The harmony of form and function in nature can jar our preconceptions. Take the hummingbird moth; I had never seen one before today. Reading quietly in the warm evening, one came by a flowering bush in the front yard. Truly an amazing creature. Similarly sized to many humming birds, it lives by feeding on nectar in the same fashion as a hummingbird; yet it is an insect. Most people would be shocked to find insects behaving in a fashion similar to humans. Yet the seeming biological discontinuity between birds and insects is more or less as large as the discontinuity humans and insects.
Mammals and birds both descended from pre-reptilian ancestors called amniotes, though the branching occurred at very different times. One of the most fascinating phenomena in evolutionary development (to me) is that of convergent evolution. That is the independent development of similar biological traits among species that have already diverged from their common ancestor.
Birds, unlike their other reptilian cousins, developed warm-blooded metabolism. Mammals developed a warm-blooded metabolism too, but mammals diverged from the ancient terrestrial vertebrate lines long before anything we might think of as birds was on the scene. Somehow along all the eons only two distantly-related branches on the tree of life developed this kind of metabolism. In the case of birds, all their closest relatives do not share this trait. Why is it mammals, those beyond-distant relations, just so happen to have it as well?
Further, not a lot of reptiles are thought of as loving or nurturing; yet birds are well known to display these tendencies in contrast to the aloofness of their cold-hearted kin. Yet their most distantly-related fellow terrestrial vertebrates do share these tendencies: the mammals. Is this mere coincidence?
How strange is it that things have developed that way! It almost makes you think that intelligence and nurturing are natural outworkings of life given a long enough timescale. Or perhaps it is just a coincidence. But one thing that is certain is there’s nothing inherently “special” about mammals in an ontological sense. We’re all part of the same organics patterns of nature that stretch back to the dawn of time and the birth of the cosmos.
We have a unique perspective from our vantage point, to be sure; and that can be celebrated. But a humming bird’s perspective must be a staggeringly interesting one, too. They are a self-contained contradiction; an amalgam of diaphanous beauty and staunch resiliency.
And then along comes this hummingbird moth… I am stunned. It boggles the mind to go far enough back in history to fathom where the lineage of a particular moth and particular bird shared an ancestor in common. It probably had to be a simple ocean-going animal of very limited size and complexity – especially compared to it’s decedents now dominating the globe in every form from roundworms to humans.
Yet in spite of that biological gulf, there it is; doing it’s hummingbird moth thing. It’s a testament to our collective lack of imagination that we couldn’t come up with a better name for them. If we can find hummingbirds remarkable, then these creatures are remarkable, too! They’re not imitating hummingbirds; through sheer unimaginable luck they stumbled upon the same winning formula as hummingbirds! Or at least a part of it.
Underwhelming nomenclature aside, this symmetry is a testament to the interconnectedness of life and it points towards the bedrock of nature. A pretty impressive feat for a small insect.
[Afterword – While fact-checking a few things as I wrote, I stumbled across this blog post that dispelled a couple of errors in my thinking regarding mammalian and avian ancestry. It was a very interesting read, all around, so I thought I would share it for anyone else who likes reading about biology:
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