How are turtles on the Galapagos Islands similar
The Galápagos archipelago is a group of volcanic Pacific islands located on the equator, 972 km west of continental Ecuador. They are probably most famous for Darwin’s historic month-long visit on the Beagle in 1835. The strange creatures that Darwin reported on, such as the birds and marine iguanas, have fascinated readers since. But the iconic species is the native giant tortoise, from which the archipelago receives its name (see ). The largest living species of tortoise, the Galápagos tortoise can weigh over 250 kg (550 lb) and live for over a century.
Darwin and the tortoise
Charles Darwin studied the tortoises, and the islands’ vice-governor told him that one could tell from its characteristics alone which island a tortoise was from. Darwin initially dismissed this statement, and rightly so, since even modern evolutionists admit that it was something of an exaggeration. So he took the differences between the varieties of tortoises to be nothing more than the sort of variation which could arise from a species being transplanted to a different habitat. But he failed to take detailed notes of the variations among the tortoises (his notes mostly record their behaviour) or to take specimens for scientific study.
The Galápagos tortoises were subject to overhunting by humans who kept them for food on ships. This decimated the population. The giant tortoises were seen to be an excellent source of fresh meat, as the tortoises could be kept for long periods of time with little food or water. The sailors on the Beagle took 30 on board for this purpose, discarding the shells and bones as they consumed them. (Woodmorappe suggests this as one more possible food source for carnivores on the Ark; fodder tortoises.)
Darwin took two young tortoises as pets. And they, along with specimens Captain FitzRoy took for the British Museum, constituted Darwin’s only evidence when he realized the tortoises’ importance.
Over 10 sub-species have been identified (four of which are extinct), because they have distinct physical characteristics. But they can all interbreed with one another, so they are classified as one species of tortoise, Geochelone nigra.
Diagram showing in principle how several tortoise varieties can arise from one, simply by sorting already-existing genes via natural selection. For example, the smaller islands tend to be drier, so they don’t support much grass; the only vegetation is cactus and shrubs. So tortoises with saddlebacked shells that can browse will be able to eat, while domed tortoises starve. Thus the only tortoises to pass on their genes to the next generation are the saddlebacked ones.
The most distinctive difference among the sub-species is the variation in the shape of their shells.
These range from a large dome shape to a saddle shape. The dome-back tortoises live where there is plentiful vegetation to support their huge size, while the smaller saddle-back tortoises tend to live in places where vegetation is sparser.
When the tortoise withdraws into its shell, the bony plates combined with scales on the legs offer protection from any predators. The length of the tortoises’ neck and limbs also vary among the sub-species; the saddle-back tortoises have longer necks and legs than the dome-shelled tortoises.
Proof of evolution?
Evolutionists cite the variations among the sub-species of Galápagos tortoise as an example of evolution. But this is the typical equivocation or the bait-and-switch game of propagandists. Evolution from goo to you via the zoo would require new genes encoding encyclopedic amounts of new information. But the tortoises’ adaptation to various island environments can be explained by the sorting out of already existing genes, with some of these then eliminated by natural selection.