Joe Pieri claims (Letters, October 17) that a watertight cap around the nipples of whales that fits tightly around the baby's snout to prevent sea water entering is a perfect illustration of intelligent design (ID) as any gradual transitional form would result in the baby whale's death. If this is the best example a supporter of ID can muster, it only helps to illustrate how flawed this non-scientific idea is and why it has absolutely no place in the science classroom. First, as a whale biologist, I can say with some certainty that no such structure exists.

Baby whales use "fringes" around the edge of their tongue to help channel milk from the nipple to their thoats. This does not to prevent the entrance of sea water into the baby whale's mouth, nor is it intended to, but only serves to reduce the mixing of sea water and milk. This leaves plenty of possibilities for functional transitional forms where the tongue is only slightly more fringed and, therefore, only slightly better at keeping the milk and sea water separate, making the milk less dilute and, therefore, beneficial to the calf as it gets more concentrated milk faster.

Secondly, there is no need for baby whales to prevent sea water entering their mouths as it will not kill them. Presumably, Mr Pieri thinks that the reason the baby whale would die if sea water entered the mouth is because it might get into the airway causing the animal to drown.

However, unlike humans, the windpipe of a whale sticks right through its oesophagous, completely separating the airway and the digestive tract (a requirement for all whales, whether adult or baby, as they need to be able to open their mouths underwater to feed) so there is no risk of drowning while nursing in baby whales. A similar, but not as complete, separation of the digestive tract and the airway is found in all young terrestrial mammals, including humans, to allow them to breath while nursing, and while adaptation is lost in older humans through a descent of the larynx, this basic mammalian separation has been enhanced by natural selection in whales because it is beneficial to their life in the sea. Incidentally, this positioning of the larynx through the digestive tract limits the size of fish whales can swallow because if the fish is too big it may displace the larynx and allow water into the airway, resulting in death.

In fact, whales are not uncommonly found washed up on the shore having died due to suffocation with large fish wedged in their throat, demonstrating that while this design works most of the time, it is far from perfect and certainly not evidence of any ID. Therefore, Mr Pieri's "perfect" example for ID is a figment of his imagination based a poor understanding of biology and no facts.

Dr Colin D MacLeod, Beaked Whale Research Project, 1 Froghall View, Aberdeen.

In reply to Joe Pieri, to suggest that the atheist is as much a believer as a theist is like saying not collecting stamps is a hobby. Utter nonsense.

Stephen Middlemass, 27 Wester Drylaw Park, Edinburgh.

I, like everyone else, cannot "know" whether or not there is a God. I believe in scientific explanations of physical processes, but I do not confine my believing to what is based on scientific evidence. There is no proper scientific evidence that any actions in the world are morally wrong, yet I believe many are, and this is fundamentally true. What sort of scientific evidence could there be for that? I believe certain authors show superb insight into the human condition, and that this statement is true however you break it down. There may be reasonable arguments for holding that opinion, but there is no scientific or empirical evidence for its truth or falsity. The literary critic can only persuade with examples.

Alan J Sangster (Letters, January 27) maintains that "the evidence for the God of the creationists and intelligent designers is non-existent". What sort of evidence does he want? What sort of evidence could there be? A copyright attached to DNA saying: "I, God, am responsible for this"? A banner appearing every now and then in the heavens saying: "Here I am, the God that made all this"? What sort of evidence would atheists accept, evidence that would prevent them from supposing that a scientific explanation had yet to be found?

All this bleating about evidence is irrelevant. Mr Sangster half sees this himself when he writes that after all natural processes have a scientific explanation "the God that remains will not be eradicated by science". He is being scornful, but how true that is. It is because belief in God has nothing to do with science, nor indeed did ancient mythology which was not, as he suggests, some kind of pre-science "making life less threatening". Making life less threatening? Most of the ancients were terrified of the gods. Maybe Dawkins and his disciples should read more widely and remove themselves from their time-warped nineteenth-century take on the so-called battle between science and religion. Read some Kierkegaard, or start with philosopher A E Taylor's Does God Exist?, where they will find, from a very intelligent man, a much wider concept of rationality than scientific method alone.

Arthur F Jones, 23 MacPhie Road, Dumbarton.