I’m spending most of the day writing now, and it’s difficult to find time to read scientific papers and report on them. So do excuse me for a while if I summarize new findings from (reliable) journalistic results, even though I’ll scan and link to the original paper when possible.
There are two evolution-related findings of note this week. I’ll highlight one today and one tomorrow.
First, Homo floresiensis, the three-foot “hobbit” human whose remains were discovered on the Indonesian island of Flores in 2003, has now been designated as a real species truly distinct from H. sapiens. This species lived fairly recently—38,000-12,000 years ago, when modern humans were already colonizing the New World—but is very distinct from H. sapiens. Because of its size and the resemblance of the skull to those seen in certain human diseases (hypothyroidism, microcephaly, etc.), some scientists speculated that this was not a tiny archaic species living at the same time as modern humans, but simply a single pathological individual of H. sapiens.
A new analysis by Baab et al. (link and free download below) suggest however, that this really was a tiny hominin species. Extensive morphological analysis of the single existing skull from Flores, along with modern H. sapiens, both “normal” and suffering from a variety of syndromes suggested to have produced the Flores skull, as well as a variety of early hominin species, shows that the Flores skull is more similar to that of H. erectus than to nearly all pathological specimens, and is thus likely to truly represent a new species. (See the New York Times report by John Noble Wilford.)
Here’s a cast of the “LB1” skull from Flores (the only existing one) that was used in the authors’ analysis:
Note that this hominin came up only to your hips (check out the reconstruction at Washington’s Museum of Natural History), and had a brain about 400 cubic centimeters: one third that of modern humans and the size of one of our earliest hominin relatives, Australopithecus afarensis. Here’s how the hobbit compares to a modern human:
Here’s the figure from the Times:
Researchers found that the cranium of Homo floresiensis, known as hobbits, top, was more similar to skulls of various human predecessors than to modern Homo sapiens, bottom.
The authors of the paper conclude with the following paragraph, allowing one possible pathology as an explanation:
Our analyses corroborate the previously suggested link between LB1 and fossil Homo and support the attribution of this specimen to a distinct taxon, H. floresiensis. Furthermore, the neurocranial shape of H. floresiensis closely resembles that of H. erectus s.l. and particularly specimens of early Eurasian H. erectus, although it is unclear whether this latter affinity is best attributed to a close phylogenetic relationship or to a size-related convergence in shape. These results also counter the hypotheses of pathological conditions as the underlying cause of the LB1 neurocranial phenotype, with the possible exception of posterior deformational plagiocephaly, a condition without significant adverse health effects/
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Baab, K. L., K. P. McNulty, and K. Harvati. 2013. Homo floresiensis Contextualized: A Geometric Morphometric Comparative Analysis of Fossil and Pathological Human Samples. PLoS ONE 8:e69119 EP -.
I love all these new additions to the human family! It sort of reminds me of finding my long lost, nearly-fossilized uncles – just like these and other homo species, my ancient uncles are all evolutionary dead-ends(childless).
I don’t think Dawkins would agree, as the genes are the vehicles. I.e. sterile worker bees are not dead-ends, in fact their genes does better than most.
Oh, but unique variation dies with the individual. So, disregarding whether they fixate or not, roughly estimating ~ 100 genes of ~ 20 000 as mutations in every individual, and ~ 2/3 of those neutral IIRC, every childless human is on average a 1 % dead-end of alleles. (Looking at successful selection or at least selective sweeps, I think this is very much an over-estimate.)
(Hobbit)life imitates art again. I find it really remarkable that this species coexisted with our own so recently. Human evolution really fascinates me; the surprises just keep coming. Thanks for the post Jerry;really interesting.
Now that “hobbits” appear to be a distinct species and assuming that their ancestors are the same as ours, more “normal” sized African primates, it’s possible that what we are seeing is insular dwarfism at work.
Which should drive creotards crazy as how could the same evolutionary forces that work on other animals also apply to us ?
I’m personally left wondering why the only skeletal remains found so far are just this one skull. If it was an extant species a dozen centuries ago, you’d think there’d be burial grounds or the like discovered by now.
And what’s with the hole on the top of the head?
b&
Perhaps the find at Flores represents the last remnant of this (sub)species. Perhaps there was never a sizable population for any length of time on Flores. There might be much more to find elsewhere. Or not. This study is valuable, but it does not seem to be definitive.
Also, how do animal remains fair in the general climate of that area at that time period? Are animal remains from that time period in that area abundant or scarce? Is the condition of the remains typically fair or poor? In addition to the one skull, partial remains of 9 individuals where found at Flores.
