Researchers speculate that training from a young age may explain this.

Researchers speculate this has something to do with their reproduction.

The researchers speculate that there may be a combination of factors at work here.

The researchers speculate that the adult may have been the mother of the juvenile.

The researchers did not speculate on the cause, and other climate experts said the warming was likely to continue.

The researchers speculated that the problem might be related to the size of boys' heads, which are bigger than girls'.

The history of the king is more difficult to examine, and the researcher can only speculate on their origins.

The researchers speculated that this could be an example of the "healthy worker effect."

Other researchers speculate that the disease may be caused by an infection or virus.

Researchers can of course only speculate about her motivation.