Let's study ID: giraffe plumbing (Introduction)

by David Turell @, Saturday, September 18, 2021, 15:19 (328 days ago) @ dhw

From the review of a book: Pump. Pump,....:


"Animal circulations vary enormously in their operating pressures. Giraffes have the highest blood pressures of any mammal, running around 280/180 mm Hg. (Ideal blood pressures in humans are around 110/80 mmHg.) This propulsive energy would wreck human brains and kidneys, but it is essential for giraffes, who need it “to force blood up to their treetop-level heads.” The long necks of giraffes enable them to feast on high vegetation, but also create hydraulic headaches. When giraffes stoop to drink, blood may pool in their heads from the effects of gravity. Evolution has developed a twofold solution. Giraffes have sprouted a network of arteries in their necks that can expand to accommodate more blood when they bend over. As well, their jugular veins have acquired a muscular layer to squeeze blood back to their hearts, and an intricate series of valves to prevent backward flow.

"Giraffe limbs are also under severe hemodynamic stress, and must withstand pressures as high as 350 mmHg. The reason that giraffes don’t get varicose veins is that their legs have taut sleeves of skin that act like compression stockings, and prevent them from swelling up."

Comment: I've mentioned most of this before. There is no way this can be developed stepwise. It must be designed. And as in all fossil gap stories, no precursors

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