> I don't get why blood pressure is relevant for heart energy expenditure. Animal bodies are full of blood, it's not like hearts pump blood up there, they just

> I don't get why blood pressure is relevant for heart energy expenditure. Animal bodies are full of blood, it's not like hearts pump blood up there, they just pump it into movement. No, blood does not get pumped in your head with just movement. You don't swing your head below your heart to replace blood in your brain. Somehow the blood needs to be replaced with fresh oxygenated blood. > I also can't imagine how that long neck evolved (and stayed there) without a huge competing advantage. The and usual advantage of large necks is feeding high, so I distrust the claim that an animal with a long neck couldn't keep his head up. It is common consensus that Giraffe necks did not evolve just under competitive advantage, and the best proof for that is the fact that their necks are much much longer than any other species. If it was only competitive advantage, other species would have displayed similar trends. Sexual selection is a more likely explanation. https://www.scienceabc.com/nature/animals/why-giraffes-have-a-long-neck.html https://www.scienceabc.com/nature/animals/why-giraffes-have-...