Hearing Horses Chasing Zebras

Let us use our imaginations and look at a key aspect of the before mentioned hummingbird and see if we can map out the evolution of a hummingbird mouth. A hummingbird has a long beak with an even longer tongue. The hummingbird uses this beak to probe the depths of various flowers allowing it to drink the nectar found inside. The hummingbird’s tongue is longer than the beak in order actually make contact with the nectar. This system is an advantage to the hummingbird as it allows it a food source many other birds cannot access.

But what did the hummingbird look like prior to the evolution of this long beak and tongue? Did the humming bird start with a short beak and tongue, similar to most other birds? How quickly did these components grow and change? Which changed first? Did the beak and tongue evolve at exactly the same time? Let’s dive more deeply into these questions.

One must assume a hummingbird’s mouth started off a good deal smaller than we find it today. Most birds have relatively short beaks while the hummingbird has a comparatively very long beak. If we want to track all birds back to a common ancestor it would make more sense for an initial short mouth. So how quickly did the hummingbird mouth grow? If we say an average hummingbird beak is three-quarters of an inch long and assume, for the sake of argument ancient hummingbirds had beaks one-quarter of an inch long, how long did it take to develop that additional half-inch? Was the next successful evolution a sixteenth longer? An eighth? A quarter of an inch? Did we get a full half inch jump? And at what point along this evolutionary trail is this bird considered a new species?

Often we hear it asked, “which came first, the chicken or the egg?” In case of the hummingbird we have to ask, “which came first, the beak or the tongue?” Not only do hummingbirds have long beaks but exceedingly long tongues as well. So as the hummingbird evolved did the beak grow first leaving the tongue to play catch up? Did the tongue grow first and the beak caught up? Can you picture a hummingbird flitting by a flowering plant with a long tongue dangling out of a short beak? The bird flipping the tongue into the heart of the flower in order to obtain the nectar. Or maybe the tongue stuck out just a little past the beak like a panting dog.

What if the beak evolved longer and longer first? How exactly did the hummingbird get access to the nectar? It is quite possible the variety of food sources would be smaller until the tongue grew longer. But did the bird use the beak to obtain the nectar more like a straw until the tongue caught up? If that was the case, why did the tongue need to grow if the beak was working?

A third option is the two components of the hummingbird’s mouth evolved at the same time. Given the randomness and chance centered constructs of evolution this appears to be a stretch. When we look at modern hummingbirds it is clear the tongue extends well past the beak. If the two pieces evolved at the same time, did they evolve at the same rate? Was the ratio of tongue to beak always the same? How would this have happened by mere chance?