Giraffe necks perplex scientists according to an article in New Scientist Zoologger 7 Jul 2010 and Journal of Zoology, online 2 July 2010.
For many years evolutionary biologists have tried to explain how the giraffe, with its two metre long neck, evolved from an animal with a short neck. The first explanation was that animals with longer necks could browse from tall trees that other animals could not reach. According to New Scientist “Giraffes in South Africa do spend a lot of time browsing for food high up in trees, but elsewhere in Africa they don’t seem to bother, even when food is scarce.” It seems the amount of time spent browsing high in trees is not worth the trade-off for the burden required to maintaining the huge neck and keeping up the blood supply to the brain, which is about 2m above the heart.
A more recent theory is that the long neck is the result of sexual selection. Male giraffes are known to use their necks in a type of push and shove combat called “necking” when competing for females. However, sexual selection usually results in significant differences in the selected trait between males and females, but male and female giraffes have necks of similar proportions to their body size.
Rob Simmons and Res Altwegg of the University of Cape Town, South Africa have recently reviewed a number studies of giraffes in the light of the two theories. They summarise the problem as follows: “The main challenge for the competing browser hypothesis is to explain why giraffe have remained about 2m taller than their tallest competitors for over one Myr, whereas the sexual selection hypothesis cannot provide an adaptive explanation for the long neck of female giraffe.” They concluded “probably both mechanisms have contributed to the evolution and maintenance of the long neck, and their relative importance can be clarified further.”
Editorial Comment: Here we have a good example of how useless evolutionary theory is to science. The fact that animals that already have long necks can browse from high trees, and the males can indulge in neck wrestling, does not, and never can, explain how a short necked animal can change into a long necked animal, complete with all the other modifications needed, such as a strong heart and sophisticated pressure controls in the head and neck blood vessels needed for when it lowers its head to drink from waterholes. That kind of change requires a lot of new genetic information and none of the stories about browsing or fighting explain where this came from. Darwin believed that animals could gradually stretch their necks and pass on this characteristic to their offspring because he lived before we really knew how genes worked, and we have now found out that acquired characteristics could not be inherited. However, 21st century scientists have no such excuse, and high browser and “necks for sex” hypotheses are just tall stories.
In reality, giraffes show no evidence of ever being designed to be anything but giraffes, and have continued to reproduce after their kind, just as Genesis says.
Evidence News 28 July 2010
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