What is life?

A video I saw on the web recently reminded me of the meaning of life. OK, that sounds a LOT more profound than I mean it to.

What I mean is . . . one of the most interesting questions in science
that I deal with is the most fundamental question, and one that comes right
at the beginning of my A&P course. The question is, what does it
mean for a human to be alive? What constitutes a living human organism?

Unbelievably, most courses set aside the core of that question and deal solely with the superficial aspects:

• defining living processes such as regulation, respiration, digestion, reproduction, etc.
• outlining the levels of organization with a human body: chemicals, cells, tissues, organs, systems
• describing the homeostatic nature of healthy human function

OK, I know it's only an beginning undergraduate course. I know that this is science and not philosophy (although I'm not certain of the distinction, really). I know we don't have much time in the course. I know the students don't really care about that right now (and quite possibly, never).

What really got me thinking about how central this question is to understanding the human organism was the book What is Life? by Lynn Margulis. Lynn, you recall, was the agent behind the serial endosymbiosis theory (SET) . . . which got us all thinking about how we can imagine ourselves more as a cooperative symbiotic community of organelles and cells than a distinct and fully integrated unit.

If the mitochondria in my cells can be thought of as bacteria-like symbionts, then am I not a collection of organisms rather than one organism? Well, no. By definition, a useful definition, my mitochondria ARE me and not a separate species living in me.

But we now know that I cannot survive without the proper functioning of the flora living on my skin, in my gut . . . just about everywhere my body makes direct or indirect contact with the outside world. Are these creatures, which are by definition NOT me, really a part of the organism? I wonder if our definition might change someday soon.

What got me thinking about this recently was a web video from a recent TED Conference and features a talk by Bonnie Bassler in which she really hones in on our concept of human life and relates it to the ability of some bacteria to regulate each other in much the same way that our cells communicate with and regulate each other.

[If you don't see the video viewer in your newsletter or feed version of this article, please go to The A&P Professor blog site to view it. Want to learn how to embed YouTube videos in your blog, website, or PowerPoint? Check it out at The A&P Professor website.]

Considering our rapidly growing understanding of our body as a set of interrelated functioning units­--perhaps even including the creatures that live on and in us--the day is upon us that we really need an understanding of what a single human organism truly is in a biological sense.

We really need such an understanding at a beginning, undergraduate level so that we can use it as a framework for building the kind of solid understanding that will inform our later studies . . . and our professional work as scientists and healers.