Giraffe's Blood Pressure

Towering above its neighbors on the savanna, the giraffe is a mind-boggling feat of natural engineering.

Consider its size. At over five meters high, the planet's tallest land animal has evolved unique mechanisms to meet the metabolic demands of maintaining its huge skeleton. And as it stretches its two meter-long neck to pull acacia leaves off the trees, the thick muscle walls of a surprisingly small but powerful heart drive blood up to the brain at a phenomenal pressure, more than double that of humans. Special support structures in the arteries withstand 300/180 millimeters of mercury, preventing them from bursting.

As it drops its head down to drink, specialized valves in the neck counter the potentially explosive effects of gravity, blocking blood flowing back into the skull. Meanwhile, a built-in pressure suit in its extraordinarily long legs prevents fluid and blood from pooling in its feet.

Understanding of these remarkable features is still relatively limited. But the giraffe's physiology is a growing area of research for evolutionary biologists and comparative physiologists looking to understand its unique characteristics and apply that knowledge to solving issues in human health.

Edson Barongo Ishengoma, a Ph.D. student at the Nelson Mandela African Institute of Science and Technology in Tanzania, is researching another of the giraffe's particular strengths - its eyesight. Ishengoma spent the summer in Basel, Switzerland as one of 21 participants in the 2015 Next Generation Science Program; an annual three-month research internship run by Novartis and the University of Basel, aiming to build scientific and leadership capability in developing countries.

His fascination with giraffes' vision is understandable. A giraffe can see well over great distances and—with bulging eyes set in the sides of its head—in almost every direction. From an evolutionary biology perspective, keen eyesight has obviously been critical to giraffes' survival. If you aren't the fastest or fiercest animal roaming the grasslands, you had better be able to see them coming. But it's baffling how giraffes' vision is unaffected by hypertension. In humans high blood pressure can damage blood vessels in the retina, causing blurred vision or blindness.