Fossil reveals 48-million-year history of zombie ants

Aug 18, 2010
A modern day ant (Camponotus leonardi) from Thailand is killed by the fungus Ophiocordyceps unilateralis. It is biting into the leaf vein and the fungal growth can clearly be seen issuing from its head. Credit: David P. Hughes

A 48-million-year-old fossilised leaf has revealed the oldest known evidence of a macabre part of nature - parasites taking control of their hosts to turn them into zombies.

The discovery has been made by a research team led by Dr David P Hughes, from the University of Exeter, who studies parasites that can take over the minds of their hosts.

All manner of animals are susceptible to the often deadly body invasion, but scientists have been trying to track down when and where such parasites evolved.

Dr Hughes, from the University's School of Biosciences, said: "There are various techniques, called a molecular clock approach, which we can use to estimate where and when they developed and fossils are an important source of information to calibrate such clocks.

"This leaf shows clear signs of one well documented form of zombie-parasite, a which infects ants and then manipulates their behaviour."

The fungus, called Ophiocordyceps unilateralis, causes ants to leave their colonies and head for a leaf which provides the ideal conditions for the host to reproduce.

When it gets there the ant goes into a 'death grip'- biting down very hard on the major vein of a leaf. This means that when the ant dies, its body stays put so the fungus has time to grow and release its spores to infect other ants.

This is the 48-million-year-old fossil leaf from Messel which bears the tell-tale death grip scars. Credit: Torsten Wappler

The death grip bite leaves a very distinct scar on the leaves. This prompted Dr Hughes, together with research partners Conrad Labandeira from the Smithsonian Institution in the USA and Torsten Wappler, from the Steinmann Institute in Germany, to search for potential evidence of the fungus at work by studying the fossilised remains of leaves.

After studying leaf fossils from the Messel Pit, a site on the eastern side of the Rhine Rift Valley in Hesse, Germany, they found clear evidence of the death grip bite in a 48-million-year-old leaf specimen.

Dr Hughes said: "The evidence we found mirrors very closely the type of scars that we find today, showing that the parasite has been working in the same way for a very long time.

"This is, as far as we know, the oldest evidence of parasites manipulating the behaviour of their hosts and it shows this parasitic association with is relatively ancient and not a recent development.

"Hopefully we can now find more fossilised evidence of parasitic manipulation. This will help us shed further light on the origins of this association so we can get a better idea of how it has evolved and spread."

Explore further: Rare albino dolphin captured in Japan's 'Cove'

More information: The paper, title Ancient death-grip leaf scars reveal ant-fungal parasitism, is published in the latest edition of Royal Society journal Biology Letters.

Related Stories

Parasite causes zombie ants to die in an ideal spot

Aug 11, 2009

A study in the September issue of The American Naturalist describes new details about a fungal parasite that coerces ants into dying in just the right spot -- one that is ideal for the fungus to grow and reproduce. The st ...

Farming and chemical warfare: A day in the life of an ant?

Nov 17, 2008

One of the most important developments in human civilisation was the practice of sustainable agriculture. But we were not the first - ants have been doing it for over 50 million years. Just as farming helped humans become ...

Recommended for you

User comments : 2

Adjust slider to filter visible comments by rank

Display comments: newest first

Jordian
5 / 5 (2) Aug 18, 2010
It's weird to see that even this "new" evolutionary trick is almost 50 million years old. Time is so vast it's extremely hard to comprehend.
jsa09
not rated yet Aug 18, 2010
How many fossil leaves did they look at before they found the evidence? With the number of leaves preserved in the fossil record I am surprised that they started looking for this one situation and found it.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.