Humans have spent tens of thousands of years/developing ways to send
signals of interest that are easy to interpret. Interestingly, many of the
signals that are easiest to interpret are also, in some sense, the costliest to send.
Biologists believe that [assist / costly signals / evolution / in the mating
(1) -
market/ sometimes leads to / that]. The peacock's tail serves an example. A
male peacock does not get a lot of direct benefit from a huge, heavy, colorful
tail that advertises his presence to enemies and makes it harder to escape from