Lee Berger put his ad up on Facebook on October 7th, 2013. He needed diggers for an exciting expedition. They had to have experience in palaeontology or archaeology, and they had to be willing to drop everything and fly to South Africa within the month. “The catch is this—the person must be skinny and preferably small,” he wrote. “They must not be claustrophobic, they must be fit, they should have some caving experience, climbing experience would be a bonus.”
“I thought maybe there were three or four people in the world who would fit that criteria,” Berger recalls. “Within a few days, I had 60 applicants, all qualified. I picked six.” They were all women and all skinny—fortunately so, given what happened next. Berger, a palaeoanthropologist at the University of the Witwatersrand, sent them into the Rising Star Cave, and asked them to squeeze themselves through a long vertical chute, which narrowed to a gap just 18 centimeters wide.
That gap was all that separated them from the bones of a new species of ancient human, or hominin, which the team named Homo naledi after a local word for “star.” We don’t know when it lived, or how it was related to us. But we do know that it was a creature with a baffling mosaic of features, some of which were remarkably similar to modern humans, and others of which were more ape-like in character.
This we know because the six women who entered the cave excavated one of the richest collections of hominin fossils ever discovered—some 1,550 fossil fragments, belonging to at least 15 individual skeletons. To find one complete skeleton of a new hominin would be hitting the paleoanthropological jackpot. To find 15, and perhaps more, is like nuking the jackpot from orbit.
RTFA. It is a delightful read. Science, adventure, perseverance.
East Gallery of the Denisova Cave
A 30,000-year-old finger bone found in a cave in southern Siberia came from a young girl who was neither an early modern human nor a Neanderthal, but belonged to a previously unknown group of human relatives who may have lived throughout much of Asia during the late Pleistocene epoch. Although the fossil evidence consists of just a bone fragment and one tooth, DNA extracted from the bone has yielded a draft genome sequence, enabling scientists to reach some startling conclusions about this extinct branch of the human family tree, called “Denisovans” after the cave where the fossils were found…
By comparing the Denisovan genome sequence with the genomes of Neanderthals and modern humans, the researchers determined that the Denisovans were a sister group to the Neanderthals, descended from the same ancestral population that had separated earlier from the ancestors of present-day humans. The study also found surprising evidence of Denisovan gene sequences in modern-day Melanesians, suggesting that there was interbreeding between Denisovans and the ancestors of Melanesians, just as Neanderthals appear to have interbred with the ancestors of all modern-day non-Africans.
“The story now gets a bit more complicated,” said Richard Green, an assistant professor of biomolecular engineering in the Baskin School of Engineering at UC Santa Cruz. “Instead of the clean story we used to have of modern humans migrating out of Africa and replacing Neanderthals, we now see these very intertwined story lines with more players and more interactions than we knew of before.”
The Denisovans appear to have been quite different both genetically and morphologically from Neanderthals and modern humans. The tooth found in the same cave as the finger bone shows a morphology that is distinct from Neanderthals and modern humans and resembles much older human ancestors, such as Homo habilis and Homo erectus. DNA analysis showed that the tooth and the finger bone came from different individuals in the same population.
It is not clear why fossil evidence had not already revealed the existence of this group of ancient human relatives. But Green noted that the finger bone was originally thought to be from an early modern human, and the tooth resembles those of other ancient human ancestors. “It could be that other samples are misclassified,” he said. “But now, by analyzing DNA, we can say more definitively what they are. It’s getting easier technically to do this, and it’s a great new way to extract information from fossil remains.”
Fascinating work. Think about this sort of research as a career or at least an avocation. Do your species some good with your spare time.
An ancient ancestor of ants has been discovered living in the soils of the Amazon rainforest. The species, named Martialis heureka, or “ant from Mars”, because of its unusual features, is a pale-bodied, blind predator that uses oversized jaws to capture prey.
Ants evolved 120m years ago from wasp-like ancestors and rapidly adapted to living in soil, trees and leaf litter. Genetic tests on the 3mm-long species show it emerged at the very earliest stages of ant evolution, said Christian Rabeling at the University of Texas at Austin.
I think the cousin of one of those ran up my pants leg the other day – and bit me.