> Uh-oh. Looks like you might have to give up out that symboling is unique to
> humans thing. :)
>
Technically, I believe Neanderthals are in the Homo genus, making them human.
>
> (How could you figure this out by looking at the genome?)
>
"Probably" is a devilish word. I mean, you could look at their skulls, complete with brain cavity size and jaw structure, and say they "probably" spoke "much like" we did. I'm guessing the researchers poked around the genome and looked for genes 1) that were in modern humans but not other living apes and 2) whose absence or irregularity are associated with speech defects and found them there.
There are, quite obviously, some methodological criticisms you could make of this, but it's a decent guesstimate, and at least one step up from e.g. evolutionary psychology, which more or less assumes characteristics on the supposition that they would have been beneficial. Plus there are the standard distortions of science reporting, &c.