单项选择题

It is widely known that birds learn to fly through practice, gradually (1) their innate ability into a finely tuned skill. (2) , a recent study conducted by the University of Sheffield’s Department of Psychology has discovered that the reason birds learn to fly so easily is because memories may have been left behind by their ancestors. These skills may be easy to enhance because of a (3) specified latent (4) for flying.
The researchers used simple models of brains called (5) neural networks and computer (6) to test his theory. They discovered that learning in (7) generations (8) induces the formation of a latent memory in the current generation and (9) decreases the amount of learning required. These effects are especially pronounced if there is a large biological "fitness cost" to learning, where biological fitness is measured in terms of the number of (10) each individual has.
The beneficial effects of learning also (11) the unusual form of information storage in neural networks. (12) computers, which store each item of information in a specific location in the computer’s memory chip, neural networks store each item (13) over many neuronal connections. (14) information is stored in this way then (15) is accelerated, explaining how complex motor skills, such as nest building and hunting skills, are (16) by a combination of innate ability and learning over many generations.
The researchers concluded that this new theory has its (17) in ideas (18) by James Baldwin in 1896, who firstly made the counter-intuitive argument that learning within each generation could guide evolution of innate behavior over future generations. Baldwin was right, (19) in ways less sophisticated than he could have imagined because concepts (20) artificial neural networks and distributed representations were not known in his time.

（20）（）