Edward O. Wilson wrote an entire book on a phenomenon he called Biophilia. The biophilia hypothesis states that humans, having evolved in natural surroundings, have a psychological need for more natural surroundings. Plants and animals make us happy. Well, it seems that plants do in fact go a long away toward making us happy with our jobs, as Clara Moskowitz observes. One of the unfortunate ideas to come out of Modernism was anti-nature architecture, resulting in offices without windows and barren public housing structures whose primary function seemed to be the dehumanization of anyone living there. Turns out that humans need natural light, and we need to see plants. And it seems that plants even win out over natural light: 69% of those who had plants but no windows said they were satisfied with their jobs, while only 60% of those with windows but no plants said they were satisfied, which is practically the same as those without either windows or plants: 58% of those people were satisfied (it's best to have both: 82% satisfaction). My guess is that having animals around would also benefit people. Perhaps they should next study the effects of having fish and/or birds in the office (I'm guessing dogs and cats might be a bit much). If employers want more productive employees (and we know happy employees are more productive than unhappy ones), they need to take such ideas as biophilia seriously.
Those who build apartment complexes, whether for public housing or not, also need to keep in mind the fact that humans evolved on the African savannas. Large grassy areas with the occasional tree and some flowers can make all the difference in the world when it comes to your residents taking care of the place.
We also need to have our architecture reflect our biophilic needs. Those needs extend too to a need for a basic level of complexity in our surroundings. Nature has a 1.2-1.6 (when analyzed on a 2-D plane) fractal dimension (a range investigated by Jackson Pollock in his drip paintings). We have a lot of information about what makes humans comfortable with their surroundings. Isn't it time we took that information into consideration in our architecture and interior design?