Design of Bird Brains for Long Migrations
Many migrating birds fly all night long. Some fly nonstop across huge ecological barriers like the Gulf of Mexico. For decades, biologists have wondered how these creatures can survive the severe sleep deprivation brought about by such migration habits. Now, a team of American biologists and neuroscientists appear to have found an answer that reveals a previously unknown level of life design and design convergence.
During the research, seven Swainson’s thrushes–birds that remain active all day and fly all night during their migration–were put into a cage where the scientists induced artificial sunrises and sunsets that mimic the migration season. For each of the birds they implanted electrodes to monitor brain activity.
The team discovered that during the simulated daylight hours the animals took mini-naps with one eye shut and the other open. The electrodes revealed that one hemisphere in each bird’s brain manifested electrical patterns resembling nighttime sleep while the other showed patterns indicative of daytime wakefulness.1 The research team concluded that the thrushes rested their brains, one half at a time, in order to catch up on sleep.
In order to remain ever vigilant against attacks these birds do not relax both brain hemispheres at the same time. Their nighttime migrations limit the risk of exposure to predators and avoid overheating.
To date, neither biologists nor neuroscientists understand how it is that the brains of migrating birds let one hemisphere sleep while the other is awake and allow the two hemispheres to periodically trade their sleeping and waking modes. Yet, there is no question that such a capacity is an amazing design feature. The idea that it could spontaneously evolve defies a naturalistic explanation.
This outstanding brain design is not unique to birds taking long migration flights. Scientists have observed the same kind of brain behavior in several marine mammals such as dolphins and whales. Thus, this particular design feature provides yet one more example of what evolutionary biologists term “convergent evolution.” A more accurate label would be a “repeated design outcome.” Two species (thrushes and whales) that are completely unrelated on any Darwinian evolutionary trees exhibit an identical and extraordinary brain characteristic. The only reasonable explanation for such an outcome is a supernatural, super-intelligent Creator repeating an optimal design. This explanation is all the more compelling in the context of hundreds of other examples of purposeful convergence for species unrelated in an evolutionary context.
- T. Fuchs et al., “Daytime Micro-Naps in a Nocturnal Migrant: an EEG Analysis,” Biology Letters (November 5, 2008): 10.1098/rsbi.2008.0405.