Observational reports of animals which were not captured are even more dubious, as even trained scientists often substantially overestimate the size of anacondas prior to capture.[10] According to the Guinness Book of World Records, this species has been perhaps subject to the most extreme size exaggerations of any living animal.[2] At the same time, determining a maximum possible or plausible size is difficult, because anacondas are known to continue to grow throughout their lives. Older reports, in particular, could include individualsthat in times of less pressure from humans, lived longer, thus reached greater sizes.[citation needed]