Also on Tuesday, the Defense Intelligence Agency investigated a case of possible biological agents being concealed in mail sent to the agency at its Bolling Air Force Base Headquarters in Washington, D.

WSJ: Ricin Charges Are Dropped

U.S. Secretary of State Colin Powell in February told the United Nations Security Council that U.S. intelligence indicated Iraq had production facilities for biological weapons "on wheels and on rails, " and on at least 18 flatbed trucks.

CNN: U.S.: Mobile labs found in Iraq

In fact, there are those that argue artificial intelligence is simply unattainable except through the biological pathways of the human brain and the restrictions of the human brain are a byproduct of the design of intelligence itself.

FORBES: The Blurring Line Between Science And Science Fiction

Autonomic systems would bear more of a resemblance to simple biological organisms than a fully fledged, HAL-style artificial intelligence.

FORBES: Computers That Fix Themselves

Our form of conscious intelligence emerged from our evolutionary heritage, which in turn was shaped by our biological environment.

FORBES: What's the Likelihood of the Singularity? Part Two: Uploading the Brain