I found a nature.com article from earlier this year reporting findings from a study by Pierre-Olivier Cheptou which documented the rapid evolution of the weed Crepis sancta growing in street-side tree-plots in Montpelier. This weed has two types of seeds – light ones carried by the wind and heavy ones which drop to the ground. The nature of its city surroundings (tiny, isolated plots of soil) favors the heavy ones which are more likely to succeed in reaching the soil and taking root, so the plant has evolved to produce more heavy seeds, in just 12 years. However, selecting for this trait puts the species at risk, as it diminishes the ability for its genes to be wide-spread and promotes genetic isolation.
I can’t help but wonder analogously about humans. First of all, regarding behavior. I wonder how I myself have adapted to city life? What traits have I adopted in order to survive? How will this affect me when I decide to pull up my roots and transplant myself in another (preferably saner) environment? Will I later have to un-learn these traits because they will no longer be desirable or necessary?
And do cities play a role in human evolution? Wondering about this, I ran a quick Google search and found that Howard Bloom speculates that they do. Unfortunately my attention span right now is too short to read the entirety of this lengthy article (a city-imposed vice?) or even get the drift of what genetic traits he believes have evolved, so I can’t give my opinion on it yet. Read it if you like; I suppose it should be interesting.
I also think there’s something telling about the isolation of plant species within the city, boxed in within mazes of pavement. It has often been noted that people tend to feel isolated in the city, living and working in lonely cramped apartments and cubicles in the midst of so many others. Also, cities attract such a large diversity of people (especially New York), and it is here that individual cultures are asserted and preserved within the boundaries of single neighborhoods. The city seems to hold together and divide at the same time.
But looking around at the weeds in my neighborhood, it seems like they’re doing pretty well. Perhaps the ones that do particularly well have lateral roots or stems underground that span large areas in search of every crack in the pavement – not sure, but whatever tactics for survival and reproduction are in place, they seem to be working. And considering the number of websites dedicated to the difficult process of their eradication and web forums filled with poor people venting their frustrations at the persistence and ingenuity of these crazy plants, it certainly seems that, like cockroaches, they’ll be around for a long time.