Why snakes have lost their legs
Snakes can reach trees without legs or arms, can swim and snake quickly. Now it can be seen that theoretically they could get their legs back. Only one law speaks against it.
There are lizards and creeps and snakes. It is precisely in this order that these reptiles have developed in the course of evolution. When the amphibian life left the water, about 375 million years ago, four legs were still very useful. The legs also remained when the early reptiles developed with their scaly, evaporation-resistant skin from the very sensitive amphibians for drought. That’s about 300 million years ago.
But at some point the running did not seem to be the optimal move for all reptiles. Legs were more of a hindrance. For example, crawls and snakes lost about two hundred million years ago, and then even all four limbs.
The fact that this has happened can easily be seen by anyone visiting an exotic treatment: lizards have legs, snakes do not. Nevertheless, both are very clear in their respective habitats. Modern snakes even belong to extreme movers, they can not just glide over the ground or a tree trunk.
Some snakes can fly almost
You can swim and some species like the brown tree snake can almost fly. At least they can reach an extreme body mechanics from a branch, which is two meters from the nearest, although they are hardly longer. They stick to it only with the last end of their tails.
In the latest issue of the current journal “Current Biology”, scientists from Florida have now solved a riddle of herpetology: they were able to show which genes are involved in the fact that some reptiles have legs – and others do not.
Thanks to this lack of limbs, the animals concerned were able to occupy certain ecological niches optimally. As fast, silent reptiles, they were an advantage over food competitors – which is why slender snakes have prevailed.
There is no back
The fact that snakes used to have legs proved not only fossil finds, such as that of a primordial snake, which scientists had found in the Crato formation in the north-east of Brazil and presented last year in the specialist magazine “Science”.
Also pythons and boas still have remains of their legs. In these snakes, the embryonic development actually shows that the Sonic-Hedgehog gene still exists: in the early development phase in the egg, the snake’s offspring still have legs and toes. It is only in the course of development until hatching that it is re-formed.
The fact that the gene still exists also means that it could theoretically be switched on again at some point – if only mutations were to occur. But evolutionary theorists have been able to establish a rule in the development and passing of animal and plant species: the Dollos law. It says that evolution goes on and on – and never goes backwards. Back to the limbs it will not go for snakes. Perhaps, however, they may develop a completely new method of movement.
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