They've got the blood of the Old Ones, mixed with the human strain.

Test results revealed an Influenza A virus but were negative for standard human strains.

Bar had not been careful to avoid breeding rebellion back into the human strain.

And if Earth-born man goes, the human strains of the younger worlds may not be viable.

"It's designed to improve the human strain, to make them stronger, healthier."

From there, he went on to success with human strains.

If avian flu combines with a more common human strain, the results could be devastating.

There are more than 100 human strains.

"The question becomes, How different is that strain from the human strain?"

The human strains appear to have diverged from the simian 3600 years ago.