A colleague, who grew up in ecology and the parks system, told me that when deer became overpopulated wolves were introduced. The wolves feasted and became overpopulated. Nature balanced the scales — the wolves caught a virus which ended up bringing the wolf population down. The ecosystem became balanced — wolves and deer together.

Could we see the effects in human systems? A study hints at it:

“Our key findings are that (i) larger groups lie more, (ii) all-male groups stand out in their proclivity to lie, (iii) already the first female in a group causes an honesty shift, and (iv) group behavior cannot be fully explained by members’ individual honesty preferences." - Honesty of Groups: Effects of Size and Gender Composition

The takeaway: diversity acts like natural balancing force. Though, be careful not to draw conclusions — human systems are complex, and the study only focused on gender.