Brain was small,
but souped-up
Controversial ‘hobbits’ may
have had complex thoughts
By Bruce Bower
In the strange and contentious world of
fossil hobbits, a chimp-sized brain may
boast humanlike powers. An analysis of
the inner surface of an 18,000-year-old
skull assigned to Homo floresiensis, also
known as hobbits, suggests that this tiny
individual possessed a brain blessed with
souped-up intellectual capacities, Dean
Falk of Florida State University in Tallahassee reported April 2.
As H. floresiensis evolved a relatively
diminutive brain, the species underwent substantial neural reorganization
that allowed its members to think much
like people do, Falk contended. She also
reported the findings online February 28
in the Journal of Human Evolution.
Falk compared a cast of the cranium’s
inner surface, or endocast, obtained
from the partial hobbit skeleton LB1
with endocasts from modern humans
and from other fossil skulls in the human
evolutionary, or hominid, family. These
casts show impressions made by various anatomical landmarks on the brain’s
surface.“LB1 reveals that significant cortical reorganization was sustained in
ape-sized brains of at least one hominid
species,” Falk said.
Evidence has shown that some hominid
species experienced marked increases
in brain size over time, but neural reorganization took center stage for others,
including hobbits, she proposed. Currently, no one knows whether a large-bodied or small-bodied species gave rise
to hobbits, whose fossils have been found
on the Indonesian island of Flores.
Although small in size, LB1’s endocast displays a humanlike shape, Falk
asserted. An endocast from
Australopithecus africanus, a roughly 3-million-year-
old South African hominid species, looks
similar to that of LB1, Falk said.
Yet unlike the earlier A. africanus,
LB1 possesses a set of brain features
that other researchers have implicated
in complex forms of thinking done by
people today, she said. These features
ran from the back to the front of the
brain. Traits such as expanded frontal
lobes and enlarged regions devoted to
integrating information from disparate
areas would have supported creative and
innovative thinking, in Falk’s view.
No signs of disease or abnormal development appear on LB1’s brain surface,
she noted. Some argue that the specimen
came from a modern human who had a
type of growth disorder and so shouldn’t
be considered a separate species.
In another presentation on April 2,
William Jungers of the Health Sciences
Center at Stony Brook University in New
York presented evidence that LB1 did not
suffer from cretinism, a growth disorder
attributed to it last year by one team that
doubts the fossils represent a distinct
species. CT scans of LB1 show no signs
of dental, skull or limb conditions associated with cretinism, Jungers said. People with cretinism generally have much
larger brains than that of LB1.
Hobbit-fueled controversy remains
strong, though. In a meeting presentation on April 3, Robert Eckhardt of Pennsylvania State University in University
Park reported that the height range
within a foraging group of people now
living on the hobbits’ Indonesian island
home overlaps with height estimates for
LB1. Eckhardt and his colleagues argue
that, given this finding and others, LB1
can’t be its own species. s
Chimps dig with right, left hands
Measurements from water holes suggest ape ambidexterity
By Bruce Bower
Give the chimpanzees living at Uganda’s
Toro-Semliki Wildlife Reserve a hand for
having the mental moxie to dig water-collection holes along the edge of a river.
In fact, give them two hands because the
wells show no evidence of having been
fashioned by either right-handers or left-handers, according to Linda Marchant of
Miami University in Oxford, Ohio.
Evidence of ambidexterity in Semliki
chimps counters a previous suggestion,
based largely on studies of captive animals, that chimps often favor one hand
over the other. If chimp handedness does
exist, it may reflect an evolutionary move
toward a brain organized like that of people — with one hemisphere dominating.
Chimps scoop out small holes in sandy
riverbeds, leaving two piles of soil on
opposite sides of each depression. During rainy times of the year, river water
fills the holes and the chimps drink it.
Marchant and her colleagues studied
more than a hundred holes along Semliki’s main river and found that all were
symmetrical and likely to be produced
by two hands working in concert. Each
of the two soil mounds adjacent to any
particular well weighed the same, she
reported April 3.
Chimps may use both hands for physically demanding jobs but prefer one for
tasks requiring fine movements, said
Elizabeth Lonsdorf of the Lester E. Fisher
Center for the Study and Conservation of
Apes at Lincoln Park Zoo in Chicago.
Chimps living in
Uganda dig holes
(like this one) to
collect drinking
water. Mounds left
near the wells suggest the chimps
don’t have a hand
preference.
