Thoughts: Carrion Crows In Japan Can Teach Us A Lesson In Evolution

Source: Reddish Vale Country Park

The path of least resistance is usually taken by each of us regardless of the task at hand.  More easily stated, each of us try to exert the minimal amount of effort to get the maximum amount of payout of a given task.  Why work hard -- when the same can be accomplished with a smaller amount of effort?  This seems to be the 'mantra' to which humans have evolved to over time.  Some argue that life today is easier for us compared to times earlier in history.  We (humans) are not alone in this evolutionary path.  Turns out that the Carrion Crows in Japan (and other areas in the eastern world) have evolved to minimize their efforts in a survival task as well.



In a recent article on the website "Aeon" titled "Evolving Streets Smarts" the author tells of the evolution of birds in cities.  An evolutionary path in which resources might be more difficult to come by at first sight.  Although, once found, Carrion Crows have learned how to minimize their efforts to get food as described in the following excerpt:

It was here that, in 1975, the local carrion crows (Corvus corone) discovered how to use cars as nutcrackers. The crows have a predilection for the Japanese walnut (Juglans ailantifolia) that grows abundantly in the city. The pretty nuts (a bit smaller than commercial walnuts, and with a handsome heart-shaped interior) are too tough for the crows to crack with their beaks, so for time immemorial they have been dropping them from the air onto rocks to open them. Everywhere in the city, you find parking lots strewn with the empty nutshells: the crows either drop them in flight or carry them to the tops of adjoining buildings and then throw them over the edge onto the asphalt below.

But all this flying up and down is tiring, and sometimes the nuts need to be dropped repeatedly before they split. So, at some point, these crows came up with a better idea. They would drop nuts among the wheels of slow-driving cars, and pick up the flesh after the car had passed. The behaviour started at the Kadan driving school, where there are plenty of slow-moving cars, was copied by other crows, and so spread to other places in the city where slow-moving giant nutcrackers were common, such as near sharp bends in the road, and at intersections. At such places, rather than dropping the nuts from above, the crows would station themselves by the roadside and place them more accurately on the road. Since then, the fad has also turned up in other cities in Japan.

In 1995, the zoologist Yoshiaki Nihei then at Tohoku University in Sendai made a detailed study of the behaviour. He observed how the crows would wait near a traffic light, wait for it to turn red, then step in front of the cars, place their nuts, and hop back to the curb to wait for the light to change. When the traffic had passed, they would return to the road to retrieve their quarry. His work revealed the crows’ finesse in handling their ‘tool’. For example, the birds would sometimes move a walnut a few centimetres if it took too long for it to be hit by a wheel. In one case, he even saw how a crow would walk into the path of an oncoming car, forcing it to brake, and then quickly toss a nut in front of its wheels.

The behavior of the Carrion Crows is quite amazing.  Further, the behavior is indicative of the theory of Evolution.  Here is an excerpt from the Wikipedia page on Evolution shown below:

Evolution is change in the heritable characteristics of biological populations over successive generations.[1][2] Evolutionary processes give rise to biodiversity at every level of biological organisation, including the levels of species, individual organisms, and molecules.[3]

Repeated formation of new species (speciation), change within species (anagenesis), and loss of species (extinction) throughout the evolutionary history of life on Earth are demonstrated by shared sets of morphological and biochemical traits, including shared DNA sequences.[4] These shared traits are more similar among species that share a more recent common ancestor, and can be used to reconstruct a biological "tree of life" based on evolutionary relationships (phylogenetics), using both existing species and fossils. The fossil record includes a progression from early biogenic graphite,[5] to microbial mat fossils,[6][7][8] to fossilised multicellular organisms. Existing patterns of biodiversity have been shaped both by speciation and by extinction.[9]

In the mid-19th century, Charles Darwin formulated the scientific theory of evolution by natural selection, published in his book On the Origin of Species (1859). Evolution by natural selection is a process first demonstrated by the observation that often, more offspring are produced than can possibly survive. This is followed by three observable facts about living organisms: 1) traits vary among individuals with respect to morphology, physiology, and behaviour (phenotypic variation), 2) different traits confer different rates of survival and reproduction (differential fitness), and 3) traits can be passed from generation to generation (heritability of fitness).[10] Thus, in successive generations members of a population are replaced by progeny of parents better adapted to survive and reproduce in the biophysical environment in which natural selection takes place.

Observing the behavior of the carrion crows in the streets along with the definition of 'evolution' above, the following questions come to mind:


1) What inheritable traits have been passed on to ensure success in the streets of Japan?

2) What traits are based on 'modifications' to gene expression in real time -- i.e. epigenetic traits -- rather than changes in the gene code which is passed onto successive generations?


Thinking critically about the process of evolution is an all encompassing adventure which never fails to provide more than enough material to consider.  Just look around yourself and ask how has the present environment in which you find yourself in been affected by evolution?  That is a very broad question.  Although, there is plenty to consider.  From the extermination of 'pests' to the state of present day society -- technology, consumer engagement, and laws of the world.




Conclusion...



There are numerous examples of evolution around us.  Depending on how much time a person has to devote to considering various examples on different scales, the process of consideration could go on ad infinitum.  Scientists spend a large amount of time (sometimes their whole life) studying traits in species in hopes of understanding the process of evolution in greater detail.  As you proceed on with your day to day business, now you can rest assured that you will never be bored again.  Where ever you find yourself at, the possibility exists to think about the environment and evolution.  Can you see any blatant examples of evolution -- similar to those cited above for the species carrion crows -- in the immediate environment in which you find yourself in presently?  I am sure that you can if you try hard.  Give it a try and see.  You might surprise yourself.