Australasian Science: Australia's authority on science since 1938

A Gold Medal for the World’s Oldest Life

By John Long

To enable science to match media coverage of sport, maybe we need to award some gold medals.

It’s funny how many sporting metaphors are used in everyday speeches by politicians or journalists. Sport gets much higher billing than science any day in any general news media. One just has to buy a newspaper (yes, the hard copy version) and note the last few pages are covered in sporting news or there is a separate lift-out section dedicated to sport.

Not so for science – usually the odd small column or article here and there if some big discovery is announced that journalists and their editors deem comprehensible enough to be able to turn into a news story. I recall the good ol’ days when I lived in Perth in the late 1980s. Every Monday there was a 16-page lift-out in The West Australian all about science and medical research. Eventually it was cut down to eight and then four pages, and then scrapped altogether.

To gain more headlines maybe science news needs to be treated like covering sport. I like to think that if Australia was competing in the Evolutionary Olympics we would bag an inordinately large number of gold medals for the oldest this, the first that or the biggest such and such. This is the first in a series of articles that will discuss the recent evidence for claims of Australian records in palaeontology.

Our first gold medal might be awarded to the country with the oldest and best-preserved fossil life on the planet. Australia has stromatolites dating to around 3.47 billion years old from the Warrawoona Group near Marble Bar.

Stromatolites are still living today in several localities, including the World Heritage-listed Shark Bay in Western Australia. They are microbial communities dominated by cyanobacteria that have a sticky outer layer that traps and binds sediment to form layered structures. It’s these structures that identify them in the fossil record.

There are microfossils of actual cells from Marble Bar dated at around 3.45 billion years also, although there is some debate over the authenticity. Recent work has identified definite microbial mat communities in the Strelley Pool Formation of the region. Dated at around 3.43 billion years old (PNAS 2009, 106: 9548), this gives support to the authenticity of the older stromatolitic fossils in the area. Work by Nora Noffke and colleagues recently proved that microbially induced sedimentary structures existed 3.48 billion years ago in the area (Astrobiology 2013, 13:1103).

Another keen contender for the title would be South Africa, where 3.2-billion-year-old kerogen filaments and spheres have been found in the Transvaal Supergroup and interpreted as cellular fossils. The lack of complex behaviour, inferred from cells being able to form mats with a preferential orientation or a colonial lifestyle, cast a shadow of doubt over their authenticity. Definite clear microfossils showing dividing cells and mating filaments occur at around 2.6 billion years in the same sequence.

Nonetheless, some of the stromatolites from here are preserved in stunning 3D form. Some exist in rows of little sharp cones, and these, without doubt, are the best preserved fossils of this age from anywhere in the world.

However, if we were going to be really picky we would only consider stromatolites or microbial mats with uncontested microbial fossils preserved within them as definite evidence for the oldest life. Taking this approach, the 2.7-billion-year-old stromatolites from the Tumbiana Formation in the Pilbara fit the bill, so even using this stricter criteria the Australian record still constitutes the oldest definite fossil life on the planet that no scientist would argue against.

So I hereby award the first gold medal to Australia for the oldest clear evidence of life on the planet.

Perhaps the cluster of closely situated localities around Marble Bar containing the oldest life on Earth should be made a World Heritage site linked to Shark Bay.

John Long is Strategic Professor in Palaeontology at Flinders University and current President of the Society of Vertebrate Paleontology.