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SCIENCE NEWS OF THE YEAR | Humans
1.76 million years | Age of the oldest known hand axes
Asia takes a bow
Often overlooked as a geographic player in human evolution, Asia has stepped into the scienti;c spotlight. New
comparisons of ancient and modern DNA indicate that
Stone Age humans migrated to Asia in two stages.
At least 44,000 years ago, initial arrivals in Southeast Asia
interbred with a humanlike population known as Denisovans
that apparently had spread southward from Siberia. Denisovans contributed a portion of genes to living New Guineans
(SN: 1/15/11, p. 10), Australian Aborigines and groups
on nearby islands (SN: 11/5/11, p. 13). A second human
in;ux gave rise to today’s East Asians, with no Denisovan
dalliances, starting between 38,000 and 25,000 years ago,
geneticist Morten Rasmussen of the Natural History Museum
of Denmark in Copenhagen and his colleagues ;nd. The work
builds on previous genetic evidence that Homo sapiens interbred with Neandertals in West Asia before heading east.
Another study raises the possibility that early members
of the genus Homo evolved in Asia and then trekked to
Africa, not vice versa as many scientists have assumed (SN:
7/2/11/, p. 8). Homo erectus inhabited a West Asian site
called Dmanisi from 1.85 million to 1.77 million years ago,
at the same time or slightly before the earliest evidence for
the species in Africa, researchers report. — Bruce Bower
Filled belly A 5,300-year-
old mummy known as “the
Iceman” dined on wild goat
before his death in the Italian
Alps (SN: 9/24/11, p. 8).
Write stuff Writing down
test-related worries before
an exam appears to dislodge
concerns and lead to higher
achievement among high
school and college students
(SN: 2/12/11, p. 9).
While the Han Chinese
(top) don’t show genetic
contributions from
Denisovans, Australian
Aborigines (bottom) do.
Paint shop In a cave along
South Africa’s coast, Stone
Age humans made a red-hued paint that they stored
in abalone shells (below) and
possibly used to decorate
themselves or their belongings (SN: 11/19/11, p. 16).
Ape to human Skeletal traits
in the proposed hominid
species Australopithecus
sediba suggest that the
species served as an evolutionary bridge from apelike
ancestors to the Homo genus
(SN: 10/22/11, p. 14).
a suspicious person to be
more uncooperative and
hostile (SN: 2/26/11, p. 15).
Easy geometry Mundurucú
villagers of the Amazon grasp
abstract geometric principles
despite having no formal
math education, suggesting
geometry is innate or learned
through general experience
(SN: 6/18/11, p. 16).
Fast track Modern humans
reached Arabia’s eastern
edge as early as 125,000 years
ago, 65,000 years earlier than
generally accepted migrations out of Africa, scientists
report (SN: 2/26/11, p. 5).
No poker face People can
tell whether a chimp acts
dominantly and is physically
active just by looking at a
picture of its expressionless
mug. The ability to discern
personality traits via facial
structure may have evolved
more than 7 million years
ago, researchers argue
(SN: 2/12/11, p. 8).
Hormone’s dark side
The brain-altering substance oxytocin amplifies
whatever social proclivities
a person already possesses,
encouraging a trusting person to be more trusting but
Clovis question Stone tools
and flaky rock bits in Texas
date to between 13,200 and
15,500 years ago, adding to
evidence that the Clovis peo-
ple were not the first in the
Americas (SN: 4/23/11, p. 12).
Built to walk A 3.2-million-
year-old fossil from East
Africa suggests
Australopithecus afarensis, best
known from the partial skeleton “Lucy,” had stiff foot
arches like those of people
today, a sign of a two-legged
stride (SN: 3/12/11, p. 8).
Oldest axes An East African
site yields the oldest known
stone hand axes (one at left),
dating to 1.76 million years
ago (SN: 10/8/11, p. 12).
Share or stash If they’ve
worked together to get
it, young kids share stuff
equally. Adult chimps don’t
mete out fair shares, sug-
gesting sharing evolved in
ancient human foraging
groups (SN: 8/27/11, p. 10).
