On Thursday, the reseachers at Weill Cornell Medical College released a study which mapped DNA present in the subway system of New York. About half of the DNA found on the surface of the system did not match any known organism.

Only 0.2 per cent matched human genome.

"People don't look at a subway pole and think, "It's teeming with life. After this study, they may. But I want them to think of it the same way you'd look at a rain forest, and be almost in awe and wonder, effectively, that there are all these species present - and that you've been healthy all along," said lead author Dr. Christopher E.Mason who is a geneticist at trhe Weil Cornell Medical College.

The project is known as PathoMarp. A team of graduate students, volunteers and medical students have been going out across the city with nylon swabs for collecting DNA , from past 17 months. The team collected DNA from various surfaces including turnstiles, poles, benches, seats and more.

The findings of the study also reflected the diversity of New York in case of human as well as microbes.

In terms of microbial species, Bronx was found to be most diverse. The second place was claimed by Brooklyn followed by Manhattan and Queens.

Dr. Mason also informed that in some cases, the DNA found in some of the stations seemed to match the demographic profile of the neighbourhood. for example, an area which has high concentration of Hispanic residents near Chinatown in Manhattan yielded Asian and Hispanic genes in large amount.

Live antibiotic-resistant bacteria were also discovered in around 27 per cent of the samples. Only 12 per cent of these were associated with disease. Researchers found samples linked to bubonic plagues as well as those with DNA fragments of anthrax. However, they pointed out that none of the samples showed any proof of being alive.

Now the researchers will be able to catalogue species and compare them against the samples taken in future to know whether certain substances used as bioterrorism weapons or certain disease have spread.