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Life on Earth
and elsewhere?

Life on Earth can be divided into three main types, Bacteria, Eucarya (organisms like animals, plants, yeast) and Archaea. Billions of years ago there was an organism that predated those three lineages of microorganisms. Bacteria and Archaea evolved from this form and Eucarya probably evolved from Archaea.  Unlike Bacteria and Eucarya there are no pathogens among the Archaea, so they can be considered as very friendly microbes. Microorganisms perform resource recycling functions that are critical to life on Earth, for example, Archaea fixes carbon dioxide in the atmosphere and turns over sulphur and iron compounds and methane gas is produced exclusively by a group of Archaea known as methanogens. 
  Life on Earth I
Life on Earth can be divided into three main types, Bacteria, Eucarya (organisms such as animals, plants, yeast) and Archaea. All of the microbes do important things to keep the planet’s ecosystems healthy. Just like Bacteria, Archaea are single-celled and are very difficult to distinguish from bacteria, even under a microscope. Unlike Eucarya, Bacteria and Archaea do not contain a nucleus. Archaea were only recently discovered to belong to a separate domain of life, a result of the development of new techniques in the 1960s and 1970s that enabled people to distinguish Archaea from the other types of microorganisms.

  Life on Earth II
Professor Philip Hugenholtz, Director of the Australian Centre for Ecogenomics at the University of Queensland, places the tree of life under the microscope and uncovers some major facts about microorganisms. The first life on Earth was single celled, thought to be forerunner of the domains of bacteria, archaea and eucarya. Our first physical records are of microbial mats which are evidence of huge communities of microbes aggregated together for common good (eg survival by not being buried by layers of sediment). Geological records include the Dresser Formation in the Pilbara WA with fossilised examples of mat structures dating back over 3.5 billion years, and the famous stromatolites in Shark Bay WA. Colonies of microorganisms gradually built up these mound shaped objects that have survived millions of years - quite an achievement for what are basically biofilms produced by single celled microscopic organisms.

Earth's longest lifelines
Dr Brendan Burns, from the University of NSW School of Biotechnology and Biomolecular Sciences, takes a closer look at ancient life on Earth, one that produced amazing structures called stromatolites. Stromatolites are basically living rocks. If you tap on them it is like tapping on concrete but they are alive, formed very slowly over vast periods of time by perhaps the simplest and most ancient forms of life on Earth - bacteria.
Earth's earliest architects
While microbial mats and stromatolites were not necessarily the first forms of life, it was the grouping together of different microorganisms that gave rise to the structures of microbial mats and stromatolites. Complex communities of microorganisms then evolved and adapted to work well together in a low oxygen environment. This assisted the survival of the entire ecosystem, making them one of the most prevalent ecosystems on early Earth.

  Mars - dead or alive?
Water, volcanoes and pingos on the not so dead red one.
Miguel de Pablo Hernandez, from the University of Alcala in Madrid (Spain) specialises in the study of the planet Mars, particularly of its water and volcanoes.While none of the volcanoes on Mars are active at the moment, there certainly are plenty of them. In fact, Mars has the biggest volcano known, being three times higher than Mt Everest. 

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