Complete the summary below. Choose ONE or TWO WORDS from the passage for each answer.

Summary

Prior to the 19th century, professional [1] did not exist and scientific research was largely carried out by amateurs. However, while [2] today is mostly the domain of professionals, a recent US survey highlighted the fact that amateurs play an important role in at least seven [3] and indeed many professionals are reliant on their [4]. In areas such as astronomy, amateurs can be invaluable when making specific [5] on a global basis. Similarly in the area of palaeontology their involvement is invaluable and helpers are easy to recruit because of the popularity of [6]. Amateur birdwatchers also play an active role and their work has led to the establishment of a [7]. Occasionally the term 'amateur' has been the source of disagreement and alternative names have been suggested but generally speaking, as long as the professional scientists [8] the work of the non-professionals, the two groups can work productively together.