November 22, 2009 | David F. Coppedge

Giraffe Has Supercharged Heart

In many ways, the giraffe has been an icon of evolution.  Why, and how, did it get its long neck?  These questions have often been the focal point of a clash of Darwinian and Lamarckian explanations.  Today, many just assume it evolved somehow.  For instance, BBC News article stated flatly, “A giraffe’s heart has evolved to have thick muscle walls and a small radius, giving it great power.”
    Diversions into how and if it evolved, however, should not distract from the point of the story: the giraffe’s heart is strong.  The BBC article said, “Now research reveals that giraffes have a small, powerful, supercharged heart that is different to that possessed by other similar mammals.”  Apparently this has not been studied before.  South African biologists studied dead specimens culled from Zimbabwe over the last few years and found that the giraffe has multiple mechanisms to pump blood two meters up to its neck to its head.  The giraffe heart is “smaller than you’d expect in similar-sized animals, but the walls are incredibly thick,” the researchers found.  It delivers blood pressure twice that in most mammals.  This also means that the blood vessels have to be thick to compensate for the high pressure.
    The blood vessels actually thicken with age.  As the giraffe grows, and its neck reaches ever higher, the thickness of the vessels is regulated.  “Giraffes have got a way of adjusting the capacity of the cardiovascular system and are able to shrink and expand their blood vessels to change the volume of the cardiovascular system very efficiently.
    Blood pressure and heart efficiency are just two of the questions the researchers are exploring with a rare chance to analyze giraffe anatomy.  What they would really like to do is further these discoveries with live giraffes in the field.  “To measure blood pressure in a free living giraffe doing its thing, that would be really interesting,” said a researcher who classed himself with “people just like me who wonder how giraffes get it right.” Taking the blood pressure of a galloping giraffe is a challenge.  Does one tighten the cuff around its neck?

The strong heart is only part of the story.  Giraffes need mechanisms to prevent damage to the brain when they bend over to drink.  Some of these are explained in the film Incredible Creatures that Defy Evolution (10/03/2009), volume I.  There are so many mechanisms that had to be in place simultaneously, it strains credulity to think they could have evolved by accident.  Another problem with the evolution tale is that the giraffe is a mammal; what about the more “primitive” dinosaurs, not in the giraffe’s supposed evolutionary ancestry, who had much longer necks?  Two meters is nothing.  Supersaurus weighed 40 tons and reached 34 meters – as much as 112 feet.  While the Darwinists get sick thinking about that, the rest of us can enjoy marveling at these wonders of design.

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Categories: Amazing Facts, Mammals

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