In the news

I like this guy
https://www.theguardian.com/cities/2016/oct/17/enrique-penalosa-mayor-bogota-colombia-bus-traffic-un-habitat

If you find trout in a mountain stream, it means the water is very pure, because the trout is a very delicate fish, susceptible to dirty water and a lack of oxygen. This is known as a “species indicator”.

In the same way, I have always said that a species indicator for a good city is to see children by themselves in a street, or elderly people, people in wheelchairs, or women by themselves. If women feel comfortable walking at night in a city, this is a good sign.