Fish's DNA Holds Clues to Evolution: Scientists
Scientists find DNA for placenta, limbs in ancient fish
By Mark Russell, Newser Staff
Posted Apr 18, 2013 11:13 AM CDT
This 2008 image made available by the Smithsonian's National Museum of Natural History shows an African coelacanth (Latimeria chalumnae).   (AP Photo/Smithsonian, Chip Clark)

(Newser) – The coelacanth doesn't just look like a prehistoric fish, it was believed to be one, extinct for some 70 million years—until one turned up at a South African fish market in 1938. Now, scientists have decoded the endangered species' genome, and they say they've found some clues as to how today's land animals evolved from a fish ancestor, reports the New York Times. First, some fascinating backstory: The Times explains that the coelacanth and lung fish—both "lobe-finned fish"—have been duking it out for the title of the closet relative to that first ancestral fish that used its fins to walk on land.

Post-decoding, the lungfish emerges as the closer relative, but in the Times' telling, the "coelacanth may have the last laugh"—that's because the lungfish genome is too long to decode using current technology. What scientists learned from the coelacanths' DNA:

  • Even though coelacanths don't have a placenta, they have a gene related to one that allows land animals to grow a placenta.
  • A DNA sequence found in coelacanths, but not ordinary fish, bolsters the genes that helps an embryo grow limbs. Researchers actually injected the coelacanth's sequence into mice; "it lit up right away and made an almost normal limb," says one.
You can check out the original article at Nature.

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Showing 3 of 116 comments
iq145
Apr 18, 2013 11:21 PM CDT
All the hardwired Biblers of the world will be pretty upset to hear this news. Religion requires you don't "ask", you just "accept"...
exprnc
Apr 18, 2013 8:35 PM CDT
Life on earth - did it really originate on earth? The Oort Belt has all of the necessary components to support life - life may have been delivered to earth by comets. Our solar system is an accumulation of debris from older supernovas [metals heavier than iron are created in a supernova]. Is the Oort Belt the remains of older oceans on planets that supported life and still carried some deep frozen DNA.
JoeQ
Apr 18, 2013 7:45 PM CDT
The hip bone's connected to the thigh bone The thigh bone's connected to the fibula and tibia bones The fibula and tibia bones' connected to the ankle bones The ankle bones' connected to the metatarsal bones