Birds Surprise Evolutionists
(Visited 28 times, 1 visits today)FacebookTwitterPinterestSave分享0 Whether considering their design or their evolution, scientists keep finding surprises in birds.Peacock tails are not a sexual-selection trade-off: Popular opinion about peacock evolution is that the males traded flying ability for extravagant sexual displays. Wrong, Science Magazine now tells us: “Peacocks need not sacrifice flying skills for sexiness.” Experiments with clipped birds showed that “there was no statistically significant difference in flight performance of peacocks with intact tail feathers and those without.” This result “complicates the common assumption in evolutionary biology that elaborate sexual ornaments must come at a cost to the animal.” PhysOrg indicates that the team was surprised when they found that the take-off penalty for the heavy tail is negligible:“Intuitively you expect that the train would detrimentally affect flight performance and so not finding a detectable effect was a bit surprising,” Dr Askew said. “These birds do not seem to be making quite the sacrifices to look attractive we thought they were.“He added: “The train of the peacock is one of the most iconic examples of sexual selection in the animal kingdom. It has been thought that such elaborate ornamentation carries a functional cost for the bearer. These results therefore have broader ramifications for evolutionary biology’s understanding of sexual selection.“Maybe sexual selection is, indeed, the zombie idea that Angela Moles said it was (1/24/14).Parrot sociality: Are parrots big-brained for their size because of complex social relationships? Science Magazine links them with “humans, dolphins and hyenas” which purportedly have big brains relative to body size for that reason. In “Complex social lives gave parrots big brains,” though, reporter Virginia Morell assumes the link, when it is hard to know which is the cause, and which the effect. Simply observing that one species of parrot (the monk parakeet) has several relationships with other members of its population does not say how, or why, a bigger brain evolved or was even needed. If this were a law of nature, why doesn’t it apply to honeybees and ants?How the hummingbird got its sweet tooth: Charles Darwin was “spot-on” when he speculated about how birds acquired their tastes, Hannah Rowland says in The Conversation. “Real taste [in] the mouth, according to my theory must be acquired by certain foods being habitual – hence become hereditary,” he had scribbled in his notes—a seeming Lamarckian suggestion. Rowland, a Lecturer in Ecology and Evolution at University of Cambridge, pointed to mutations in taste genes that she says gave hummingbirds a sweet tooth, or rather sweet tongue: “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.” A just-so story was sure to follow:Baldwin’s results show that Darwin was spot-on. 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.How did other nectar-loving birds get their sweet tastes? “Future research” will be required to confirm the just-so story for lorikeets, sunbirds and tanagers. Rowland failed to mention if mutations also “allowed” the hummingbirds to evolve their unique rotating shoulder, new flapping behaviors, vibrant optical feathers, nectar-trapping tongues and other designs highlighted in Flight: The Genius of Birds.The green wave: Speaking of Flight, the film shows Arctic Terns taking an asymmetrical route on each leg of their annual journey. PhysOrg notes that some 26 species of migrating birds also follow looped routes, apparently riding a “green wave” of vegetation that gives insectivorous birds a steady food supply over the seasons. This is the conclusion of a crowdsourcing tool called eBird that allows citizen scientists to record their birdwatching observations. This article did not mention evolution.Ostrich fun: On Live Science, Alina Bradford listed some interesting facts about ostriches without any evolutionary storytelling. Though the giant birds may seem handicapped because they can’t fly, they are very successful in their hot, dry habitat, getting the water they need from food. They can live up to 75 years, run a sustained 40 miles an hour, and kill a lion with one kick. They also have the largest eyes (2 inches) of any land animal. “It may seem amazing that an ostrich’s thin legs can keep their large bodies upright,” Bradford says. “Their legs are perfectly placed so that the body’s center of gravity balances on top of its legs,” giving them speed and maneuverability. A male is called a rooster; a female a hen. Incidentally, ostriches are listed in Job 39 as examples of the Creator’s handiwork. Though not endowed with sense enough to care about her large eggs left on the ground, she has no fear: “When she rouses herself to flee, she laughs at the horse and his rider.” (The horse gets its comeuppance in the next few verses.)Breastbone evolution problem: The dinosaur-to-bird evolution story just became a little more complicated. PhysOrg explains the conundrum:It has always been difficult to understand how birds evolved from dinosaurs because of the strange combination of features observed in taxa inferred to be situated near this great evolutionary transition. For example, the sternum, also called the ‘breastbone’, is a large bone to which the lower ends of the bird’s ribs are attached. It is intrinsic to modern avian flight, providing the attachment surface for the two largest muscles in the body, the primary fight muscles the pectoralis and supracoracoideus. This bone is present in many dinosaurs inferred to be closely related to birds (e.g. Microraptor, Epidexipteryx) and most basal birds (e.g. Confuciusornis, enantiornithines) but strangely is absent in troodontid dinosaurs and the early birds Archaeopteryx and Sapeornis.A survey of all the extant fossils of Anchiornis, Archaeopteryx and Sapeornis published by Zhonge Zhou’s team in PNAS failed to find any clear evidence of a sternum in the three species, although they held out the possibility that “given the vagaries of taphonomy and preservation and the delicate nature of the thin sternum even when ossified, we cannot conclude unequivocally that a chondrified sternum was absent in either Anchiornis or Sapeornis.” They invoked “developmental plasticity” as an explanation—a term Evolution News & Views said is teleological.The Chinese team had to sacrifice the notion that these species constituted an evolutionary sequence: “Based on this comparison, we suggest that Archaeopteryx, the oldest and most basal bird, also had no sternum, cartilaginous or otherwise,” they concluded. “This observation suggests that this feature was the plesiomorphic [original ancestral] condition in Aves, which, in turn, suggests that basal bird sterna may not be truly homologous.” It’s hard to imagine how these creatures could have flapped their wings, though, without a sternum.Were you ever told that “It has always been difficult to understand how birds evolved from dinosaurs”? Most likely, you were given the impression that it was simple, a straight-line process, and an established fact. There was an episode in one of the TV documentaries about bird evolution that portrayed a two-legged dinosaur walking, then running, then evolving into an Archaeopteryx and taking off into the air, all within a few seconds on screen. Here at CEH, we bring you the real dirt from the journals, showing that the simplistic picture is cute, simple, and wrong.If we stripped the evolutionary assumptions and just-so stories out of the articles above, we would be left with clear evidence of design. The design would be so impressive you might be tempted to build a nano-air vehicle (NAV) imitating a hummingbird. You might take greater enjoyment with your pet parakeet’s cleverness. You might be inspired to become a bird watcher with eBird, helping real science understand these amazing creatures that bring color and fascination to the skies, just like the Creator intended on day 6 of creation.