This is a common semantic issue in this discussion, I've found. What he means when he's saying "humanness" would better be described as "personhood," "sentience" or "self-awareness." A brain-dead human is still a human organism, but not a "person" in the common sense of the word, as the brain is the seat of personality.
I have had problems with some of his choices of words, too.
I wonder why such a smart man as Trefil (who has received an award for bridging the gap between science and society) made the choice to use the word "humanness?"
James S. Trefil, Clarence J. Robinson Professor of Physics, George Mason University
Physicist and author James S. Trefil is known for his writing and his interest in teaching science to nonscientists. He is a Fellow of the APS and a former Guggenheim Fellow.
His numerous books and articles include works written for general audiences. He co-authored The Dictionary of Cultural Literacy (3rd ed., 2002) and in 1992 published The Facts of Life (Harold Morowitz, co-author). Science Matters: Achieving Scientific Literacy, was co-authored with Robert Hazen in 1991, and in 1995 they published The Sciences: An Integrated Approach. Dr. Trefil's A Scientist in the City appeared in 1994. Are We Unique: A Scientist Explores the Complexity of the Human Brain appeared in 1997. The National Geographic Society published his book Other Worlds: The Solar System and Beyond in 1999. He was the general editor of The Encyclopedia of Science and Technology (2002) and co-author of Good Seeing, a scientific history of the Carnegia Institution.
His most recent book is The Laws of Nature (2002). He is a regular contributor to Smithsonian Magazine and was previously University Professor and Professor of Physics at the University of Virginia.
In 2000 American Institute of Physics chose him to receive the Andrew W. Gemant Award, presented for outstanding and sustained contributions in bridging the gap between science and society. In 2003-2004, he will be a Phi Beta Kappa Visiting Scholar.
You would think he would know which word to use.
It's a puzzlement.