|MadSci Network: General Biology|
That's an excellent question, Nathan. People have wondered and argued for centuries over what behaviors are genetic and which are learned. The honest answer in this case (and in many cases) is that we just don't know. Magpies have short wings and long tails which make certain flight patterns more natural for them than others, but in order to find out whether swooping is learned or inherited, we would have to raise baby magpies in a completely natural environment but without letting them see their parents swoop. If they still flew that way, we could say it was genetic -- but there would still be questions. An experiment like that has been performed on a species of sparrow to find out whether their songs are learned or genetically "coded." This species learns songs from exposure to the adult songs during a certain time in its "chickhood." When a single chick was raised without exposure to the parents' song, it grew up unable to sing the song properly. This would seem to indicate that the song is learned. However, when four chicks were raised together without exposure to the parents' song, they took a little longer, but eventually they taught themselves the correct song! This means the whole matter is more complex than simple "heredity vs. environment." The sparrows may have an instinct that tells them what a correct song sounds like when another bird sings it, but not one that tells them how to produce it. Or they may have to learn their song by judging the reaction of other birds. So there isn't an easy answer to your question. Most likely, it's some combination of genetics and learning. And people will probably be debating this for many decades to come.
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