographs of her two dogs and
described their temperament and
behaviour. Many of the children
were familiar with the actual
dogs and their puppies, and this
motivated their discussion of
terms including ‘pedigree’, ‘breed’
and ‘cross breed’.
The children were provided
with images of various dogs
and asked to choose two dogs
from which to create their own
‘designer dog’ that they would
later promote to people who were
looking for a pet with particular
characteristics. As they did so,
some inkling of their thinking
about how characteristics were
Box 4
Designer
dog
‘That isn’t what
it would exactly
look like … They
come together
and have babies.
It gives you a
little bit of an
idea what they
would look like. You’d probably get little bits of it black and little bits
white.’ (11-year-old child)
The folding of the images seemed to help children think about how the
different features might be combined in offspring.
20
Primary Science 138 May/June 2015
Selective breeding and
domestication
Public opinion about the
acceptability of wearing animal
fur has shifted over time. What
had been functional for our
hominid ancestors became stylish
and prestigious before being
perceived as a cruel treatment of
Evolution and inheritance
animals. Captive breeding for the
fur trade has been banned in the
UK from the turn of the century.
Both the Arctic fox (Vulpes lagopus
– also known as the white, polar
or snow fox) and the silver fox
(Vulpes vulpes – also known as
the Siberian fox) were formerly
prominent in the fur trade.
The role of the Arctic fox
has shifted from a starring
role in Hollywood to a more
modest mention in the National
Curriculum for science. Nonstatutory guidance for upper key
stage 2 advises that pupils should
‘appreciate that variation in offspring
over time can make animals more
or less able to survive in particular
environments, for example … the
development of insulating fur on the
arctic fox’. Camouflage against
the Arctic background coupled
with insulation from the cold
has led to greater survival of
animals inheriting denser, white
winter fur. The survival of more
such animals enhanced their
breeding success and the spread
of advantageous features through
the Arctic fox population.
A fascinating offshoot of this
trade in fox fur is a breeding
programme for ‘tameability’ of the
silver fox (Vulpes vulpes – a morph
of our familiar red fox) initiated
in the 1950s in Russia (Trut,
Oskina and Kharlamova, 2009).
Fifty generations later, with those
that tolerated humans selected
for breeding and aggressive
individuals excluded, significant
changes are apparent: ‘cuddly’
juvenile appearance, tail wagging,
whimpering, licking and ‘reading’
human expressions and gestures.
The authors suggest parallels
with the domestication of grey
wolves (Canis lupus) to dogs (Canis
familiaris).
Furthermore, the foxes bred
for tame temperament showed
changes not only in behaviour,
but also in form and physiology:
curly tails, piebald colouring
and shorter legs. Darwin (1868)
was aware that domesticated
animals tend to share a common
set of characteristics, with smaller
stature, floppier ears and curlier
tails than their wild forebears, as
well as often having spotted coats.
This ‘piebald’ trait occurs in cows,
sheep, dogs, pigs, chickens and
even fish (Ratliff, 2011).
The silver fox study’s authors
suggest that selection of wild
animals for ‘tameability’ can
be inferred as the mechanism
underlying other transformations
from wild to domestic animals
over the last 10–15,000 years
of human history. It was
apparent from our research that
both selective breeding and
domestication of animals (and
plants) by human intervention
would form a useful bridge
between ideas about evolution and
notions of inheritance. Selective
breeding is also important in
human social, cultural and
economic history, especially in
the context of food production. A
further endorsement of the value
of enquiries into selective breeding
of animals is the affective aspect
evident in children’s interest in
pets.
This perspective can be
pursued by children ‘working
scientifically’, using secondary
sources of information on
domestication to find out more
about organisms that interest
them. Research into inherited
features requires particular
attention to traits that are
deliberately sought or eliminated
in offspring, so discourse is
focused on the deliberate shaping
of animals or plants to enhance
particular features. The timescale
of change, over generations
of selective breeding, is more
comprehensible to children than is
the timescale of evolution through
natural selection.
Of course, enormous gamechanging advances in 21st-century
technology have resulted in
scientists being able to manipulate
the genetic make-up of plants
and animals to enhance or avoid
particular traits, for example, in
the interests of increased food
Websites
Assistance Dogs UK: www.assistancedogs.org.uk
Pet population 2013: www.pfma.org.uk/pet-population
production. ‘DNA’ and ‘genetic
modification’ are terms that
are likely to be encountered
outside formal education
and often in controversial
circumstances (as, for example,
‘three-parent-babies’). The
science is truly cutting edge
and knowledge of the human
genome (the complete human
genetic blueprint) will have an
increasing impact on health
management. For the primary
phase, children will not yet
have the knowledge at the
molecular level to inform their
thinking (and in most cases,
nor will their teachers). The
introduction of evolution and
inheritance to the key stage 2
curriculum suggests that ways
of managing discourse in this
area, but at a level appropriate
to the more general knowledge
background of children, will
need to be found. We are
currently discussing with
secondary colleagues the
implications for transition and
‘secondary readiness’.
References
Darwin, C. (1868) The variation of
animals and plants under
domestication. London: John
Murray.
Donaldson, J. and Scheffler, A. (2000)
Monkey puzzle. London: Macmillan
Children’s books.
Ratliff, E. (2011) Taming the wild.
National Geographic, March
2011. Available from: http://ngm.
nationalgeographic.com/2011/03/
taming-wild-animals/ratliff-text
Reynolds, P. and New York Hall of
Science (2011) Charlie and Kiwi: an
evolutionary adventure. New York:
Atheneum Books for Young Readers.
Trut, L., Oskina, I. and Kharlamova, A.
(2009) Animal evolution during
domestication: the domesticated fox
as a model. BioEssays, 31(3), 349–
360. Available at: www.ncbi.nlm.nih.
gov/pmc/articles/PMC2763232
Terry Russell is emeritus
professor and Linda McGuigan
is honorary senior research
fellow at the University of
Liverpool. Emails:
[email protected]
[email protected]
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