Sunday, January 31, 2016

Teaching Biology Differently: Teaching The Design Principles

I used to hate biology in school and even in college. I used to hate it for all those difficult-to-pronounce names and lengthy descriptions. Eventually, my skills in drawing and storytelling, helped to sail through biology examinations. 

Ask a student of biology 101 class, which is compulsory for all our undergraduate students, you will get similar answer.

We all love physics for its laws and principles. Math is our darling as it gives the power to understand a phenomenon magically by some equations. It is logic in its purest form. Biology, as the books and teachers present, does not have any law, rule or principle. You just observe a phenomenon and accept it as fact, as it is. Read it; remember it. Molecular level biology, at the college level, is often taught in the same fashion; only the level of observations changes.

Is it true that biology is nothing but a compilation of information? Is it really devoid of any underlying principles? Or we are teaching biology in a wrong way?

Modern biology evolved from natural history, the art of observing and recording nature. Once, biology was like astronomy: you can observe but cannot manipulate the objects that you are studying. However, modern biology gives us tools to manipulate and interrogate living things.

Even when you merely observe, you can draw generalized principles. The heliocentric theory of our solar system was not developed by manipulating sun and planets. It was developed by observation, mathematical calculations and rational imagination. In fact, the theory of evolution proposed by Darwin was developed in the same fashion, by systematic observation and logical deductions. While teaching physics, we starts with the heliocentric theory and theory of gravitation; rather than teaching list of names of universes, stars and their planets. Why can't we follow the same in teaching biology?

But are there any principles or laws in biology? Biology deals with living beings and they follow laws of nature that are equally applicable to inanimate and animates. We learn those in physics and chemistry (that again is an extension of physics). Something living cannot violate those laws. Whatever a living being does, from birth to death, must be following those laws of nature; either we know them or some may be still unknown to us.
Some of my biologist friends will not be happy with this. They will protest that I am equating biology with physics. Trust me, I’m not.

Living things are definitely more complicated than a ball rolling on a ramp, as we have studied in physics textbooks. So are weather, geology, hydrology etc. Most natural systems are much more complicated than the pendulum you used to calculate acceleration due to gravity. Be it living or nonliving. Phenomena observed in these complicated systems are not easy to explain by just few simple equations. (At least not till now!!)

Also living systems are very diverse. Same thing can be achieved by multiple strategies, without violating laws of nature. That is where biology becomes difficult for students. Teachers often over-emphasizes on the diversity, not on the unifying principles. That is where the concepts of design principles help.

Imagine yourself as a designer. You want to design something tangible, having some specific properties and functions. As a designer, you have to think different ways to design the same. Those designs will have advantages and disadvantages. Above all, as the system is real and physical, none of the designs should violate the laws of nature. So your options in design, are bounded by those laws.

Same is true for biology. While studying biology we can look from the perspective of a designer. You have some target to achieve and you have some basic building blocks in hand: molecules, cells, tissues etc. Each of these building blocks has properties. How will you design the system?

Let us take the case of immune system. The objective is to create a defense system against ‘others’. How will you go for it?

First, you have to define the border. Then you have to create the first line of defense at the border; something robust. That is where comes your innate immune system. Making the system more sophisticated, you have multiple tires of soldiers and officers, having different capabilities. That is how you have different immune cells.

You must have a system to check foreigners and keep valid citizens safe. You need some sort of passport with identification stamps. That is achieved through self-nonself discrimination and immune memory. You must also have a spies snooping around for invaders. So you use cells like macrophages.

Like a modern army, you want to create a tight command system by segregating people with different skills and responsibilities. So comes your different immune cells with different capabilities and their interactions to control each other's activities. You do not want your boys to move around freely with loaded arms. That is why you create cantonments, the lymphatic organs, where you keep your soldiers.

When you have a bomb that causes collateral damage, you do not trust to put the trigger in the hand of only one person. You make sure that at least two people agree to push the trigger. That is what they do for atom bombs. And that’s why we have “two signal” system for immune response.

Now put all these design principles together. Introduce the molecules, cells and others, in this context of defense design. Along with these, introduce the students to chemistry, kinetics, and thermodynamics of molecular recognition, diffusion limits of molecular signaling, mechanics of cell migration. Even one can introduce students to stochastic processes like diversification of B-cell repertoire.
With these, students will realize how the immune design is constrained by laws of nature. Biology will be connected to physics, chemistry, and math. It will be easy for them to comprehend and appreciate biology.

Yes, one have to know what is a B-cell and how it differs from T-cell. But I will not bug my students to remember names of all the molecules and cells. Rather, I will focus on the bare minimum ones and emphasize more on the design. In fact, one can comprehend the principle of immune memory and vaccination, even without remembering all the different variants of B-cells and molecules involved.

Someone who will eventually work in the field of biology, say during his//her PhD, will learn those details in time. They will mostly learn the finer things while working on those. For rest, let us focus more on the principles.

For rest, let us instigate their imaginations with design problems. For example, after basics of immunology, one can ask the student to think about design principles for immune tolerance in pregnancy. An embryo is genetically different from mother. Mother's immune system should consider it as foreign. How will you design a safety net, to save the embryo from the attack of mother's immune system? This way, we will be able to instigate the students to think about an active field of research.

One can use this approach of teaching design principles in other topics of biology. Let it be basics of molecular biology, metabolism, or signal transduction. We can shift the focus from “what happens in biology” to “why they happen that way”. I call it teaching the design principles.

It also helps to connect biology with physics and chemistry. Even to engineering. It helps to introduce mathematics in biology. Above all, it instigates students to ask questions and learn. This approach is particularly helpful for a heterogeneous class, with students from different disciplines.

Over the years, I have practiced this. I have always got positive response. It allows me to break the first barrier, to tantalize students to know more. Once they are hooked, you can insist them to remember those names and information.

1) This writing is focused primarily on teaching undergraduate students; not for teaching students having higher and specialized study in biology.

2) There are amazing teachers, all around, who teach biology in their own ways. Opinion given here in this writing is NOT the only way to teach biology.