Science did make one major mistake in assuming these diseases could not jump the species barrier.

"People talked about there being species barriers - you're reorganizing nature in some way."

Finally, an experiment created to study a strong species barrier recently stunned those in the field.

Cracking the species barrier has the potential of opening up vast new areas of research.

They knew what animals did, but somehow they never quite made the jump across the species barrier.

This can result in spread of disease across species barriers.

On six separate occasions that we know of it has crossed the species barrier.

So, I just think we have to get over what must be some innate fear about species barriers and understand how nature really works.

Precisely which infectious agents can infect across species barriers, and how often?

Attempts to bridge species barriers are often said to involve no little hubris.