Penelitian ilmuwan sudah begitu jauh mejelaskan bahwa manusia itu adalah hasil
evolusi, tapi orang-orang dungu kayak babi seperti
Abbas Amin, arra_s, ayub yahya, Dipo,
PAREWA PAREWA, Pinpin, rezameutia, Roman Proteus, safin _blanc itu masih
bersedia menjadikan sebagai kitab suci khurafah najis al-Mushaf susunan orang
Arab primitif yang ngibul bilang semua manusia itu keturunan Adam yang
diciptakan allah takhyaul dari tanahliat...
--
Web address:
http://www.sciencedaily.com/releases/2012/08/
120822124708.htm
More Sophisticated Wiring, Not Just Bigger Brain, Helped Humans Evolve Beyond
Chimps, Geneticists Find
enlarge
Where does the chimp brain end and the human brain begin? A new study pinpoints
uniquely human patterns of gene activity in the brain that could shed light on
how we evolved differently than our closest relative. (Credit: © Megan Lorenz /
Fotolia)
ScienceDaily (Aug. 22, 2012) Human and chimp brains look anatomically similar
because both evolved from the same ancestor millions of years ago. But where
does the chimp brain end and the human brain begin?
A new UCLA study pinpoints uniquely human patterns of gene activity in the
brain that could shed light on how we evolved differently than our closest
relative. Published Aug. 22 in the advance online edition of Neuron, these
genes' identification could improve understanding of human brain diseases like
autism and schizophrenia, as well as learning disorders and addictions.
"Scientists usually describe evolution in terms of the human brain growing
bigger and adding new regions," explained principal investigator Dr. Daniel
Geschwind, Gordon and Virginia MacDonald Distinguished Professor of Human
Genetics and a professor of neurology at the David Geffen School of Medicine at
UCLA. "Our research suggests that it's not only size, but the rising complexity
within brain centers, that led humans to evolve into their own species."
Using post-mortem brain tissue, Geschwind and his colleagues applied
next-generation sequencing and other modern methods to study gene activity in
humans, chimpanzees and rhesus macaques, a common ancestor for both chimpanzee
and humans that allowed the researchers to see where changes emerged between
humans and chimpanzees. They zeroed in on three brain regions -- the frontal
cortex, hippocampus and striatum.
By tracking gene expression, the process by which genes manufacture the amino
acids that make up cellular proteins, the scientists were able to search the
genomes for regions where the DNA diverged between the species. What they saw
surprised them.
"When we looked at gene expression in the frontal lobe, we saw a striking
increase in molecular complexity in the human brain," said Geschwind, who is
also a professor of psychiatry at the Semel Institute for Neuroscience and
Behavior at UCLA.
While the caudate nucleus remained fairly similar across all three species, the
frontal lobe changed dramatically in humans.
"Although all three species share a frontal cortex, our analysis shows that how
the human brain regulates molecules and switches genes on and off unfolds in a
richer, more elaborate fashion," explained first author Genevieve Konopka, a
former postdoctoral researcher in Geschwind's lab who is now the Jon Heighten
Scholar in Autism Research at University of Texas Southwestern Medical Center.
"We believe that the intricate signaling pathways and enhanced cellular
function that arose within the frontal lobe created a bridge to human
evolution."
The researchers took their hypothesis one step further by evaluating how the
modified genes linked to changes in function.
"The biggest differences occurred in the expression of human genes involved in
plasticity -- the ability of the brain to process information and adapt," said
Konopka. "This supports the premise that the human brain evolved to enable
higher rates of learning."
One gene in particular, CLOCK, behaved very differently in the human brain.
Considered the master regulator of Circadian rhythm, CLOCK is disrupted in mood
disorders like depression and bipolar syndrome.
"Groups of genes resemble spokes on a wheel -- they circle a hub gene that
often acts like a conductor," said Geschwind. "For the first time, we saw CLOCK
assuming a starring role that we suspect is unrelated to Circadian rhythm. Its
presence offers a potentially interesting clue that it orchestrates another
function essential to the human brain."
When comparing the human brain to the non-human primates, the researchers saw
more connections among gene networks that featured FOXP1 and FOXP2. Earlier
studies have linked these genes to humans' unique ability to produce speech and
understand language.
"Connectivity measures how genes interact with other genes, providing a strong
indicator of functional changes," said Geschwind. "It makes perfect sense that
genes involved in speech and language would be less connected in the non-human
primate brains -- and highly connected in the human brain."
The UCLA team's next step will be to expand their comparative search to 10 or
more regions of the human, chimpanzee and maque brains.
Geschwind and Konopka's coauthors included Tara Friedrich, Jeremy Davis-Turak,
Kellen Winden, Fuying Gao, Leslie Chen, Rui Luo, all of UCLA; Michael Oldham of
UC San Francisco; Guang-Zhong Wang of the University of Texas Southwestern
Medical Center; and Todd Preuss of Emory University.
The research was supported by grants from the National Institute of Mental
Health (R37MH060233) and (R00MH090238); a NARSAD Young Investigator Award, the
National Center for Research Resources (RR00165) and Office of Research
Infrastructure Programs/OD (P51OD11132); and a James S. McDonnell Foundation
grant (JSMF 21002093).
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Story Source:
The above story is reprinted from materials provided by University of
California, Los Angeles (UCLA), Health Sciences, via Newswise.
Note: Materials may be edited for content and length. For further
information, please contact the source cited above.
Journal Reference:
Genevieve Konopka, Tara Friedrich, Jeremy Davis-Turak, Kellen Winden,
Michael C. Oldham, Fuying Gao, Leslie Chen, Guang-Zhong Wang, Rui Luo, Todd M.
Preuss, Daniel H. Geschwind. Human-Specific Transcriptional Networks in the
Brain. Neuron, 2012; 75 (4): 601 DOI: 10.1016/j.neuron.2012.05.034
Need to cite this story in your essay, paper, or report? Use one of the
following formats:
APA
MLA
University of California, Los Angeles (UCLA), Health Sciences (2012, August
22). More sophisticated wiring, not just bigger brain, helped humans evolve
beyond chimps, geneticists find. ScienceDaily. Retrieved August 23, 2012, from
http://www.sciencedaily.com /releases/2012/08/120822124708.htm
Note: If no author is given, the source is cited instead.
Disclaimer: This article is not intended to provide medical advice, diagnosis
or treatment. Views expressed here do not necessarily reflect those of
ScienceDaily or its staff.
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