Being an excellent stylist doesn't stop one making the odd clanger...
I quite agree with you here,
Stephen.
...and that is what Bryson has done.
But I seriously doubt this. If I'm not mistaken, Bryson has cleverly and correctly used the language in a way that illuminates one of the common misconceptions many people (yes, even English teachers) hold about modal auxiliaries as a class of words, and also about the individual meaning of
will. Modal auxiliaries are not verbs (though they occur in the verb phrase). My point in asserting this is to suggest that they do not lend meaning to the sentence in the same way that verbs do. What they achieve is quite remarkable, and unique. Verbs are an intregal part of the proposition. Modal auxiliaries signal the user's present-time opinion about certain elements of the proposition advanced by the rest of the sentence. It is though he speaks the sentence, but simultaneously stands off to the side and comments on the viability of the proposition. The exact nature of his comment varies with the use of individual modal auxiliaries. For example, use of
can or
could allows the speaker to judge (at the exact moment of use) his opinion of the ability or possibility of the proposition.
She can run very fast.
...is a fundamentally different statement from
She runs very fast.
...in that in the first, the producer of that sentence has added his momentary, present-time opinion of the runner's ability. The second sentence states the proposition as fact. Note, too, that the meaning conveyed in either sentence, despite the verb being cast in present-tense form, has nothing whatever to do with assertions about present time, or any time. Nor does it suggest anything about the runner's habits. The first sentence is an assessment, the second a fact. (Of course, subsequent experience may either confirm or deny the actual truth of the assertion).
Each modal auxiliary has its own set of meanings (context does play a part in the exact interpretation, of course).
Will is one of the most awkward to describe, but one thing is for sure: the fundamental meaning of
will is
not bound to any concept of time. It is
always misleading to say that
will means the future. It may, in certain contexts, be correct to say that
will puts an event into the future
in this particular context. In other contexts, will expresses a connection (in the user's momentary judgment) between two sets of data: a first set representing what he knows about an event at the present moment, with a second set which he believes is probably true, based on what he knows now, but about which he cannot be certain because of obvious circumstances. Sometimes (perhaps even often) those circumstances are that the event referred to is in future time, hence the use of
will arises accordingly. But there are other reasons why a speaker may not be able to know the facts of an event. He may be physically removed from the event, giving rise to uses such as,
They will be home by now. In the case in point, Bryson, I think, is connecting what he knows (about being in extreme cold climates, etc.) with what he believes to be true about Neandertals, but, owing to the fact that it occurred not in the future, but in the distant past, he cannot represent the event(s) purely as fact. He certainly could have said, "...
even so they would have experienced...", where
would has the same meaning as
will, with the added overlay of remoteness, which clearly could be justified in this case. But he chose
will because he did not wish to add the element of remoteness, and I believe he chose it consciously and with deliberation. I doubt it was a mistake. Nothing about English grammar
forces him to choose one way or the other...it is his choice as the producer. But it sure got my attention.
Larry Latham