Guest Post: The Intricacy of the Ear

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Sound wave by betmari. Flickr. (CC BY-NC 2.0)

Music, whispers, phone calls, the alarm clock, the cry of a baby – the ear mediates our auditory interactions with the world. The things we hear may make us laugh or cry, enhance a film or make a subtle point without words, cheer us up or soothe an angry mood. The interpretation of sound and what it means to us is the responsibility of the brain, but the pathway that takes Continue reading

Biological Fine-Tuning

© Sharlene Jackson, freeimages.com

It’s reasonably common to hear physicists and astronomers talk about ‘fine-tuning’, or the ‘anthropic principle’. The idea is that a large number of physical properties (such as the strength of gravity, or the forces within the atom) need to be at very, very precise values or life as we know it would not exist. The numbers are incredible – probabilities with more decimal places than there are atoms in the universe!

Is there any evidence of fine-tuning in biology? Biology is a much newer science than astronomy and the systems involved are far more complex, but even so, there are a few glimmerings of fine-tuning on the biological horizon. There has been a good deal of interest in Cambridge Palaeobiology Professor Simon Conway Morris’s research on convergent evolution. In his popular level book, ‘Life’s Solution: Inevitable Humans in a Lonely Universe’ (CUP, 2003), he describes how the course of evolution navigates towards fixed points in the total space of biological possibilities. This winding path towards higher levels of complexity, and ultimately intelligent life, is entirely consistent with the Christian belief in the purposeful sustaining of the universe by its Creator.

So has anyone else approached the subject of fine-tuning in biology, or is Conway Morris a lone voice? Theologian and biochemist Alister McGrath has spent time on this subject (see A Fine-Tuned Universe and a less technical reworking of similar material in Surprised by Meaning). The main point McGrath makes is that the biological world relies on the same fine-tuned physical and chemical properties that astronomers spend so much time discussing.  Without compounds such as carbon, oxygen, hydrogen and phosphorus, life simply wouldn’t exist.

McGrath also points to an interesting paper in the April 2003 issue of the International Journal of Astrobiology. In it, astronomers Bernard Carr (St Mary’s, London) and Martin Rees (Cambridge) give an account of a 2002 conference on biological aspects of the anthropic principle. Even in a conference with this title, issues of chemical evolution took up part of the proceedings, but what was most interesting was the section on ‘evolution of biological fine-tuning’. The research in this area was all too tentative to be published more fully, but covered areas such as robustness in biological networks, and the ‘choice’ of DNA and proteins as information carrying molecules in biological systems.

Biological systems are enormously complex, which is why it’s taken us so long to get around to even beginning to understand things at the level of whole organisms. But there is a trend, in that although the total ‘space’ of possibilities (for example, for the sequence of a protein of a particular length) is usually enormous, in reality the number of variants present in nature is relatively small. At times it is possible to pinpoint why certain solutions have been arrived at – for example, the camera eye is quite simply the best way to see light. At other times the reason why a particular solution has been arrived at is less clear, as in the origin of biochemical systems and cellular life.  Whether the existing systems we see are an accident of history (i.e. where a number of potential solutions could work) or are another example of fine-tuning, is yet to be determined. What is clear to me, however, is that the astonishingly fertile chemistry of life and evolvability that we see is entirely consistent with the existence of the God revealed in the Bible who provides us with a rich source of teaching and guides us though the process of learning by our mistakes.

Songs about…biology?

Astrocyte (type of nerve cell) by Karin Pierre

I’ve been blogging about astronomy recently. It’s an easy target really – anything that involves staring at the night sky is likely to move people to worship. But what about my own subject of biology? The living world is a lot messier, but it is just as amazing.

Our own development from sperm and egg to squalling baby takes just nine months. During that time, the instruction manual for a unique physical human being is read off from the DNA code that resides in every cell in our bodies.* It’s incredible that the information is all there in the 2 metres or so of code in each cell. DNA is about a billionth of a metre (2nm) wide, and is not visible with even the best light microscopes (these can only see things as small as about 50 nm). Inside the cell DNA is coiled up, in a number of complex stages, into a tiny mass that fits inside the nucleus of the cell.

Until recently I believed that we had enough DNA in our bodies to take us on an amazing journey.  I was told that if all the DNA in each cell of your body – all 2m of it – was extracted and added end to end it would reach as far as the moon and back. That’s quite a thought.

But then I checked the numbers for a children’s talk that I was preparing and discovered that the story I had been told was way off the mark.

  • We have about 50 trillion (50 x 1012) cells in our bodies.
  • Multiply that by 2m, and you have about 100 trillion metres, or 100 billion (100 x 109) kilometres of DNA.

So yes, we do have enough DNA in our bodies to take us to the moon and back, but you can go much further than that – to the sun and back more than 300 times! I can’t even begin to comprehend that, but it’s very impressive. And I’ve ended writing about astronomy again…

I’ve been criticised for making the leap from ‘wow that’s amazing’ to belief in God. But that’s not what I’m doing. I don’t believe in God because of anything to do with science (see my earlier post for more on this). The point is that I believe in a big God, and learning more about how incredible the universe is helps me to understand a little more about just how big God is.

*Except mature red blood cells or the lens in our eyes – in these cell types the DNA would get in the way so it’s broken down.