Featured Research

from universities, journals, and other organizations

Solution To Darwin's Dilemma Of 1859

Date:
January 9, 2009
Source:
The Geological Society of London
Summary:
A solution to the puzzle which has come to be known as ‘Darwin’s Dilemma’ has been uncovered. Darwin puzzled, ‘To the question of why we do not find rich fossiliferous deposits belonging to these…periods prior to the Cambrian system, I can give no satisfactory answer’.

A solution to the puzzle which has come to be known as ‘Darwin’s Dilemma’ has been uncovered by scientists at the University of Oxford, in a paper to be published in the Journal of the Geological Society.

Related Articles


‘To the question of why we do not find rich fossiliferous deposits belonging to these…periods prior to the Cambrian system, I can give no satisfactory answer’.

These words, written by Charles Darwin in The Origin of Species in 1859, summarise what has come to be known as ‘Darwin’s Dilemma’ – the lack of fossils in sediment from the Precambrian (c. 4500 – 542 Mya). If Darwin’s theory of natural selection was right, life evolved gradually over millions of years. However, the Cambrian period, which began around 542 million years ago, seemed to herald a sudden rapid increase in species diversity, an event which has come to be known as the ‘Cambrian explosion’.

Darwin could find no evidence for fossils prior to the Cambrian, and the mystery has continued to perplex palaeontologists. The study, carried out by Richard H. T. Ballow and Martin D. Brasier at the Department of Earth Sciences at the University of Oxford, focused on a rock formation from Shropshire, England, known as the Longmyndian Supergroup. These rocks had been examined in Darwin’s time by the geologist J. W. Salter, who suspected them of containing records of Precambrian life, but he was unable to identify anything beyond ‘trace fossils’: unusual markings which may have been left behind by organisms.

The study used Salter’s collection as well as fresh samples from the Longmyndian Supergroup, and identified microscopic fossils of exceptional preservation. The fossils represent a wide array of microbial life from the Ediacaran period, the period immediately preceding the Cambrian (630 – 542 Mya). They were preserved in a number of ways. Some had been compressed under layers of sediment until they formed a thin film of carbon residue on the surface of the rock. Others were preserved in three dimensions and are thought to have undergone permineralisation, a process where water containing minerals seeps into the spaces within an organism and evaporates, leaving behind mineral deposits which build up into a hard fossil. Some had also been preserved as impressions and moulds within layers of sediment, appearing as sharp ridges on bedding planes, or as their equivalent negative impressions.

It is not clear how the microbes kept themselves alive. As they lived in shallow marine environments, they may have survived either by converting light into energy in a similar way to plants, or by converting organic substances into energy as animals and humans do. Suggestions as to what organisms they might be related to include algae, fungi or a wide variety of other filamentous bacteria.

Darwin himself was confident that fossils from the Precambrian would eventually be found, believing it to be a time when ‘the world swarmed with living creatures’. Although the importance of the Longmyndian supergroup in solving the dilemma has been recognised since Darwin first identified the puzzle, it is only now, with more sophisticated techniques for examining specimens, that the secrets of the Longmyndian rocks and their exceptionally preserved fossils can be uncovered.


Story Source:

The above story is based on materials provided by The Geological Society of London. Note: Materials may be edited for content and length.


Journal Reference:

  1. Richard H. T. Callow and Martin D. Brasier. A solution to Darwin's dilemma of 1859: exceptional preservation in Salter's material from the late Ediacaran Longmyndian Supergroup, England. Journal of the Geological Society, Vol. 166, 2009, pp 1-4

Cite This Page:

The Geological Society of London. "Solution To Darwin's Dilemma Of 1859." ScienceDaily. ScienceDaily, 9 January 2009. <www.sciencedaily.com/releases/2009/01/090108082914.htm>.
The Geological Society of London. (2009, January 9). Solution To Darwin's Dilemma Of 1859. ScienceDaily. Retrieved November 24, 2014 from www.sciencedaily.com/releases/2009/01/090108082914.htm
The Geological Society of London. "Solution To Darwin's Dilemma Of 1859." ScienceDaily. www.sciencedaily.com/releases/2009/01/090108082914.htm (accessed November 24, 2014).

Share This


More From ScienceDaily



More Fossils & Ruins News

Monday, November 24, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Amphipolis Tomb Architraves Reveal Faces

Amphipolis Tomb Architraves Reveal Faces

AFP (Nov. 22, 2014) — Faces in an area of mosaics is the latest find by archaeologists at a recently discovered tomb dating back to fourth century BC and the time of Alexander the Great in Greece. Duration: 01:05 Video provided by AFP
Powered by NewsLook.com
US Returns Looted Artifacts to Thailand

US Returns Looted Artifacts to Thailand

AFP (Nov. 19, 2014) — The United States has returns over 500 vases, bowls, axes, and other ancient artifacts mostly from the Ban Chiang archaeological site which were illegally looted from Thailand decades ago. Duration: 01:13 Video provided by AFP
Powered by NewsLook.com
How To Search Through Every Public Tweet Sent Since 2006

How To Search Through Every Public Tweet Sent Since 2006

Newsy (Nov. 19, 2014) — Twitter has announced improvements to its search index that allow users to search through every public tweet sent since its inception in 2006. Video provided by Newsy
Powered by NewsLook.com
Professor Unlocks the Mystery of Paintings

Professor Unlocks the Mystery of Paintings

AP (Nov. 19, 2014) — Richard Johnson, a computer and engineering professor at Cornell University, is using technology to uncover mysteries about the age and authenticity of historic paintings by artists like Johannes Vermeer and Vincent Van Gogh. (Nov. 19) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:

Strange & Offbeat Stories

 

Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins