• Christian Moore Anderson

The big questions of the big ideas in biology, and how they should inform our teaching

Updated: Dec 3, 2020

Previously I have written about the big ideas in biology and how they fit into the secondary curriculum. Here I'd like to elaborate on how these ideas are split between two different ways of explaining them. Below I discuss what the division consists of, and then later how it should inform how we formulate the questions that we ask our students.

Image by Christian Moore Anderson & Blanca Martínez Valiente

In the 1960s Erst Mayr published his ideas on the distinction between what he referred to as ultimate, and proximate causes in biology. Proximate causes are those events that occur just before an effect, for example, the titanic sunk because water rushed into a hole in its hull. However, the ultimate cause was the fact that it ran into an iceberg. Mayr's distinction in biology designated the ultimate cause of biological phenomena to evolution and the proximate causes were those that could be described by physiology.

Questions about ultimate causes often answer questions that begin with why. Whereas those about proximate causes often begin with how.

However, in a critique of Mayr's ideas, Ariew (2003) suggested that Mayr's 'ultimate cause' idea wasn't satisfactory as it only referred to natural selection while, since the 1960s and Kimura's Nearly Neutral theory, biologists accept that drift plays an important role in evolution (alongside gene flow, and mutation of course).

Ariew therefore describes questions on evolution to be statistical questions, as they refer to why certain traits have become, and continue to be prevalent at the population level, and not at the organismal level. Therefore, he prefers the term evolutionary causes/explanations over Mayr's ultimate causes.

All other causes, Ariew suggests, are those that deal with mechanistic explanations of physiology. They are still proximate causes, but answer different questions, such as how? While developmental questions, such as 'How did it come about/be built?' are different to 'How does it work?' Ariew suggests that as they both deal with describing a physiological mechanism within a biological system, they are both similar.

How does this relate to the biology classroom?

To recap, the big ideas that I suggested for secondary biology were:

  • Evolution

  • Information

  • Energy & Matter

  • Organisation

  • Homeostasis

Which types of questions and explanations are natural to each? Evolution, of course, requires evolutionary explanations, such as why is this trait predominant, but the other four could be explained with why questions and also mechanistically with how questions depending on the context.

In fact, the latter four big ideas are facets of biological systems. Ben Zvi Assaraf & Snapir (2018) suggest that all biological systems show dynamism, hierarchy, and homeostasis.

  • Energy & matter plus Information represent the dynamism of biological systems

  • Organisation refers to the hierarchy of biological systems (molecular, cellular, organismal level, etc)

  • Homeostasis represents that ability of systems, via feedback loops, to maintain a constant state

Therefore, I suggest that there is a division of explanations in the big ideas of biology, explanations about evolution (why?), and explanations about systems (how?). Depending on our area of study our questioning should match how we present and question about the big ideas of biology.

Questioning on mechanisms of systems and avoiding teleology

If we are exploring the cell as a system (and not its evolution), and we ask our students why questions, then we are likely to instill teleological mindsets in our students (Kampourakis, 2012). Let's see how this plays out:

During a lesson on mitosis the teacher asks the students 'Why do the spindle fibres pull the chromosomes to opposite poles of the cell?' A possible student answer is 'Because each daughter cell needs a full copy of the genome'. This is a teleological explanation, using the purpose of the mechanism for explaining its action.

Here's another example: During a lesson on the circulatory system and how blood is diverted towards muscles, a teacher may ask why? To which students will probably say something like 'because the muscles need more oxygen...'

Kampourakis suggests that biology students are quite content with teleological explanations, especially those that include a fulfillment of a need, and that this may be due to teachers focusing explanations on the benefits of mechanisms, rather than on the mechanisms themselves.

When are teleological explanations acceptable?

We can cause problems as teachers if our questioning has not consistently divided our explanations into evolutionary and systems questions as students begin to misuse and misunderstand why and how questions. If we use why for evolutionary explanations, but also when we seek systems explanations, students may conflate the two. If we then focus on teleological explanations when answering why questions for systems, students may use them to explain evolution (via design).

Lennox & Kampourakis (2013) argue that teleology is fine as part of an evolutionary explanation as long as it refers to natural selection and not design. For example, giraffes have long necks so they can reach the high leaves on trees, is acceptable as long as the student has a notion of how natural selection led it to that trait.

Are teleological arguments satisfactory in systems explanations?

This is the cause of many woes for the biology teacher as students describe molecules wanting to and needing to do things in a cellular system. For students to begin understanding organisms as systems then we may need to be more consistent in our questioning, and that means focusing more on the how than the result of system mechanisms. Indeed, if we don't, then students will be left without context and simply rote learn that certain biological components carry out certain functions for X reason.

Nevertheless, the results and purposes of mechanisms are important for students to understand, however, they need to be linked to the (important) how.

van Mil et al. (2016) carried out an interesting study with post-16 students, in which they implemented a learning sequence with animations and simulations of molecules to promote systems-thinking and mechanistic explanations at the molecular level. They used a 'Functional analysis' to guide questioning about the cellular system:

1. The downward question (descending the levels of the system): “How does it arise from the underlying parts and their activities?”

(This is the how question)

2. The upward question: “What is its role or function, or how does it contribute to the

larger whole?”

(This is the what for question rather than why)

I think this is a useful and succinct guide for our questioning when dealing with systems explanations. We need to make sure we are questioning the how, as much as we deal with the what for. We need upward and downward questions to go in conjunction.

Students should be guided to understand the distinction between evolutionary questions and systems questions. But to give students the true ability to explain mechanisms of biological systems then we must give prominence to the how over the what for. To ensure students develop an ontological understanding of these differences maybe we should reserve why for referring to evolutionary questions.

Christian Moore Anderson

@CMooreAnderson (follow me on twitter)

Other posts you may like:

How typical biology curricula get it wrong

Developing a biologist’s gaze: the organism in its environment


Ariew, A., 2003. Ernst Mayr’s ‘ultimate/proximate’ distinction reconsidered and reconstructed. Biology and Philosophy, 18(4), pp.553–565.

Ben Zvi Assaraf, O., Snapir, Z., 2018. Human Biology. In K. Kampourakis & M. Reiss, ed. Teaching biology in schools: Global research, issues, and trends. Londen: Routledge, pp.62-73.

Kampourakis, K., Pavlidi, V., Papadopoulou, M., Palaiokrassa, E., 2012. Children’s teleological intuitions: What kind of explanations do 7–8 year olds give for the features of organisms, artifacts and natural objects? Research in Science Education, pp. 42(4), pp.651–671.

Lennox, J., Kampourakis, K., 2013. Biological teleology: The need for history. In K. Kampourakis, ed. The philosophy of biology. London: Springer, pp.421-454.

van Mil, M., Postma, P., Boerwinkel, D., Klaassen, K., Waarlo, A., 2016. Molecular Mechanistic Reasoning: Toward Bridging the Gap Between the Molecular and Cellular Levels in Life Science Education. Science Education, 100(3), pp.517–585.

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