Ontogeny

Growing is inevitable, just like dying. But not all creatures grow in the same way, or for the same reason. But unlike dying, growing is less final and can take many different trajectories. A skill acquired by one who learns neither exist in a vacuum nor is it the same as another when both have reached the highest level. However, even given the endless potentialities of growth, what is learned is rarely a choice.

Many a creature grows and lives like a machine, and rightly so. The environment is too hazardous to learn from birth to death and live purposefully. Past experiences passed down through generations fabricate the instincts of living. The instincts guiding rock-dwelling creatures will be different from ones guiding seafaring ones, following their own paths to become nature’s algorithm. But although these paths arise from different needs and problems, they sometimes converge and form parallel solutions, dotting groups of seemingly unrelated creatures with the same traits and abilities.

One of the most measurable behaviours to approximate learning is speech, because it links the mind with actions unbound by instinct. Speaking is the most efficient skill for conveying information in a short amount of time. But learning what to say and when to say it requires something more than sensorimotor abilities. What is that something?

The short answer lies in improvisation, and the freedom to do so. The more protected the growing by those more experienced, the higher the chance vocal learning will evolve and persist.

The longer answer lies in whether such an ability is preferred by nature. The freedom to learn must also have a purpose, which in nature means survival. But this idea seems contradictive. If surviving is the purpose, then why risk a large chunk of time growing? Why not rely on the tried-and-tested instincts from the get-go?

For this, I look to songbirds. The many learning mistakes that occurs in complex songs diversified them into the largest group of vocal learners, and the fastest group of proliferators by means of vocal differentiation. Their brains, structured in a slightly different way than humans, allowed them to have the same growing patterns as human language. With more than 6000 songbirds, we may well just uncover how and even why vocal learning is so favourable! However, the development of song in early birdhood is known only in a handful of model species where the sequence of notes in their songs is highly structured and easily compared between life stages. In addition to the bodily constraints of sound production, they seem to have a template in their brain that tells them what to learn. That brings me back to square one. I still do not know how vocal learning arises and what makes it so special, or necessary.

That brought me to New Zealand where songbirds have been isolated from the rest of the world for millennia. Here, a particular bird would catch your attention if you listen closely. The tītipounamu flits about in the canopy of age-old trees amongst other ancient creatures. They do not pretend to flaunt complex, melodic tunes. Their high pitched notes are barely audible amongst the loud tūī, tīeke, and korimako. However, its basic vocalizations contain strange patterns and shapes. You see, this tiny bird is one of the world’s first songbirds. What secrets they hold that made them the predecesor of all songbirds? How does their voice grow compared to these modern song learners?

A feisty tītipounamu fledgling female

Thanks for your interest! For more info please stay tuned for my thesis chapter on tītipounamu vocal ontogeny when I get it published within the next year or so :)