Robert Burne, Tracy Slatyer, Murray Batchelor
Link to the ANU press article.
The full ANU Reporter Proof of Life article PDF (72dpi version, 873K).
Link to the more recent ScienceWise article.
We have begun to model the growth and form of microbial communities from the perspective of the mathematics and physics of evolving surfaces. These microbial 'mats' arise from the environmental interactions of microbial communities (microbialites). The mats evolve over time to form internally laminated organosedimentary structures (stromatolites).
Stromatolites play a central role in the at times heated debate on the earliest evidence of life. Fortunately Australia is blessed with a remarkable "fossil" record of ancient stromatolites.
Our field trip in 2003, to the Northern Territory, was centered on locating conical stromatolites. The picture below shows Jim Jackson standing near a striking example of an approx 1,600 million year old Conophyton. The biological origins of these stromatolites is not in dispute.
Our aim is to model such conical structures. Among other things, this will lead to a better understanding of ancient environments.
The 1st paper, A case for biotic morphogenesis of coniform stromatolites, by M.T. Batchelor, R.V. Burne, B.I. Henry and M.J. Jackson, was published in Physica A, 337 (2004) pp 319-326. PDF (467K)
The 2nd paper, Statistical physics and stromatolite growth: new perspectives on an ancient dilemma, by M.T. Batchelor, R.V. Burne, B.I. Henry and T. Slatyer, was published in Physica A, 350 (2005) pp 6-11. PDF (535K)
In this work we proposed a biotic model which considers the relationship between upward growth of a phototropic or phototactic biofilm and mineral accretion normal to the surface. These processes are seen to be sufficient to account for the growth and form of many ancient stromatolities. These include domical stromatolites and coniform structures with thickened apical zones typical of Conophyton. More angular coniform structures, similar to the 3,500 million year old Australian "stromatolites" claimed as the oldest macroscopic evidence of life, form when the photic effects dominate over mineral accretion. In our view, this lends weight to their biological origins.
Stromatolites appeared in a remarkable array of shapes. The picture below shows a spectacular example of Organ Pipe Stromatolites found on our N/W Queensland Field Trip in 2002. Imagine a field of long tube-like structures "growing" in a shallow water environment and you begin to get a picture of what life was like for much of the Earth's history. But what is the advantage of tubes over cones? Moreover, what environmental settings were responsible for the observed range of morphologies? These are some of the questions that we are trying to get a handle on.