Doubt there is any other intelligent life in the Universe. It
took five billion years to get it here.
http://news.independent.co.uk/world/science_technology/article1219720.ece
Revealed: the gene that gave us bigger brains
By Steve Connor, Science Editor
Published: 17 August 2006
Scientists have come a step closer to understanding one of the key
moments in man's evolution when the human brain underwent a dramatic
increase in size.
Our brain is three times larger than that of our closest living
relative - the chimpanzee - and yet how the transformation happened is
one of the biggest mysteries of human evolution.
A large brain is the physical essence of humanity. It enabled
language, consciousness and culture and yet scientists can only
speculate as to why it evolved to be so much bigger than the brain of
our ape-like ancestors.
A comparison of the human genome with that of the chimp - along with
several other animals - has now revealed the existence of a key region
of man's DNA that appears to play an important role in the growth of
the human brain.
Many different animals possess the same region of DNA but it is only
in humans that it has undergone a rapid and dramatic evolutionary
change.
The difference between chickens and chimps - which are separated by
310 million years of evolution - is just two mutations out of a total
DNA sequence of 118 "letters" of the genetic code. Yet the difference
between chimps and humans - separated by 6 million years - is 18
mutations in the same DNA region.
Professor Katherine Pollard of the University of California, Davis,
said that this region of the human genome has changed more than any
other since humans diverged from the rest of the apes.
"It's evolving incredibly rapidly. It's really an extreme case,"
Professor Pollard said. "We found 18 differences between chimps and
humans, which is an incredible amount of change to have happened in a
few million years."
The gene, called human accelerated region 1 (HAR1), is one of 49 that
the scientists have identified as changing the most since humans
diverged from our chimp-like ancestors.
"Some DNA regions have hardly changed at all over many millions of
years in most species. My twist was to look for the subset of these
regions that have changed just in humans," Professor Pollard said.
Further research showed that the region is most active during the
crucial gestation period in the womb when the human brain begins to
form the outer cortex, the brain region responsible for "higher"
activities such as language and consciousness.
Professor David Haussler, of the University of California, Santa Cruz,
said the precise function of the gene is not yet known but it may have
been responsible for the expansion of the brain during human
evolution.
Professor Haussler said: "At this point we can only speculate about
this gene's role in the evolution of the human brain, but it's
exciting to find a new gene involved in brain development."
"The evidence is very suggestive that this gene is important in the
development of the cerebral cortex, and that's exciting because the
human cortex is three times as large as it was in our predecessors,"
he said.
"Something caused our brains to evolve to be much larger and have more
functions than the brains of other mammals."
The region works differently to ordinary genes in that it does not
appear to "code" for a protein but instead it produces a short
molecule of a DNA-like substance called RNA.
The study, published in the journal Nature, shows that the RNA
molecule formed from the human DNA was substantially different in
structure to the RNA made from the chimp's DNA.
Scientists have come a step closer to understanding one of the key
moments in man's evolution when the human brain underwent a dramatic
increase in size.
Our brain is three times larger than that of our closest living
relative - the chimpanzee - and yet how the transformation happened is
one of the biggest mysteries of human evolution.
A large brain is the physical essence of humanity. It enabled
language, consciousness and culture and yet scientists can only
speculate as to why it evolved to be so much bigger than the brain of
our ape-like ancestors.
A comparison of the human genome with that of the chimp - along with
several other animals - has now revealed the existence of a key region
of man's DNA that appears to play an important role in the growth of
the human brain.
Many different animals possess the same region of DNA but it is only
in humans that it has undergone a rapid and dramatic evolutionary
change.
The difference between chickens and chimps - which are separated by
310 million years of evolution - is just two mutations out of a total
DNA sequence of 118 "letters" of the genetic code. Yet the difference
between chimps and humans - separated by 6 million years - is 18
mutations in the same DNA region.
Professor Katherine Pollard of the University of California, Davis,
said that this region of the human genome has changed more than any
other since humans diverged from the rest of the apes.
"It's evolving incredibly rapidly. It's really an extreme case,"
Professor Pollard said. "We found 18 differences between chimps and
humans, which is an incredible amount of change to have happened in a
few million years."
The gene, called human accelerated region 1 (HAR1), is one of 49 that
the scientists have identified as changing the most since humans
diverged from our chimp-like ancestors.
"Some DNA regions have hardly changed at all over many millions of
years in most species. My twist was to look for the subset of these
regions that have changed just in humans," Professor Pollard said.
Further research showed that the region is most active during the
crucial gestation period in the womb when the human brain begins to
form the outer cortex, the brain region responsible for "higher"
activities such as language and consciousness.
Professor David Haussler, of the University of California, Santa Cruz,
said the precise function of the gene is not yet known but it may have
been responsible for the expansion of the brain during human
evolution.
Professor Haussler said: "At this point we can only speculate about
this gene's role in the evolution of the human brain, but it's
exciting to find a new gene involved in brain development."
"The evidence is very suggestive that this gene is important in the
development of the cerebral cortex, and that's exciting because the
human cortex is three times as large as it was in our predecessors,"
he said.
"Something caused our brains to evolve to be much larger and have more
functions than the brains of other mammals."
The region works differently to ordinary genes in that it does not
appear to "code" for a protein but instead it produces a short
molecule of a DNA-like substance called RNA.
The study, published in the journal Nature, shows that the RNA
molecule formed from the human DNA was substantially different in
structure to the RNA made from the chimp's DNA.
bobber - 18 Aug 2006 00:42 GMT
Cause and effect is not established here. Humans could be doing things
that caused their brain to increase in size, most likely cause (in my
opinion) being use of communal hunting practices. Communal or group
hunting requires major coordination, keeping track of multiple pieces
of information at the same time. This need to manage increasing
complexity led to brain development. Its well known that as you
increase the size of the group, the number of communication channels
within them increases exponentially n(n-1)/2. Only a large brain could
handle the complexity of handling coordination while hunting together.
> Doubt there is any other intelligent life in the Universe. It
> took five billion years to get it here.
[quoted text clipped - 151 lines]
> molecule formed from the human DNA was substantially different in
> structure to the RNA made from the chimp's DNA.