Ancient fossil bee nest reveals clues to Taung Child's home
Did Australopithecus africanus live in caves or out in the open? Research suggests the latter, but it's certainly not definitive. Angus Bezzina reports.
A fossilised bee nest uncovered near the “Taung Child” in South Africa indicates that the famous human ancestor may actually have lived in a dry, savannah-like environment rather than caves, as previously thought.
Jennifer Parker from the University College London in the UK and colleagues scanned the little nest, which is around 13 millimetres long, and determined the insect that constructed it was a solitary soul that lived in grassy plains. The work was published in the PLOS One.
The Taung Child is the 2.8-million-year-old skull from an infant of the Australopithecus africanus species. Unearthed in 1924, it was the first fossil of this hominin to be discovered and represented the first evidence scientists found of a bipedal human ancestor.
While it was originally believed that this hominin species lived in caves, analysis of sediments reported in a 2013 study argued that the creature preferred an open landscape.
The new viewpoint is corroborated by a fossilised bee nest that was discovered in the same deposits of pink clay and siltstone from where the Taung Child was uncovered, at the Buxton-Norlim Limeworks on the southeastern edge of the Kalahari Desert.
The researchers tried to identify the extinct genus – called the “ichnogenus” – of the bee that constructed the nest and by extension, outline the nature of the environment that both it and the Taung Child inhabited.
This process involved scanning 14 samples the scientists recovered from the nest and converting them into 3-D digital models using sophisticated software.
Parker and her team also removed a visible cell from the nest for petrographic analysis, where a sample is viewed with an optical microscope designed for examining minerals and rocks (called a petrographic microscope).
Their findings showed a series of flask-shaped cells in the nest. These were not arranged in rows, nor did they have tunnels running between them, but they contained what the scientists claim to be plant material in some of the cells.
Parker and her team suggest that these results indicate the nest was built by a member of the solitary, ground-dwelling extinct bee ichnogenus Celliforma.
They write the nest is the work of either a single bee or a group of individuals that chose to cluster their nests together due to favourable environmental conditions such as a short distance to pollinating flowers and moisture levels in the soil.
Since the conditions in which Celliforma bees like to nest include bare, light and dry soil, good sun exposure and be close to a reliable source of pollen, Parker and her colleagues contend that this nest was built in grass plains.
Michael Batley, an entomologist at the Australian Museum in Sydney who specialises in the taxonomy of native Australian bees, says that while the conclusion drawn by the study is likely, it is not definite, noting the possibility that the nest was simply in the mouth of a cave.
“It is not impossible that bees can nest in the ground, but underneath an overhang for example or in a shallow cave,” he says pointing to the tendency of blue-banded bees to camp under houses in Brisbane.
“Finding nests in the ground doesn’t mean it has to be right out in the open, but it wouldn’t be deep inside a cave.”
Batley also explains that Parker and her colleagues have made a stretch by claiming that the bee species responsible for this nest is a member of the Celliforma ichnogenus.
“The researchers have identified the only group of bees that is known to use plant material in their nest chambers and to nest in the ground,” he explains.
“[But] the evidence that there is plant material in there [the nest fossil] is not strong.”
If the conclusion drawn by Parker and her colleagues is accurate, they contend there would be greater potential for further hominin remains to be discovered at the site where the Taung Child was found.
At the very least, it seems this study has shown that insect trace fossils have the potential to assist palaeo-environmental investigations, which in turn could provide new insights of our human ancestors’ ecology.