Ini kutipan dari National Geographic news. Sejak ditemukan tahun lalu, ada
studi yang intensif tentang tengkoraknya, termasuk rekayasa otak di baliknya.
Sekali rekayasa otak bisa dilakukan (dengan mencetak volume otak melalui
tengkoraknya), maka bisa dipetakan jalur2 otak. Sekali jalur2 otak bisa
dipetakan maka terbukalah interpretasi ke kecerdasan, sebab setiap jalur/locus
di otak punya keterkaitan tersendiri ke pusat2 kecerdasan (kuncinya tetap : the
present is the key to the past - mereka tahu jalur2 otak manusia moderen dan
locus kecerdasannya dan tinggal membandingkan saja dengan fosil tengkorak yang
ditemuinya).
Penemuan tengkorak "Hobbit", kalau analisis origin spesies ini benar, maka akan
mengoreksi teori evolusi kecerdasan anthropoid, bahwa semakin besar volume otak
maka spesies akan semakin cerdas. Sebab tengkorak Hobbit jauh lebih kecil
daripada Homo erectus, tetapi ia secerdas bahkan melebihi Homo erectus.
Sampai saat ini, ada dua teori origin Hobbit : (1) Homo erectus yang bermigrasi
ke Flores 800.000 tyl lalu mengalami "island dwarfing", seluruh makhluk di situ
mengerdil (termasuk stegodon kerdil) karena isolasi pulau, (2) Hobbit yang
kerdil sudah ada di Flores sebelum migrasi Homo erectus. Mana yang benar ?
Masih menjadi bahan diskusi di antara para ahli paleo-antropologi.
Mestinya biologi molekuler genom mitokondria yang diekstraksi dari fosil Hobbit
bisa menjawab masalah ini, tetapi kelihatannya belum sampai ke situ studi ini.
Sebab, biologi molekuler telah terbukti punya bukti tangguh menjawab dua scholl
of thoughts besar di bidang evolusi manusia : out of Africa or multi-regional ??
Salam,
awang
"Hobbit" Brains Were Small but Smart, Study Says
Hillary Mayell
for National Geographic Channel
and National Geographic News
March 3, 2005
On TV: Don't miss Tiny Humans: The "Hobbits" of Flores on Explorer, Sunday,
March 13, at 8 p.m. ET/PT on the National Geographic Channel.
The recently discovered "hobbit" fossils do in fact represent a new human
species, according to a new study of a hobbit braincase. What's more, the
little humans seem to have been more intelligent than expected, given their
extremely small brains�a finding that may completely change how scientists view
human evolution. Last October a team of Australian and Indonesian
archaeologists reported the discovery of the18,000-year-old bones of an adult
female hobbit. The only known hobbit skull is from this female, though
archaeologists later found partial remains of seven other individuals. Formally
known as Homo floresiensis, the fossil skeleton has a unique combination of
features not seen in any other humans or human ancestors. Flores, an isolated
island in Indonesia, was colonized by early humans as far back as 800,000 years
ago. But from at least 95,000 years ago until around 12,000 years ago, it was
occupied by these tiny humans. H. floresiensis grew to be only about three feet
(one
meter) tall�prompting archaeologists to christen them "hobbits," after the
diminutive Lord of the Rings characters. Despite having very small
brains�roughly the size of a chimpanzee's�they appear to have hunted animals
twice their size, made stone tools for hunting and butchering, and used fire
for cooking. "It's remarkable. We've always been taught and thought that as
humans evolved, the bigger the brain, the better they are," said Charles
Hildebolt, a physical anthropologist at Washington University in St. Louis,
Missouri. "If this little creature actually made the tools and was using the
tools, built the fire and was using the fire, then that really tips human
evolution upside down and changes the way we have to think about brain
evolution. It may indicate that the reorganization of the brain was just as
important and may be even more important than size." Hildebolt was a member of
the team, led by paleoneurologist Dean Falk of Florida State University, that
studied the b
raincase
of the species.
