Yes, as you might have guessed, evolutionary biologists are once again PUZZLED (we hear that alot these days) about how flightless birds managed to migrate to all over the world as the above article/video shows. The answer is of course that they flew there when they were smaller birds and lost the use of their wings as a means of flight DO-AH! Isn’t this just what Lamarck said – the dis-use of limbs/organs would cause the lose of function if the creatures didn’t use them. Lamarck is synonymous with alternative ideas of how evolution may have occurred via acquired characteristics (traits that can be inherited), which in modern parlance is known as: EPIGENETICS.
Darwin himself was not actually adverse to this idea and thought, particularly in his later versions of the ‘Origins’ that Lamarckian ideas of environment shaping the development/evolution of a creature may have been important alongside natural selection (this is all in my Book One: The Darwin Delusion, just released on Kindle). Anyway, the point is that limbs are developed, or not, according to requirements in the environment via a mechanism during the embryonic/developmental stages (which is equally applicable to the earlier phases of evolution), known as epigenesis and then epigenetic factors take over. (again too much to go into here, it’s in the book).
The take home point is that the epigenome operates beyond the genes as in your relatively fixed DNA and it is how these are expressed (which ones are turned on or off/silenced or expressed and their timing and combination of which genes are on or off at crucial points in development) that actually appears to drive speciation (change from one species to another), or big or large changes in an in existing one.
Now this brings me to the CONVERGENT evolution mentioned in the video above, which judging by my research, is how evolution occurred: i.e: independent origins of traits and features and even body parts for the same function. In other words, bats (flying mammals) have wings and so do EMUs and penguins (birds) and so do butterflies (insects), yet, nobody would claim that these wings or birds, mammals or insects are related. Are there any flying reptiles? Hum, maybe there used to be and they became chickens?? Sorry, I digress.
So, what I’m saying is that all these major kingdoms of animals evolved independently, some didn’t even need their flight capabilities after some time and there you have it: Birds originally flew to all parts of the world and found themselves within a perfectly adapted niche, so why expend all that energy if you don’t need to fly anywhere – think of the air miles you would save on fuel.
Until the next post