A half flat flatfish!

Last updated on: November 14, 2014 at 5:30 am by Epiphenom

A half flat flatfish! 2014-11-14T05:30:30+01:00 Epiphenom

LOGO Patheos Explore the world's faith through different perspectives on religion and spirituality! Patheos has the views of the prevalent religions and spiritualities of the world.

One of the common challenges thrown at evolutionary theory is the apparent uselessness of intermediate forms. What use is half a wing, for instance, or half an eye? If it doesn’t have any survival benefit, then how could it evolve? Evolution, after all, is blind – there is no plan or purpose. Each organism survives or dies on its own merits (or plain dumb luck).

Most of these challenges have been answered long ago. As Prof David Dutch (University of Wisconsin) points out, half a wing – and less – could make all the difference in the world if it lets you jump an extra centimetre. And half an eye puts you way ahead of blind competitors.

But what about flatfish?

Flatfish make a living lying on the sea floor, peering upwards by virtue of the fact that both eyes are on one side of their head. But what earthly use could it be for some ancestor flatfish to have one eye shifted only part-way round its head? It would, after all, still point into the sand. Just not straight down…

The truth is that no-one knows what use it would be, which has lead some to propose that no such intermediate forms exist or are needed. In this ‘hopeful monster’ argument (first made by the geneticist Robert Goldschmidt in the 1930s), some freak mutation may have generated a fish with two eyes on one side in one step – and this freak managed to put the mutation to good use.

But it turns out that this is not what happened. Today’s Nature carries a report of the discovery of an intermediate flatfish ancestor, with eyes swivelled part way round. Now, flatfish start off symmetrical, and one eye moves round as the fish develops. But these are not immature fish, because they are too big and also the bones are ossified – which only happens after metamorphosis.

Still, what good is a half-formed flatfish? This discovery doesn’t answer that – though Dan Cressey, writing in Nature, suggests

“It’s possible that the asymmetrical eyes may have allowed the creatures to bottom-feed, watching for predators above while lifting themselves up on their fins to look for prey on the sea floor.”

What’s just as remarkable about this new discovery is that it wasn’t made in some fossil bed newly discovered in an exotic location, but rather in the bowels of the Natural History Museum in Vienna (and other museums in England, France and Italy). They were originally dug out of limestone quarries in Northern Italy and underneath modern-day Paris, and have lain in collections ever since – until Matt Friedman, a PhD student studying evolutionary biology at the University of Chicago in Illinois, discovered their significance. According to Matt,

“I suppose there is a general perception that museum collections are dusty, static archives, and that everything in them has been carefully studied and precisely identified. But the truth is that they are much more than just long-term storage, because as our interpretive framework matures, we can begin to make sense of specimens that evaded or baffled earlier generations of researchers, or draw new conclusions about materials we mistakenly thought we had figured out ages ago.”

Makes you wonder how many other missing links are field away in some museum drawer somewhere, just waiting to be discovered!

Refs

Friedman M. (2008) The evolutionary origin of flatfish asymmetry. Nature, 454(7201), 209-212. DOI: 10.1038/nature07108

Daniel Cressey. The eyes have it. Published online 9 July 2008 | Nature | doi:10.1038/news.2008.946

University of Chicago Medical Center. “Flatfish Fossils Fill In Evolutionary Missing Link.” ScienceDaily 10 July 2008.

Living the Scientific Life blog:
The mysterious origin of the wandering eye.

Uncategorized

Previous Post

July 8, 2008

Science in ‘The Mist’

Next Post

July 14, 2008 Thoughts on the individual scientist, prompted by Ian McEwan

Browse Our Archives

Select a Category Causes of religion - evolution Causes of religion - psychological Causes of religion - social Demographics Digest Effects of religion - health Effects of religion - psychological Effects of religion - social Notifications Politics Uncategorized

Select a Month March 2016 February 2016 January 2016 December 2015 November 2015 October 2015 September 2015 August 2015 July 2015 June 2015 May 2015 April 2015 March 2015 February 2015 January 2015 December 2014 November 2014 October 2014 September 2014 August 2014 July 2014 June 2014 May 2014 April 2014 March 2014 February 2014 January 2014 December 2013 November 2013 October 2013 September 2013 August 2013 July 2013 June 2013 May 2013 April 2013 March 2013 February 2013 January 2013 December 2012 November 2012 October 2012 September 2012 August 2012 July 2012 June 2012 May 2012 April 2012 March 2012 February 2012 January 2012 December 2011 November 2011 October 2011 September 2011 August 2011 July 2011 June 2011 May 2011 April 2011 March 2011 February 2011 January 2011 December 2010 November 2010 October 2010 September 2010 August 2010 July 2010 June 2010 May 2010 April 2010 March 2010 February 2010 January 2010 December 2009 November 2009 October 2009 September 2009 August 2009 July 2009 June 2009 May 2009 April 2009 March 2009 February 2009 January 2009 December 2008 November 2008 October 2008 September 2008 August 2008 July 2008 June 2008 May 2008 April 2008 March 2008 February 2008 January 2008 December 2007 November 2007 October 2007

TAKE THE

Religious Wisdom Quiz

Who was the major prophet during King Hezekiah's reign in Judah?

Select your answer to see how you score.

Ezekiel Isaiah Jeremiah Daniel