This morning, I happened upon a fascinating article about the discovery of a link between heart disease and evolutionary differences between mammals and all other species. Mammals are the only creatures on earth that possess Platelet cells, a vital tool the mammalian body uses to help blood clot during excessive bleeding.
Platelet Cell
We would be undoubtedly be dead without Platelets. However, these cells come with a drawback, because they also form clots at the site of cholesterol buildups in the blood vessels, ultimately resulting in cardiovascular diseases like heart attack and stroke.
Researchers at the University of Pennsylvania wanted to see just how detrimental Platelets were in comparison to other species. To test the difference, they decided to compare the blood clotting abilities of mice and birds. They chose birds because, like mammals, they have an extremely high pressure arterial system.
The difference is that instead of Platelets birds have clotting cells called Thrombocytes.
Thrombocyte Cell
The researchers found that the Thrombocyte cell, though composed of many of the same proteins as Platelets, was fundamentally different in that it could not form "three dimensional aggregates under high-flow conditions." This means that the Thrombocyte cell in avians is missing characteristics that the Platelet cell has which contribute to the first stages of heart attack and stroke.
Researchers speculate that Platelets are probably present in mammals as the manifestation of an evolutionary need for early mammals to survive traumatic injury. Although at one time this might have been an evolutionary advantage, it now seems that the avians have the upper hand. For while humans possess a keen ability to form blood clots quickly after injury, our Platelet cells make us more susceptible to detrimental intra-vascular clotting, which often precedes cardiovascular disease.
Joanna
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