Huh! Maybe they really were Hobbits!
Aliens…
It’s probably just a missing part of the reconstructed skull.
Regarding animal remains from that period and location there is this little blurb (from Wikipedia) regarding these remains specifically.
Probably poor conditions for preservation of bone.
As “darelle” and “gbjames” suggest below, the original papers cited that the fossils were very poorly preserved, with little mineralisation left (hence the comment about “blotting paper” consistency). As I recall, they were quite deep into a cave on the island, and my geological suspicion is that this would have reduced “flushing” of ground-water through the site. Flores (and the adjacent islands) are predominantly volcanic in origin, so the cave is likely not in limestone, which would reduce the amount of buffering of the groundwater pH against humic (soil organic matter-derived) acids. The archaeologists are always complaining about humic acids dissolving the mineral component of their bones, so this hangs together for me. Material closer to the cave entrance was even more degraded. There were several Nature podcasts about this discovery at the time, and I think the preservation was discussed in that, or in some “Horizon”-like programme at the time, and I paid close attention to this aspect as both geologist and troglodyte (“spelunker” to some Americans).
I think the wording is confusing – only one skull was found, but other skeletal elements were found.
The hole in the top looks like a “fontanelle” to me. These don’t suture on modern humans until … I’m not sure, but it’s well into the second six months after birth (judging from memories of having relatives shoved under my nose to coo at). http://en.wikipedia.org/wiki/Fontanelle , but the positioning of the frontal fontanelle isn’t very consistent between plan and elevation … lateral and anterior ? … views in that page’s diagram. Or am I mis-reading the orientation of the diagrams?
The cave is in fact limestone.
What still boggles my mind is that these hobbits were there only 12,000 years ago. If you wanted to pick a place to look for a relict population of dwarf humans, yeah, Flores Island might be a good choice. But it’s not THAT isolated.
Wouldn’t that suggest the skull is of an infant and not an adult?
b&
Partial skeletons of 9 individuals have been found, according to Wikipedia. This is the only skull (but i do not know if any other skull fragments were found).
Anyway, look at the relative length of those arms in the reconstruction!
Other skull fragments were found.
Reblogged this on Mark Solock Blog.
I think you mean a dozen millennia, right?
Is there indication of tool use or other artifacts found near the skull?
Yes. A good deal of evidence for tool use and cooking were found at the site.
Sorry, that was meant to be in reply to Ben @ #4.
They have also found tentative tools elsewhere on Flores ~ 980 ky old IIRC. This would be mutually reinforcing with those finds.
No DNA sequences available from these samples?
I’m no expert on ancient DNA, but I believe the hot, humid conditions of a tropical cave are very unfavourable to its preservation. The oldest and best-preserved sequences tend to come from remains frozen in Arctic permafrost.
Not yet. Not for lack of trying though:
““The specimens are not fossilized and have been described as having “the consistency of wet blotting paper”;”” (see above). Moist (and heat) degrades DNA AFAIK.
When I was doing pediatric neurosurgery, I saw ‘posterior plagiocephaly’ quite often. It flattens the skull posteriorly, but does not reduce overall skull capacity. The specimen shown does not look like plagiocephaly, which, BTW, can be induced by strapping a baby to a board, as some cultures have done.
This is fantastic. I will have to read more when I have time! Stupid work.
.
Not unexpected, especially the link to H. erectus.
But, not having access to the rate of false positives, I wonder if not every fossil species of Homo is routinely advanced as pathological humans? It is a bad prior, and it seems like a bad posterior as well.
So, it needs to be checked, but why all the furor signifying (nearly) nothing?
I saw Morwood speak at ANU (Canberra) some years ago. At that stage they were working on getting DNA; but the lack of news since then would indicate they’ve had no luck. That’s a pity, as the DNA of such a strange species would no doubt be revealing, and would presumably put to rest once and for all any idea of the hobbits being microcephalic et al. But as remarked above, the tropics are unkind to DNA.
I can recommend the Morwood/ van der Zee book by the way (“The Discovery of the Hobbit”), as a fascinating and accessible account of the discovery. The struggles with the Indonesian bureaucracy, the relations with the local Flores people, and the problems of coping with Teuku Jacob’s sudden intervention and all the attendant publicity are described in humorously painful detail. The book also includes a useful discussion of biogeography in the Indonesian context.
Reblogged this on Sarvodaya.
How do these tiny people compare to African Bushmen or Pigmys?