Teaching Evolution

Last year I attended an excellent lecture at the IOE by Professor Martie Sanders on teaching evolution to young children. I’ve been meaning to share this.

As evolution now has to be taught in Key Stage 2,  I think it’s really important for teachers to think carefully about how to do this, and do it well. To begin with I’m going to use a quote Martie used:

“Nothing in biology makes sense except in the light of evolution”            

  (Dobzhansky, 1973:125)

You can also watch a quick Ytube clip below explaining this in a snappy set of clips, but in essence life processes and living things begin and end with evolution. If children understand the basic concept of evolution it will mean they have a fundamental foundation for understanding all the other biological concepts. Even if pupils don’t become scientists, which most won’t do, understanding evolution brings the individual a clearer sense of the relationship between living things and the environment; this helps them become an informed citizen. For example, take the over use of anti-biotics causing bacteria to become resistant to common drugs then developing into ‘super bugs’. This is evolution!!

Why evolution is important:    https://www.youtube.com/watch?v=lRJnqJqBfsY

Worries about teaching evolution

Martie shared her studies carried out in South Africa and found that when confronted with teaching evolution, teachers were most worried about their own subject knowledge and also conflicts with their own or pupil’s religious ideas. However, her quote ‘knowledge is power’ really made sense here. The best thing to do then is not to shy away from teaching it, but jump right in and try to understand what’s going on here.

One suggestion is to present the scientific ideas about evolution as ‘scientists’ explanations’. A teacher then should never use scientific theories to confront religious beliefs. In fact it is important to make a distinction between scientific explanations and religious beliefs and not set them against each other, even if they seem contradictory. For me, it’s a mistake to present religious and scientific ideas as both theories because we are then using ‘theory’ in a very causal way and not the scientific way. A theory comes about when a hypothesis has been tested using evidence. A theory is not a belief; a theory is a viewpoint arrived at using all the evidence presented so far; theories themselves can also evolve and change depending on the evidential base. So – I would say, please don’t call beliefs theories; you need evidence to have a theory.

So, once you’re comfortable with presenting these scientific explanations, and have not set these against any ‘beliefs’ in the room, then it’s all about getting the subject knowledge and the teaching method right.

Subject knowledge

Let’s start with variation in a population (a group of the same species living in a particular area). A farmer wants to breed sheep with thick curly brown fleeces.  He has a heard of sheep with different kinds of fleeces: grey, brown, black etc. What does he do? He selects two sheep with the thickest, curliest, brown fleeces and breeds them. This is selective breeding. The two curly, brown sheep have a few lambs. Of these the farmer only allows the ones with the curliest brown coats to breed. He continues like this so that over the generations, more and more offspring have the thick, curly brown feature and any other colour or texture is bred out.

 coloured~lambs

Now, what Darwin thought was ‘maybe this happens in nature too’! Maybe somehow, there is a process of natural selection so that certain attributes become dominant? He was right, but here comes a problem and a potential misconception for pupils!

Anthropomorphism  and evolution on demand

The trouble is that the way we talk about living things often sends the wrong message and forms the basis of misconceptions for young children. Like this, when we say things like ‘some plants prefer more light’ or ‘roots try to find water’ we are implying that these living things possess volition (or decision making abilities). They don’t. So as teachers we need to be really careful how we say things. Most of biology is process driven and not decision driven, and we need to use language to indicate this.

The point here is that living things do not choose to evolve that’s why Darwin used the word ‘natural selection’. A polar bear did not at one time choose to grow thicker hair in order to live way up North, just as a tiger did not choose to grow a stripy coat so it could hide in the leafy jungle and hunt. Instead, these were naturally selected attributes that became dominant over generations. In fact let’s use Martie’s quotes to make the three key areas clear:

  • Evolution: “Changes in a population, resulting from the increase of certain features in the population over many generations
  • Natural selection: “The mechanism by which evolution occur.”
  • Adaptations: “Evolutionary results of natural selection, in a population”

Let’s take the tiger and its stripes. We take a population of big cats in the jungle. Some of the cats have are born with a stripe of two. While hunting this gives them a slight advantage, they are better camouflaged and as a result they have a better diet. In turn, they have more energy to breed and reproduce more offspring. These offspring are born with the same kind of stripes because they share the same genes. These tigers are also at an advantage to the less stripy cats and hunt more and reproduce more. So now there are more stripy cats and less non stripy cats. The stronger stripy cats are more likely to mate with another stripy cat. Eventually, this goes on over the generations and eat generation is more stripy because the adaptation of ‘stripy fur’ has been naturally selected. Remember, the tiger didn’t decide to get more stripes, or decide to choose a stripy mate even, but they might reproduced with the fittest mate who was stronger because he had stripes and was more successful at hunting – see ‘survival of the fittest’.  Even that term can be misinterpreted, like living things having some big kind of fight and the strongest one winning – as you can see, it’s not quite like that. It simply means that the living being with attributes best suited the environment is more likely to survive and reproduce than one that doesn’t. Remember, no decision making – just process.

tiger      tiger eating

Children rightly love stories with animals, but this can also serve to  create misconceptions about them. But please don’t stop reading them wonderful stories! Just make sure you don’t carry it on during science lessons!

Evolution is learnt mostly through observation

Just as Darwin arrived at his theory of evolution through observing living things and recording evidence, children will learn about evolution in the same way so they need to be provided with lots of opportunities to ‘play at evolution’ themselves. Martie Sanders suggested for example, using the attributes of insects to investigate camouflage and survival. For example, on a leafy green plant, which beetle is more likely to be spotted by a predator:

 green leaves   gren beetle   black beetle    yellow beetle

There are lots of games children can play like this. You could darken the room, like a deep jungle, cut the beetles out, lie them on a green leafy background and give the children ten seconds to pick up as many as they can. Because they will naturally find it easier to pick out the black and then yellow beetles against the green, they will see how more of the green beetles will be left to survive and reproduce with other green beetles. What I find fascinating here is that this shows the localised nature of evolution. Children often think all polar bears came at once or all tigers, or green beetles suddenly appeared. The point is that if evolution begins with variation in a population this is referring to groups of living things living nearby each other. In this way, the adaptations are local to the population, which of course might be so well adapted to where they are that they get bigger and bigger then you get migration and larger, more global populations. But all this is at the heart of the great ‘tree of life’ and the huge variety of life on earth. Amazing!!!

There’s also a similar game using different utensils to model bird beaks and different food types of food (see below).

Bird beak activity and speciation

So, if you’re having to teach evolution for the first time I hope this was useful.

normal_tree_of_life

 

3 thoughts on “Teaching Evolution

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