The Mind Pool
From back cover Baen paperback December 1998:

CALLING ALL HUMANS...

In the 23rd century, out of all the races of the galaxy, only humanity has discovered the secret of travel between the stars -- not so much because we're so smart, but because we are incredibly gadget-oriented.  We are also, compared to the galaxy's highly sophisticated norms, very, very, tough, which most of the time does nothing for our social acceptability.  But when a thread to all life in the galaxy arises from non-living biological constructs, suddenly the peculiar human virtues of valor and stubbornness make us the sword-wielding saviors of All....
Science Fiction
Charles Sheffield