Cancer, with us since the dawn of cellular life, is a companion we may never be rid of, says Arizona State University evolutionary biologist Athena Aktipis. But a fresh look at the disease could bring new strategies for managing it, she told a Harvard audience on Wednesday.

Aktipis’s work employs the nontraditional approach of applying models of how plants and animals relate to each other ecologically to systems in the human body. In her lecture at the Harvard Museum of Natural History, “Why Cancer Is Everywhere,” she focused on the relation of cancer cells to healthy ones, saying that cancer cells can be thought of as “cheaters” within a system of working cells. The “everywhere” in the lecture’s title was a reference to cancer’s presence in plant as well as animal life.

Aktipis began her presentation by showing a slide of a rare crested cactus that is found near her home in Arizona. “This picture is one of the reasons that I started looking at cancer from an evolutionary perspective,” she said.

The cactus displays clustered cells that have a cancer-like appearance — an example of fasciation, or abnormal growth in plants. This led her to make two observations: Humans aren’t alone in their struggle with cancer, and these plants were able to grow and survive despite the abnormal growths. These realities, she noted, have profound implications for human research.

Cancer is an inevitable byproduct of cell cooperation, Aktipis noted. “We have approximately 30 trillion cells in our bodies that cooperate with each other and coordinate their gene expression. This is far beyond any cooperation you could hope to achieve in a human society.”

As multicellular organisms evolve and the system grows larger, so does the possibility that “cheater” cells may appear to exploit the system. This is what cancer cells do: Proliferate without limit, avoid cell death, monopolize resources, co-opt the labor of other cells, and destroy the surrounding environment. When cancer is present, the rules of intercellular cooperation break down.

“Cellular cheating isn’t a metaphor. You have cells that are taking advantage of the cells around them that are following the rules.”