There might be no better way to gauge connection than to look straight into the eyes of another.
If Kerry Bowman didn't know this before, he learned it soon enough when he peered through the Sumatran rain forest to find an orangutan, right there at ground level.
"He looked up, and when we had eye contact, it was a very powerful experience," Mr. Bowman says, recalling a 1980s work stint, in the midst of his post-university travels, when he helped document the great apes' movements.
"When my eyes caught his eyes, I just felt nothing different than as if I was coming across a human."
Of course, he knew there were major differences between him and the "big orange guy." But, the intensity of the similarities struck him more, and he found the common ground beneath them far more palpable than the seven or eight metres between them.
As much as this epiphany has served Mr. Bowman in his long volunteer career as an ape conservationist, it applies just as well to his paid work as a clinical ethicist at Toronto's Mount Sinai Hospital, where he helps humans find their way to each other over the toughest terrain life and death can offer.
"I think they're getting closer together all the time," Mr. Bowman, a youthful 47, says of his two lives. (He's also known as Dr. Bowman for his PhD in bioethics, and holds a master's degree in social work).
"Whether you're dealing with an end-of-life issue or a conservation issue, you need every skill and every head and every heart you can get; broad opinions from different perspectives."
In his work to save gorillas from extinction in central Africa, that has meant spending time in a hunters' camp, surrounded by bloody carcasses of exotic species, to get an understanding of the economics of the bush meat trade.
"This was not fun for me," Mr. Bowman says, recalling a 1997 trip to Cameroon. "It was a lot of stress to try and be objective and not interfere in any way."
But, unlike more criminally organized forms of poaching, "these were African men trying very hard to make money to support their families," he says. "They weren't monstrous people."
Tempting as it might have been to confront the hunters, Mr. Bowman directed his energy to setting up the Canadian Ape Alliance, a network of volunteers who have been raising money for projects, particularly in the Democratic Republic of the Congo, where several years of war have taken a toll on the gorilla population.
Mr. Bowman has made several trips, at considerable risk, through the war zone to deliver money to African conservation groups working directly with the gorillas but who were cut off by the fighting.
His exploits have led to a question he has heard often: "How on Earth could you ever be worrying about gorillas with the amount of human suffering in the Democratic Republic of Congo?"
Mr. Bowman's philosophy, however, is "not these silos of environment or people; I see them as together. Human beings are part of the ecosystem, and the great apes of Africa will not make it if Africa doesn't make it."
And so, most of the ape alliance's projects in the Congo are focused on people - an environmental school, agricultural programs, supports for women - to raise awareness and lower families' reliance on bush meat.
In his role as Mount Sinai's ethicist, meanwhile, Mr. Bowman deals with all the tough questions - whether a patient should accept or reject treatment; termination of life support; selective reduction of fetuses in a multiple pregnancy; sperm collection from a man who has just died (which can happen only with his clear prior consent).
Contrary to popular misconception, he says, "I do not weigh in saying 'this is what is ethical' and 'this is what is not ethical.' What I do is really to illuminate the ethical questions that are associated with decisions for a course of action."
Often, that means resolving conflicts between family members by getting them to think more deeply about the issues before they make a decision. Given the circumstances, the choices to be made are usually difficult, and involve unpleasant outcomes that might differ only slightly in degree.
That can be tough in a hospital, where evidence-based answers can carry more currency than reflection and further questioning, Mr. Bowman says, "but I think a lot of people realize that there's questions that simply defy easy answers."
Sometimes, mutual understanding in lousy circumstances is the best anyone can expect.
"It's a lot more questions than answers, and that's where the interesting elements of the experience come from," he says. "And that part has not a lot to do with me; it depends on what they say and how they say it, and you see a lot of strength."
Depressing as it all might sound -- whether it's slaughtered gorillas or people's end-of-life decisions -- Mr. Bowman has come to know the odd sense of renewed life that can spring from working so close to death. That's what keeps him going.
"Beauty's a very strange word to use in a situation like this, but there's an element of human beauty, almost, to the strength of human beings at a time like that," he says. "I feel actually quite privileged to have a position where I can see something like that."