Small but Powerful Brains
Falk and her team created a virtual, three-dimensional cast of the interior of
the fossilized H. floresiensis skull. Called an endocast, the model shows a
variety of features, including the brain's size, shape, vessels, and
convolutions. This hobbit endocast was then compared with virtual endocasts and
latex endocasts of modern humans, gorillas, chimpanzees, an adult female Pygmy,
and three early human ancestors: Australopithecus africanus, a species that
lived around 2.5 million years ago; Paranthropus aethiopicus, a species that
appears in the fossil record about 2.7 million years ago, and Homo erectus, a
species that lived from about 1,600,000 to 250,000 years ago. Some scientists
have speculated that the hobbit fossil was not of a new species but rather of a
modern human with microcephaly, a birth defect in which a person has an
abnormally small brain. To address this concern, Falk's team also compared the
hobbit braincase to that of a known modern human microcephalic. "W
e think
it least resembles a microcephalic," Hildebolt said. "It has a lateral profile
that is somewhat similar to a Homo erectus, but it has other features that are
similar to modern humans. The combination is unique." Falk agrees and contends
that the exhaustive analysis puts skeptics' claims that the hobbit is really a
microcephalic to rest. "The scaling of brain to body isn't at all what we'd
expect to find in Pygmies, and the shape is all wrong to be a microcephalic,"
Falk said. "This is something new." Although much smaller than in modern
humans, the hobbit's frontal lobe contains a region known as Brodmann's area
10, which is very convoluted and has large swellings. In the modern human
brain, area 10 is associated with higher cognitive processes such as planning
ahead and taking initiative. When scaled for size, the hobbit also has larger
temporal lobes than Homo erectus does. In modern humans the temporal lobes are
associated with hearing and understanding speech. "This spec
ies was
undergoing its own long evolution on this island," Falk said. "Our data are
consistent with the kinds of sophisticated behaviors being reported." H.
floresiensis "is a really strange combination of some very advanced traits,
some that are very primitive, and some that are unique," said Mike Morwood, an
archaeologist from the University of New England in Australia. Morwood led the
team that first found the hobbit remains. Morwood said the stone tools found
close to the H. floresiensis fossils represent "a very sophisticated assemblage
of stone artifacts and are directly associated with evidence of hunting and
butchering of stegadon, a dwarf elephant." Hildebolt, though, pointed out that
this doesn't automatically mean that the tools and cooking evidence are
associated with the new species. Other scientists agree with him. "I am
cautious about drawing too many conclusions about brain quality from
endocranial surface features [features inside the skull], and I am still
cautious
about
the extent of the 'advanced' behavior inferred for Homo floresiensis from the
archaeological evidence," said Chris Stringer, director of the Human Origins
Program at the Natural History Museum in London. "For me, the most significant
aspects of this new study are the demonstration that the endocranium is very
different from that of a small-bodied, or a microcephalic, H. sapiens and that
it does, with some differences, most resemble endocasts of H. erectus." The
Falk team's report appears in today's issue of the online version of the
journal Science. Their findings will also be featured on the National
Geographic Channel's Explorer TV series on March 13 at 8 p.m. ET/PT.
Tiny Contemporary Humans?
Scientists have long thought that, with the extinction of the Neandertals
roughly 30,000 years ago, H. sapiens was the only human species left on the
planet. The discovery that another human species, vastly different from us,
existed up until about 13,000 years ago is a stunning find. Who were they and
how did they get to Flores? There are several hypotheses. The team of
archaeologists that found the hobbit fossils�led by Mike Morwood, Bert Roberts,
and Thomas Sutikna�suggested that the hobbits' small stature was the result of
a phenomenon known as island dwarfing. Flores island has been inhabited by some
species of human since at least 800,000 years ago. The team that found the
fossils leans toward the theory that, once there, this earlier species evolved
into H. floresiensis. Over thousands of years, the theory goes, their bodies
adapted to the constraints of island living in the same way that many other
mammals' bodies do. With food in short supply, their skeletons grew sm
aller�a
process called island dwarfing. And because reptiles on islands frequently
grow larger, the hobbits may have been both predators and prey. If so, they
would have needed to be smarter just to survive�there would be a significant
evolutionary advantage to developing a more highly evolved brain. "Small and
smart is definitely better than small and dumb," Hildebolt laughed. The authors
of the braincase study, which was funded by the National Geographic Society,
support an alternative hypothesis that was originally presented by the team
that found the fossils. They suggest that H. floresiensis existed as a species
before arriving on Flores�that it was already tiny on arrival. It's possible,
they say, that there was a small-bodied, small-brained, as yet unknown species
of human ancestor (possibly H. floresiensis) that may have left Africa at
around the same time as Homo erectus, about 1.8 million years ago. "We're not
dismissing the island-dwarfing hypothesis. It's just that we th
ink the
other seems maybe a little stronger," Hildebolt said.
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