Hummingbirds, those iridescent jewel-like flyers that adorn our gardens and sip from our feeders, give more evidence of design than we were previously aware.
Researchers at Vanderbilt University found that the wing flaps of hummingbirds are more like those of insects than other birds. Modeling their motions with a supercomputer, they found that the wingbeats create "invisible vortices of air that produce the lift they need to hover and flit from flower to flower."
You might think that if the hummingbird simply beats its wings fast enough and hard enough it can push enough air downward to keep its small body afloat. But, according to the simulation, lift production is much trickier than that.
For example, as the bird pulls its wings forward and down, tiny vortices form over the leading and trailing edges and then merge into a single large vortex, forming a low-pressure area that provides lift. In addition, the tiny birds further enhance the amount of lift they produce by pitching up their wings (rotate them along the long axis) as they flap. (Emphasis added.)
A video clip shows the vortices that are created during wing beats. The Vanderbilt study, published in the Royal Society Interface, reinforces what the documentary Flight explained, that by rotation of a specialized shoulder joint, hummingbird can create lift on both forward and backward strokes. That’s what insects do, too, although they are much smaller.
The hummingbird hover is "surprisingly easy to hack," the University of British Columbia claims. How did they find this out? They tried to make some poor lab hummingbirds dizzy with optical illusions:
UBC zoologists Benjamin Goller and Douglas Altshuler projected moving spiral and striped patterns in front of free-flying hummingbirds attempting to feed from a stationary feeder.
Even minimal background pattern motion caused the hummingbirds to lose positional stability and drift. Giving the birds time to get used to the stimuli didn’t eliminate the disruption. Projecting a combination of moving and stationary patterns in front of the birds didn’t help either, although birds were able to regain some stability.
They were "very surprised" at this result and figured that the birds rely on a stationary visual field. "We think the hummingbird’s brain is so precisely wired to process movement in its field of vision," they say, "that it gets overwhelmed by even small stimuli during hovering."
"Hummingbirds are giving up some of their secrets," Keith Ridler writes at PhysOrg. Here are a couple of discoveries from banding experiments:
The perfecting of placing tiny numbered bands on their legs in the last decade has led researchers to discover hummingbirds can live longer than 10 years as opposed to the two or three once thought likely.
And astonishing migrations have been found, with one bird caught in Florida showing up a few months later and more than 3,500 miles away in Alaska.
How does one band a hummingbird? Very carefully — so carefully, Ridler says, it takes years of apprenticeship to learn the skill. There are only 225 people in the U.S. qualified to do it.
Many birds don’t have a tongue for sugar, but hummingbirds consume more than their body weight in nectar each day. At The Conversation, Hannah Rowland informs us, "Most birds can’t taste sugar — here’s why the hummingbird can." With a tip of the hat to Darwin, she offers a just-so story by way of explanation:
Hummingbirds have co-opted genes that originally allowed dinosaurs to savour the taste of flesh, and transformed them into the sugar detectors most modern birds live without.
For authority, she cites Darwin himself, not seeming to notice that the father of evolutionary theory borrowed notions from Lamarck:
Charles Darwin, scribbling in the rough notebooks to which he would later refer when writing the Origin of Species, pondered how animals in new environments learn which foods are worth eating and which should be avoided. He concluded that this problem drove the evolution of a sense of taste: "Real taste [in] the mouth, according to my theory must be acquired by certain foods being habitual — hence become hereditary."
That’s Lamarckian inheritance of acquired characteristics, not natural selection, but Rowland claims Darwin was "spot-on" in this tale:
Perhaps ancestral hummingbirds that lacked the sweet receptor frequented flowers to catch insects. On occasion they accidentally consumed some nectar. Small mutations in T1R1 and T1R3 would have allowed them to taste this sugary liquid, giving them access to a vital source of energy. This could have given nectar-sipping individuals the evolutionary upper hand compared to insect-eaters.
Why are there still so many insect-eaters? She doesn’t say, but commends a scientific paper: a study by a Harvard grad student speculating that T1R1-T1R3 genes in dinosaurs mutated in hummingbirds to become sweet sensors. That student tries to defend that story in Science Magazine.
Did Hummingbirds Evolve?
As Casey Luskin reported the other day, Science published a series of new papers on bird phylogeny that relies heavily on ideas of "convergent evolution" and rapid diversification — so rapid it’s been called the "avian explosion" and the "‘big bang’ of bird evolution." Where do hummingbirds fit in?
Science Magazine’s slideshow on the subject actually begins with a picture of a hummingbird. There’s nothing about hummingbird evolution here except for a story of gene loss, and the surprising statement that humans and hummingbirds have the same genes for singing. This comes from one of the papers in Science‘s special issue. The idea is summarized by New Scientist, which says this resemblance is "not just superficial," but related to the same genes for language. But where do hummingbirds come from?
A search on "hummingbird" in the other papers reveals precious little about their evolution amid all the talk about tooth loss, explosions, putative crocodile/dinosaur ancestors, and convergent evolution. Can Elizabeth Pennisi give us the scoop? No, just another tale of the seemingly miraculous: "The results go beyond family relations, showing, for example, that song learning evolved three separate times: on the branches leading to songbirds, hummingbirds, and parrots."
If there were a clear evolutionary line from T. rex to hummingbird, this would surely have been the perfect time for the AAAS to produce it. But on that score the reader is left disappointed.
So, summing up, here we observe systems with high-precision, integrated subsystems that perform with exquisite beauty and perfection, overcoming numerous physical constraints to achieve seemingly effortless mastery of flight. From our ample experience in designing aircraft, we already know a necessary and sufficient cause to explain such a thing. That cause, the only one known, is intelligence.