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  (Source: Matt Groening/Fox)
Crucial gene controls higher brain growth

To the uninformed observer it may seem baffling how geneticists, biochemists, paleontologists, and other researchers can claim that two creatures that look as different as a man and a monkey could not only be "related" but have been produced by evolution over the last couple million years.

I. It's All in the Genes

But the key to understanding evolution is to understand genetics: our body is driven by protein enzymes, which catalyze critical processes inside the body.  Many proteins share common domains.  And the blueprints to all the proteins a creature makes are stored in a special highly-ordered storage construct called DNA.

While living organisms go to great lengths to preserve their genetic code without errors like swapped sections or deletions, occassionally during the process of making sperm and eggs such an error is made.  Most errors result in infertility or death of the offspring.  But occasionally just the right combination of protein domains has accidentally been clumped together, producing something that fundamentally transforms the organism.

Researchers have finally found a gene -- perhaps the gene -- which separates humans from the ancestors they share with apes.

Humans and apes, both members of the order Primates, share 96 percent of their genetic code.  Most of the remaining 4 percent is so-called "junk" DNA; stretches of mostly inactive code.

Rhesus macaque
Humans share 96 percent of their genetic code with primates, like this Rhesus macaque monkey.
[Image Source: Mark Snelson]

Of course, junk DNA is not useless geneticists and biochemists have recently discovered.  It has been shown to in many cases play a key role in regulation of other genes' expression and other "epigenetic" effects.

But researchers had yet to discover a truly active gene that humans have that apes lack -- until now.

II. miR-941 May Hold the Key to How Mankind is so Crafty

Researchers at the University of Edinburgh in Scotland have discovered a gene called miR-941, which is only found in humans and is absent in their primate relatives.

The gene was absent not only in the gorilla and chimpanzee genomes, but also in the genomes of other non-primates, such as mice and rats.  The gene, absent in all the other critters except for man, is mainly active in the brain; particularly in areas of the brain associated with so-called "higher brain" functions.  

The gene was actively being transcribed in the regions of the brain responsiible for language learning and decision making. Researchers hypothesize that it may play a key role in abilities that are largely unique to humans, such as formulating, understanding, and preserving multiple complex communications codes (languages) and developing advanced tools (weapons, machinery).

Human brain activity
The newly discovered human-unique gene is active in areas of the brain associated with higher thinking processes. [Image Source: Neuroimages Tumblr]

Some other creatures -- gorillas, parrots, dolphins, and whales -- show different levels of sign language or spoken/sung language skills.  And chimpanzees, octupi, and other creatures have been shown to use basic implements, like sticks, as tools.  However, only humans are known to manifest these helpful survival skills in more complex manners.

Now, modern genetics may have cracked a key mystery of human evolution and explained why.

The research was published in the prestigious peer-review journal Nature Communications.

Source: Nature Communications



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RE: Religion and science.
By Gurthang on 11/28/2012 12:40:48 PM , Rating: 2
On the question about human level intelligence and why it is so "rare".

It is well known that humans pay a heavy price to have such a large and complex brain. (energy costs, extended dependance on the parents, etc.) This along with the difficulty in even producing such large brained prodgeny likely represents a large hurtle that required just the right conditions for it to develop.

Systems like evolution tend to favor "least cost/change" solutions. So the question becomes what happened at the dawn of hominids that put us on this trajectory? There is no simple answer to that. So I would expect that for a proto-hominid to move from a social but mild tool user to a highly social heavy tool user you would need a push like some large disaster or climate change altering existing habitats, increased competition in the existing habitat, preditory pressure, or some combination there-in.

Now one thing I wonder is why we don't see any pockets of other hominids left, my guess is that none could develop a niche large enough that they could survive "unchanged/challenged" in since each new line only expanded their range.


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