ARDI AND her troop lived 4.4 million years ago in an open woodland setting near a lake or a river and with patches of forest close by. This would have offered a plentiful supply of different food types for an omnivore like Ardi, who moved about as comfortably in the trees as on the ground.

The research effort around Ardi included extensive work to find and identify what her local habitat was like and what other animals, birds and insects might have lived there with her. This was not open savannah, a topography long used as a reason why our ancient ancestors began to walk upright as a way to reach food supplies and water.

Tree species identified as part of this environment included hackberry, fig and palms. There was no evidence of a tropical type rainforest, nor of the type of plants typically seen in arid conditions.

Even so, there was plenty of tree cover and lots of plants, fruit, berries and small animals and insects about that might have featured on Ardi’s dinner menu. The study identified 29 species of bird including several new to science. Another 20 new species of small mammals were recorded in the fossil record including shrews, bats, rodents, hares and small carnivores.

There are few aquatic species in the record, but these probably only arrived periodically during river flooding. Catfish are the most abundant species found close to where Ardi lived. All together the researchers assembled 150,000 plant and animal fossils and more than 6,000 vertebrate specimens were identified.

The researchers believe that there would have been very little male-to-male conflict to gain access to fertile females, and so life in the troop would possibly have been relatively harmonious.

This is not to say there weren’t noisy neighbours. The fossil record shows there were colobine monkeys and a small baboon-like monkey sharing nearby space in the woodlands. The other large mammal about was the spiral- horned antelope, Tragelaphus.

Researchers do not have to speculate about what Ardi might have eaten. Carbon isotopes taken from tooth enamel can show this, with grass eaters having a different isotope profile than say animals feeding on seeds, fruit and other mixed sources.

Tooth enamel also provides one more insight--what the weather must have been like. In this case oxygen isotopes allow the authors to suggest that the weather was certainly humid, but temperatures were likely cooler that those experienced in the Rift Valley today.