DISAMPING KANAN INI.............
PLEASE USE ........ "TRANSLATE MACHINE" .. GOOGLE TRANSLATE BESIDE RIGHT THIS
.................
boom
teknologi 50.000 tahun yang lalu berkorelasi dengan kurangnya testosteron
........Ilmuwan
telah menunjukkan bahwa tengkorak manusia berubah dalam cara-cara yang
menunjukkan penurunan kadar testosteron di sekitar waktu yang sama bahwa mekarnya budaya . Berat alis keluar, kepala bulat......... Inovasi
teknologi, membuat seni dan pertukaran budaya cepat mungkin datang pada waktu
yang sama............
Society bloomed with gentler personalities, more feminine faces:
Technology boom 50,000 years ago correlated with less testosterone
Date:
August 1,
2014
Source:
Duke University
Summary:
Scientists have shown that human skulls changed in
ways that indicate a lowering of testosterone levels at around the same time
that culture was blossoming. Heavy brows were out, rounder heads were in.
Technological innovation, making art and rapid cultural exchange probably came
at the same time that we developed a more cooperative temperament by dialing
back aggression with lower testosterone levels.
..........................
Modern humans appear in the fossil record about 200,000
years ago, but it was only about 50,000 years ago that making art and advanced
tools became widespread.
A new study
appearing Aug. 1 in the journal Current Anthropology finds that human
skulls changed in ways that indicate a lowering of testosterone levels at
around the same time that culture was blossoming.
"The
modern human behaviors of technological innovation, making art and rapid
cultural exchange probably came at the same time that we developed a more
cooperative temperament," said lead author Robert Cieri, a biology
graduate student at the University of Utah who began this work as a senior at
Duke University.
The study,
which is based on measurements of more than 1,400 ancient and modern skulls,
makes the argument that human society advanced when people started being nicer
to each other, which entails having a little less testosterone in action.
Heavy brows
were out, rounder heads were in, and those changes can be traced directly to
testosterone levels acting on the skeleton, according to Duke anthropologist
Steven Churchill, who supervised Cieri's work on a senior honors thesis that
grew to become this 24-page journal article three years later.
What they
can't tell from the bones is whether these humans had less testosterone in
circulation, or fewer receptors for the hormone.
The research
team also included Duke animal cognition researchers Brian Hare and Jingzhi
Tan, who say this argument is in line with what has been established in
non-human species.
In a classic
study of Siberian foxes, animals that were less wary and less aggressive toward
humans took on a different, more juvenile appearance and behavior after several
generations of selective breeding.
"If
we're seeing a process that leads to these changes in other animals, it might
help explain who we are and how we got to be this way," said Hare, who
also studies differences between our closest ape relatives -- aggressive
chimpanzees and mellow, free-loving bonobos.
Those two
apes develop differently, Hare said, and they respond to social stress
differently. Chimpanzee males experience a strong rise in testosterone during
puberty, but bonobos do not. When stressed, the bonobos don't produce more
testosterone, as chimps do, but they do produce more cortisol, the stress
hormone.
Their social
interactions are profoundly different and, relevant to this finding, their
faces are different, too. "It's very hard to find a brow-ridge in a
bonobo," Hare said.
Cieri
compared the brow ridge, facial shape and interior volume of 13 modern human
skulls older than 80,000 years, 41 skulls from 10,000 to 38,000 years ago, and
a global sample of 1,367 20th century skulls from 30 different ethnic
populations.
The trend
that emerged was toward a reduction in the brow ridge and a shortening of the
upper face, traits which generally reflect a reduction in the action of
testosterone.
There are a
lot of theories about why, after 150,000 years of existence, humans suddenly
leapt forward in technology. Around 50,000 years ago, there is widespread
evidence of producing bone and antler tools, heat-treated and flaked flint,
projectile weapons, grindstones, fishing and birding equipment and a command of
fire. Was this driven by a brain mutation, cooked foods, the advent of language
or just population density?
The Duke
study argues that living together and cooperating put a premium on
agreeableness and lowered aggression and that, in turn, led to changed faces
and more cultural exchange.
"If
prehistoric people began living closer together and passing down new
technologies, they'd have to be tolerant of each other," Cieri said.
"The key to our success is the ability to cooperate and get along and
learn from one another."
Story
Source:
The above
story is based on materials provided by Duke University. Note: Materials may be edited for content and
length.
Journal
Reference:
- Robert L. Cieri, Steven E. Churchill, Robert G. Franciscus, Jingzhi Tan, Brian Hare. Craniofacial Feminization, Social Tolerance, and the Origins of Behavioral Modernity. Current Anthropology, 2014; 55 (4): 419 DOI: 10.1086/677209