The last visit we made to the zoo was on the same day a baby giraffe had been born. He was just a few hours old when we were allowed a peak at him. When I think about how the giraffe evolved from that first living organism and time, it just doesn’t seem possible. Call it personal incredulity, but it seems every idea regarding the evolution of the giraffe centers on a certain feature evolving, but doesn’t take into consideration everything about the animal that is so unique.
A adult giraffe's heart weighs over 24 pounds and pumps 16 gallons a minute. Due to the giraffe’s heart being much larger than it’s head, a series of special one-way, back-flow preventer valves are needed in the neck to regulate the flow of blood to the head. This is especially important when the giraffe is bending down to drink water. Elastic blood vessels in the giraffe's head hold enough blood to prevent the giraffe from passing out when bent in this position.
Scientists have found that the giraffe's tight skin and the muscles in its legs keep blood from pooling in its lower body, and the arterial pressure near the giraffe's heart is about twice that in humans to provide adequate blood pressure and blood flow to the brain.
Darwin commented on giraffe evolution in the sixth edition (1872) of his seminal book, Origin of Species:
The giraffe, by its lofty stature, much elongated neck, fore-legs, head and tongue, has its whole frame beautifully adapted for browsing on the higher branches of trees. It can thus obtain food beyond the reach of the other Ungulata or hoofed animals inhabiting the same country; and this must be a great advantage to it during dearths.... So under nature with the nascent giraffe the individuals which were the highest browsers, and were able during dearth to reach even an inch or two above the others, will often have been preserved; for they will have roamed over the whole country in search of food.... Those individuals which had some one part or several parts of their bodies rather more elongated than usual, would generally have survived. These will have intercrossed and left offspring, either inheriting the same bodily peculiarities, or with a tendency to vary again in the same manner; whilst the individuals, less favoured in the same respects will have been the most liable to perish.... By this process long-continued, which exactly corresponds with what I have called unconscious selection by man, combined no doubt in a most important manner with the inherited effects of the increased use of parts, it seems to me almost certain that an ordinary hoofed quadruped might be converted into a giraffe. (Darwin 1872, pp. 177ff.)
Luther D. Sunderland, Darwin’s Enigma , wrote:
"It is speculated by neo-Darwinists that some ancestor of the giraffe gradually got longer and longer bones in the neck and legs over millions of years. If this were true, one might predict that there would be fossils showing some of the intermediate forms or perhaps some living forms today with medium-sized necks. Absolutely no such intermediates have been found either among the fossil or living even-toed ungulates that would connect the giraffe with any other creature.Darwin’s natural selection idea regarding the length of the giraffe’s neck is interesting, but there is so much more to the giraffe than the length of his neck. Taking evolution back to first causes, I find it incredible that we are to believe that this animal evolved, along with everything else in our universe from a common first organism. Considering the evolutionary process of that 2 foot long heart branching from a lower life form, it seems nonsensical to imagine these elaborate systems evolving through time.
Evolutionists cannot explain why the giraffe is the only four-legged creature with a really long neck and yet everything else in the world [without that long neck] survived. Many short-necked animals, of course, existed side by side in the same locale as the giraffe. Darwin even mentioned this possible criticism in The Origin, but tried to explain it away and ignore it.
Furthermore it is not possible for evolutionists to make up a plausible scenario for the origination of either the giraffe's long neck or its complicated blood pressure regulating system. This amazing feature generates extremely high pressure to pump the blood up to the 20-foot high brain and then quickly reduces the pressure to prevent brain damage when the animal bends down to take a drink. After over a century of the most intensive exploration for fossils, the world's museums cannot display a single intermediate form that would connect the giraffe with any other creature."—Luther D. Sunderland, Darwin's Enigma (1988), pp. 83-84..
Here is an evolutionary hypothesis:
Giraffes have caused controversy in science as there is very little evidence found on its long neck. A new hypothesis is Here.
Giraffes: Branched off from the deer just after Eumeryx. The first giraffids were Climacoceras Drawing (very earliest Miocene) and then Canthumeryx(also very early Miocene), then Paleomeryx (early Miocene), then Palaeotragus (early Miocene) a short-necked giraffid complete with short skin-covered horns. From here the giraffe lineage goes through Samotherium (late Miocene), another short-necked giraffe, and then split into Okapia(one species is still alive, the okapi, essentially a living Miocene short-necked giraffe), and Giraffa (Pliocene), the modern long-necked giraffe.