Tuesday, March 6, 2012

But Some Have Evolved Further Than Others

HUMANS have evolved from this two-inch worm, scientists claim. The extinct Pikaia gracilens lived in the sea more than 500million years ago.

Now scientists have linked it to humans, saying that it is a primitive ancestor of animals with spinal cords. It also gave rise to fish, birds, reptiles and other mammals.

Although Pikaia was first discovered in 1911, scientists assumed it was only related to leeches and earthworms. But the spinal cord, paired with zig-zag patterened blocks of muscle tissue known as myomeres, relates it to humans.
I don't know why this is considered fresh news, I learned similar things back in High School.  And according to the Smithsonian Institution, the inference that it is in the direct line to human evolution might just be a bit premature.
PLEASE NOTE. Pikaia is not a vertebrate - no one can say if this particular creature is our direct predecessor. Nevertheless, Pikaia is a representative member of the chordate group from which we undoubtedly arose. It resembles a living chordate commonly known as the lancelet.
 So who are you gonna trust, a British Tabloid, or the Smithsonian Institution?  Tough choice...

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