Quote:
Originally Posted by festeringZit
Who wrote that software (DNA)? Magic? Random mutations? (cough cough)
Natural processes wrote the software:
When a living being reproduces there is a small chance that there will be an error in the reproduction of particular genes in its DNA code. With enough living beings reproducing, the chance of such errors occurring, increases. Some of these errors lead to some sort of important diversity (e.g., sharper nails, thicker skin, or smarter brain). Some of these errors thus, may provide that particular offspring with an advantage over others of that species.
This is where the environment comes into play. For this let's use the example of birds.
Let's say that the environment, or island, on which this bird species lives, does not have shelled nuts anymore (as a source of energy/food). It use to have lots of shelled nuts, but now, most of the species of nuts went extinct on the island. However, the island has lots and lots of insects (as a source of energy/food for birds).
In this case, we would observe that prior to the extinction of shelled nuts on the island, the bird species that thrived were ones with larger/stronger beaks (for breaking shells, and eating nuts). After the extinction of shelled nuts however, the bird that has a smaller beak that's evolved more precisely for hunting insects will now be the new thriving species.
To wrap this up, imagine how such a small-beak bird would come about
: by an error in the reproduction of the DNA of a large-beak bird - as described earlier. The small-beak bird, more adept at hunting insects is then more likely to reproduce and spread its genes throughout the island, while the large-beak bird is likely to go extinct, or find another source of energy/food.
Natural processes as such, write the 'software' on their own.