The silence of the lambs was caused by hungry Hannibal Lecter hosting a dinner party, but what's causing the silence of the crickets on the island of Kauai?
A researcher named Marlene Zuk first noticed the silence of the crickets in 2003, a very noticeable silence compared to when she first started studying the crickets on the island back in 1991, and she knew something was wrong because she continued to see the crickets everywhere despite their vow of silence.
After dissecting a few of the insects she discovered the source of their silence- the male crickets had developed flat wings that didn’t make a sound to avoid being eaten by a parasitic fly.
Here’s more on this interesting evolution to silence:
Zuk’s team discovered that the crickets were targeted by a parasitic fly, whose larvae burrow inside them and devour them alive. The flies finds the crickets by listening out for their songs and they’re so effective that, in the early 90s, they had parasitised a third of the males. In 2002, the cricket population had fallen dramatically, and Zuk thought that they were done for.
But the silent males escaped the attention of the fly. As they bred and spread, they carried the flatwing mutation with them. By 2003, the cricket population had rebounded. And in fewer than 20 generations, they had gone from almost all-singing to almost all-silent. The crickets have become a classic textbook example of rapid evolution.
-Via National Geographic
For a human example, if a particular country decided to "remove" everyone within their country that didn't fit a narrowly defined set of attributes, would we say that country has "evolved" as humans, or that they are now less than what they were before since they are now missing the variety that was there previously?
That's all I see going on here. The species of crickets originally included a variety, some that made noise, some that were silent. Now the noisy ones have all been killed, and all that's left are the silent ones that were there all along. Nothing's new has happened, only that one type has been removed from the area. If the killing were stopped somehow, would the noisy ones make a comeback? Perhaps, if that information hasn't been completely removed from their DNA.
And that's where the evolution equation isn't complete here. It's not enough to just remove information from the system: new information has to be entered in somehow (mutation, virus, etc.). That hasn't happened here.