Skip to comments.New Insight Into Horse Evolution
Posted on 07/03/2005 2:03:06 AM PDT by nickcarraway
Genetic evidence is shedding new light on the origins of horses in the New World, during a particularly hazy period in their evolution.
As the Great Ice Age came to an end, some 11,000 years ago, North America was thought to be home to as many as 50 species and subspecies of horse.
But studies of ancient DNA tell a rather different story, suggesting the horses belonged to just two species.
These are the stilt-legged horses, now extinct, and the caballines.
The caballines are thought to be the ancestors of today's domestic horse.
"It looks like, as far as we can tell from the DNA, there is only evidence of two species in North America," Dr Alan Cooper from the University of Adelaide, Australia, told the BBC News website.
"We think that, in fact, people have been looking at these fossils and over-interpreting signs of changes in shape and size," he added.
"Probably these animals are adapting to local environments and perhaps they are [anatomically] more [changeable] than the palaeontologists had perhaps thought."
The work has implications for understanding other animals because horses are a textbook example of using fossil evidence to explain evolution.
Although the horse fossil record is very rich, our picture of when and where different species arose is clouded.
Analysis of mitochondrial DNA from fossilised bones, only possible in recent years, gives scientists a new tool to study evolution.
In research published in the open access journal Plos Biology, Dr Cooper and colleagues at Oxford University, UK, analysed mitochondrial DNA from fossilised horse bones.
Mitochondria, the powerpacks of the cell, have their own DNA and are inherited along the maternal line. Their DNA mutates at a stable rate, allowing researchers to look back in time at when different species diverged.
The Oxford research suggests that the stilt-legged horse, which was thought to have migrated into North America from Asia, at a time when the continents were linked by a land bridge, appears, in fact, to be native to North America.
And the Patagonian Hippidion horse found in South America appears to be much younger than previously thought.
It probably moved into South America about 3 million years ago, when the gap between North and South America closed up.
This was a seminal period of evolution, when animals from the two continents were able to mix after a long period of isolation.
My brain hurts....
Actually, I didn't realize that there was any doubt involved. I don't follow closely, but on my last reading the conclusions were that horses were descent from the "Eohippus".
Now in doing some quick research, I've run across a site stating in detail why the evolution of the horse, as stated in previous text, is a fraud. Take it for what it's worth I suppose.
Interesting either way. The Eohippus was said to make it's appearance some 55 million years ago. 50 different subspecies existing some 11,000 year ago isn't such a surprise to me. I don't see their evolution as being limited to a single line resulting in our modern horses. It could have been a series of experiments in design arriving at our present day species. Many people believe the same of early man, who may have faced competition from co-existing with several other man-like species. Even cro-magnon man may have had encounters with the neandertal. So it's not such a leap of imagination to believe in 50 different subspecies of horse.
Of course, more detail would be useful. Yet my coffee is done and my addiction is compelling me to leave my fellow FReepers with the Monty Python GIF, then make a quick exit.
Cool post. Thanks!
Now why would professional scientists do such a thing???
Never mind. I know.
Gotta prove something.....
Let's cut to the chase...I think someone's playing the Race Card again...
Ohio Voter Fraud!!!
As the Great Ice Age came to an end, some 11,000 years ago, North America was thought to be home to as many as 50 species and subspecies of horse. But studies of ancient DNA tell a rather different story, suggesting the horses belonged to just two species... The caballines are thought to be the ancestors of today's domestic horse... The Oxford research suggests that the stilt-legged horse, which was thought to have migrated into North America from Asia, at a time when the continents were linked by a land bridge, appears, in fact, to be native to North America.Fascinating that the horse appears to be native to North America. I believe the same used to be said of the wolf and all domesticated dogs. I doubt that these findings will catch on. I would like to think that they would lead to the demise of mtDNA GIGO.
Mitochondria, the powerpacks of the cell, have their own DNA and are inherited along the maternal line. Their DNA mutates at a stable rate...Heh... Please ping me, if you see articles appropriate for GGG ping.
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I wish I had me one of them three-toed horses. It would save a fortune on farrier's bills.
I wasn't aware that anyone thought otherwise.
Why, it is undisputable; and any doubter needs only to take a look at Kansas School Board.
Maybe, maybe not. They were pad-footed, kind of like a dog, but with little "hoofies" on their toes. You might have had to have the farrier shoeing 14 little hooves per horse. The Eohippus was also a fairly small critter, about the size of a dog.
On the plus side, they were browsers instead of grazers. I wonder if they ate salal and blackberry bushes? :-)
OK, what gives here? How is it that fossilized bones can contain any DNA. Isn't everything replaced during the fossilization process. I've really got to get out from under this rock more.
Creationist horses say that they aren't related to these earlier horses and say it's a fraud.