1.   Scientists are debating the possible derivation of birds from dinosaurs.

2.   But it was held up by international suspicions and intellectual free-for-alls as scientists debated whether they could detect secret explosions.

3.   But scientists debate whether restoration of the immune system occurs.

4.   But scientists have debated the exact size and shape of the sun for decades.

5.   For centuries, scientists have debated the cause of differences in human skin color.

6.   For decades, scientists have debated reports of the discovery of chemicals in meteorites that allegedly hinted at the possible existence of extraterrestrial life.

7.   It was raised several days later by salvaging specialists, but the extent of ecological damage is still being debated by scientists.

8.   Scientists have debated for more than a decade about the cause of Creutzfeldt-Jakob disease.

9.   Scientists have debated whether anti-HIV drugs should be made available in Africa in the absence of such monitoring.

10.   Scientists have long debated the reasons for such ornateness of penile shape, or morphology.