BREAKING NEWS ABOUT THE MARCH FOR SCIENCE
Just as I was locking up this post came news about public attitudes toward last month’s March for Science. You will probably not be astonished to learn that a Pew Research Center survey has found that people’s opinions differed depending on age and political leanings.
Democrats and young people think that events like the March will help scientists’ causes. “Republicans and older adults believe the marches will not raise public support for scientists, aid efforts to increase government funding of science, enhance the role of scientists in policy debates or lead to increased efforts to combat global climate change.”
Here’s a summary of the findings. A PDF of the complete report and the questions asked are at the same URL.
Last week I meandered through some recent news about human paleontology, leading with the breathtaking claim that people were in southern California 130,000 years ago. (The reason that’s breathtaking: mainstream scientific opinion holds that humans have been in the New World for less than 15,000 years.)
There was also lots of chatter in that post about our remarkable new African relative, Homo naledi. This news I picked up through tweets and other informal sources rather than official documents (i.e., scientific papers.)
These informal sources revealed that the H. naledi fossils were much younger, between 200,000 and 300,000 years old, than had originally been inferred from their ape-like upper torsos and small brains. Also, their chimp-size brains were nonetheless organized in ways more similar to our own. Also, a second group of H. naledi bones, including the most nearly complete H. naledi skull yet found , had been discovered in another cave nearby.
Now the official papers have been published in the open-source journal eLife. There’s one on the very complex dating research, another on H. naledi‘s place in African hominin evolution, and a third on H. naledi fossils in the new cave. There’s also a digest.
This is the time to point out a not-much-emphasized fact: this project–officially called Rising Star after the intricate cave system being investigated–is perhaps the most transparent scientific program ever. Not only are the researchers publishing in open-access journals, they are blogging about it at National Geographic, a funder. John Hawks, one of the project researchers (and apparently its chief writer and photographer) has also blogged about it.
Dating the original finds at between 200,000 and 300,000 years–the new cave’s fossils are not yet dated–was enormously complex; John Timmer goes into details at Ars Technica. Hawks told Nathaniel Scharping at D-brief that the cave is the most rigorously dated site ever in South Africa. Anatomically Modern Humans (aka AMH, that’s us, the last Homo standing) appeared about 200,000 years ago, which would make H. naledi a contemporary of ours rather than an ancestor.
Timmer points out that the study demonstrates that a fossil’s anatomical features are not necessarily an indicator of its age. H. naledi is in some ways similar to Australopithecus, aka Lucy, who was around in East Africa some 3 million years ago. Of course, even though the H. naledi fossils are relatively young, H. naledi as a species could be much older.
IS THE HOMO NALEDI SITE A TOMB?
For all of H. naledi‘s puzzlements, the biggest is how the remains of at least 18 individuals got into the near-inaccessible caves. For various reasons, some detailed in last week’s On Science Blogs post, the simplest explanation appears to be that they were placed there deliberately. Interred, in fact. The caves seem to be tombs.
The idea of deliberate burial among such small-brained humans has been startling and of course controversial. Burial appears to be the case in the new cave too, which probably strengthens the argument.
At the Human Evolution Blog, Nathan Lents describes some reasons for concluding these caves were subterranean sepulchers. A major factor is their inaccessibility. (Discover magazine published legible maps of the convoluted Rising Star system, which I won’t bother reproducing here because you couldn’t read them.)
Lents observes, “On the one hand, the evidence is all circumstantial and it may be impossible to ever know for sure. On the other hand, no strong alternative explanations supported by evidence have emerged in the last eighteen months, and surely not from lack of attention. ‘It’s getting harder and harder to deny that the only reason we have a hard time accepting [the notion of intentional body disposal] is because we just don’t want to,’ says [Lee] Berger[who heads the Rising Star project]. Indeed, the idea that an otherwise primitive hominin might have developed enough social complexity to care about disposing of their dead is jarring, to say the least.”
So there’s plenty of skepticism. “I fail to see how the new chamber and the few [new] specimens within it contribute anything new or meaningful to the prior speculation that H. naledi engaged in mortuary behaviors. I’m also not sure that dumping dead, decomposing conspecifics – if that is indeed what happened – would imply anything funerary or especially cognitive,” paleoanthropologist William Junger told Scharping.
And paleoanthropologist Chris Stringer told Sarah Wild at Nature News, “Although no other satisfactory explanation for the deposition of the remains has yet been proposed, many experts, including myself, consider such complex behaviour [burial of the dead] unlikely for a creature with a brain size close to that of a gorilla, particularly when a requirement for the controlled use of fire (for lighting) probably has to be added in.”
ONCE MORE, THE HOBBIT
There’s another example of very early human anatomical features (including very small brains) surviving until (relatively) recent times: Homo floresiensis, aka The Hobbit. The remains were found on the Indonesian island of Flores in 2003, and ever since then scientists have been fighting about what they mean, sometimes savagely.
“Bits of modern human here, pieces of Lucy’s kind there, chimpanzee resemblances everywhere! The Hobbit’s the weirdest looking human we’ve found so far,” says paleontologist Darren Curnoe at The Conversation. “The overall picture we get from the bones is of a creature that had a very small brain, large teeth and walked about on two-feet but in way very different to our own style of moving. Yet, strangely, it also had very short legs and long arms like a chimpanzee, and probably spent a lot of time living in the trees as well as toddling about on the ground.”
Originally the remains were thought to be as young as 17,000 years, but recently the dating has settled on between 50,000 and 100,00 years ago, still very recent. There have been two main claims to explain the Hobbit’s oddities:
Is it a tiny descendant of Homo erectus who was subject to the phenomenon called island dwarfing, evolving smaller size in response to an island’s limited resources? That is plausible because H. erectus, a tall big-brained hunter, was on site, having gotten to Indonesia nearly 2 million years ago. H. floresiensis does possess some erectus-like anatomical features.
The other idea was that the Hobbit was a modern human, Homo sapiens, with some kind of abnormality. Microcephaly maybe, or Down syndrome.
NEW PAPER, NEW THEORY
So now there’s a new paper with a new theory. The perfectly named Debbie Argue and her colleagues compared anatomical features of the Hobbit to those of other human species (including AMH and H. erectus) and claim that H. floresiensis is something completely different. They say the Hobbit most resembles Homo habilis, not descended from H. habilis but a sister species. They may have had a common ancestor.
H. habilis is a very early human, so early that some experts think habilis shouldn’t be placed in our genus Homo at all, but rather in Australopithecus, like Lucy. They also point out that, unlike H. erectus and other Homo species, there’s no evidence that H. habilis ever left Africa.
Still, Curloe thinks Argue’s argument is plausible. This is the only study that explains the Hobbit’s weird limb bones. If the researchers are correct, “early humans must have migrated out of Africa more than 2 million years ago and spread right across Asia into the far reaches of oceanic Indonesia. Until the Hobbit came along we thought this region had only been settled by Homo sapiens perhaps 50,000 years ago.”
At Ars Technica, Cathleen O’Grady quotes others who aren’t so sure. If the Hobbit started out as Indonesia-based H. erectus but was under enough evolutionary pressure on the small island of Flores to shrink so dramatically in size, maybe evolution generated other radical changes too. Stringer told her something I found very persuasive, not that I’m entitled to an opinion: “We do know from other dwarfed mammals that primitive features can seemingly re-evolve.”