"So that if a cecal valve became necessary the lizard was ready to go . Having the built-in redundancy makes this possible without missing a beat ."
"`` Ready to go `` , in the sense that living things are equipped with a means of making small errors which are used by natural selection to make new structures . Barbarian , regarding mutations : There is a lot of that . Many mutations are recessive and a population over time accumulates a lot of genetic variation that can become useful if the environment changes . The founder population of lizards , for example , could have had at most , 20 alleles for any gene locus , since each lizard can only have 2 . The new ones evolved by mutation . Sometimes , we can even observe that happening , or trace the mutation back to a known ancestor . Would you like to learn about it ? ."
"So that if a cecal valve became necessary the lizard was ready to go ."
"Would you like to learn about it ? ."